Cardiovascular System

Cardiovascular System



Cardiovascular System

Chapter 3 Notes

Enzyme – a protein that speeds up a specific chemical reaction, such as breaking the bonds of a nutrient, without undergoing change itself. A protein catalyst.
Tissues – systems of cells working together to perform specialized tasks. (Ex: muscles, nerves, blood and bone)
Organs – discrete structural units made of tissues that perform specific jobs. (Ex: the heart, liver, and brain)
Body system – a group of related organs that work together to perform a function. (Ex: circulatory system, nervous system, respiratory system)

The Body Fluids and the Cardiovascular System
Blood – the fluid of the cardiovascular system; composed of water, red and white blood cells, other formed particles, nutrients, oxygen, and other constituents.
Lymph – the fluid that moves from the bloodstream into tissue spaces and then travels in its own vessels, which eventually drain back into the bloodstream
Arteries – blood vessels that carry blood containing fresh oxygen supplies from the heart to the tissues
Veins – blood vessels that carry blood, with the carbon dioxide it has collected, from the tissues back to the heart
Capillaries – minute, web like blood vessels that connect arteries to veins and permit transfer of materials between blood and tissues.
Plasma – the cell-free fluid part of blood and lymph
Extracellular fluid – fluid residing outside the cells that transports material to and from the cells
Intracellular fluid – fluid residing inside the cells that provides the medium for cellular reactions
Lungs – the body’s organs of gas exchange. Blood circulating through the lungs releases its carbon dioxide and picks up fresh oxygen to carry to the tissues
Intestine – the body’s long, tubular organ of digestion and the site of nutrient absorption.
Liver – a large, lobed organ that lies just under the ribs. It filters the blood, removes and processes nutrients, manufactures materials for export to other parts of the body, and destroys toxins, or stores them to keep them out of circulation
Kidneys – Pair of organs that filter wastes from the blood, makes urine, and releases it to the bladder for excretion from the body.

Body fluids supply the tissues continuously with energy, oxygen, and nutrients, including water. They constantly circulate to pick up fresh supplies and deliver wastes to points of disposal. Every cell continuously draws oxygen and nutrients and releases carbon dioxide and other wastes into them. 
- The body’s circulating fluids are the blood and the lymph.
- blood travels within the arteries, veins, and capillaries, as well as within the heart’s chambers. 
- lymph travels in separate vessels of its own. Ciculating around the cells are other fluids such as the plasma of the blood, which surrounds the white and red blood cells, and the fluid surrounding muscle cells. The fluid surrounding cells (extracellular fluid) is derived from the blood in the capillaries; it squeezes out through the capillary walls and flows around the outsides of cells, permitting exchange of materials. Some extracellular fluid returns to the body by reentering the capillaries. The fluid remaining outside the capillaries forms lymph, which travels around the body by way of lymph vessels. The lymph eventually returns to the bloodstream near the heart where large lymph and blood vessels join. 
-the fluid inside cells (intracellular fluid) provides a medium in which all cell reactions take place. Its pressure also helps the cells hold their shape. Intracellular fluid is drawn from the extracellular fluid.
-blood circulates to the lungs where it picks up oxygen and releases carbon dioxide wastes from the cells. Then the blood returns to the heart, heartbeat pushes fresh oxygenated blood from the lungs out to all body tissues. 
- as blood passes through the digestive system the blood delivers oxygen to the cells there and picks up most nutrients other than fats and their relatives from the intestine for distribution elsewhere. All blood leaving the digestive system is routed directly to the liver which chemically alters the absorbed material to make them better suited for use by other tissues. Blood passes through the kidneys and is cleaned of wastes. 
- lymphatic vessels pick up most fats from the intestine and then transport them to the blood.
- to make sure you have efficient circulation of fluid to all your cells, you need an ample fluid intake. This means drinking sufficient water to replace what is lost each day.

Key point – Blood and lymph deliver nutrients to all the body’s cells and carry waste materials away from them. Blood also delivers oxygen to cells. The cardiovascular system ensures that these fluids circulate properly among all organs.

The Hormonal and Nervous System

Hormones – chemicals that are secreted by glands into the blood in response to conditions in the body that require regulation. These chemicals serve as messengers, acting on other organs to maintain constant conditions.
Pancreas – an organ with two main functions. One is an endocrine function (endo meaning into the blood) – the making of hormones such as insulin, which it releases directly into the blood. The other is an exocrine function (exo meaning out into a body cavity or onto the skin surface) – the making of digestive enzymes, which it releases through a duct into the small intestine to assist in digestion. 
Insulin – a hormone from the pancreas that helps glucose enter cells from the blood
Glucagon – a hormone from the pancreas that stimulates the liver to release glucose into the bloodstream.

-blood also carries hormones from one system of cells to another. Hormones communicate changing conditions that demand responses from the body organs. 
-hormones are secreted and released directly into the blood by glands. Each gland monitors a condition and produces one or more hormones to regulate it. 
-when the pancreas detects a high concentration of glucose, it releases insulin. Insulin stimulates muscle and other cells to remove glucose from the blood and to store it. The liver also stores glucose. When the blood glucose level falls, the pancreas secretes glucagons, which the liver responds by releasing into the blood some of the glucose it stored earlier. 
-nutrition affects the hormonal system. Fasting, feeding, and exercise alter hormonal balances. (ex: people who become very thin have an altered hormonal balance that may make them unable to maintain their bones)
-Hormones affect nutrition. They regulate hunger and affect appetite. They carry messages to regulate the digestive system, telling the digestive organs what types of food have been eaten and how much of each digestive juice to secrete in response. A hormone produced by the fat tissue informs the brain about the degree of body fatness and helps to regulate appetite. Hormones also regulate the menstrual cycle or women, and they affect the appetite changes many women experience during the cycle and in pregnancy.

Cortex – the outermost layer of something. The brain’s cortex is the part of the brain where conscious thought takes place.
Hypothalamus – a part of the brain that senses a variety of conditions in the blood, such as temperature, glucose content, salt content, and others. It signals other parts of the brain or body to adjust those conditions when necessary.
Fight-or-flight reaction – the body’s instinctive hormone- and nerve – mediated reaction to danger. Also known as the stress response.
Neurotransmitters – chemicals that are released at the end of a nerve cell when a nerve impulse arrives there. They diffuse across the gap to the next cell and alter the membrane of that second cell to either inhibit or excite it.
Epinephrine – the major hormone that elicits the stress response
Norepinephrine – a compound related to epinephrine that helps to elicit the stress response
Metabolism – the sum of all physical and chemical changes taking place in living cells; includes all reaction by which the body obtains and spends the energy from food.

How does the nervous system interact with nutrition?
-the nervous system is the body’s major communication system. With the brain and the spinal cord it receives and integrates information from sensory receptors all over the body (sight, hearing, touch, smell, taste, and others) which communicate to the brain the state of both the inner and outer worlds.
-role in hunger regulation is coordinated by the brain. The sensations of hunger and appetite are perceived by the cortex. Deep inside the brain the hypothalamus monitors many body conditions, including the availability of nutrients and water. To signal hunger (the physiological need for food) the digestive tract sends messages to the hypothalamus by way of hormones and nerves. The signals also stimulate the stomach to intensify its contracting and secretions, causing hunger pangs and gurgling sounds. 
-hormonal and nervous systems work together to enable a person to respond to physical danger. Fight-or-flight reaction (or stress response). When danger is detected, nerves release neurotransmitters and glands supply epinephrine and norepinephrine. Every organ of the body responds and metabolism speeds up. The pupils of the eyes widen, so you can see better; the muscles tenses up so you can jump, run, or struggle with maximum strength; breathing quickens and deepens to provide more oxygen; the heart races to rush oxygen to the muscles, and blood pressure rises so that the fuel the muscles need for energy can be delivered; the liver pours glucose from it’s stores, and the fat cells release rat; the digestive system shuts down to permit all the body’s systems to serve the muscles and nerves. In ancient times, stress usually involved physical danger, and the response was violent physical exertion. Now, stress is seldom physical but the body reacts the same. Daily exercise as part of a healthy lifestyle releases pent-up stress and helps to protect the heart.

Key Point – The nervous system joins the hormonal system to regulate body processes through communication among all the organs. Together, the hormonal and nervous systems respond to the need for food, govern the act of eating, regulate digestion, and call for the stress response.

The Immune System

Microbes – bacteria, viruses, or other organisms invisible to the naked eye, some of which cause diseases. Also called microorganisms.
Antigen – a microbe or substance that is foreign to the body
Immune system – a system of tissues and organs that defend the body against antigens, foreign materials that have penetrated the skin or body linings
Lymphocytes – white blood cells that participate in the immune response; B-cells and T-cells
Phagocytes – white blood cells that can ingest and destroy antigens. The process by which phagocytes engulf materials is called phagocytosis.
T-cells – lymphocytes that attack antigens. T stands for the thymus gland of the neck, where the T-cells are stored and matured.
B-cells – lymphocytes that produce antibodies. B stands for bursa, an organ in the chicken where B-cells were first identified.
Antibodies – proteins, made by cells of the immune system, that are expressly designed to combine with and inactivate specific antigens. 

Many of the body’s tissues cooperate to maintain defenses against infection. 
-the skin presents a physical barrier, and the body’s cavities (lungs, digestive tract) are lined with membranes that resist penetration by invading microbes and other unwanted substances. These linings are highly sensitive to vitamin and other nutrient deficiencies. 
If an antigen penetrates the body’s barriers the immune system rushes in to defend the body against harm. Of the 100 trillion cells that make up the human body, one in every hundred is a white blood cell. The actions of two types of white blood cells, the phagocytes and the lymphocytes are of interest.

*Phagocytes – these scavenger cells travel throughout the body and are the first to defend body tissues against invaders. When a phagocyte recognizes a foreign particle, such as a bacterium, it forms a pocket in its own outer membrane, engulfing the invader. Then the phagocytes may attack with oxidative chemicals or may otherwise digest or destroy them. They also leave a chemical trail that helps other immune cells to join the defense against infection.

*T-Cells – Killer T-cells recognize chemical messages from phagocytes and “read” and “remember” the identity of an invader from the messages. They then seek out and destroy all foreign particles having the same identity. T-cells defend against fungi, viruses, parasites, some bacteria, and some cancer cells. Helper T-cells do not attack invaders but help other immune cells to do so. 
--People suffering against the disease AIDS are rendered defenseless against other diseases because HIV selectively attacks and destroys their helper T-cells.

*B-cells – B-cells respond rapidly to infection by dividing and releasing antibodies into the bloodstream. Antibodies travel to the site of the infection and stick to the surface of foreign particles, killing or inactivating infection. They also retain a chemical memory of each invader and if the encounter recurs, the response is swift. 
--Immunizations work this way – a disabled or harmless form of a disease-forming organism is injected into the body so that the B-cells can learn to recognize it. Later, if the real live infectious organism invades, the B-cells quickly release antibodies to destroy it.

Key Point – The immune system enables the body to resist diseases.

The Digestive system

Digestive system – the body system composed of organs that break down complex food particles into smaller absorbable products
Digest – to break molecules into smaller molecules, a main function of the digestive tract with respect to food
Absorb – to take in, as nutrients are taken into the intestinal cells after digestion, the main function of the digestive tract with respect to nutrients

The Digestive Tract
After eating, the brain and hormones direct the many organs of the digestive system to digest and absorb chewed and swallowed food. The tract is a flexible, muscular tube extending from the mouth through the throat, esophagus, stomach, small intestine, large intestine, and rectum to the anus (26 feet). Only when a nutrient or other substance passes through the wall of the digestive tract does it actually enter the body’s tissues.

Digestive system’s job is to digest food to its components and then to absorb the nutrients and some nonnutrients, leaving behind the substances, such as fiber, that are appropriate to excrete. To do this, the system works on two levels, mechanical and chemical.

Key point – the digestive tract is a flexible muscular tube that digests food and absorbs its nutrients and some nonnutrients. Ancillary digestive organs aid digestion.

Peristalsis – the wavelike musclcular squeezing of the esophagus, stomach, and small intestine that pushes their contents along
Stomach – a muscular, elastic, pouchlike organ of the digestive tract that grinds, and churns swallowed food and mixes it with acid and enzymes, forming chime
Sphincter – a circular muscle surrounding, and able to close, a body opening
Chyme – the fluid resulting from the actions of the stomach upon a meal
Pyloric valve – the circular muscle of the lower stomach that regulates the flow of partially digested food into the small intestine, also called pyloric sphincter
Small intestine – the 20ft length of small-diameter intestine, below the stomach and above the large intestine, that is the major site of digestion of food and absorbtion of nutrients
Large intestine – the portion of the intestine that completes the absorption process
Colon – the large intestine
Feces – waste material remaining after digestion and absorption are complete, eventually discharged from the body

Mechanical Aspects of Digestion
-begins in the mouth. Large, solid food pieces are torn into shreds that can be swallowed. Chewing adds water in the form of saliva to soften rough or sharp foods to prevent tearing the esophagus. Saliva also moistens and coats each bite of food making it slippery so that it can easily pass down the esophagus.
-stomach and intestines liquefy foods through mashing and squeezing actions (peristalsis). Stomach also holds swallowed food for a while and mashes it into fine paste, stomach and intestines add water so the paste becomes more fluid as it moves along
-sphincter muscle at the base of the esophagus squeezes the opening at the entrance to the stomach to narrow it and prevent the stomach’s contents from going back up the esophagus as the stomach contracts. 
-stomach stores food in a lump in its upper portion and squeezes the food little by little to the lower portion. There the food is ground and mixed thoroughly, ensuring that digestive chemicals mix with the entire thick liquid mass, which is now chyme. 
-pyloric valve controls the exit of chyme from the stomach, letting small amounts into the small intestine at a time over a few hours.
-when contents arrive in the large intestine digestion and absorbtion are nearly complete. Large intestine/colon reabsorbs the water donated earlier by digestive organs and to absorb minerals, leaving fiber and undigested materials (feces) for excretion. Fiber provides bulk for the colon’s muscles to work. 
-rectum stores fecal material to be excreted at intervals. From mouth to rectum, transit can take from a single day to as long as three days.

Key point – the digestive tract moves food through its various processing chambers by mechanical means. The mechanical actions include chewing, mixing by the stomach, adding fluid, and moving the tract’s contents by peristalsis. After digestion and absorption, wastes are excreted.

Gastric juice – the digestive secretion of the stomach
pH – a measure of acidity on a point scale. Solution with a pH of 1 is a strong acid, solution with a pH of 7 is neutral, solution with a pH of 14 is a strong base.
Mucus – a slippery coating of the digestive tract lining (and other body linings) that protects the cells from exposure to digestive juices (and other destructive agents).
Bile – a cholesterol-containing digestive fluid made by the liver, stored in the gallbladder, and released into the small intestine when needed. It emulsifies fats and oils to ready them for enzymatic digestion
Emulsifier – a compound with both water-soluble and fat-soluble portions that can attract fats and oils into water, combining them
Pancreatic juice – fluid secreted by the pancreas that contains both enzymes to digest carbohydrate, fat, and protein and sodium bicarbonate, a neutralizing agent
Bicarbonate – a common alkaline chemical, a secretion of the pancreas

Chemical Aspect of Digestion
- chemical digestion begins in the mouth, where food is mixed up with an enzyme in saliva that acts on carbohydrates. Disgestion continues in the stomach where stomach enzymes and acid break down protein. Digestion then continues in the small intestine; there the liver and gallbladder contribute bile that emulsifies fat, and the pancreas and small intestine donate enzymes that continue digestion so that absorption can occur. Bacteria in the colon break down certain fibers.

If “I am what I eat”, then how does a sandwhich become “Me”?
(wait for slides online or get notes from someone else from class)

Source: http://community.nbtsc.org/~engnyath/storage/UMass/ESPE/Chapter%203%20Notes.doc

Web site to visit: http://community.nbtsc.org/

Author of the text: not indicated on the source document of the above text


Shier, Butler, and Lewis:  Hole’s Human Anatomy and Physiology, 12th ed.   

Chapter 15:  Cardiovascular System


I.  Introduction

A.  The heart pumps 7,000 liters of blood through the body each day.
B.  The cardiovascular system includes the heart and blood vessels.

  1. The pulmonary circuit sends oxygen-depleted blood to the lungs to pick up oxygen and unload carbon dioxide.
  2. The systemic circuit sends oxygen-rich blood and nutrients to the body cells and removes wastes.

II.  Structure of the Heart

A.  Size and Location of the Heart
1.  An average size of an adult heart is generally 14 cm long and 9 cm wide.
2.  The heart is bounded laterally by the lungs, anteriorly by the sternum, and posteriorly by the vertebral column.
3.  The base of the heart lies beneath the second rib.
4.  The apex of the heart is at the level of fifth intercostal space.
B.  Coverings of the Heart
1.  The pericardium is a covering that encloses the heart and the proximal ends of the large blood vessels to which it attaches.
2.  The fibrous pericardium is the outer fibrous layer of the pericardium.
3.  The visceral pericardium is a serous membrane that is attached to the surface of the heart.
4.  The parietal pericardium is a serous membrane that lines the fibrous layer of the pericardium.
5.  The pericardial cavity is the space between the visceral pericardium and parietal pericardium.
6.  Serous fluid reduces friction between the pericardial membranes as the heart moves.
C.  Wall of the Heart
1.  The three layers of the heart wall are endocardium, myocardium, and pericardium.
2.  The epicardium is composed of a serous membrane that consists of connective tissue covered by epithelium, and it includes blood capillaries, lymph capillaries, and nerve fibers.
3.  The middle layer is the myocardium.
4.  The myocardium is composed of cardiac muscle tissue.
5.  The inner layer is the endocardium.
6.  The endocardium consists of epithelium and connective tissue that contains manly elastic and collagenous fibers. It also contains blood vessels and Purkinje fibers.
7.  The endocardium of the heart is continuous with the inner lining of the blood vessels attached to the heart.
D.  Heart Chambers and Valves
1.  The two upper chambers of the heart are the right atrium and the left atrium.
2.  Auricles are small, earlike projections of the atria.
3.  The two lower chambers of the heart are the right ventricle and the left ventricle.
4.  The interatrial septum separates the right and left atrium.  
5.  The interventricular septum separates the right and left ventricles.
6.  An atrioventricular orifice is an opening between an atrium and a ventricle.
7.  An atrioventricular orifice is protected by an A-V valve.
8.  The atrioventricular sulcus is located between the atria and ventricles.
9.  The right atrium receives blood from the superior and inferior vena cavae and the coronary sinus.
10.  The tricuspid valve is located between the right atrium and right ventricle and functions to prevent the back flow of blood into the right atrium.
11.  Chordae tendinae are fibrous strings and function to prevent cusps of A-V valves from swinging back into atria.
12.  Papillary muscles are located in ventricular walls and contract when the ventricles contract.
13.  The right ventricle receives blood from the right atrium.
14.  The right ventricle pumps blood into the pulmonary trunk.
15.  The pulmonary trunk divides into pulmonary arteries.
16.  Pulmonary arteries deliver blood to the lungs.
17.  The pulmonary valve is located between the right ventricle and pulmonary trunk and opens when the right ventricle contracts.
18.  Pulmonary veins carry blood from the lungs to the left atrium.
19.  Blood passes from the left atrium into the left ventricle.
20.  The mitral valve is located between the left atrium and left ventricle and functions to prevent the back flow of blood into the left atrium.
21.  The left ventricle pumps blood into the aorta.
22.  The aortic valve is located between the left ventricle and aorta and opens when the left ventricle contracts.
23.  The tricuspid and mitral valves are also called A-V valves because they are positioned between atria and ventricles.
24.  The pulmonary and aortic valves are also called semilunar valves
because of their structures.
E.  Skeleton of the Heart
1.  The skeleton of the heart is composed of rings of dense connective tissue and other masses of connective tissue in the interventricular septum.
2.  The skeleton of the heart provides attachments for the heart valves and for muscle fibers.
F.  Path of Blood Through the Heart
1.  Blood that is low in oxygen and rich in carbon dioxide enter the right atrium of the heart through venae cavae and the coronary sinus.
2.  As the right atrium contracts, blood passes into the right ventricle.
3.  When the right ventricle contracts, blood moves into the pulmonary trunk.
4.  From the pulmonary arteries blood enters the lungs.
5.  The blood loses carbon dioxide in the lungs and picks up oxygen.
6.  Freshly oxygenated blood returns to the heart through pulmonary veins.
7.  The pulmonary veins deliver blood to the left atrium.
8.  When the left atrium contracts, blood passes into the left ventricle.
9.  When the left ventricle contracts, blood passes into the aorta.
G.  Blood Supply to the Heart
1.  The first two branches of the aorta are the left and right coronary arteries. 
2.  Coronary arteries supply blood to the tissues of the heart.
3.  The circumflex artery is located in the atrioventricular groove between the left atrium and left ventricle and supplies blood to the walls of the left atrium and left ventricle.
4.  The anterior interventricular artery is located in the anterior interventricular groove and supplies blood to walls of both ventricles.
5.  The posterior interventricular artery is located the posterior interventricular groove and supplies the posterior walls of both ventricles.
6.  The marginal artery is located along the lower border of the heart and supplies blood to the wall of the right atrium and right ventricle.
7.  Blood flow in coronary arteries is poorest during ventricular contraction because the contracting myocardium interferes with blood flow and the openings of the coronary arteries are partially blocked by cusps of the aortic valve.
8.  Cardiac veins drain blood that passes through the capillaries of the myocardium.
9.  The coronary sinus is an enlarged vein on the posterior surface of the heart.

III.  Heart Actions

A.  Introduction
1.  Atrial systole is atrial contraction.
2.  Ventricular diastole is ventricular relaxation.
3.  Atrial diastole is atrial relaxation.
4.  Ventricular systole is ventricular contraction.
5.  When the atria of the heart contract, the ventricles relax.
6.  When the ventricles of the heart contract, the atria relax.
B.  Cardiac Cycle
1.  During a cardiac cycle, the pressure within the heart chambers rises and falls which is what causes the valves to open and close.
2.  The pressure in the ventricles is low during ventricular diastole.
3.  During diastole, the A-V valves are open.
4.  About 70% of the blood flows passively from the atria into ventricles and the remaining blood is pushed into the ventricles when the atria contract.
5.  As ventricles contract, the A-V valves close.
6.  When the pressure in the atria is lower than venous pressure, blood flows from the veins into atria.  
7.  During ventricular systole, ventricular pressure increases and the pulmonary valves open.
8.  As blood flows out of the ventricles, ventricular pressure decreases.
9.  The semilunar valves close when the pressure in the ventricles is lower than pressure in the aorta and pulmonary trunk.
C.  Heart Sounds
1.  Heart sounds are produced by the movement of blood through the heart and by the opening and closing of heart valve.
2.  The first heart sound is lubb and occurs during ventricular systole
when the A-V valves close.
3.  The second heart sound is dupp and occurs during ventricular diastole when the pulmonary and aortic valves close.
4.  A murmur is an abnormal heart sound.
D.  Cardiac Muscle Fibers
1.  A functional syncytium is a mass of merging cells that act as a unit.
2.  Two syncytiums of the heart are in the atrial walls and the ventricular walls.
3.  The atrial syncytium and ventricular syncytium are connected by fibers of the cardiac conduction system.
E.  Cardiac Conduction System
1.  The cardiac conduction system is responsible for coordinating events of the cardiac cycle.
2.  The S-A node is located in the wall of the right atrium and initiates one impulse after another.
3.  The S-A node is called the pacemaker because it generates the heart’s rhythmic contractions.
4.  As a cardiac impulse travels from the S-A node into the atrial syncytium, it goes from cell to cell via gap junctions.
5.  Conducting fibers deliver impulses from the S-A node to the A-V node.
6.  The A-V node is located in the inferior part of the interatrial septum and provides the only normal conduction pathway between the atrial and ventricular syncytiums.
7.  Impulses are delayed as they move through the A-V node because this allows time for atria to contract.
8.  From the A-V node, impulses pass to the A-V bundle.
9.  The A-V bundle is located in the superior part of the interventricular septum and gives rise to bundle branches.
10.  Purkinje fibers carry impulses to distant regions of the ventricular myocardium.
11.  The ventricular myocardium contracts as a functioning unit.
12.  Purkinje fibers are located in the inferior portion of the interventricular septum, papillary muscles, and in the ventricular walls.
13.  The ventricular walls contract with a twisting motion because the muscle fibers in the ventricular walls form irregular whorls.  The twisting motion produces a pushing motion.
14.  Contraction of the ventricles begins at the apex of the heart and pushes blood superiorly toward the aortic and pulmonary semilunar valve.
F.  Electrocardiogram
1.  An electrocardiogram is a recording of the electrical changes that occur in the myocardium during a cardiac cycle.
2.  An ECG is recorded by placing electrodes on the skin and connecting the electrodes to an instrument that respond to very weak electrical changes by moving a pen on a moving strip of paper.
3.  A P-wave is produced when atrial fibers depolarize.
4.  A QRS-wave is produced when ventricular fibers depolarize.
5.  A T-wave is produced when the ventricular fibers repolarize.
6.  Physician’s use ECG patterns to assess the heart’s ability to conduct impulses.
G.  Regulation of Cardiac Cycle
1.  The volume of blood pumped changes to accommodate cellular requirements.
2.  The parasympathetic nerve to the heart is the vagus nerve.
3.  The vagus nerve innervates the S-A and A-V nodes.
4.  The vagus nerve can alter heart rate by secreting acetylcholine onto the nodes.
5.  Sympathetic fibers reach the heart via the accelerator nerves.
6.  The endings of accelerator nerves secrete norepinephrine which increases the rate and force of myocardial contractions.
7.  The cardiac control center controls the balance between the inhibitory actions of the parasympathetic nervous system and the stimulatory actions of the sympathetic nervous system.
8.  Baroreceptors detect pressure changes.
9.  When baroreceptors in the aorta detect an increase in pressure, they signal the cardioinhibitory center of the medulla oblongata.
10.  If blood pressure is too high, the medulla oblongata sends parasympathetic impulses to the heart to decrease heart rate.
11.  If venous blood pressure increases abnormally, sympathetic impulses flow to the heart and heart rate and contraction increases.
12.  Rising body temperature increases heart action.
13.  The most important ions that influence heart action are potassium and calcium.

IV.  Blood Vessels

A.  Introduction
1.  Blood vessels form a closed circuit of tubes that carries blood from the heart to the body cells and back again.
2.  Five types of blood vessels are arteries, arterioles, capillaries, venules, and vein.
3.  Arteries conduct blood away from the heart and to arterioles.
4.  Venules and veins conduct blood from capillaries and to the heart.
5.  The capillaries are sites of exchange of substances between the blood and the body cells.
B.  Arteries and Arterioles
1.  Arteries are strong, elastic vessels that are adapted for carrying the blood away from the heart under high pressure.
2.  Arteries give rise to arterioles.
3.  The three layers of the wall of an artery are the endothelium, tunica media, and tunica adventitia.
4.  The inner layer of an artery is called endothelium and functions to provide a smooth surface for blood flow and prevents blood clotting.
5.  The middle layer of an artery is called the tunica media and is composed of smooth muscle fibers.
6.  The outer layer is the tunica adventitia and consists of connective tissues with collagenous and elastic fibers.
7.  The vasa vasorum of an artery is a series of blood vessels that supply the wall of large arteries.
8.  The sympathetic nervous system innervates smooth muscle in arteries and arterioles.
9.  Vasomotor fibers stimulate smooth muscle cells to contract, decreasing the diameter of the vessel.
10.  Vasoconstriction is the contraction of smooth muscle cells in blood vessel walls.
11.  Vasodilation is the relaxation of smooth muscle cells in the walls of blood vessels and occurs when the blood vessel diameter increases.
12.  Changes in the diameters of arteries and arterioles greatly influence blood flow and blood pressure.
13.  The wall of a very small arteriole consists of an endothelium and some smooth muscle cells and connective tissue.
14.  Metarterioles are branches of arterioles and help regulate blood flow to an area.
15.  Arteriovenous shunts are connections between arterioles and venous pathways.
C.  Capillaries
1.  Introduction
a.  The smallest diameter blood vessels are capillaries.
b.  Capillaries connect arterioles to venules.
c.  The wall of a capillary consists of endothelium.
2.  Capillary Permeability
a.  The most permeable capillaries are located in the liver, spleen, and red bone marrow.
b.  Protective and tight capillaries are located brain.
3.  Capillary Arrangement
a.  The higher a tissue’s rate of metabolism, the denser its capillary networks.
b.  Tissues richly supplied with capillaries are muscle and nervous tissues.
c.  Tissues that lack capillaries are cartilage and epithelial tissues.
d.  During exercise, blood is directed to capillary networks of skeletal muscle and it bypasses some of the capillary networks of the digestive tract.
4.  Regulation of Capillary Blood Flow
a.  Precapillary sphincters are located at the opening of capillaries and their function is to control the flow of blood into a capillary.  
b.  When cells have low concentrations of oxygen, precapillary sphincters relax and blood flow increases.
5.  Exchanges in the Capillaries
a.  The vital function of exchanging gases, nutrients, and metabolic by-products between the blood and the tissue fluid surrounding body cells occurs in the capillaries.
b.  Biochemicals move through capillary walls by diffusion, filtration, and osmosis.
c.  Diffusion is the most important means of transfer.
d.  Oxygen and nutrients diffuse out of the capillary walls into surrounding cells because they are in a lower concentration in surrounding cells.
e.  Carbon dioxide and other wastes diffuse into the capillary blood because they are in a lower concentration in the capillary blood.
f.  Plasma proteins generally remain in the blood because they are too big to cross through capillary walls.
g.  In filtration, hydrostatic pressure forces molecules through a membrane.
h.  In the capillaries, the force for filtration is provided by blood pressure.
i.  Blood pressure is greater at the arteriole end of the capillary.
j.  Colloid osmotic pressure is osmotic pressure and is created by plasma proteins in the blood of capillaries.
k.  At the arteriolar end of the capillary, filtration predominates.
l.  At the venular end of the capillary, osmotic pressure predominates.
D.  Venules and Veins 
1.  Venules are blood vessels that continue from capillaries and merge to form veins.
2.  The middle layer of the wall of a vein is very thin and poorly developed compared to that of an artery.
3.  The function of valves in veins is to keep blood flowing toward the heart.
4.  Veins also function as blood reservoirs.

V.  Blood Pressure

A.  Introduction
1.  Blood pressure is the force the blood exerts against the inner walls of the blood vessels.
2.  Blood pressure most commonly refers to pressure in arteries.
B.  Arterial Blood Pressure
1.  Systolic pressure is the maximum pressure and is created when the ventricles contract.
2.  Diastolic pressure is the minimum pressure and is created when the ventricles relax.
3.  A pulse is the alternate expanding and recoiling of an arterial wall.
4.  Common places to detect a pulse are the radial artery, the brachial artery, the carotid artery, the temporal artery, the facial artery, the femoral artery, the popliteal artery, and the posterior tibial artery.
C.  Factors that Influence Arterial Blood Pressure
1.  Heart Action
a.  Stroke volume is the volume of blood discharged from the ventricle with one contraction.
b.  Cardiac output is the volume of blood discharged from a ventricle in one minute.
c.  If stroke volume or heart rate increases, cardiac output increases.
2.  Blood Volume
a.  Blood volume equals the sum of the formed elements and plasma volumes in the vascular system.
b.  Blood pressure is normally directly proportional to blood volume.
3.  Peripheral Resistance
a.  Peripheral resistance is the friction between blood and the walls of the blood vessels.
b.  If peripheral resistance increases, blood flow decreases and blood pressure increases.
c.  Dilation of blood vessels reduces peripheral resistance.
4.  Viscosity
a.  Viscosity is the thickness of a fluid.
b.  As blood viscosity rises, blood pressure increases.
c.  Blood cells and plasma proteins contribute to blood viscosity.
D.  Control of Blood Pressure
1.  Blood pressure is determined by cardiac output and peripheral resistance.
2.  Cardiac output depends on the stroke volume and heart rate.
3.  Stroke volume is the difference between EDV and ESV.
4.  End Diastolic Volume is the volume of blood in each ventricle at the end of ventricular diastole.
5.  End Systolic Volume is the volume of blood in each ventricle at the end of the ventricular systole.
6.  Factors affecting stoke volume and heart rate are mechanical, neural, and chemical.
7.  Preload is the mechanical stretching of a ventricular wall prior to ventricular contraction.
8.  The greater the EDV, the greater the preload lengthening of myocardial fibers.
9.  Starling’s Law of the Heart is the relationship between fiber length and force of contraction.
10.  The more blood that enters the heart, the greater the ventricular distention, the stronger the ventricular contractions, the greater the stroke volume, and the greater the cardiac output.
11.  The less blood that returns from veins to the heart, the less ventricular distension, the weaker the ventricular contractions, the lesser the stroke volume, and the lesser the cardiac output.
12.  Starling’s Law of the Heart ensures that the volume of blood discharged from the heart is equal to the volume entering its chambers.
13.  If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex which decreases blood pressure.
14.  If blood pressure falls, the cardioaccelerator reflex occurs which increases sympathetic stimulation to the heart, which increases heart rate and cardiac output, which increases blood pressure.
15.  Other factors that increase heart rate and blood pressure are emotional responses, exercise, and a rise in body temperature.
16.  When arterial blood pressure suddenly increases, baroreceptors signal the vasomotor center, and sympathetic outflow to arterial walls decreases, which results in a decrease in blood pressure.
17.  Chemicals that influence peripheral resistance are carbon dioxide, oxygen, and hydrogen ions.
E.  Venous Blood Flow
1.  Blood pressure decreases as the blood moves through the arterial system into capillary networks.
2.  Blood flow through the venous system largely depends on skeletal muscle contractions and valves in veins.
3.  The squeezing action of skeletal muscles helps push blood toward the heart.
4.  During inspiration, the pressure in the thoracic cavity is reduced and the pressure in the abdominal cavity increases.
5.  An increases in abdominal pressure will squeeze blood out of abdominal veins.
6.  When venous pressure is low, sympathetic reflexes stimulate smooth muscles in the walls of the veins to contract.  
F.  Central Venous Pressure
1.  Central venous pressure is the pressure within the heart.
2.  Central venous pressure is of special interest because it affects the pressure within the peripheral veins.
3.  Other factors that increase central venous pressure are an increase in blood volume or widespread venoconstriction.
4.  An increase in central venous pressure can lead to peripheral edema.

VI.  Paths of Circulation

A.  Introduction
1.  The two major pathways of blood vessels are the pulmonary circuit and the systemic circuit.
2.  The pulmonary circuit consists of vessels that carry blood from the heart to the lungs and back to the heart.
3.  The systemic circuit carries blood from the heart to all parts of the body and back again.
B.  Pulmonary Circuit
1.  Blood enters the pulmonary circuit as it leaves the right ventricle through the pulmonary trunk.
2.  The pulmonary trunk divides into pulmonary arteries.
3.  Within the lungs the pulmonary arteries divide into lobar branches.
4.  The lobar branches give rise to arterioles that continue into capillary networks.
5.  The blood in the arteries and arterioles of the pulmonary circuit is low in oxygen and high in carbon dioxide.
6.  Gases are exchanged between the blood and the air as the blood moves through alveolar capillaries.
7.  The arterial pressure in the pulmonary circuit is less than in the systemic circuit because the right ventricle contracts with a force less than that of the left ventricle.
8.  Higher osmotic pressure of the blood removes any fluid that gets into the alveoli.
9.  Blood entering the venules of the pulmonary circuit is oxygen rich and low in carbon dioxide.
10. Venules merge to form veins.
11.  Pulmonary veins return blood to the left atrium and this completes the pulmonary circuit.
C.  Systemic Circuit
1.  Freshly oxygenated blood moves from the left atrium to the left ventricle.
2.  Contraction of the left ventricle forces blood into the systemic circuit.
3.  The systemic circuit includes the aorta and its branches that lead to all of the body tissues, as well as the companion system of veins that returns blood to the right atrium.
VII. – VIII.  Arterial System – Venous System
A.  Introduction
1.  The aorta is the largest diameter artery in the body.
2.  The aorta extends upward from the left ventricle, arches over the heart to the left, and descends just anterior and to the left of the vertebral column.
B.  Principal Branches of the Aorta
1.  The ascending aorta is the first portion of the aorta.
2.  An aortic sinus is a swelling of the aortic wall.
3.  Coronary arteries arise from the aortic sinus.
4.  Aortic bodies are small structures located within the aortic sinuses
and contain chemoreceptors that sense blood concentrations of oxygen and carbon dioxide.
5.  Three arteries originating from the aortic arch are the brachiocephalic artery, the left common carotid artery, and the left subclavian artery.
6.  The brachiocephalic artery supplies blood to the tissues of the upper limb and head.
7.  The brachiocephalic divides into the right common carotid artery and the right subclavian.
8.  The common carotids supply blood to the head and neck.
9.  The subclavian arteries supply blood to the arms.
10.  The descending aorta moves through the thoracic and abdominal cavity.
11.  The thoracic aorta is portion of the descending aorta above the diaphragm.
12.  Branches of the thoracic aorta are the bronchial, pericardial, and esophageal arteries.
13.  The abdominal aorta is the portion of the descending aorta below the diaphragm.
14.  Branches of the abdominal aorta are celiac, phrenic, superior mesenteric, suprarenal, renal, gonadal, inferior mesenteric, lumbar, and middle sacral arteries.
15.  The celiac artery gives rise to gastric, splenic, and hepatic arteries which supply upper portions of the digestive tract, spleen, and liver.
16.  Phrenic arteries supply the diaphragm.
17.  The superior mesenteric artery branches to many parts of the intestinal tract.
18.  The suprarenal arteries supply the adrenal glands.
19.  The renal arteries supply the kidneys.
20.  The gonadal arteries supply the ovaries and testes.
21.  The inferior mesenteric artery branches into arteries leading to the descending colon, sigmoid colon, and the rectum.
22.  Lumbar arteries supply muscle of the skin and posterior abdominal wall.
23.  The middle sacral artery supplies the sacrum and coccyx.
24.  The abdominal aorta terminates near the brim of the pelvis and divides into common iliac arteries.
25.  The common iliac arteries supply lower regions of the abdominal wall, the pelvic organs, and the lower extremities.
C.  Arteries of the Neck, Head, and Brain
1.  Branches of the subclavian and common carotids supply structures within the neck, head, and brain.
2.  The main divisions of the subclavian artery to the neck, head, and brain are the vertebral, thyrocervical, and costocervical arteries.
3.  The common carotid artery communicates with these regions by means of the internal and external carotid arteries.
4.  The vertebral arteries arise from the subclavian arteries and supply the base of the neck.
5.  A basilar artery is formed by the union of vertebral arteries.
6.  The basilar artery divides into posterior cerebral arteries that supply portions of the occipital and temporal lobes of the cerebrum.
7.  The cerebral arterial circle is formed by the posterior cerebral arteries.
8.  Functions of the cerebral arterial circle are supply brain tissue and to provide alternate routes through for blood to reach brain to circumvent for blockages and equalize blood pressure in the brain’s blood supply.
9.  Thyrocervical arteries give rise to branches to the thyroid gland, parathyroid glands, larynx, trachea, esophagus, and pharynx.
10.  Costocervical arteries carry blood to muscles of the neck, back, and thoracic wall.
11.  The common carotid arteries ascend deeply within the neck and divide to form internal and external carotid arteries.
12.  The external carotid artery gives off branches to structures of the neck, face, jaw, scalp, and base of skull.
13.  Main branches of external carotid arteries are superior thyroid, lingual, facial, occipital, and posterior auricular arteries.
14.  The superior thyroid artery supplies the hyoid bone, larynx, and thyroid gland.
15.  The lingual artery supplies the tongue and salivary glands.
16.  The facial artery supplies the pharynx, palate, chin, lips, and nose.
17.  The occipital artery supplies the back of the scalp, the meninges, the mastoid process, and muscles of the neck.
18.  The posterior auricular artery supplies the ear and scalp over the ear.
19.  The external carotid artery terminates by dividing into maxillary and superficial temporal arteries.
20.  The maxillary artery supplies the teeth, gums, jaws, cheek, nasal cavity, eyelids, and meninges.
21.  The temporal artery supplies the parotid glands and various regions of the face and scalp.
22.  The major branches of the internal carotid artery are ophthalmic, posterior communicating, and anterior choroid arteries.
23.  The ophthalmic artery supplies the eyeball and various muscles and accessory organs within the orbit.
24.  The posterior communicating artery forms part of the cerebral arterial circle.
25.  The anterior choroids artery supplies the choroid plexus and structures within the brain.
26.  The internal carotid artery terminates by dividing into anterior and middle cerebral arteries.
27.  The middle cerebral artery supplies the lateral surfaces of the cerebrum.
28.  The anterior cerebral artery supplies the medial surfaces of the cerebrum.
29.  A carotid sinus is an enlargement of each carotid artery and contains baroreceptors that control blood pressure.
D.  Arteries to the Shoulder and Upper Limb
1.  As it passes into the arm, the subclavian artery becomes the axillary artery.
2.  The axillary artery supplies structures of the axilla and chest wall.
3.  The axillary artery becomes the brachial artery.
4.  The brachial artery gives rise to deep brachial artery.
5.  The branches of the brachial artery supply structures of the arm.
6.  Within the elbow, the brachial artery divides into ulnar and radial arteries.
7.  The branches of the ulnar artery supply structures on the ulnar side of the forearm.
8.  The branches of the radial artery supply structures on the radial side of the forearm.
9.  Blood supply to the wrist, hands, and fingers come from branches of the radial and ulnar arteries.
E.  Arteries to the Thoracic and Abdominal Walls
1.  The internal thoracic artery is a branch of a subclavian artery.
2.  The internal thoracic artery gives off two anterior intercostal arteries to each of the upper six intercostal spaces.
3.  The anterior intercostals arteries supply intercostal muscles and mammary glands.
4.  The posterior intercostals arteries arise from the aorta and enter the intercostal spaces between the third through the eleventh ribs.
5.  The posterior intercostals arteries supply intercostal muscles, the vertebrae, the spinal cord, and deep muscles of the back.
6.  Branches of the internal thoracic and external iliac arteries provide blood to the anterior abdominal wall.
7.  Phrenic and lumbar arteries supply the posterior and lateral abdominal wall.
F.  Arteries to the Pelvis and Lower Limb
1.  The abdominal aorta divides to form common iliac arteries.
2.  The common iliac arteries provide blood to pelvic organs, gluteal, and lower limbs.
3.  Each common iliac divides into internal and external iliacs.
4.  The internal iliac artery gives off branches to pelvic organs and muscles, genitals, and gluteal muscles.
5.  Branches of the internal iliac artery are iliolumbar, gluteal, internal pudendal, vesical, middle rectal, and uterine arteries.
6.  The iliolumbar arteries supply the ilium and muscles of the back.
7.  Superior and inferior gluteal arteries supply gluteal muscles, pelvic muscles, and skin of the buttocks.
8.  Internal pudendal arteries supply muscles to the distal portion of the alimentary canal, external genitals, and the hip joint.
9.  Superior and inferior vesical arteries supply the urinary bladder, seminal vesicles, and prostate gland.
10.  Middle rectal arteries supply the rectum.
11.  Uterine arteries supply the uterus and vagina.
12.  The external iliac artery provides the main blood supply to the lower limbs.
13.  Two branches of the external iliac artery are inferior epigastric and deep circumflex arteries.
14.  The inferior epigastric artery and deep circumflex artery supply muscles and skin of the lower abdominal wall.
15.  The external iliac artery becomes the femoral artery.
16.  The femoral artery gives off branches to muscles and superficial tissues of the thigh.
17.  Important subdivisions of the femoral artery are superficial circumflex iliac artery, superficial epigastric artery, pudendal arteries, deep femoral, and deep genicular arteries.
18.  Superficial circumflex iliac arteries supply skin and lymph nodes of the groin.
19.  Superficial epigastric arteries supply skin of lower abdominal wall.
20.  Superficial and deep external pudendal arteries supply skin of lower abdomen and external genitalia.
21.  Deep femoral arteries supply the hip joint and thigh muscles.
22.  Deep genicular arteries supply thigh muscles and knee joint.
23.  The popliteal artery is derived from the femoral artery.
24.  Branches of the popliteal artery supply the knee joint and muscles of the thigh and calf.
25.  The popliteal artery divides into anterior and posterior tibial arteries.
26.  The anterior tibial artery supplies skin and muscles of the leg.  
27.  The dorsalis pedis artery is derived from the anterior tibial artery.
28.  The posterior tibial artery supplies skin and muscles of the leg.
29.  The posterior tibial artery divides into medial and lateral plantar arteries which supply the foot.
30.  The fibular artery is the largest branch of the posterior tibial artery and supplies the ankle.
G.  Characteristics of Venous Pathways
1.  The vessels of the venous system begin with the merging capillaries into venules, venules into small veins, and small veins into larger ones.
2.  Venous pathways are hard to follow because veins commonly connect in irregular networks.
3.  The larger veins typically parallel arteries.
4.  The veins from most body parts converge into superior and inferior vena cavae.
H.  Veins from the Brain, Head, and Neck
1.  The external jugular veins drain blood from the face, scalp, and superficial regions of the neck.
2.  The external jugular veins empty into subclavian veins.
3.  The internal jugular veins arise from numerous veins and venous sinuses of the brain and from deep veins in various parts of the face and neck.
4.  The brachiocephalic veins are formed from internal jugular and subclavian veins.
5.  The brachiocephalic veins merge to give rise to the superior vena cava.
I.  Veins from the Upper Limb and Shoulder
1.  A set of deep veins and a set of superficial veins drain the upper limb.
2.  The deep veins generally parallel the arteries in each region.
3.  The superficial veins connect in complex networks beneath the skin  and also communicate with deep vessels of the upper limb.
4.  The main vessels of the superficial network are the basilic and cephalic veins.
5.  The basilic vein is located along the back of the forearm on the ulnar side and along the anterior surface of the elbow and joins the brachial vein.
6.  The axillary vein is formed by basilic and brachial veins.
7.  The cephalic veins are located on the lateral side of the upper limb and empties into the axillary vein.
8.  Beyond the axilla, the axillary vein becomes the subclavian vein.
9.  The median cubital vein is located on the lateral side of the forearm and in the bend of the elbow, and is often a site for the retrieval of a blood sample.
J.  Veins from the Abdominal and Thoracic Walls
1.  Tributaries of the brachiocephalic and azygos veins drain the abdominal and thoracic walls.
2.  The azygos vein originates in the dorsal abdominal wall and ascends  through the mediastinum on the right side of the vertebral columns.  
3.  The azygos vein drains muscle tissue of the thoracic and abdominal walls.
4.  Tributaries of the azygos vein include posterior intercostal veins, hemiazygos veins, and ascending lumbar veins.
5.  The superior and inferior hemiazygos veins drain posterior intercostal veins.
6.  The ascending lumbar veins drain lumbar and sacral regions.
K.  Veins from the Abdominal Viscera
1.  Veins carry blood directly to atria of the heart, except those of the hepatic portal system.
2.  The hepatic portal vein drains the stomach, intestine, pancreas, and spleen, and carries blood to the liver.
3.  The hepatic portal system is the venous pathway that includes the hepatic portal vein and the hepatic sinusoids.
4.  Tributaries of the hepatic portal system include gastric veins, superior mesenteric, and splenic veins.
5.  The gastric veins drain the stomach.
6.  Superior mesenteric veins drain the intestines.
7.  Splenic veins drain the spleen, pancreas, and a portion of the stomach.
8.  The blood flowing to the liver in the hepatic portal system is oxygen poor and nutrient rich.
9.  The liver metabolizes the nutrients.
10.  Kupffer cells are located in hepatic sinusoids and function to phagocytize microbes.
11.  Blood leaves the liver through hepatic veins.
12.  Hepatic veins empty blood into the inferior vena cava.
13.  Veins that empty into the inferior vena cava are lumbar, gonadal, renal, suprarenal, and phrenic veins.
L.  Veins from the Lower Limb and Pelvis
1.  Veins that drain the lower limb can be divided into deep and superficial groups.
2.  The deep veins of the leg have names that correspond to arteries that they accompany.
3.  The popliteal vein is formed from tibial veins.
4.  The femoral vein originates from the popliteal vein.
5.  The external iliac vein originates from the femoral vein.
6.  The small saphenous vein begins in the lateral portion of the foot and passes upward behind the lateral malleolus.
7.  The small saphenous vein ascends along the back of the calf and joins the popliteal vein.
8.  The great saphenous vein originates on the medial side of the foot  and ascends upward along the medial side of the leg and thigh, and eventually joins the femoral vein. 
9.  The longest vein of the body is the great saphenous vein.
10.  The saphenous veins communicate with deep veins of the leg and thigh.
11.  In the pelvic region, vessels leading to internal iliac veins carry blood away from organs of reproduction, urinary, and digestive systems.
12.  Tributaries that form the internal iliac vein are gluteal, pudendal, vesical, rectal, uterine, and vaginal veins.
13.  The common iliac veins are formed from external iliac and internal iliac veins.
14.  The common iliac veins merge to form inferior vena cava.

IX.  Life-Span Changes

1.  Sixty percent of men over the age of sixty have at least one narrowed coronary artery.
2.  Some degree of cholesterol deposition in blood vessels may be part of normal aging.
3.  During exercise, cardiac output decreases with age.
4.  Cardiovascular disease may cause enlargement of the heart.
5.  The number of cardiac muscle fibers in the heart falls, and fibrous and adipose tissue increases.
6.  With age, heart valves begin to thicken.
7.  Systolic blood pressure increases with age.
8.  The increase in systolic blood pressure is due to the decreasing diameters and elasticity of arteries.
9.  Resting heart rate decreases with age.
10.  With age, changes in arteries include thickening of the tunica interna and a decrease of elasticity.
11.  The number of capillaries declines with age.
12.  Exercise can help maintain a “young” vascular system.


Source: http://highered.mheducation.com/sites/dl/free/0077262557/631228/ch15_answer_key_12edition_corrected.doc

Web site to visit: http://highered.mheducation.com

Author of the text: indicated on the source document of the above text

If you are the author of the text above and you not agree to share your knowledge for teaching, research, scholarship (for fair use as indicated in the United States copyrigh low) please send us an e-mail and we will remove your text quickly. Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test. (source: http://en.wikipedia.org/wiki/Fair_use)

The information of medicine and health contained in the site are of a general nature and purpose which is purely informative and for this reason may not replace in any case, the council of a doctor or a qualified entity legally to the profession.


Cardiovascular System


The texts are the property of their respective authors and we thank them for giving us the opportunity to share for free to students, teachers and users of the Web their texts will used only for illustrative educational and scientific purposes only.

All the information in our site are given for nonprofit educational purposes


Cardiovascular System



Topics and Home
Term of use, cookies e privacy


Cardiovascular System