Compendium Review Chapter 5

Table of Contents:
I. Overview of the Cardiovascular System
II. Types of Blood Vessels
III. The Heart is a Double Pump
IV. The Heartbeat is Controlled
V. Features of the Cardiovascular System
VI. Two Cardiovascular Pathways
VII. Exchange at the Capillaries
VIII. Cardiovascular Disorders

I. Overview of the Cardiovascular System
A. Consists of: the heart, (to pump blood), and the blood vessels, (through which the blood flows.)
(Insert cardiovascular system picture / www.trendenterprises.com http://www.trendenterprises.com/ProductLrg.cfm?ITEMID=T-38090)
B. Circulation: Circulation of blood depends on the pumping of the heart.
1b. The purpose of the circulation is to service the cells.
2b. Blood exchanges substances with tissue fluid, not directly with cells. Blood removes waste products from tissue fluid, and it brings tissue fluid the oxygen and nutrients cells require. (Mader 86)
(Insert circulation picture / www.pediheart.org http://www.pediheart.org/kidzone/The_heart/Circulation/circulation.html)
C. Functions of the Cardiovascular System:
- Blood pressure is generated when the heart contracts, and the blood is moved from the heart, through the "big" vessels that leave the heart. (Frolich PowerPoint Slide 4)
- Blood vessels are the transporters of the blood, which moves from the heart into the arteries, capillaries, and veins, and is then returned to the heart.
- Capillaries: smallest of blood vessels. Exchanges at the capillaries refreshes the blood and then the tissue (interstitial) fluid.
- The heart and blood vessels control the blood flow, according to what the body requires. (Mader 86)
- SUMMARIZED: In the cardiovascular system, the heart pumps the blood, and the blood vessels transport blood about the body. Exchanges at capillaries refresh the blood and then tissue fluid. (ARIS Text Website Chapter 5)
D. Lymphatic System: Assists the cardiovascular system because lymphatic vessels collect excess tissue fluid and return it to the cardiovascular system.
- When blood exchanges occur between blood and tissue fluid, water collects in tissues.
- H2O then enters lymphatic vessels, which being in the tissues and end at cardiovascular veins in the shoulder.
- As soon as fluid enters lymphatic vessels, it is called "lymph". (Mader 86)
(Insert lymphatic system picture /www.longevity.ca / http://www.longevity.ca/info_theory_of_cell.htm)
- Blood divides and splits to all major parts of body: limbs, head, guts,major organs, body wall, skeleton, muscles (Frolich PowerPoint Slide 4)

II. Types of Blood Vessels
A. The Arteries: From the Heart
1a. Arterial wall has 3 layers:
- Inner layer: thin layer of cells called endothelium.
- Middle layer: relatively thick layer of smooth muscle and elastic tissue.
- Outer layer: connective tissue.
2a. Strong walls give it support for to hold the pressurized blood. The elastic tissue allows for expansion to absorb the pressure.
(Insert artery picture / plus.maths.org /http://plus.maths.org/issue36/interview)
3a. Arterioles: small arteries, just visible to naked eye. Middle layer has some elastic tissue but is mostly smooth muscle. The smooth muscle fibers encircle the atriole.
4a. When these muscle fibers contract, the vessel constricts; when these muscle fibers relax, the vessel dilates, thus regulating blood pressure. Low blood pressure depends on the vessels being dilated. (Mader 87)
(Insert arteriole picture / science.nhmccd.edu / http://science.nhmccd.edu/Biol/cardio/vessels.htm)
B. Capillaries
1b. Arterioles branch into capillaries.
2b. Each capillary is an extremely narrow, microscopic tube with a wall made of only endothelium (single layer of epithelial cells) with a basement membrane. (Mader 87)
3b. "Inside organs, muscles, structures, and bones, big vessels divide into smaller and smaller vessels and then into network-like capillary beds. This is where diffusion can happen rapidly, at the microscopic level. Then, to get blood back to heart, capillaries feed into smaller veins into larger and larger veins into major veins that return to heart." (Frolich PowerPoint Slide 6)
4b. Capillary beds are present in all regions of the body, so cells are always close to capillaries. (Mader 87) This is very important, because ALL cells need oxygen (respiration*), nutrients (metabolism),immune cells nearby (eliminate microbes), and the removal of waste (metabolism). (Frolich PowerPoint Slide 7)
* Gas Exchange During Respiration: The direction of gas movement is determined by partial pressure differences. The Po2 in lungs is greatere than the Po2 in blood, and the Pco2 in lungs is less than the PCo2 in blood. The Po2 in blood is greater than the Po2 in tissues, and the Pco2 in blood is less than Pco2 in tissues. (ARIS Mader Text Website)
5b. Capillaries are the "in and out" of blood. Diffusion of needed substances only occurs in the capillaries. Blood exchange: capillaries deliver oxygen into the lungs and carbon dioxide leaves the lungs. (Frolich PowerPoint Slide 5, 8)
(Insert capillary picture / cellbio.utmb.edu / http://cellbio.utmb.edu/microanatomy/cardiovascular/cardiovascular_system.htm)
(Insert Anatomoy of a capillary bed picture / Frolich PowerPoint Slide 6)
(Insert realistic view of capillaries picture / Frolich PowerPoint Slide 9)
- "More realistic drawing showing network of capillaries connecting arteries to veins and threading through tissue. Open-ended lymph capillaries pick up excess fluid from tissue and also give immune cells route back into blood circulation." (Frolich PowerPoint Slide 8)

C. The Veins: To the Heart
1c. Venules: Small veins that drain blood from the capillaries and then join to form a vein.
2c. Walls of venules have the same three layers as arteries, but less smooth muscle in the middle layer and less connective tissue in the outer layer. (The wall of a vein is thinner than that of an artery.)
3c. Valves: allow blood to flow only toward the heart when open and prevent the backward flow of blood when closed. Veins act as a blood reservoir, because they are think and can expand to a great extent. (Mader 87)
(Insert vein picture / By kugel on Flickr / http://www.flickr.com/photos/kugelfisch/2110234091/)
III. The Heart is a Double Pump
1a. Heart: Cone-shaped, muscular organ located between the lungs, directly behind sternum.
- Tilted, with apex (pointed end) points to the left.
2a. Myocardium: Consists mostly of cardiac muscle tissue.
- Serviced by the coronary artery and cardiac vein, not by the blood it pumps.
3a. Pericardium: Thick, membranous sac that supports and protects the heart.
4a. Septum: Separates the heart into a right and left side. It has 4 chambers: right-atrium and left-atrium (two upper, thin-walled atria with wrinkled, protruding auricle) ), and the two lower chambers, the thick-walled ventricles (right and left).
5a. Valves: Keep flood flowing in the right direction and prevents it from going backwards.
- Atrioventricular valves: Lie between the atria and the ventricles. Supported by strong fibrous strings called the chordae tendineae. These project from the ventricular (papillary muscles) support the valves and prevent them from inverting when the heart contracts.
- AV valve on right: tricuspid valve because it has three flaps.
- AV valve on left: bicuspid (aka mitral) because it has two flaps.
- Other two valves: semi-lunar, flaps shaped like half-moons.
B. Passage of Blood Through the Heart
1b. Blood flows through the heart in the following manner: first, the superior vena cava and the inferior vena cava carry oxygen-poor blood into the right atrium. Next, the right atrium send blood through an atrioventricular valve to the right ventricle. Then, the right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk. The pulmonary trunk, which carries the oxygen-poor blood divides into two pulmonary arteries, which go to the lungs. Then, four pulmonary veins, which carry oxygen-rich blood, enter the left atrium. The left atrium sends blood through an atrioventricular valve to the left ventricle, and finally, the left ventricle sends blood through the aortic semilunar valve into the aorta to the body.
2b. "Double pump" because the right ventricle of the heart sends blood through the lungs and the left ventricle sends blood throughout the body.
3b. Because the left side of the heart is the stronger pump, blood pressure is greatest in the aorta. Blood pressure then decreases as the total cross-sectional area of arteries and then arterioles increases. (Mader 89)
(Insert blood flow picture / catalog.nucleusinc.com http://catalog.nucleusinc.com/generateexhibit.php?ID=4579&ExhibitKeywordsRaw=&TL=16353&A=2)
* Note: Blood must go through the lungs in order to pass from the right side to the left side of the heart.
IV. The Heartbeat is Controlled
A. Each heartbeat is called a cardiac cycle.
B. Process of a heartbeat: First, the two atria contract at the same time. Next, the two ventricles contract at the same time. Then, all chambers relax.
-Systole: The contraction of the chambers.
- Diastole: The resting phase, the relaxation of the chambers.
- The heart beats approximately 60-80 beats per minute.
C. Internal Control of the Heartbeat
1c. Sinatrial node: Located in the upper dorsal wall of the right atrium. Known as the pacemaker because it keeps the heartbeat regular. Initiates the heartbeat and automatically sends out an excitation impulse, which causes the atria to contract.
2c. Atrioventricluar node: Located in the base of the right atrium very near the septum. Sends signals for the ventricles to contract goes from the AV node through the two branches of the atrioventricular bundle before reading the numerous and smaller Purkinje fibers. These three work well together because gap junctions all electrical current to flow from cell to cell. (Mader 90)
3c. If more oxygen is needed, heart pumps faster.
- A great deal of oxygen is used by the brain and "guts".
- Muscles during physical activity uses the most oxygen.
- Heart pumps faster when oxygen is needed = increased heart rate during exercise.
- Pulse: Measurement of how fast the heart is beating. (Frolich PowerPoint Slide 10)
D. External Control of Heartbeat
1d. There is a cardiac control center in the medulla oblongata, a portion of the brain that controls internal organs. Can alter the beat of the heart by parasympathetic (associated with resting state) and sympathetic portions (brings about responses associated with fight or flight) of the nervous system.
- Parasympathetic division decreases SA and AV nodal activity when we are inactive.
- Sympathetic division increases SA and AV nodal activity when we are active.
E. Electrocardiogram: Record of heartbeat.
1e. Recording of the electrical changes that occur in myocardium during a cardiac cycle.
- Detected by recording the electrical changes in myocardium due to ions that conduct electrical currents. (Mader 90-91)
V. Features of the Cardiovascular System
A. Pulse rate = heart rate.
1a Pulse: Blood surges into the arteries causing their elastic walls to stretch, but then they almost immediately recoil. This rhythmic expansion and recoil of an arterial wall is a pulse, and it can be felt by placing several fingers on the radial artery, near the outer border of the palm side of the wrist. Can also be felt on the carotid artery on either side of the trachea in the neck.
B. Blood Flow is Regulated
1b. Beating of heart is required for homeostasis, because it makes the pressure that propels blood in the arteries and arterioles.
- Arterioles lead to capillaries where exchange with tissue fluid occurs. (Mader 92)
2b. Blood pressure measures the force of blood against the wall of blood vessels.
- Systolic pressure is highest point, as blood is being forced out of heart by contraction of heart muscle.
- Diastolic pressure is lowest point, between heart “beats,” when heart is inactive. (Frolich PowerPoint Slide 11)
3b. Blood moves slowly through the capillaries to allow for the exchange of substances between the blood and the surrounding tissues.
4b. There are three things other than blood pressure that contribute to blood flow:
- Skeletal Muscle Pump: Dependent on skelskeletalcle contraction.
- Respiratory Pump: Dependent on breathing.
- Valves in veins. (Function of veins- to return blood to the heart.) (Mader 93)
V. Two Cardiovascular Pathways
1a. Blood flows in two circuits: the pulmonary and the systemic.
- Pulmonary Circuit: Circulates blood through the lungs. The path: Blood collects in right atrium, passes into right ventricle, which pumps it into the pulmonary trunk. Pulmonary trunk divides into right and left pulmonary arteries, which branch as they approach the lungs. Arterioles take blood to pulmonary capillaries, where CO2 is given off and oxygen is picked up. Blood then passes through pulmonary venules, which lead to the four pulmonary veins that enter the atrium. In this case, the arteries carry the oxygen poor blood and the and the veins carry the oxygen rich blood (opposite than "normal").
- Systemic Circuit: Serves the needs of body tissues. Heart pumps blood through 60000 miles of blood vessels to deliver nutrients and oxygen and remove wastes from all body cells. Blood always begins with the left ventricle, which pumps blood into the aorta.
- Both necessary to homeostasis.
2a. Aorta: Largest artery in systemic circuit. Receives blood from heart.
3a. Superior and Inferior Venae Cavae: Return blood to heart. Superior vena cava collects blood from heat, chest, and arms. Inferior: Collects blood from lower body regions. Both enter the right atrium. (Mader 94)
4a. Coronary Circulation: Coronary arteries serve the heart muscle itself. First branches off the aorta. Coronary capillary beds join to form venules. The venules converge to form the cardiac veins, which empty into the right atrium.
5a. Hepatic Portal Vein: Takes blood from capillary bed of digestive tract to capillary bed in liver. This blood is oxygen poor, but rich in glucose and anime acids.
(Insert Capillary Bed picture / www.sci.sdsu.edu / http://www.sci.sdsu.edu/class/bio590/pictures/lect5/5.3.html)
- Hepatic Vein: Leaves liver and enters inferior vena cava. (Mader 95)
VII. Exchange at the Capillaries
A. Two forces control movement of fluid through capillary wall: Blood pressure (tends to cause h2o to move from capillary to tissue fluid) and Osmotic pressure (tends to cause h2o to move in the opposite direction.) Osmotic is created by the presence of salts and the plasma proteins.
1a. Blood pressure is higher than osmotic pressure at the arterial end of a capillary, so water exits a capillary at this end.
2a. Midway along capillary, blood pressure is lower, and the two forces cancel each other, and there is no net movement of water. Oxygen and nutrients then diffuse out of the capillary; carbon dioxide and wastes diffuse into the capillary. At teh venule end of a capillary, osmotic pressure is greater than blood pressure and water tends to move into the capillary.
3a. Lymph: Tissue fluid contained within lymphatic vessels.
VIII. Cardiovascular Disorders
A. Cardiovascular disease: Leading cause of untimely death in Western countries.
B. Disorders of Blood Vessels: Hypertension,occurs when blood moves through the arteries at a higher pressure than normal. (AKA high blood pressure.) Diastolic pressure is the most "important" in medical diagnosis. atherosclerosis: Accumulation of soft masses of fatty materials, including cholesterol, under the inner linings of arteries, called plaque. Both lead to stroke due to a blood clot blocking an artery, or a heart attack due to plaque clogging a coronary artery. Aneurysm: Burst blood vessel.
1b. Thrombus: A stationary clot.
2b. Embolus: A dislodged clot that moves along with blood.
- Thromboembolism: Clot carried in bloodstream but becomes stationary.
3b. - Cerebrovascular Accident: AKA Stroke: Results when a small cranial arteriole bursts or is blocked by an embolus. Lack of oxygen causes a portion of the brain to die, resulting in paralysis or death.
- Myocardial Infarction: AKA Heart Attack: Occurs when a portion of the heart muscle dies due to lack of oxygen.
(Insert heart attack picture / www.flickr.com / http://www.flickr.com/photos/gandhiji40/395241000/)
- Angina Pectoris: A coronary artery becomes partially blocked, and there is radiating pain in left arm.
- Aneurysm: A ballooning of a blood vessel, usually the abdominal artery or the arteries leadcing to the brain.
C. Treatments:
- Thromobembolism: t-PA, beiotechnology drug. Converts plasminogen into plasmin, an enzyme that dissolves blood clots.
- Aspirin: For angina, heart attach, stroke. Reduces the stickiness of platelets, lowering the probability of a clot forming.
- Bypass Surgery: for cardiovascular diseae.
- Coronary Bypass: Operation for an artery clogged with plaque.
- Gene Therapy: Grows new blood vessels to carry blood to cardiac muscle.
- Stent: Small, metal mesh cylinder that holds a coronary artery open after a blockage is cleared.
(Insert Stent picture / www.nhlbi.nih.gov http://www.nhlbi.nih.gov/health/dci/Diseases/Angioplasty/Angioplasty_WhatIs.html)
- Angioplasty: Plastic tube is inserted into an artery of an arm or a leg and then guided through a major blood vessel toward heart.
(Mader 99)
D. Disorders of the Heart
1d. Heart Failure: Heart no longer pumps as it should. Treatment: cardioverter-defibrillator: Regulates the heartbeat . Implanted just beneath skin of chest. Can generate missing heartbeats and send a jolt of electricity to heart to slow it down if it beats too fast.
E. Heart Transplants: Not enough hearts to go around! Bone marrow stem cells have been known to become cardiac muscle! Left ventricular assist device is an alternative to heart transplants.
- Total Artificial Heart: Still a work in progress.