Bio11 homework. Cardiovascular system. Blood Vessels. Types of blood vessels. Capillaries: Exchange. Arteries have strong walls.

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1 Bio11 homework Read Ch 5, 6 Assignment #1: Cardiovascular system On my website Due next Mon Oct pts Lose 5 pts if 1 class period late Cardiovascular system Blood The Heart Blood vessels Blood Vessels Types of blood vessels If the heart is the body s pump, then the plumbing is the system of arteries, veins, and capillaries. Arteries away from the heart Branch arterioles Capillaries venules Veins to the heart Arteries have strong walls Arteries have relatively thick elastic walls that enable them to withstand the high pressure of blood pumped from the heart. Endothelium Smooth muscle Connective tissue Capillaries: Exchange Arteries and veins are designed for transporting blood from and to the heart Exchange occurs in the capillaries How can material cross a capillary wall? Easily, because the capillary walls are only one-cell-thick

2 Capillaries: where exchange with cells takes place Capillaries: Exchange Microscopic and delicate Found in all parts of the body Capillary Tissue cell Red blood cell Diffusion of Diffusion of capillary and into tissue cells of tissue cells and into capillary To vein of CO2 and O2 and nutrients out wastes out Do the real work of the CV system Fr om a rt e ry Interstitial fluid To Only blood vessels whose walls permit exchange between the blood and tissue fluid ve LM in (b) Chemical exchange (a) Capillaries The walls of capillaries are thin and leaky WBCs can move across capillary walls Veins: to the heart Endothelium Smooth muscle Veins return blood to the heart Walls of veins are thinner than arteries because blood pressure is lower in veins Connective tissue Veins: to the heart Veins that carry blood against gravity have valves that keep blood moving toward the heart One-way valves Surrounding skeletal muscles compress the veins Varicose veins To heart Valve (open) Skeletal muscle Valve (closed) The valves do not function properly, allowing blood to remain in the vein. Pooling of blood in a vein causes it to enlarge.

3 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. v. v = vein; a = artery How can you tell the difference between an artery and vein? a. blood flow valve blood flow elastic tissue endothelium smooth muscle precapillary sphincter artery arteriole venule capillary bed When the precapillary sphincter contracts, it narrows the opening to cap bed and diverts the blood vein Ways to regulate blood flow Precapillary sphincters smooth muscles that surround a capillary When they contract, blood cannot enter those capillaries. This way we control which capillaries (and thus, which cells) get blood. The blood vessels in our skin vasodilate when we are hot, and Vasoconstrict when we are cold. Two cardiovascular pathways O 2 Lung Lung O 2 O 2 Heart O 2 -rich blood O 2 O 2 -poor blood (a) Pulmonary circuit (b) Systemic circuit Exchange of O 2 and Exchange of nutrients Figure 23.2 and wastes Another CV pathway: the hepatic portal system Brings blood rich in amino acids and glucose from the digestive tract to the liver The liver regulates the nutrient content of blood Stores the glucose as glycogen Synthesizes proteins Composition of blood in systemic circuit is relatively stable Features of the Copyright The CV McGraw-Hill Companies, system Inc. Permission required for reproduction or display. Blood pressure moves blood in the arteries Blood pressure is highest in the arteries remember the thick, muscular walls Progressively drops pressure is minimal in the veins and venules Blood flow is slower in the capillaries allows time for exchange between cells Magnitude arteries arterioles capillaries venules veins blood total pressure cross-sectional area of vessels velocity BP is the pressure of blood against a blood vessel wall It s the main force driving the blood from the heart to the capillary beds. Blood Flow

4 No sounds What does a blood pressure of 120/80 mean? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. How is blood pressure categorized? Average blood pressure is 120/80 (systolic/diastolic) Systolic pressure - the pressure when the ventricles contract Diastolic pressure - the pressure when the ventricles relax (artery is closed) Sounds heard (artery is opening and closing) No sounds (artery is open) Why do health care professionals measure blood pressure? Hypertension (high blood pressure) puts unnecessary stress on your heart and blood vessels. Over time, this can increase your susceptibility to cardiovascular diseases. Pulse rate = heart rate When the left ventricle contracts, a surge of blood enters the arteries and causes the walls of the arteries to stretch Check your pulse rate Cardiovascular Diseases Hypertension/high blood pressure Atherosclerosis Heart attack Stroke Aneurysm Why should we care about cardiovascular disease? Cardiovascular disease (CVD) is the most common cause of death in the western world

5 The heart s blood supply: Coronary circulation The heart has its own separate blood supply Heart muscle cells need a constant supply of oxygen and nutrients Coronary arteries supply the heart muscle Found on the surface Coronary artery disease Partial or complete blockage of the coronary circulation Cause? Formation of a fatty deposit, or atherosclerotic plaque, in the wall of a coronary vessel Heart attack or myocardial infarction (MI) Part of the coronary circulation is blocked and heart muscle cells die from lack of oxygen Heart attack Also known as a myocardial infarction (MI) Blocked coronary artery part of the heart muscle dies due to lack of oxygen Can lead to permanent damage to heart muscle 1/4 of heat attack victims die almost immediately Symptoms of a heart attack Heart failure Disorder: Heart failure when the heart no longer pumps properly Treatments: Left ventricular assist device (LVAD) Heart transplant either natural or artificial replacement heart wireless external internal external rechargable energy wireless controller battery internal transfer driver pack battery system Artificial heart Photograph of artificial heart Artificial heart inside body Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (right): Courtesy of SynCardia Systems, Inc.

6 5.7 Cardiovascular disorders Atherosclerosis Stroke A build up of plaque in blood vessels Associated with a stroke, heart attack and Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. aneurysm coronary artery plaque Usually occurs when a cranial artery is blocked or bursts Part of the brain dies dues to lack of oxygen Symptoms include: numbness of hands or face difficulty speaking inability to see in one eye normal artery artery with plaque (plaque): Biophoto Associates/Photo Researchers, Inc.; (normal): Ed Reschke Aneurysm How are disorders of the blood vessels treated? A ballooning of a blood vessel Atherosclerosis and hypertension can weaken a vessel and cause ballooning The most commonly affected arteries: abdominal artery arteries leading to the brain Dissolving blood clots: t-pa is a drug that dissolves clots Treating clogged arteries: Bypass surgery: usually a vein from the leg is used to bypass a clogged artery How are disorders of the blood vessels treated? Preventing Cardiovascular Disease Treating clogged arteries: Stents: wire mesh cylinder inserted into a clogged artery to hold it open Angioplasty: a tube with a balloon is inserted into the clogged area and the balloon is then inflated to open the vessel A stent and angioplasty used in combination Preventable risk factors include: Use of tobacco products Drug and alcohol abuse Obesity and a sedentary lifestyle Poor Diet Stress