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

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1 Blood Vessels Cardiovascular system Blood The Heart If the heart is the body s pump, then the plumbing is the system of arteries, veins, and capillaries. Blood vessels Types of blood vessels Types of blood vessels Arteries and veins are designed for transporting blood from and to the heart Veins TO the heart Arteries AWAY FROM the heart From the heart 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 Arteries away from the heart Capillaries exchange Veins to the heart Capillaries: Exchange Exchange of oxygen, nutrients, etc 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 Do the real work of the CV system Only blood vessels whose walls permit exchange between the blood and tissue fluid om a rt wastes and nutrients out e ry into capillary To vein To Interstitial fluid ve LM Diffusion of C and Diffusion of Fr in (b) Chemical exchange (a) Capillaries The walls of capillaries are thin and leaky Veins return blood to the heart Walls of veins are thinner than arteries Endothelium Veins: to the heart blood pressure is lower in veins Veins contain valves Connective tissue How can you tell the difference between an artery and vein? Valve (open) Skeletal muscle One-way valves Smooth muscle To heart Veins that carry blood against gravity have valves that keep blood moving toward the heart Surrounding skeletal muscles compress the veins Valve (closed) Two cardiovascular pathways C artery arteriole a. capillary bed precapillary sphincter blood flow elastic tissue endothelium smooth muscle v. valve blood flow Lung C When the precapillary sphincter contracts, it narrows the opening to cap bed and diverts the blood vein Lung Heart -rich blood -poor blood venule v = vein; a = artery C (a) Pulmonary circuit Exchange of and CO 2 C (b) Systemic circuit Exchange of, C, Figure 23.2 nutrients and wastes

3 Another CV pathway: the hepatic portal system Blood supply in the small intestine 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 CV system Features of the Copyright The CV McGraw-Hill Companies, system Inc. Permission required for reproduction or display. Blood pressure moves blood in the arteries 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 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 with cells Magnitude arteries arterioles capillaries venules veins blood total pressure cross-sectional area of vessels velocity Blood Flow What does a blood pressure of 120/80 mean? 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 heart relaxes No sounds (artery is closed) Sounds heard (artery is opening and closing) No sounds (artery is open)

4 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. 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 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

5 Heart failure Disorder: Heart failure Atherosclerosis when the heart no longer pumps properly replacement heart Treatments: Left ventricular assist device (LVAD) Heart transplant either natural or artificial A build up of plaque in blood vessels Associated with a stroke, heart attack and aneurysm plaque coronary artery wireless energy transfer system external internal external rechargable wireless controller battery internal driver pack battery Photograph of artificial heart Artificial heart Artificial heart inside body (right): Courtesy of SynCardia Systems, Inc. Stroke normal artery artery with plaque (plaque): Biophoto Associates/Photo Researchers, Inc.; (normal): Ed Reschke Aneurysm Usually occurs when a cranial artery is blocked or bursts Part of the brain dies dues to lack of oxygen Symptoms include: Dissolving blood clots: t-pa is a drug that dissolves clots Treating clogged arteries: numbness of hands or face difficulty speaking inability to see in one eye How are disorders of the blood vessels treated? Bypass surgery: usually a vein from the leg is used to bypass a clogged artery 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 How are disorders of the blood vessels treated? 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

6 Preventing Cardiovascular Disease Preventable risk factors include: Use of tobacco products Drug and alcohol abuse Obesity and a sedentary lifestyle Poor Diet Stress Bacteria are everywhere; almost all are harmless What are pathogens? Pathogens (Ch. 10) Agents that cause disease Germ theory: diseases are caused by microorganisms ( pathogens ) Very controversial theory at first! Others felt disease was spontaneously generated or inherent within a person Sphere Shaped Rod Shaped Human Cell Less than 0.5% of bacteria cause harm to humans Your body hosts more bacterial cells than human cells! Bacterial cell is ~1/15 the size of a human skin cell Bacteria are everywhere; almost all are harmless Bacteria are responsible for a variety of diseases Tuberculosis Mouth Food poisoning Skin The body contains 10 times more bacteria and other microbes than human cells Intestine Bacterial Cell Strep throat Urinary tract Urinary tract infections

7 Viruses tiny protein shells filled with DNA or RNA Viruses insert their DNA/RNA into nucleus of your cells Viral DNA might remain dormant in cell Human Cell Bacterial Cell Flu virus particle is ~1/15 the size of a bacterial cell Virus Particle Flu viruses use protein spikes to bind to our cells N Spike Protein We identify flu strains by the types of H and N proteins or it might cause your cell to assemble more viruses using its genes Viruses cause most epidemics Polio Chickenpox Swine Flu (H1N1) H protein type 1 N protein type 1 Bird Flu (H5N1) H protein type 5 N protein type 1 Influenza (Flu) Common Cold Herpes RNA H Spike Protein Protein molecules can cause disease Parasites & fungi can also cause disease Ticks, worms, and molds are multicelled parasites that cause disease Misshapen prions cause normal prions to change shape. Malaria parasites are single celled organisms Organelles Cell Membrane Buildup of misshapen prions damages brain, causing mad cow disease or Creutzfeldt-Jakob disease in humans RARE diseases