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98 Cards in this Set
- Front
- Back
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What are the classes of blood vessels?
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Arteries> Arterioles> Capillaries> Venules> Veins
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What is the function of arteries?
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Carry blood away from the heart |
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What is the function of arterioles? |
The smallest branches of arteries |
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What is the function of capillaries? |
Location of exchange between blood and interstitial fluid |
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What is the function of venules?
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Collect blood from capillaries |
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What is the function of veins? |
Return blood to heart
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Where are the largest blood vessels?
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Pulmonary trunk Aorta |
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What is the function of the pulmonary trunk?
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What is the function of the aorta? |
Carries blood from left ventricle to systemic circulation |
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What are the smallest blood vessels?
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-Have small diameter and thin walls -Chemical and gases diffuse across walls |
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What are the basic structures of blood vessels?
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-Tunica interna (intima) -Tunica media -Tunica externa Modifications account for 5 types of blood vessels and their structural/functional differences |
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What are the characteristics of the tunica interna?
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Endothelium continuous with endocardial lining of heart Role in vessel related activities |
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What are the characteristics of the tunica media?
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Greatest variation among vessel types Smooth muscle regulates diameter of lumen |
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What are the characteristics of the tunica externa?`
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-Contains collagen fibers -Elastic fibers In veins -Contains elastic fibers -Smooth muscle cells |
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What is vasa vasorum?
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Small arteries and veins In walls of large arteries and veins Supply cells of tunica media and tunica externa |
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What are the differences between arteries and veins?
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Arteries have thicker walls and higher blood pressure Collapsed artery has small, round lumen Vein has a large, flat lumen Vein lining contracts, artery lining does not Artery lining folds Arteries more elastic Veins have valves |
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What are the functions and structure of arteries?
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Elasticity allows arteries to absorb pressure waves that come with each heartbeat Contractility -Arteries change diameter -Controlled by sympathetic division of ANS Vasoconstriction -The contraction of arterial smooth muscle by the ANS Vasodilation -The relaxation of arterial smooth muscle -Enlarging the lumen |
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How do arteries change from the heart to capillaries?
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From elastic arteries to muscular arteries to arterioles |
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What is the function and structure of elastic arteries?
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Large vessels (e.g., pulmonary trunk & aorta) Tunica media has many elastic fibers and few muscle cells Elasticity evens out pulse force |
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What is the function and structures of muscular arteries?
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Medium sized (most arteries) Tunica media has many muscle cells Capable of great vasoconstriction/dilatation to adjust rate of blood flow |
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What are two examples od muscular arteries?
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Brachial and radial
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What are arterioles?
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Have thin or incomplete tunica media Abundant Metarteriole has precapillary sphincter which monitors blood flow into capillary Local chemical mediators can alter diameter and thus blood flow and resistance Resistance vessels - opposition to blow flow Vasoconstriction can raise blood pressure |
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How does artery diameter affect small muscular arteries and arterioles?
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Constricted arteries oppose blood flow Resistance (R) -Resistance vessels - arterioles |
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What is an aneurysm?
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Pressure may rupture vessels |
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What are the functions of capillaries?
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-Connect arterial outflow and venous return Microcirculation - flow from metarteriole through capillaries and into postcapillary venule Exchange vessels - exchange between blood and interstitial fluid Lacks tunica media & externa |
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What are the affects of capillaries having a lack of a tunica media and externa? |
Capillary beds arise from single metarteriole |
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What is the structure and function of continuous capillaries?
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Are found in all tissues except epithelia and cartilage Functions of continuous capillaries -Permit diffusion of water, small solutes, and lipid-soluble materials -Block blood cells and plasma proteins |
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What are the functions and structures of fenestrated capillaries?
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Permit rapid exchange of water and larger solutes between plasma and interstitial fluid Are found in; Choroid plexus Endocrine organs Kidneys Intestinal tract |
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What are the functions and structures of sinusoids (Sinusoidal capillaries)
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-Liver -Spleen -Bone Marrow -Endocrine Organs Permit free exchange of water and large plasma proteins between blood and interstitial fluid Phagocytic cells monitor blood at sinusoids |
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What are the functions and structure of capillary beds?
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AKA capillary plexus Connect one arteriole and one venule Precapillary sphincter guards entrance to each capillary. Opens and closes, causing capillary blood to flow in pulses Thoroughfare channels Direct capillary connections between arterioles and venules Controlled by smooth muscle segments (metarterioles) |
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What is the structure and function of collaterals?
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Multiple arteries that contribute to one capillary bed allows circulation if one artery is blocked Arterial anastomosis -Fusion of two collateral arteries Arteriovenous anastomoses -Direct connections between arterioles and venules -Bypass the capillary bed |
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What is the structure and function of angiogenesis?
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Vascular endothelial growth factors (VEGF) Occurs in the embryo as tissues and organ develop Occurs in response to factors released by cells that are hypoxic |
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What is the function of capillary pressure and capillary exchange?
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Moves materials across capillary walls by diffusion, filtration, and reabsorption |
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What is diffusion?
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The movement of ions or molecules from high concentration to lower concentration along the concentration gradient |
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What are diffusion routes?
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2. Some ions (NA+, K+, Ca2+, Cl-) Diffuse through channels in plasma membranes 3. Large water-soluble compounds pass through fenestrated capillaries 4. Lipids and lipid-soluble materials such as O2 and CO2 diffuse through endothelial plasma membranes 5. Plasma proteins cross endothelial lining in sinusoids |
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What is filtration?
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Water and small solutes forced through capillary wall Leaves larger solutes in bloodstream |
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What is reabsorption?
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-Blood Colloid Osmotic Pressure (BCOP) --Caused by suspended blood proteins that are too large to cross capillary walls Size increases the interior pressure of capillaries and reduces the tendency of fluids to leak out Fluids are pulled into the capillaries |
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What happens in reabsorption when plasma proteins are low? |
Pressure decreases and capillary filtration increases. This imbalance leads to edema, or excessive fluid build up in the surrounding tissue |
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What is edema? |
Excessive fluid build up in the surrounding tissues |
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How does the interplay between filtration and reabsorption affect the body?
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Has flushing action that carries bacterial toxins and other chemical stimuli to lymphatic tissues and organs responsible for providing immunity to disease |
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What are the structure and function of venules?
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Postcapillary venule - smallest venule Form part of microcirculatory exchange unit with capillaries Muscular venules have thicker walls with 1 or 2 layers of smooth muscle |
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What are the structure and functions of veins?
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Structural changes not as distinct as in arteries Very thin walls in relation to total diameter Same three layers -Tunica interna - thinner than arteries -Tunica media - thinner with little smooth muscle -Tunica externa - thickest layer |
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How does blood move through the veins?
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Two factors assist in movement of blood through veins; veins and muscular contractions |
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What are varicose veins? Besides disgusting...
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When such stretching occurs, the valves of the veins do not function properly, and backflow occurs Common in the legs, from crossing legs or sitting in a chair so that its edge presses against the back of the knees |
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How is the blood distributed?
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-30-35% of blood volume Venous system -60-65% --1/3 of venous blood is in the large venous networks of the liver, bone marrow, and skin |
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What pressure can be measured in the circulatory system?
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Capillary Hydrostatic Pressure (CHP) Venous Pressure |
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Where does blood pressure come from?
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Arterial pressure (mm Hg) |
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Where does capillary hydrostatic pressure come from?
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Pressure within the capillary beds |
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Where does venous pressure come from? |
Pressure in the venous system |
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What is vascular resistance?
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Depends on vessel length and vessel diameter -Adult vessel length is constant -Vessel diameter varies by vasodilation and vasoconstriction --R increases exponentially as vessel diameter decreases |
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What is turbulence in the blood stream?
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Occurs in heart chambers and great vessels Atherosclerotic plaques cause abnormal turbulence |
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What instrument do physicians use to measure blood pressure?
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A Sphygmomanometer |
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What should the normal bp of a resting adult be?
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Under 120/80 |
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What is blood flow?
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The volume of blood that flows through any tissue in a given period of time (in mL/min) |
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How is total blood flow is cardiac output (CO) measured?
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Volume of blood that circulates through systemic (or pulmonary) blood vessels each minute |
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What does the distributions of CO depend on? |
Resistance to blood flow in specific blood vessels -High resistance means lower blood flow |
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How does CO affect blood pressure?
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Changes in CO due to changes in stroke volume or heart rate will affect blood pressure |
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How is blood volume affected by blood pressure? |
Hemorrhage will reduce volume and pressure Blood infusion or eating a lot of salt will increase blood pressure |
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What is peripheral resistance?
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What happens if peripheral resistance increases?
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Blow flow decreases |
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The diameter of the blood vessels is inversely proportional to what? |
The amount of resistance |
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If a blood vessel gets clogged, what happens to the resistance?
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The resistance increases
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Vasoconstriction does what to peripheral resistance? |
Vasoconstriction increases peripheral resistance
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Vasodilation does what to peripheral resistance? |
Vasodilation decreases peripheral resistance |
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Peripheral resistance depends on what?
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Blood viscosity - higher viscosity means higher resistance Blood vessel length - directly proportional to length of vessel -400 miles of additional blood vessels for each 2.2lbs of fat |
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How does the venous return work?
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Occurs due to pressure generated by constriction of left ventricle Small pressure differences from venule (16mmHg) to right ventricle (0mmHg) sufficient |
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Where is blood velocity slowest?
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Where total cross sectional area is greatest |
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As it moves away from the heart, what happens to blood flow?
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It becomes slower
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Why is blood flow slowest in capillaries? |
It aids in exchange |
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How long does it take for one drop of blood to pass from RA, through pulmonary and systemic circulation and back to RA? |
Normally one minute at rest
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How does interconnected negative feedback systems control blood pressure?
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Some act faster than others Some shorter or longer term |
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What does the nervous system control?
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What does the cardiac center do? |
Adjusts the force and rate of heart contractions |
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What does the vasomotor center do?
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Regulates blood pressure by acting on the smooth muscle in the walls of blood vessels (vasoconstriction and vasodilation) |
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What are the two types of reflexes that negative feedback loops from?
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Baroreceptor reflexes Chemoreceptor reflexes |
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How do baroreceptor reflexes affect blood pressure?
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-Carotid sinus reflex helps regulate blood pressure in brain -Aortic reflex regulates systemic blood pressure When bp falls baroreceptors stretched less, slower rate of impulses to CV |
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How do chemoreceptor reflexes affect blood pressure?
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Detect hypoxia (low O2) hypercapnia (high CO2), acidosis (high H+), send signals to CV CV increases sympathetic stimulation to arterioles and veins producing vasoconstriction and an increase in blood pressure Receptors also provide input to respiratory center to adjust breathing rate |
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How do renal controls regulate blood pressure?
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Kidneys release renin, and enzyme that causes the formation of angiotensin- to deal with decrease in blood pressure (vasoconstrictor) |
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Vasoconstriction and the secretion of aldosterone does what?
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Raises blood pressure by increasing water reabsorption in kidneys to raise blood volume and pressure |
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What is ADH? |
A hormone released when blood pressure falls Causes vasoconstriction which increases blood pressure |
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What is Adrenal Medulla Hormone?
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Epinephrine (increases cardiac output) and norepinephrine (vasoconstrictor) |
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What is atrial natriuretic?
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Hormone produced by the atria, it reduces blood volume and blood pressure |
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What is hypotension?
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Low blood pressure (below 100) |
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What is hypertension?
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High blood pressure, a resting pressure over 140-95 |
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What is arteriosclerosis?
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Thickening in the arteries |
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What is atherosclerosis?
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Formation of fatty plaque in the walls
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What is the cardiovascular response to light exercise?
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Venous return increases with muscle contractions Cardiac output rises -Venous return -Atrial stretching |
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How does the cardiovascular system respond to heavy exercise?
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Cardiac output increases to maximum -About four times resting level Restricts blood flow to "nonessential" organs Redirects blood flow to skeletal muscles, lungs, and heart Blood supply to brain is unaffected |
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Regular to moderate exercise does what to the body?
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Lowers total blood cholesterol levels |
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What can happen with intense exercise?
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Can cause severe physiological stress |
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What does it mean when there is vascular supply to special regions?
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Through organs with separate mechanisms to control blood flow Three important examples 1. Brain 2. Heart 3. Lungs |
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Blood flow to the brain is what?
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Top priority |
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Why is blood flow to the brain top priority? |
When peripheral vessels constrict, cerebral vessels dilate, normalizing blood flow |
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What happens during a stroke?
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Blockage or rupture in a cerebral artery Stops blood flow |
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What happens during blood flow to the heart?
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Oxygen demand increases with activity Lactic acid and low O2 levels -Dilate coronary vessels -Increase coronary blood flow |
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What does epinephrine do to blood flow to the heart?
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increases heart rate Strengthens contractions |
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What happens during a heart attacks?
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Its a blockage of coronary blood flow that can cause angina, tissue damage, heart failure, or death |
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How does blood flow to the lungs?
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High O2 content- vessels dilate Low O2 content- vessels constrict |
