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AP marieb ch19
Anat and phys Marieb chap 19 blood vessels
| Question | Answer |
|---|---|
| 3 types of blood vessels | Arteries Veins Capillaries |
| When do arteries not carry oxygenated blood? | pulmonary circulation, umbilical vessels of fetus |
| All blood vessels have three layers except _______ | capillaries |
| Name the three layers found in arteries and veins | tunica intima, tunica media and tunica externa |
| What is the central space where blood flows through the vessel? | the lumen |
| __________ lines the lumen of all vessels | simple squamous endothelium |
| What is the innermost layer and has intimate contact with the blood. | tunica intima |
| What layer of the blood vessel is circularly arranged smooth muscle cells and sheets of elastin and is responsible for relaxing or constricting based on the body's needs | tunica media |
| What is composed largely of loosely woven collagen fibers that protect and reinforce the vessel. It also anchors the vessels to surrounding structures | tunica externa |
| Why would an artery have a thicker tunica media layer? | Contain muscle and elastic fibers to aid in stretch and withstand pressure |
| Name the three types of arteries | Elastic, muscular and arterioles |
| _____ arteries have large thick walls, elastin in all three tunics, large lumen with low resistence and act as pressure resevoirs | Elastic arteries |
| Elastic arteries are also called the _______ arteries | Conducting |
| ______ arteries deliver blood to organs and have more smooth muscle to aid in vasoconstriction | Muscular |
| Muscular arteries are also called the _______ arteries | Distributing |
| _____ are the smallest arteries, lead to capillary beds, and are associated with peripheral resistance | arterioles |
| Name some characteristics of veins: | Thiner walls and larger lumens than arteries, have thin tunica media but thick tunica externa consisting of collagen fibers, have valves |
| Veins are also called ___________ vessels (blood resevoirs) | Capacitance |
| How do veins serve as blood reservoirs? | They are usually only partially filled |
| _________ are formed when capillary beds unite, are very porous, and have one or two layers of smooth muscle cells | Venules |
| What are venous valves formed from and where are they most abundant and where are they absent? | folds of the tunica intima; in the veins of the limbs, where the upward flow of blood is opposed by gravity; they are absent in veins of the ventral body cavity |
| The venous system contains about what % of the total blood volume? | 65% |
| Name the three types of capilaries | Continuous, Fenestrated, Sinusoidal |
| What are the most permeable capillaries? | sinusoids (wide, tortuous channels) |
| What are the 2nd most permeable capillaries? | fenestrated capillaries |
| What are the most common least permeable capillaries and why? | continuous capillaries, which lack pores |
| What is found on capillaries and aid in the exchange between the blood and interstitial fluid? | clefts |
| What is a cuff of smooth muscle fibers that surround the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary called | precapillary sphincter |
| What do vascular shunts connect? | terminal arteriole and venule at opposite ends of a capillary bed |
| Where are continuous capillaries found? | Skin and muscles and brain |
| Tight junctions in the continuous capillaries of the brain form the _______ | blood brain barrier |
| Sinusoidal capillaries are found in the ______ | Liver, bone marrow, lymphoid tissues, and spleen |
| What removes and destroys any contained bacteria and are found in the lining of the endothelium of the sinusoids in the liver? | Kupffer cells |
| In a capillary bed, what is the vessel structurally intermediate between an arteriole and a capillary? | metarteriole |
| Which circulation system transports oxygen-poor, carbon dioxide rich blood to the lungs for oxygenation and carbon dioxide unloading? | pulmonary circulation |
| Which circulation system transports oxygenated blood from the left ventricle to all body tissues via the aorta and its branches? | systemic circulation |
| What regulates the relative amount of blood entering a capillary bed? | local chemical conditions and arteriolar vasomotor nerve fibers |
| What low-pressure adaptations ensure venous blood is returned to the heart at the same rate it is pumped into the circulation? | large diameter lumens and valves that prevent blood from backflowing |
| What is a homeostatic imbalance of veins that causes them to become tortuous and dilated because of leaky valves? | Varicose veins |
| What are several factors that contribute to varicose veins? | heredity; prolonged standing in one position, obesity, pregnancy; elevated venous pressure |
| What are highly specialized, flattened veins with extremely thin walls composed only of endothelium called and where are they found? | venous sinuses, ie coronary sinus of the heart and dural sinuses of the brain |
| What are alternate blood pathways in case one branch is cut or blocked by a clot, provided by anastomoses called? | collateral channels |
| Where do arterial anastomoses occur? | around joints, abdominal organs, the brain and the heart |
| What is friction encountered by blood in the systemic circulation called and what are the 3 important sources? | peripheral resistance; blood viscosity, vessel length, and vessel diameter |
| What is the internal resistance to flow that exists in all fluids and is related to the thickness or "stickiness" of a fluid? | blood viscosity |
| How is blood flow related to the peripheral resistance in the systemic circulation? | inversely proportional |
| What is the pressure that propels the blood to the tissues called? | mean arterial pressure (MAP) and it is roughly equal to the diastolic pressure plus one-third of the pulse pressure |
| In what 3 ways do veins adapt to venous return to overcome low pressure? | respiratory pump-breathing which squeezes veins & forces blood toward heart;muscular pump-as skeletal muscles surrounding deep veins contract/relax, they 'milk' blood toward heart;layer of smooth muscle around veins that constricts under SNS control |
| Cardiac output (CO) is equal to Stroke volume times what? | heart rate |
| What is normal CO (cardiac output)? | 5.0 to 5.5 L/minute |
| What is usually in charge of heart rate? | cardioinhibitory center in the medulla |
| What nerves maintain the resting heart rate? | parasympathetic vagus nerves |
| During stress, which center take over, activating the sympathetic nervous system and increasing both heart rate (by acting on SA node) and stroke volume (by enhancing cardiac muscle contractility)? | cardioacceleratory center |
| What is the neural center - the cluster of neurons in the medulla - that oversees changes in the diameter of blood vessels called? | the vasomotor center |
| How does the cardiovascular center integrate blood pressure control? | by altering cardiac output and blood vessel diameter |
| How is vasomotor tone achieved in the arterioles? | by impulses transmitted by the vasomotor center, along sympathetic efferents called vasomotor fibers and innervate the smooth muscle of blood vessels, (mainly arterioles) |
| What happens in the carotid sinuses when arterial blood pressure rises? | neural receptors called baroreceptors are stretched, sending a rapid stream of impulses to vasomotor center which results in vasodilation of arterioles and veins and a decline in blood pressure |
| What does a decline in mean arterial pressure (MAP) initiate? | reflex vasoconstriction and increases cardiac output, causing blood pressure to rise. |
| What are regulated together so that changes in blood pressure are minimized? | peripheral resistance and cardiac output |
| What is the function of rapidly responding barorecptors? | to protect the circulation against short-term changes in blood pressure, such as those which occur when you change your posture |
| When do chemoreceptors in the aortic arch and large arteries of the neck transmit impulses to the cardioacceleratory center, to increase cardiac output and to the vasomotor center, which causes reflex vasoconstriction? | when the oxygen content or pH of the blood drops sharply or the CO2 levels rise |
| What are the 2 most prominent chemoreceptors located close by the baroreceptors in the carotid sinus and aortic arch? | carotid and aortic bodies |
| Where are reflexes that regulate blood pressure found? | integrated in the medulla of the brain stem |
| Hormones that affect blood pressure are: | Adrenal medulla hormones - norepinephrine and epinephrine; atrial natriuretic peptide (ANP); ADH(vasopressin); angiotensin II |
| What mechanisms are a long term control of blood pressure? | renal mechanisms |
| How does the direct renal mechanism alter blood volume? dependently or independently of hormones | independently |
| How does the indirect renal mechanism (renin-angiotensin mechanism) alter blood volume? | kidneys release renin into blood which triggers a series of reactions that produce angiotensin II which increasing peripheral resistance via its potent vasoconstriction properties |
| How does aldosterone affect blood pressure? | enhances renal reabsorption of sodium and prods posterior pitutiary to release ADH, which promotes more water reabsorption, causing both blood volume and blood pressure to rise |
| What is hypotension? | low blood pressure - systolic pressure below 100 mm Hg |
| What is orthostatic hypotension? | temporary low blood pressure and dizziness when suddenly arising |
| What can chronic hypotension be a sign of? | Addison's disease; hypothyroidism, or severe tissue wasting. Can be an important signs of circulatory shock |
| What can happen in cases of prolonged hypertension? | heart failure, vascular disease, renal failure, and stroke |
| What factors can contribute to hypertension? | diet; obesity; age (over 40); diabetes mellitus; heredity; stress; smoking |
| How can primary hypertension be controlled? | by restricting salt, fat, and cholesterol intake, losing weight, stopping smoking, managing stress, and antihypertensive drugs (diuretics, beta-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors. |
| What is the function of tissue perfusion? | delivery of oxygen and nutrients to and removal of wastes from, tissue cells, gas exchange in the lungs; absorption of nutrients from digestive tract; urine formation in the kidneys |
| What is the primary role of the sympathetic nervous system in ruling blood vessel diameter? | vasoconstriction |
| What is the dramatically increased blood flow into a tissue that occurs after the blood supply to the area has been temporarily blocked? | reactive hyperemia |
| What organ in the the body is the most metabolically active but the least able to store essential nutrients? | the brain |
| What is the usual result of pressures over 160 mm Hg, which dramatically increases brain capillary permeability? | cerebral edema |
| What is the force exerted by a fluid pressing against a wall? | hydrostatic pressure |
| What is the process of forcing fluids thru the capillary walls via capillary hydrostatic pressure? | filtration |
| What is the force opposing a hydrostatic pressure, created by the presence in a fluid of large nondiffusible molecules such as plasma proteins, called? | colloid osmotic pressure |
| What is the condition called in which blood vessels are inadequately filled and blood cannot circulate normally resulting in inadequate blood flow to meet tissue needs? | circulatory shock |
| What is the most common form of circulatory shock, resulting from large scale loss of blood, as in hemorrhage, severe vomiting or diarrhea or extensive burns? | hypovolemic shock |
| What occurs when the heart is so inefficient that it cant sustain adequate circulation, usually caused by myocardial damage, such as heart attack? | cardiogenic shock |
| What is a degenerative vascular disease that decreases the elasticity of arteries? | arteriosclerosis |
| What is the formation of fatty subendothelial lesions called? | atherosclerosis |
| Where is the steepest drop in BP? | in the arterioles, where resistance is greatest |
| What does arterial blood pressure depend on? | compliance of the elastic arteries and on how much blood is forced into them |
| When does arterial blood pressure peak? | during systole |
| What varies directly with CO (cardiac output), peripheral resistance, and blood volume? | blood pressure |
| How does the vasomotor center regulate blood pressure? | regulates blood vessel diameter |
| How do kidneys regulate low bp? | releasing renin, which triggers the formation of angiotensin II (a vasconstrictor) and release of aldosterone |
| What is the major cause of myocardial infarct, stroke, and renal disease? | hypertension |
| What is considered chronic hypertension? | 140/90 or higher |
| Which other 2 organs are most affected vascularly by chronic hypertension? | eyes and kidneys |
| How do water soluble substances move across capillary walls? | thru clefts or fenestrations |
| Where do fat-soluble substances pass thru the capillary wall? | through the lipid portion of the endothelial cell membrane |
| How are larger molecules transported through capillary walls? | actively transported via pinocytotic vesicles or caveolae |
| What collects the small net loss of fluid and protein into the interstitial space and returns it to the cardiovascular system? | the lymphatic vessels |
| By which week is the fetal vasculature functioning? | the 4th week |
| What results in the failure of vessels to transport blood? | Ischemia |
| Symptoms of blood vessel ischemia | Pain, pulselessness, pallor, parenthesia, paralysis, coolness |
| Definition of blood pressure | The force exerted against the walls of the (large) arteries due to the pumping of the heart |
| Where are baroreceptors located? | Aortic arch, carotid sinus |
| Sensory nerves involved in maintaining BP? | Glossopharyngeal (CN IX) and vagus (CN X) |
| Hormones involved in maintaining BP | Epinephrine and norepinephrine |
| Rapidly acting mechanisms involved in maintaining BP? | Baroreceptors, sensory nerves, medulla oblongata, motor nerves, nor/epinephrine |
| What are slow acting mechanisms? | Hormone regulated long-term maintenance |
| Where is atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) produced? | The heart (also lower BP) |
| What causes vasodilation of vessels of skin? | Temperature elevation |
| When body temp. increases more blood flows to skin thereby releasing: | Heat and lowering body temp |
| When body temp. decreases less blood flows to skin thereby: | Diverting warm blood to core of body |
| With age baroreceptors become less effective. This can result in: | Dizziness and falls |
| With age, increased capillary membrane permeability, there's increased: | Edema formation |
| What areas of the body do not have capillaries? | lens, cornea, cartilage, epithelial layers |
| A cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter? | Vasomotor Center |
| Which of the receptors are located in the carotid sinuses, aortic arch, and walls of the large arteries of the neck and thorax? | Baroreceptors |
| Receptors located in the carotid sinus, aortic arch, and large arteries of the neck? | Chemoreceptors |
| Hormone that causes intense vasoconstriction in the cases of extremely low BP? | Antidiuretic Hormone |
| Hormone that causes blood volume and blood pressure to decline, causes generalized vasodilation? | Atrial Natriuretic Peptide |
| Hormones that cause generalized vasoconstriction and increased cardiac output? | Epinephrine and Norepinephrine |
| Generated by kidney release of renin, causes vasoconstriction? | Angiotensin II |
| Which branch of the autonomic nervous system innervates blood vessels and which layer is innervated? What are the effector cells that carry out the response? | Sympathetic vasomotor, tunica media, smooth muscle |
| The vascular shunt is comprised of the ________ and the ________. | Metarteriole and the thoroughfare channel |
| Short term BP mechanisms are mediated by the NS and blood borne chemicals. This is done via _______, ________, and occassionally __________. | Reflex arcs involving baroreceptors, vasomotor centers of the medulla, and occasionally inputs from chemoreceptors. |
| Long term BP mechanisms are influenced by ______ and ________. | Hormonal controls such as NE, epinephrine, angiotensin II, ANP, ADH; and renal regulation via renin-angiotensin mechanism and aldosterone. |
| List some intrinsic mechanisms of autoregulation of blood flow | (metabolic)amounts of pH, O2, CO2, prostagladins, adenosine, nitric oxide, endothelins and (myogenic) stretch |
| List some extrinsic mechanisms of autoregulation of blood flow | (nerves) sympathetic, (hormones) alpha and beta receptors, angiotensin II, ADH, ANP |
| items that cause vasoconstriction | Sympathetic nervous system, alpha receptors of epinephrine and norepinephrine, angiotensin II, ADH, Endothelins, myogenic stretch |
| items that cause vasodialation | Decrease pH or O2, increase CO2, K, prostoglandins, adenosine, nitric oxide, ANP, beta receptors of epinephrine and norepinephrine |
| Peripheral resistance increases in anemia T/F | False |
| Peripheral resistance is inversely related to the diameter of the arterioles T/F | True |
| A local increase in histamine would not result in the dilation of the feeder arterioles and opening of the precapillary sphincters in systemic capillary beds. | False |
| The presence of ___________ stabilizes the wall of capillaries. | pericytes |
| An elastic lamina on both sides of the tunica media is a characteristic of: | muscular arteries |
| When would the capillary beds surrounding the gastrointestinal organs be open? | during a meal |
| Fluids would be likely to leave or filter out of the capillary if: | net hydrostatic pressure (HP) is greater than net osmotic pressure (OP). |
| Cardiogenic shock is most likely to result from: | multiple heart attacks |
Created by:
hkrawietz
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