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96 Cards in this Set
- Front
- Back
Blood vessels in adult humans stretch for how far?
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60,000 miles
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Vessel Lumen (arteries) are surrounded by what three layers?
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Tunica interna (intima), Tunica Media and Tunica externa
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Tunica Interna is made up of what?
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simple squamous epithelium
makes it perfect for gas exchange |
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Tunica Media is made up of what?
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smooth muscle
constricts and dilates to REGULATE blood flow |
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Tunica Externa is made up of what?
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collagen connective tissue: hold the structure: mostly in arteries
-veins just mold in with whatever tissue they're in |
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Characteristic of Elastic (conducting) arteries and an example of one...
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large diameter; has the ability to snap back into original shape. aorta and its major branches
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purpose and characteristic of Muscular (distributing) arteries
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deliver blood to organs; proportionately it is the thickest media: distributes by dilating and constricting
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Arterioles....
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-smallest of arteries
-largest of the arterioles have all three tunics -blood flow into capillaries determined by arteriole diameter -distributes to specific tissues by way of capillaries |
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Capillaries...
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-smallest blood vessels
-allow exchange of materials between blood and interstitial fluid -tunica interna ONLY -continuous are most common |
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Two different types of capillaries...
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Fenestrated (oval pores) and Sinusoidal
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Fenestrated...
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-active capillary absorption or filtrate formation
-small intestine, kidneys |
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Sinusoidal...
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-highly modified, leaky
-large molecules, blood cells can pass -liver, bone marrow, lymphoid tissues, some endocrine organs |
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Precapillary Sphincters...
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-control blood route
-rerouting controlled by vasomotor nerve fibers, local chemical conditions |
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Vascular "shunting" is controlled based on....
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waste
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Postcapillary venules, venules...
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extremely porous for white blood cells and fluid to move through
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Pasadence
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the ability to stretch and hold, like a reservoir; a characteristic of veins
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What drives blood through arteries?
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smooth muscle; it constricts and dilates, redirecting blood flow
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what moves blood in veins back to the heart?
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skeletal muscle contraction puts pressure on the veins in order to get the blood moving back to the heart.
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venous valves....
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-prevent backward blood flow
-resemble semilunar valves of heart -most abundant in limbs-to fight gravity -varicose veins result when valves are incompetent |
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Venous sinuses...
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coronary and dural
flattented, extremely thin, supported by tissues around them |
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Vascular Anastomoses
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-occur where vascular channels unite
-provide alternate pathways called collateral channels -found in joints, abdominal organs, brain, heart |
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Arteriovenous anastomoses...
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capillary bed
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Venous anastomoses
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common; visible on back of hand
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Blood Flow
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volume of blood flowing through a vessel, organ, or entire circulation (cardiac output) in a given period
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Blood Pressure
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-force per unit area exerted on the blood vessel wall by its contained blood
-usually means systemic arterial pressure in largest arteries -pressure gradient drives blood movement |
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Resistance...
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-friction or opposition to flow
-mostly occurs away from heart, peripheral resistance |
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Blood viscosity...
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-internal resistance to flow
-related to stickiness of fluid -causes polycythemia and anemia |
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Total blood vessel length; the longer the length the...
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greater the resistance
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Blood vessel diameter...
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-smaller diameter = greater resistance
-resistance varies with the 4th power of the vessel radius |
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Blood flow is directly ________ to difference in blood pressure and ______ proportional to peripheral resistance
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proportional; inversely
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why doesn't the blood pressure come crashing down when the heart is at rest?
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arteriol elasticity; the closing of the artery causes the diastolic pressure
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Systemic blood pressure is _____ in the aorta and _____ in the right atrium
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highest; lowest
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Arterial blood pressure pulsatile...
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-peak is systolic pressure
-diastole, aorta pressure its lowest -diastolic pressure |
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Pulse pressure = ...
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difference between systolic and diastolic pressures
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mean (average) arterial pressure = ...
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diastolic pressure + pulse pressure/3
-drives blood to tissues **2/3 of the hearts time is spent in diastole |
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Blood flow = ...
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blood pressure/resistance (F = P/R)
OR CO x R OR MAP = SV x HG x TPR |
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MAP stands for...
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Mean Arterial Pressure
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TPR stands for...
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Total Peripheral Resistance
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If blood pressure homeostasis is affected, body compensates by changing what two things?
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-peripheral resistance (short term controls)
-blood volume (slower-acting renal mechanisms) |
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Neural controls act on _____ to accomplish what?
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peripheral resistance;
-alter blood distribution -maintain adequate MAP by altering vessel diameter |
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baroreceptors measure blood pressure in _______ if they detect change, they send a message to the _____, smooth muscle ____, increasing _____, increasing blood pressure
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aortas; medulla; increases; resistance
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Vasomotor center (sympathetic neurons in medulla)...
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-oversee changes in diameter of blood vessels
-vasomotor efferents innervate smooth muscle of arterioles praimarily -any increase in sympathetic response increases vasoconstriction and blood pressure |
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Baroreceptors are found where?
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carotid sinuses, aortic arch, walls of large elastic arteries of neck and thorax
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What does the baroreceptor do?
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sends signal to inhibit vasomotor center
peripheral resistance and CO regulated in tandem by baroreceptor inputs they are ineffective at protecting against sustained pressure changes |
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MAP is not a change in pressure because when it kicks in, pressure from the heart is basically _____
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zero
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TPR: what it stands for and definition....
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Total Peripheral Resistance; resistance of all the veins in the systemic system
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Chemoreceptors are located in...
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aortic arch and large arteries of the neck
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How are chemoreceptor s stimulated?
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When oxygen content decreases, pH drops, or carbon dioxide rises
Impulses to cardioacceleratory center to increase CO and to vasomotor center to increase vasoconstriction |
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What do chemoreceptors tell us?
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when to breathe more in order to get rid of waste or bring in more oxygen
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the Hypothalamus mediates what?
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fight or flight response and redistribution of blood flow during exercise/body temperature change
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what are the short term mechanisms?
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adrenal medulla, atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), Angiotensin II, endothelium-derived factors, inflammatory chemicals, alcohol
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How does the adrenal medulla control blood pressure?
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-stress increases epinephrine and epinephrine and NE are released into blood
-NE causes vasoconstriction -Epinephrine increases CO and vasoconstriction but vasodilates skeletal and cardiac muscle |
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how does atrial natriuretic peptide (ANP) effect blood pressure?
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-ANP is produced in atria
-decreases blood volum and blood pressure by forcing kidneys to excrete more sodium and water |
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how does Antidiuretic hormone (ADH) effect BP?
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-ADH is produced in hypothalamus
-stimulates kidneys to conserve water -much released when blood pressure very low -can cause vasoconstriction |
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how does Angiotensin II affect BP?
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-inadequate blood through the kidneys stimulates release of Renin
-Renin causes intense vasoconstriction -stimulates release of aldosterone and ADH (this part is long term) |
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How do Endothelium-derived factors affect bp?
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-vasoconstrictors: endothelin and PDGF
-nitric oxide has major role in producing vasodilation |
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Inflammatory chemicals...
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histamine, prostacyclin; promote capillary permeability
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how does alcohol control BP?
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blood pressure drops by inhibiting ADH release, depressing vasomotor center, skin vasodilation (that's why people who have drank a lot have a red face)
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Long-term mechanisms....
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kidneys regulate blood volume
Direct mechanism and Indirect mechanism |
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How do the kidneys regulate blood volume?
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through the use of ADH and Aldosterone, any increase in blood volume causes increased blood pressure
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how does Direct mechanism work?
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if blood pressure rises-kidneys are unable to filter all of the fluid, more leaves as urine
-blood volume decreases -water is conservedin the converse situation |
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how does Indirect Mechanism work?
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-renin and angiotensin
-decreased blood pressure, kidneys release renin into blood -angiotensin II produced (vasoconstrictor -angiotensin II stimulates adrenal cortex to secrete adosterone (renal reabsorption of sodium) and posterior pituitary to realease ADH |
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Hypotension can indicate...
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poor nutrition, inadequate blood proteins, addison's disease
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if Hypertension continues long term untreated, it can cause...
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heart failure, vascular disease, renal failure and stroke
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how is hypertension treated?
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by controlling factors through drugs that include diuretics, beta-blockers, calcium channel blockers, and ACE inhibitor5s
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What are some secondary causes of hypertension?
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excessive renin secretion, arteriosclerosis, endocrine disorders
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Tissue perfusion refers to...
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blood flow to the tissues
oxygen/nutrient delivery and waste removal from tissues absorption of nutrients from digestvie tract urine formation by kidneys |
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exercise ________ blood flow.
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redistributes
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when blood vessels branch out to capillaries, blood pressure in the capillaries ____. is this good or bad and why?
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drops; good; so that gas exchange can more effectively occur
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Autoregulation....
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automatic adjustment of blood flow to each tissue in proportion to its requirements at any given time
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Organs regulate their own blood flow by varying _____ of their arterioles
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resistance
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organs autoregulate in response to _____ and ____ stimuli
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metabolic; myogenic
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Metabolic Controls (4)....
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-decline in nutrients (oxygen)
-metabolic products (potassium, hydrogen ions, adenosine, lactic acid) -prostaglandins and inflammatory chemicals (histamine, kinins) -trigger vasodilation of arterioles feeding the capillary bed |
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myogenic controls ...
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-keep tissue perfusion constant in spite of varying systemic pressure
-gnerally both metabolic and myogenic controls involved |
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explain how tissue perfusion is kept constant in spite of varying systemic pressure?
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high arterial pressure and perfusion:
passive stretch, vascular smooth muscle resists, causing vasoconstriction, prevents damage converse: reduced stretch promotes vasodilation |
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blood flow in special areas: skeletal muscles...
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-blood flow extremely changeable
-exercise hyperemia -arterioles have cholinergic but alpha and beta adrenergic receptors: cholinergic mediate vasodilation; low epinephrine, binds beta adrenergic receptors and get vasodilation; high epinephrine, binds alpha adrenergic receptors and get vasoconstriction |
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what two hormones come from the adrenergic gland?
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epinephrine and norepinephrine
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if your blood pressure is low, then you need to increase ______. this will ______ everything.
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TPR; constrict
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ischemia: definition...
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a tissue that doesn't receive blood
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Syncope: definition....
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faing, causes you to fall over so that the blood flow doesn't have to work against gravity
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Medullary cardiovascular centers trigger rise in systemic pressure occurs where?
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in the brain
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why would you send more blood to the lungs?
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-in order to conduct gas exchange: opposite from the gas exchange that occurs in the capillaries
-if there is a portion of the lungs that have less oxygen and more carbon dioxide, you want to send less blood there. -vessels will constrict until you ventilate (breathe): once you breathe, the vessels will dilate allowing more blood flow to come in and pick up more oxygen |
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autoregulatory mechanism opposite of other organs occurs where and give details....
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lungs; low oxygen, vasoconstriciton and fits gas exchange role
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vasomotion: definition....
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slow and intermittent blood flow of the capillaries
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Capillary Dynamics: four possible transport mechanisms....
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-intercellular cleft
-simple diffusion -Fenestrations -endo/exocytosis |
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intercellular clefts....
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allows for transport of fluid and solutes dissolved in the fluid from the capillaries and to the tissues and vise versus
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simple diffusion...
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gases can move through the simple squamous epithelium whether there are intercellular clefts or not
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Fenestrations....
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found in the kidneys and small intestines; holes right in the middle of the more permeable capillaries
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Endocytosis...
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when things are just too big to fit through fenestrations,
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transcytosis....
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is the entire mechanism of endo and exo-cytosis: this is very important in the blood brain barrier: not intercellular cleft or fenestration: just simple diffusion and transcytosis: allows for better control
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Bulk fluid flow....
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direction and amount of fluid flow depends upon two opposing forces: hydrostatic pressure (HP) and colloid osmotic pressure (OP)
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NFP = (HP-HP) - (OP - OP)
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net fluid loss or gain determined from net filtration pressure (NFP)
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overall net movement is
_____ to tissues, lymphatics recover |
loss
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what is blood pressure?
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-pushing of blood against the walls of the blood vessels
-blood still has a pressure pushing on the walls of the capillaries -the pressure causes the fluids to be pushed out through the intercellular clefts and fenestrations |
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osmotic pressure...
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pressure determined by the things dissolved in it: moves from high concentration to low.
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water moves from _____ solute concentration to ____ solute concentration
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low; high
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