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35 Cards in this Set
- Front
- Back
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what controls capillary blood flow?
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- arteriole tone
- precapillary sphincters in metarterioles |
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how do gases and other lipid-soluble solutes get across capillary wall?
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simple diffusion
- concentration gradient - large surface area |
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how do water-soluble solutes get across capillary wall?
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clefts between endothelial cells
- smaller surface area - osmosis |
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how do proteins cross capillary wall?
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small proteins through fenestrations (pores) or pinocytotic vesicles (caveolae)
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what do hydraulic pressures promote?
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- fluid movement from high to low pressure
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what do oncotic pressures promote?
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- pulls fluid to higher protein concentration (oncotic pressure)
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Net fluid movement equation
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Jv = Kf [(Pc-Pi) - (pic-pii)]
+ filtration - absorption Kf - hydraulic conductance |
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what are the driving forces for lymph flow
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smooth muscle contraction in lymphatic vessels and contraction of surrounding skeletal muscle
- one way valves |
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4 causes of edema
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1. increased Pc
2. decreased PIc 3. increased Kf 4. impaired lymph drainage |
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how does myogenic hypothesis related to maintaining constant blood flow?
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an increase in pressure produces reflex constriction so blood flow is not altered
- opposite happens too Q = P / R |
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blood flow proportional to metabolic activity
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active hyperemia
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increased blood flow after a period of decreased flow or occlusion
- accumulation of oxygen debt, repaid after occlusion removed |
reactive hyperemia
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spontaneous increase in Pa does what to vasodilator metabolites?
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washes them out, causing vasoconstriction
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vasodilators
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* histamine (arterioles)
* adenosine * some PG * ANP |
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vasoconstrictors
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* histamine (venules)
* serotonin * bradykinin (venules) * some PG * angiotensin II * ADH |
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control of coronary circulation
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LOCAL
- hypoxia - adenosine vasodilate and increase blood flow |
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control of cerebral circulation
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LOCAL
- CO2 - H+ vasodilate and increase blood flow |
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control of skeletal muscle during exercise
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LOCAL
- lactate, K+, adenosine - vasodilation E --> Beta2 --> vasodilation (sans, secondary) |
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skeletal muscle at rest controlled by...
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SANS
- vasoconstriction - NE --> alpha 1 |
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control of skin circulation
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SANS
- vasoconstriction - NE --> alpha1 HEAT-vasodilation |
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normal body temp ranges
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97-99 F
higher with exercise lower in the am |
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mechanisms for generating or preserving heat
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* increased basal metabolic rate - thyroid hormone
* SANS -cutaneous vasoconstriction A1 & thermogenesis B1 * Shivering |
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mechanisms for dissipating heat
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* SANS - decreased - vasodilation; increased - sweat glands
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Heat exhaustion
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high environmental temps
sweating lowered ECF lowered BV low Pa --> fainting, exhaustion, hypovolemic shock |
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heat stroke
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heavy exercise - high body temperatures
tissue damage inability to dissipate heat hotter *N/V, delirium, LOC, sweating, circulatory shock |
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how do pyrogens cause fever?
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PG to hypothalamus to raise set point
body starts heat generating mechanisms |
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chills: or heat generating mechanisms of fever
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1. vasoconstriction
2. piloerection 3. epinephrine 4. shivering |
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how is fever reduced?
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infection clears, set point is lowered
heat dissipating mechanisms * vasodilating * sweating |
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what do cyclooxygenases inhibitors do?
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decreases synthesis of PG in anterior hypothalamus
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how does exercising a small muscle effect arterial pressure?
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increases Pa
CO and TPR |
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how does exercising whole body effect arterial pressure?
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CO is greatly increased
TPR decreased Pa slightly increased |
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during exercise what happens to arteries and veins?
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arteriole vasoconstriction - nonexercising (SANS)
arteriole vasodilation - skeletal muscle & cutaneous venoconstriction - SANS increases CO no constriction in coronary or cerebral |
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how does exercise effect CV function curves?
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Cardiac - rotates upward - decreased TPR and increased SANS
vascular - rotates upward - decreased TPR; shifts R - venoconstriction and compression of blood vessels |
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main point about response to hemorrhage before and after compensation?
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CO increases after compensation
but doesn't get as high as it was before hemorrhage |
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what decreases during hemorrhage response?
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unstressed volume
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