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14 Cards in this Set
- Front
- Back
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What are the characteristics of capillaries? |
Simple squamous epithelium waste and hormones can diffuse easily across walls of capillaries- all other BV's are too thick for diffusion There is no smooth muscle so they cannot be innervated by nerves |
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What does the pre capillary sphincter do? |
Can open and close like a faucet Can regulate how fast blood moves through capillaries |
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When ventricles are in systole, what does arterial pressure do? |
Increases |
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What does Autoregulation do? |
maintains homestasis of perameter w/o using neural or endocrine system and maintain local perameters If local cells O2 is low, CO2 high, ph low So these cells need increased blood flow so oxygen can get back up, and release CO2. pH will also rise and become less acidic. So precapillary sphincter will relax and will dilate to allow more blood flow. More blood flow means faster gas exchange so cells can get more oxygen, release CO2 and |
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What happens if pre-capillary sphincter is dialated? |
Increase blood flow thru cap. Beds, raise rate of gas exchange--->Is O2 up, decrease CO2, increase pH |
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What are characteristics of arteries? |
Thicker walls smaller lumen than veins, they hold less blood Harder for arteries to keep a clot because pressure rises in arteries during systole |
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Characteristics of veins? |
Pressure is very low and pressure does not change thin walls, Carry more blood |
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What are the different types of capillary pressures? |
Diffusion Filtration Reabsorption |
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What does Capillary BP do as it moves from arterial end to venous end of a capillary? |
It decreases So, rates of filtration and reabsorption gradually change as blood passes along length of capillary |
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What is Net hydrostatic presssure? |
difference between hydrostatic pressure inside capillary wall and outside |
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What is the difference between hydrostatic pressure and osmotic pressure? |
hydrostatic pressure tends to push water and solutes out of the membrane, while osmotic pressure tends to draw water and solutes back in from interstitial fluid. |
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What happens during capillary filtration? |
Water and small solutes are forced across capillary wall. Larger solutes and suspended proteins are left in bloodstream Takes place primarily at the end of a capillary, where hydrostatic pressure is the highest |
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When does reabsorption occur and will continue until? |
As a result of osmosis. and will continue until solute concentrations are equalized or an opposing hydrostatic pressure prevents movement. |
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How does the nervous system regulate BP? |
?? |
