Questions and Answers
What is capillary exchange?
What is diffusion in the context of capillaries?
It is an important exchange mechanism used to move glucose and oxygen between blood and tissues, and to move wastes and CO2 between tissues and blood.
What is transcytosis?
It occurs when endothelial cells transport fluid-filled vesicles that contain albumin, fatty acids, or insulin across capillaries.
What is bulk flow?
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What is filtration?
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What does BHP stand for?
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BHP is higher at the venous end of the capillary bed than at the arterial end.
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What is IFOP?
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What is reabsorption?
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What does BCOP stand for?
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IFHP is negligible.
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Net filtration pressure (NFP) is calculated as ______. What does NFP equal?
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The arterial end of a capillary has net outward pressure.
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BCOP is higher at the arterial end of the capillary bed.
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At the venous end of the capillary, fluid moves from the capillary beds into interstitial space.
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About 85% of fluid filtered out of capillaries each day gets ________ into blood.
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What happens to the remaining fluid filtered from capillaries?
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Study Notes
Capillary Exchange Overview
- Movement of substances into and out of capillaries is known as capillary exchange.
- Key mechanisms include diffusion, transcytosis, and bulk flow, facilitating the transfer of nutrients, gases, and waste.
Diffusion
- Diffusion is crucial for moving glucose and oxygen from blood to tissues.
- Also facilitates the transport of waste and carbon dioxide from tissues back to blood.
Transcytosis
- Transcytosis involves endothelial cells transporting fluid-filled vesicles containing substances like albumin, fatty acids, or insulin across capillary membranes.
Bulk Flow
- Bulk flow is a passive process where dissolved substances move between blood and interstitial fluid.
- Filtration moves substances from blood into interstitial fluid, while reabsorption moves them back into blood.
Filtration
- Filtration is influenced by blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure (IFOP).
Blood Hydrostatic Pressure (BHP)
- BHP is generated by the heart's pumping action, creating pressure within the capillaries.
- It is higher at the arterial end of the capillary bed compared to the venous end, promoting fluid movement outward.
Interstitial Fluid Osmotic Pressure (IFOP)
- IFOP helps draw water out of capillaries due to solutes present in interstitial fluid.
Reabsorption
- Reabsorption occurs as a result of colloid osmotic pressure (BCOP) and hydrostatic pressure in the interstitial fluid.
- BCOP draws water into the capillaries because of proteins present in plasma.
Filtration and Reabsorption Dynamics
- The inward pressure at the venous end of capillaries causes fluid to move from the capillary beds into the interstitial space.
- Approximately 85% of the fluid filtered out of capillaries is reabsorbed back into the blood.
Net Filtration Pressure (NFP)
- NFP is calculated using the formula: NFP = (BHP + IFOP) - (BCOP + IFHP), indicating the balance of forces affecting fluid exchange.
Remaining Fluid
- Any remaining fluid that is not reabsorbed is absorbed by the lymphatic system to prevent tissue fluid accumulation and is eventually returned to blood.
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Test your knowledge on capillary exchange with these flashcards. Cover key concepts such as diffusion and transcytosis that are essential for understanding the movement of substances in the circulatory system. Ideal for students studying physiology and related topics.
