32 Questions
Which of the following determines net fluid movement across capillaries?
Hydrostatic and colloid osmotic pressures
What is the main function of the lymphatic system in relation to excess fluid?
Returning excess fluid to circulation
What is the primary factor contributing to fluid filtration across capillaries?
Hydrostatic pressure
What is the primary means of transfer between plasma and interstitial fluid?
Diffusion
Which structures are the major solid components of the interstitium?
Collagen fibers and proteoglycan filaments
What is the abnormal accumulation of fluid in the interstitial space called?
Edema
What regulates blood flow in capillaries through the intermittent contraction of metarterioles and precapillary sphincters?
Vasomotion
Which type of capillary has specific functions and locations, and is one of the three main types mentioned in the text?
Sinusoid
What are the thin-walled vessels composed of a single layer of endothelial cells, facilitating the exchange of O2, CO2, and nutrients?
Capillaries
What is the space between cells containing interstitial fluid, collagen fibers, and proteoglycan filaments called?
Interstitium
What causes the abnormal accumulation of fluid in the interstitial space, often due to increased capillary permeability or impaired lymphatic drainage?
Edema
What is the most important means of transfer between plasma and interstitial fluid?
Diffusion
Which type of capillary has extreme differences in permeabilities among capillaries in different tissues?
Sinusoid
What are the modes of exchange across capillaries mentioned in the text?
Lipid-soluble molecules passing through cells, membrane carriers facilitating ion movement, and transcytosis for large molecules
What are the microcirculation's surface area for solute and fluid exchange in square meters, as mentioned in the text?
500–700
Valves are found in which of the following?
All lymph vessels
The Starling force with the highest outwardly directed filtration pressure is:
Capillary hydrostatic pressure
Most lymph of the body returns to circulation via the:
Thoracic duct
The net filtration pressure is calculated as:
Pc - πp - Pif + πif
What is the approximate normal capillary hydrostatic pressure?
17 mm Hg
What is the approximate normal interstitial fluid pressure in most tissues?
Negative 3 mm Hg
What contributes to lymphatic pumping?
Smooth muscle filaments in lymph vessels
What is the major route for absorption of nutrients from the GI tract?
Lymphatic vessels
What is the primary factor propelling lymph?
Muscle contractions
What is the approximate normal plasma colloid osmotic pressure?
28 mm Hg
What is the approximate normal interstitial colloid osmotic pressure?
8 mm Hg
What opposes filtration by causing osmosis of water inward through the membrane?
Plasma colloid osmotic pressure
Valves are found in which of the following:
All lymph vessels
The Starling force with the highest outwardly directed filtration pressure is:
Capillary hydrostatic pressure
Most lymph of the body returns to circulation via the:
Thoracic duct
What are the thin-walled vessels composed of a single layer of endothelial cells, facilitating the exchange of O2, CO2, and nutrients?
Capillaries
What are the modes of exchange across capillaries mentioned in the text?
Filtration and reabsorption
Study Notes
Formation of Edema in the Interstitium
- The microcirculation consists of over 10 billion capillaries with a surface area of 500–700 square meters for solute and fluid exchange.
- Vasomotion, the intermittent contraction of metarterioles and precapillary sphincters, regulates blood flow in capillaries.
- Capillaries are thin-walled vessels composed of a single layer of endothelial cells, facilitating the exchange of O2, CO2, and nutrients.
- Modes of exchange across capillaries include lipid-soluble molecules passing through cells, membrane carriers facilitating ion movement, and transcytosis for large molecules.
- Three main types of capillaries are continuous, fenestrated, and sinusoid, each with specific functions and locations.
- Substances pass through the endothelium by diffusion and filtration, with diffusion being the most important means of transfer between plasma and interstitial fluid.
- The interstitium is the space between cells, containing fluid called interstitial fluid, with collagen fibers and proteoglycan filaments as the major solid structures.
- The permeability of capillary pores for different substances varies according to their molecular diameters, with extreme differences in permeabilities among capillaries in different tissues.
- The interstitium is primarily composed of gel-like fluid proteoglycan mixtures, with very little free fluid under normal conditions.
- Edema is the abnormal accumulation of fluid in the interstitial space, often caused by increased capillary permeability or impaired lymphatic drainage.
- Excess CO2 in the brain and lack of O2 are key factors influencing capillary flow and vasomotion.
- The diameter of capillaries varies, with different diameters at the arterial and venous ends, affecting the movement of solute and water across the capillary wall.
Learn about the microcirculation, capillaries, different types of capillaries, modes of exchange, interstitium, and the formation of edema. Understand how substances pass through endothelium by diffusion and filtration and the factors influencing capillary flow and vasomotion.
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