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The microcirculation and lymphatics
N/A
39
Physiology
Graduate
01/15/2012

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Cards

Term
Microcirculation is defined as extending between what two structures?
Definition
1st order arteriole to 1st order venule with true capillaries in between
Term
Which end of the capillary is most permeable?
Definition
Venous
Term
How are capillaries organized into groups depending on their "leakiness?"
Definition
Continuous, fenestrated, sinusoidal
Term
What is the most common type of capillary? 
Definition
Continuous capillaries
Term
What is the defining feature of continuous capillaries? What is the exceptiion?
Definition
Interendothelial junctions, blood brain barrier has tight junctions instead
Term
What kind of capillaries with thin, perforrated fenestration in endothelial cells are found in surrounding epithelia such as those seen in the small intestines, exocrine glands, and glomerular tufts of the kidney?
Definition
Fenestrated capillaries
Term
Which type of capillaries have large gaps in addition to fenestrae and are primarily found in the sinusoids of the liver?
Definition
Sinusoidal
Term
What term is defined as flow through capillaries?
Definition
Vasomotion
Term
What is the primary regulator of vasomotion?
Definition
Tissue oxygen concentration
Term
What signal increases vasomotion?
Definition
Low tissue oxygen concentration
Term
What formula is used to determine the average amount of flow in capillaries?
Definition
Fick's law of diffusion 
Term
What limits net movement of flow for small molecules diffusing across capillaries?
Definition
Rate of blood flow
Term
What limits the diffusion of larger molecules at capillaries?
Definition
Capillary permeability
Term
What are the solid structures in the interstitium and interstitial fluid?
Definition
Collagen fiber bundles, proteoglycan filaments
Term
What is the difference between gel and plasma?
Definition
Gel has lower concentration of protein, fluid is trapped in the proteoglycan filaments and moves via diffusion
Term
Fluid that is not trapped in the gel is referred to as what?
Definition
Free fluid
Term
What proportion of fluid is "free?" What is the exception?
Definition
1%, except during edema where over half of the fluid is free of the proteoglycan filaments
Term
What is the principles trans-cellular pathway for water?
Definition
Aquaporins
Term
What moves betwee capillary walls via convection driven by what forces?
Definition
Capillary pressure, plasma colloid osmotic pressure, interstitial fluid pressure, and interstitial fluid colloid osmotic pressure
Term
If Pc(capillary pressure) is greater tha Pif(interstitial fluid pressure), what is the result?
Definition
Fluid leaves the capillary
Term
What are the factors that effect P(capillary pressure)? 
Definition
Resistance, change in upstream/downstream pressure, location, gravity
Term
Though interstitial fluid pressure (Pif) is generally close to zero or slightly negative, where must it be positive?
Definition
Rigid compartments like bone marrow or brain, encapsulated organs like kidney
Term
What determines colloid osmotic pressure?
Definition
Plasma proteins and interstitial fluid proteins and proteoglycans
Term
Colloids are defined as what?
Definition
Molecules with MW greater than 30,000
Term
What occurs when pic (plasma colloid osmotic pressure) is greater than piif (interstitial fluid colloid osmotic pressure)?
Definition
Promotes absorption and fluid entering the capillary
Term
What is the principle force of capillary absorption?
Definition
Oncotic pressure
Term
How do you calculate net filteration pressure?
Definition
deltaP - deltaPi: NFP = (Pc-Pif) - (Pic-Piif)
Term
What variation in net filtration pressure exists in interstitial mucosa?
Definition
Pc is much lower than pic, re-absorption occurs continually
Term
What variation in net filtration pressure exists in the kidney glomerular capillary?
Definition
Pc exceeds pic so filtration occurs almost continually
Term
Lymph becomes interstitial fluid once it has entered what?
Definition
Lymphatic vessels
Term
How do lymphatics maintain fluid balance?
Definition
Transports interstitial fluid and proteins back to circulation
Term
How do lymphatics aide in purification and defense?
Definition
Clears extra-cellular space of particulate matter, exudates, and bacteria, also brings immune cells in contact with invaders
Term
How do lymphatics aide in nutrition?
Definition
Absorption of fats from the small intestines
Term
What propels lymph?
Definition
Pulsations of nearby arteries and contractions of smooth muscle
Term
At what end is filtration of lymphatics greatest in microcirculation? What does this permit?
Definition
Arteriolar end, returns excess interstitial fluid to the blood stream
Term
What factors can impact lymph flow?
Definition
Capillary hydrostatic pressure, plasma protein concentration, interstitial protein concentration, capillary permeability, interstitial hydrostatic pressure
Term
What are the different avenues for circulation of extracellular fluid?
Definition
Cardiovascular loop, trans-vascular loop, lymphatic loop
Term
How are most proteins returned to the blood stream?
Definition
Lymphatics
Term
Edema is most commonly the result of increased fluid accumulation in what area?
Definition
Interstitial space, though can also be a result of increased fluid inside of cells
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