Microcirculation Flashcards
Functions of microcirculation:
-transport nutrients
-remove waste products
-maintain homeostasis
What are the vessels involved in microcirculation?
Arterioles, venules, capillaries
What are AV shunts?
Direct connections between and arteriole and a venule without passing through the capillary bed
Where are AV shunts located?
Palm, soles, nose, lip, penis tip
Continuous capillaries:
-Non-fenestrated
-muscle, skin, fat, nervous tissue
Fenestrated capillaries
-have pores for diffusion across endothelial lining
-kidneys, intestines, endocrine glands
-in the BBB
Sinusoidal capillaries:
-thin-walled with large lumen and larger gaps
-bone marrow, liver, spleen
What fluid is filtered in the capillary beds of the tissues?
Interstitial fluid
How do lipid-soluble substances cross capillary wall?
Diffuse directly through the membrane
How to lipid-insoluble substances cross capillary wall?
Diffuse across using intercellular clefts
Interstitium
Space between cells
Interstitial fluid
Fluid within the spaces of interstitium
Where is lymph derived from?
Interstitial fluid
How would interstitial fluid pressure be increased?
By increasing the lymph flow
What does capillary hydrostatic pressure cause?
-forces fluid out of the capillary membrane
-decrease arteriole resistance
-increase venous pressure
What is interstitial fluid pressure do?
Opposes filtration from capillary
What does plasma osmotic pressure do?
Opposes filtration that causes osmosis of water into the capillary membrane
What factors increase plasma colloid osmotic pressure?
Cirrhosis, nephrosis, dilutional
Interstitial fluid osmotic pressure does what?
Promotes filtration by causing osmosis of fluid out of the capillary
What does an imbalance of determinants lead to?
Edema
What system is responsible for edema?
Lymph
What is edema?
Excessive fluid in interstitial compartment between cells
What does edema cause?
-Increased capillary pressure
-loss of plasma proteins
How does ADH control fluid balance ?
By promoting reabsorption of water into the blood from kidney and tubules
