7 Flashcards
Function of capillaries
Site of exchange between blood and tissue
Function of capillaries requires
- very thin walls (thick wall make it a barrier to exchange processes)
- large CSA of capillary bed
- slow and moved blood flaw
Large total ____ of the _____ _____ (compared to arteries) means much ________ _____ _______
Latte totals area of capillary bed (compared to arterioles) means much slower blood flow
Strucutre of capillary
Capillary is just a cell (endothelial cell) forming a tube (no imina or media)
- blood cells in single file
Electron microscopy in lumen of capillary - CONTINOUS
8-10 micrometers in diameter
- only one blood cell in single file at once
- this means passage of diffusion is short for oxygen
- intercellular junctions - tight junctions - forms a seal - this depends on how leaky the capillary is
Precapillary sphincters function
- can dial up and dial down how much blood gets to capillary bed
- at inflow sites precapillary sphincters wrap around terminal arteriole - these can constrict prevent blood going into side pathways
- this forms a direct pathway through the vascular shunt to the venuole
- can get partially shut off - its a dial system not on/off - fills half capillary bed
What are precapillary sphincters made of
Precapillary sphincters are composed of smooth muscle cell
- involuntary contraction - smooth muscle - involuntary muscle - under autonomic tone
Terminal arteriolr and postcapillary
The strucurte of capillaries varies according to the ________ of _______ needed, and how _____ the ________ must be
The structure of capillaries varies according to the rate of exchange needed, and how controlled the exchange must be
Which cells of the cell wall do you alter to make the capillary more or less leaky?
Endothelium cells
Three types of capillary structure
- Continuous capillaries (most wide spread)
- Fenestrated capillaries (leaky)
- Sinusoid capillaries (very Leaky)
Continuous capillary
- Intercellular Cleft is tightly fused
- found in skeletal and cardiac muscle
- no adventiia or media
- specific size - efficient diffusion - only one red blood cell
Diameter of continuous capillary
8-10 micrometer diameter
Epithelial cell of lumen determines leakyness by how many tight cells it lays down
Yep
Basement membrane
- layer of extracellular matrix - collagen ( not phospholipid )
- layer of tissue that site around cells and is an anchor point