Capillaries (Smith) Week4 Flashcards
Why is blood velocity low in capillaries?
It is slow or sluggish to allow enough time for gas exchange.
Blood flow is fastest in the aorta and slowest in the capillaries
What is Hydrostatic blood pressure?
Force exerted on the WALL of a blood vessel by blood
-This force is the driving force to move blood from higher to lower pressure areas
How are capillaries involved in regulating body tempurature?
TO release heat, capillaries dialate increasing blood flow to skin which reapidly releases out.
What is a vascular shunt?
Metartiole connection artiole directly with postcapillary venule (bypassing true capillary)
Precapillary sphincter
Smooth muscle surrounding each true capillary, can shunt blood off and on.
Name the 3 exchange mechanisms through capillary
- Diffusion (lipid soluble substances)
- Vesicular transport - Translocation of larger macromolocules i.e. pinocytosis
- Bulk flow - movement of protein free fluid, electrolytes and water soluble substances
What 2 forces drive filtration of bulk flow (starling forces)
- Hydrostatic pressure
2. Oncotic pressure (interstitial fluid)
Briefly describe starlings law
Fluid leaves (filtration)
Fluid re-enters (absorption)
What is the name of the blood that does not get reabsorbed in to the venous end of the capillary?
Insterstitial fluid and is removed by the lymphatic system.
List some characteristics of lymphatic capillaries
Low pressure
wider than blood capillaries
Unidirectional (only towards heart)
What is lymphedemia
Abnormal accumulation of proteins in lymphatic interstitial compartments
Hwat are the 4 potential cause of Edema
Increased blood pressure
decreases oncotic pressure
increased capillary permeabilty
obstruction of lymphatics
