Blood flow and perfusion Flashcards
Perfusion
Blood flow through tissues and organs
what controls the flow of blood?
pressure - Blood travels down pressure gradient
How is pressure for blood flow created
- heart pumping
- raises aortic pressure
- increases the pressure between the aorta and veins
How much blood needs to pass through tissues
Enough to match the metabolic need for 02
ischaemia
Insufficient 02 to tissues
What is the effect of not enough 02 to tissues
Lowers the pH of cells which will alter the plasma membrane. Can lead to necrosis (death of tissue)
Necrosis from ischaemia is called
infraction
Myocardial infractions
Obstruction of the cardial vessels stopping 02 get to the heart
How is blood flow to tissues and organs regulated?
By monitoring: Temp, 02 drop, C02 incrrease and release of mediators (vasocontrictors)
Controlled by ANS SNS and Endocrine
What forces control the movement of solutes and water between capillaries and interstitial fluid?
Hydrostatic pressure and osmotic pressure
How do hydrostatic and osmotic pressure (OP) effect the movement of water and salutes in capillaries?
At the atrial end of the capillary BP is higher then OP this allows for solutes to leave the capillary into the interstitial fluid. 10mmHG
At the centre of the capillary BP and OP are equal so solutes equally swap in and out of the capillary.
at the venous end OP is higher then BP so only a small er amount of fluid can enter back into the capillary (8mmHg) and the excess enter the lymphatic system
What happens to the excess fluid after been filters by the capillaries?
Will be absorbed by a lymphatic vessel and enter the lymphatic system. and return to the venous circulation via the lymphatic duct.
Where is the lymphatic duct?
The junction of the right subclavian and internal jugular vein and thoracic duct.
