Flashcards in control of arteriolar resistance Deck (15):
what does blood pressure depend on?
MAP= C.O. X TPR
what happens when you decrease TPR
you decrease MAP
You also increases blood flow
What are the extrinsic control systems in the body?
-norepinephrine released from sympathetic nerves binds to b1 receptors
-causes arteriolar constriction
-reduced blood flow, increases TPR
-Epinephrine released from adrenal medulla
-binds to L1 receptors and leads to arteriolar constriction
-in the cardiac muscle and skeletal muscle binds to b2 receptors and leads to arteriolar dilation and therefore increased blood flow and reduced TPR
What are the intrinsic control systems in the body?
-during exercise the concentration of metabolites in the blood increases
-EDFR- endothelium deliberate relaxing factor- is released and diffused into smooth muscle
-Leads to the relaxation of arterioles
-leads to increased blood flow and flushes metabolites away which reduces TPR
-Decrease in MAP- leads to build up of metabolites
-same system as active
-Blockage of a blood system leads to increase in blood flow
what does pressure regulation allow?
Allows the blood supply to match pressure requirement
What does active hyperaemia allow?
Allows blood supple to match metabolic needs
What is injury response
-when damage to the endothelium occurs - factor P is released which leads to the release of histamine
-This leads to arteriole dilation
-increased blood flow and decreased TPR
-increased blood flow to damaged area
What are the system specific mechanisms?
-Pulmonary: areas which are poorly ventilated are constricted
-Cerebral: shows autoregulation as needs to always be stable
An increase blood flow to an area of the body in order to meet metabolic demands
-Coronary blood flow is mainly derived from diastolic Blood flow
-Diastolic blood flow to the coronaries are interrupted during systole
-Very good at active hyperaemia
-Has many beta 2 receptors
-Very sensitive to metabolites especially Adenosine
-When adenosine binds to beta 2 receptors it causes the arterioles to dilate and increase blood flow
Filtration highly affected by blood pressure
When there is a high MAP lots of urine is lost:
-less na+ retention and h20 retention
Flow= difference in pressure/ Resistance
Radius controls blood flow
What is pressure equal to?
CVP: central venous pressure. Very very small so can be omitted