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Flashcards in control of arteriolar resistance Deck (15):
1

what does blood pressure depend on?

MAP= C.O. X TPR

2

what happens when you decrease TPR

you decrease MAP
You also increases blood flow

3

What are the extrinsic control systems in the body?

Neural:
-norepinephrine released from sympathetic nerves binds to b1 receptors
-causes arteriolar constriction
-reduced blood flow, increases TPR

Hormonal:
-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

4

What are the intrinsic control systems in the body?

Active Hyperemia:
-during exercise the concentration of metabolites in the blood increases
-EDFR- endothelium deliberate relaxing factor- is released and diffused into smooth muscle
-contains NO
-Leads to the relaxation of arterioles
-leads to increased blood flow and flushes metabolites away which reduces TPR

Pressure regulation:
-Decrease in MAP- leads to build up of metabolites
-same system as active

Reactive hyperaemia:
-Blockage of a blood system leads to increase in blood flow

5

what does pressure regulation allow?

Allows the blood supply to match pressure requirement

6

What does active hyperaemia allow?

Allows blood supple to match metabolic needs

7

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

8

What are the system specific mechanisms?

-Coronary
-Pulmonary: areas which are poorly ventilated are constricted
-Renal
-Cerebral: shows autoregulation as needs to always be stable

9

define hyperaemia

An increase blood flow to an area of the body in order to meet metabolic demands

10

Coronary regulation

-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

11

Renal autoregulation

Filtration highly affected by blood pressure
When there is a high MAP lots of urine is lost:
-less na+ retention and h20 retention

12

Darcy's Law

Flow= difference in pressure/ Resistance

13

Poiseuille's law?

Radius controls blood flow

14

What is pressure equal to?

MAP- CVP
CVP: central venous pressure. Very very small so can be omitted

15

How to increase MAP

-Venoconstriction and arteriole constriction- sympathetic release of epinephrine on alpha receotors
-Increase HR
-Increase SV