intergration of cardivascular mechanisms

Question 1

How is systemic vascular resustance regulated?

Answer 1

By vascular smooth muscle

Question 2

Where is the main site of Systemic vascular resistance?

Answer 2

Arterioles

Question 3

How is SVR increased by vascular smooth muscle?

Answer 3

Contraction of vascular smooth muscles causes vasoconstriction and increases SVR and MAP

Question 4

How is SVR decreased by vascular smooth muscle?

Answer 4

Relaxation of vascular smooth muscles causes vasodilatation and decreases SVR and MAP

Question 5

By which two mechanisms are vascular smooth muscles controlled by?

Answer 5

extrinsic and intrinsic mechanisms

Question 6

What are the three things resistance is reliant on?

Answer 6

length of blood vessels, blood viscosity and radius of blood vessels

Question 7

Resistance to blood flow is: indirectly proportional to blood viscosity and length of blood vessel. True/false

Answer 7

False. Resistance to blood flow is: directly proportional to blood viscosity and length of blood vessel

Question 8

How does radius of blood vessels affect resistance?

Answer 8

The smaller the radius the larger the resistance. Small changes in the radius of the vessels leads to a large change in flow

Question 9

What is vasomotor tone?

Answer 9

The vessels are partially constricted at rest

Question 10

What causes vasomotor tone?

Answer 10

continuous release of noradrenaline by sympathetic nervous system at resting conditions causes vasomotor tone which aids in maintaining our regular BP

Question 11

What effect does decreased vasomotor tone have on vessels?

Answer 11

Causes vasodilation

Question 12

Why is intrinsic control of vascular smooth muscle important?

Answer 12

At different ties you may need different blood flow to different organs. It is the main way in which local control is maintained

Question 13

What components are intrinsic control made of?

Answer 13

chemical and physical factors

Question 14

List the factors that cause vasodilation and metabolic hyperaemia

Answer 14

Decreased local PO2
Increased local PCO2

Increased local [H+] (decreased pH)
Increased extra-cellular [K+]
Increased osmolality of ECF
Adenosine release (from ATP)

Question 15

Other than metabolites, what else causes contraction of smooth muscle?

Answer 15

local humoral agents

Question 16

When are local humoral agents realeased?

Answer 16

in response to tissue injury or inflammation.

Question 17

What are examples of humoral agents that cause vasodilation?

Answer 17

histamine, bradykinin and nitric oxide

Question 18

What is nitric oxide and why is it important?

Answer 18

a gas produced by vascular endothelium. It is a potent vasodilator with a very short life(coupe seconds). It is important in regulation of blood flow and vascular health

Question 19

What are examples of humoral agents which cause vasoconstriction?

Answer 19

serotonin, thromboxane A, leukotrienes and endothelin

Question 20

What can damage to endothelium be caused by?

Answer 20

high Bp, high cholesterol, diabetes and smoking

Question 21

Why is endothelium important?

Answer 21

It is important in the maintenance of vascular health. It has a lot of functions and is not just a lining. Damage to it can cause many cardiovascular diseases.

Question 22

What are examples of endothelial produced vasodilators?

Answer 22

anti-thrombotic, anti-inflammatory, anti-oxidants

Question 23

What are examples of endothelial produced vasoconstrictors?

Answer 23

are pro-thrombotic, pro-inflammatory, pro-oxidants

Question 24

What are the effects of temperature on vascular smooth muscle?

Answer 24

cold causes vasoconstriction and warmth causes vasodilation

Question 25

What effect does the myogenic response have on vascular smooth muscle?

Answer 25

If MAP rises resistance vessels automatically constrict to limit flow If MAP falls resistance vessels automatically dilate to increase flow

Question 26

What is the effect of sheer stress on vascular smooth muscle?

Answer 26

Dilatation of arterioles causes sheer stress in the arteries upstream to make them dilate. This increases blood flow to metabolically active tissues

Question 27

What is the normal range for MAP?

Answer 27

70-105

Question 28

Does the brain usually participate in baroreceptor response?

Answer 28

No. Myogenic response regulates blood flow in important organs like the brain by keeping the blood flow constant despite changes in MAP.

Question 29

What does increased venomotor tone increase?

Answer 29

venous return. stroke volume and MAP

Question 30

What does vasomotor tone increase?

Answer 30

Systemic vascular resistance and MAP

Question 31

What does muscle activity increase?

Answer 31

Venous return to the heart via contraction of muscles.

Question 32

What are the acute CVS responses to excerise?

Answer 32

- increased sympathetic activity - increased HR and SV - reduced flow to kidneys and gut - increased flow to skeletal and cardiac muscles - increased systolic but equal/lowered diastolic

Question 33

What causes post exercise hypotensive response?

Answer 33

pooling of blood into beds with vasoconstricted areas

Question 34

What are the chronic CVS responses to exercise?

Answer 34

- reduction of sympathetic - incread parasympathetic tone to heart - cardiac remodelling - reduced plasma renin levels - reduced arterial stiffening - more vasodilators less vasoconstrictors