Integration of cardiovascular mechanisms

Question 1

What does MAP equal?

Answer 1

CO x TPR

Question 2

What are the three things that regulate stoke volume?

Answer 2

Pre-load
Myocardial contractility
Afterload

Question 3

How is total peripheral resistance regulated?

Answer 3

Control of vascular smooth muscle through intrinsic and extrinsic mechanisms

Question 4

What is the main site of TPR?

Answer 4

Arterioles

Question 5

What is TPR?

Answer 5

The total periphery resistance in the blood pressure across the body

Question 6

What is resistance to blood flow proportional to?

Answer 6

Directly proportional to blood viscosity and the length of blood vessels
Inversely proportional to the radius of the blood vessels

Question 7

What is the equation for resistance to blood flow?

Answer 7

R (fish sign) (n.L)/ r4

Question 8

Explain the nervous extrinsic control of vascular smooth muscle

Answer 8

Baroreceptor reflex

Sympathetic nerve fibres - noradrenaline and a receptors

Question 9

What term described the vascular smooth muscles being partially constricted at rest?

Answer 9

Vasomotor tone

Question 10

What is the result of increased vasomotor tone?

Answer 10

Vasoconstriction

Question 11

What is the hormone involved in extrinsic control of vascular smooth muscle?

Answer 11

Adrenaline from the adrenal medulla

Largely organ specific effect

Question 12

What receptor does adrenaline act on to cause vasoconstriction and where are these receptors predominant?

Answer 12

a receptors

Skin, gut and kidney arterioles

Question 13

What receptor does adrenalin act on to cause vasodilation and where are these receptors predominant?

Answer 13

B receptors

Cardiac and skeletal muscle arterioles

Question 14

Name two hormones, other than adrenalin, that affect vascular smooth muscle

Answer 14

Angiotensin II (vasocontriction)
Antidiuretic hormone (vasoconstriction)

Question 15

Give 5 metabolic changed within an organ that cause vasodilation

Answer 15

Decreased local PO2
Increased PCO2
Increased local [H+] 
Increased extra-cellular [K+] 
Increased osmolality of ECF 
Adenosin release

Question 16

Give 4 humoral agents that cause relaxation of arteriolar smooth muscles causing vasodilation

Answer 16

Histamine
Prostaglandins
Bradykinin
Nitric oxide

Question 17

Where is NO produced?

Answer 17

Vascular endothelium

Question 18

What enzyme is involved in the formation of NO?

Answer 18

Nitric Oxide Synthase (NOS)

Question 19

When NO diffuses into smooth muscle cells what does it activate?

Answer 19

The formation of cGMP

Question 20

Give four humoral agents that cause vasoconstriction

Answer 20

Serotonin
Thromboxane A2
Leukotrienes
Endothelin

Question 21

What is the affect of cold on the vascular smooth muscles?

Answer 21

Causes vasoconstriction

Question 22

What is the myogenic response to stretch?

Answer 22

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

Question 23

Name two organs where myogenic response to stress is important

Answer 23

Kidney and brain

Question 24

Explain the effect of sheer stretch on vascular smooth muscles

Answer 24

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

Question 25

Give 4 factors that increase venous return

Answer 25

Increased venomotor tone Increased blood volume Increased skeletal muscle pump Increased respiratory pump

Question 26

What does venomotor mea?

Answer 26

Controlling dilation or constriction of the veins

Question 27

What is the affect of increased venomotor tone?

Answer 27

Increased venous return, SV and MAP

Question 28

What is the affect of increased vasomotor tone?

Answer 28

Increased TPR and MAP

Question 29

What is the affect of muscle activity on venous return to the heart?

Answer 29

Increases venous return to the heart