3.4 Cardiovascular Regulation

Question 1

Two levels of regulation

Answer 1

1) Local: occurs within the tissue

2) Non-local: maintaining body-wide MAP

Question 2

Local control of blood flow through capillaries

Answer 2

Controlled by ARTERIOLES

Question 3

What causes vascular smooth muscle relaxation (local control through capillaries)

Answer 3

Local increases in metabolites generated as waste products of anaerobic cellular respiration / decreases in nutrients

Question 4

What happens after vascular smooth muscle dilation? (local control through capillaries)

Answer 4

Dilation and increased blood flow (Active hyperemia)

Question 5

What does increased dilation and blood flow do?

Answer 5

Reduces SVR if widespread

Question 6

Metabolites with vasodilatory effects

Answer 6

CO2, lactic acid, O2, glucose

Question 7

A(n) ______ in CO2 and lactic acid (decrease in pH) would lead to vasodilation

Answer 7

Increase

Question 8

A(n) ______ in O2 or glucose would lead to vasodilation

Answer 8

Decrease

Question 9

Mechanism of local control though capillaries

Answer 9

Vasodilation follows endothelial cells release of NO (nitric oxide)

Question 10

Essential sensory receptors in cardiovascular reflexes

Answer 10

• Baroreceptors

- Chemoreceptors

Question 11

Baroreceptors

Answer 11

Stretch receptors monitor pressure in large arteries

Question 12

Chemoreceptors

Answer 12

Detect pH (indirectly CO2, O2) in carotid and aortic bodies and medulla oblongata

Question 13

What is the signal integrator of cardiovascular reflexes?

Answer 13

Cardiovascular center in medulla

Question 14

Effectors of cardiovascular reflexes

Answer 14

1) Heart

2) Vascular smooth muscle

Question 15

What does the heart control in terms of blood regulation?

Answer 15

Cardiac output (both HR and SV)

Question 16

What does vascular smooth muscle control in terms of blood regulation?

Answer 16

SVR and CO
Vasoconstriction / vasodilation
Venous return (impacts CO)

Question 17

Vessels innervated by adrenergic fibers…

Answer 17

Vasoconstrict (e.g. vessels to skin, abdominal organs)

Question 18

Vessels innervated by cholinergic fibers…

Answer 18

Vasodilate (e.g. vessels to skeletal muscles, coronary muscles)

Question 19

Vessels innervated by cholinergic fibers…

Answer 19

Vasodilate (e.g. vessels to skeletal muscles, coronary muscles)

Question 20

Two ways of maintaining MAP through cardiac output

Answer 20

• Intrinsic regulation

- Extrinsic regulation

Question 21

Intrinsic regulation

Answer 21

Property of myocardium
Frank Starling Law of the Heart (blood pumps all of the blood that it receives)
-Dependednt on venous return

Question 22

Extrinsic regulation

Answer 22

By ANS

Question 23

How does the sympathetic nervous system increase CO?

Answer 23

Increases SV and HR

Question 24

How does the sympathetic NS decrease CO?

Answer 24

Decreases HR

Question 25

Frank Starling Law of the Heart

Answer 25

Increase in venous return -> Increase in end diastolic volume -> Increase in stroke volume

Question 26

What underlies the Frank-Starling law?

Answer 26

Length-tension relationship in cardiac muscle

Question 27

What does the parasympathetic nervous system use to decrease HR?

Answer 27

Acetylcholine (cholinergic / muscarinic receptors)

Question 28

First way that Acetylcholine decreases HR

Answer 28

Increasing K+ currents
Hyper polarizes
-Pacemaker cells in SA node
-Conductive cells in AV node

Question 29

Second way that acetylcholine decreases HR

Answer 29

Decreasing rate of Na+ leakage, slows the rate that the pacemaker cell reaches threshold

Question 30

How much of an effect does the parasympathetic nervous system have on myocardial contractility (power of muscle contraction)?

Answer 30

Little

Question 31

What does the sympathetic nervous system use to increase HR and force of contraction?

Answer 31

Norepinephrine

Question 32

First way that norepinephrine increases HR

Answer 32

Decreasing / slowing outflow of K+ and depolarizing pacemaker cells in SA node

Question 33

Second way that norepinephrine increases HR

Answer 33

Increases rate of Na+ leakage (speeds rate that pacemaker cells reach threshold)

Question 34

How does norepinephrine increase strength in contraction of heart muscle?

Answer 34

Increasing Ca2+ currents in ventricular myocytes

Question 35

Parasympathetic regulation of systemic vascular resistance

Answer 35

Acetylcholine decreases SVR
Vasodilation of systemic arterioles in organs that assist with resting and digesting
-Constriction in underutilized muscle is controlled locally

Question 36

Effects of norepinephrine and epinephrine in sympathetic regulation of systemic vascular resistance depends on…

Answer 36

Target tissue

Question 37

Acetylcholine receptors in sympathetic nervous system systemic vascular resistance regulation

Answer 37

In arterioles of skeletal, cardiac and pulmonary vascular smooth muscle causes vasodilation in these organs

Question 38

Adrenergic receptors in sympathetic nervous system systemic vascular resistance regulation

Answer 38

Expressed just about everywhere else

• Alpha-adrenergic tend to be vaso-constrictive
• Beta adrenergic tend to be vasodilatory along with Ach

Question 39

Net effect of sympathetic nervous system in systemic vascular resistance

Answer 39

Sympathetic division DECREASES SVR generally in areas of immediate need (muscles) but INCREASES SVR in areas that require lots of blood (liver)