Lecture 4: Hormonal Control Of The Heart

Question 1

What is characteristic of the postganglionic neurons from the adrenal medulla?

Answer 1

No axon - blood used as transport

Question 2

What does an inotropic agent affect?

Answer 2

Contractility

Question 3

What does a chronotropic agent affect?

Answer 3

HR

Question 4

What are the actions of adrenaline?

Answer 4

Adrenaline has positive inotropic and chronotropic action, coronary vasodilation and systemic constriction.

Question 5

Where are beta 1 receptors, what is there effect and what neurotransmitter acts on them?

Answer 5

Nodes and heart muscle
Increase HR and contraction
Respond to adrenaline

Question 6

Where are beta 2 receptors, what is there effect and what neurotransmitter acts on them?

Answer 6

Coronary vessels
Dilation
Respond to adrenaline

Question 7

Where are alpha 1 receptors, what is there effect and what neurotransmitter acts on them?

Answer 7

Heart muscle
Increase contraction
Respond to noradrenaline

Question 8

Where are alpha 2 receptors, what is there effect and what neurotransmitter acts on them?

Answer 8

Systemic Vessles
Constrict
Respond to noradrenaline

Question 9

What does beta-1 do to increase contraction?

Answer 9

Increase calcium current, SR calcium ATPase, SR calcium release

Question 10

What is the beta 1 pathway?

Answer 10

Gas - alpha subunit - adenylyc cyclase - cAMP -PKA activation - faster calcium transients

Question 11

What is the alpha 1 pathway?

Answer 11

Gq
beta&gamma activate PLC PIP2 - DAG & IPS
PKC activated
Increase pH
Increase myofilament calcium sensitivity

Question 12

What is the normal myocyte pH?

Answer 12

7.1

Question 13

How much does beta stimulation increase force?

Answer 13

20%

Question 14

How much is calcium transit increased by beta stimulation?

Answer 14

400%

Question 15

What is endothelin 1?

Answer 15

21 aa peptide

Question 16

Where is ET-1 derived from?

Answer 16

Blood vessel endothelium, endocardial and endothelial cells, fibroblasts

Question 17

What is Ang II?

Answer 17

8 aa peptide

Question 18

What does Ang II do when infused systemically?

Answer 18

Decreases cardiac contractility

Question 19

What does Ang II do when applied to isolated heart muscle?

Answer 19

Increase contraction

Question 20

Where are Ang II and ET-1 both produced?

Answer 20

Heart endocardium

Question 21

What are Ang II and ET-1 produced in response to?

Answer 21

Stretch and other growth mediators

Question 22

What do Ang II and ET-1 activate?

Answer 22

PKC and PKA

Question 23

What happens when there is cardiac overexertion of Ang II?

Answer 23

Myosin heavy chain promoter, normotensive, hypertrophy - increased mortality

Question 24

What does acute Ang II lead to?

Answer 24

Increased pump function

Question 25

What does chronic Ang II lead to?

Answer 25

Decreased pump function

Question 26

What does ANF do?

Answer 26

Decreases how hard the heart pumps - cardiomyocyte relaxation, water excretion, reduced BV

Question 27

Where is ANF synthesises and released from and what is this in response to?

Answer 27

Atria and ventricles in response to stretch

Question 28

What is the ANF signalling pathway?

Answer 28

``` Guanylyl cyclase GTP - cGMP PKG Decrease calcium current and increase SR calcium ATPase Relaxation ```

Question 29

What is IP3 involved in?

Answer 29

Transcription and hypertrophy