Lecture 4: Hormonal Control Of The Heart Flashcards

1
Q

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

A

No axon - blood used as transport

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2
Q

What does an inotropic agent affect?

A

Contractility

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3
Q

What does a chronotropic agent affect?

A

HR

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4
Q

What are the actions of adrenaline?

A

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

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5
Q

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

A

Nodes and heart muscle
Increase HR and contraction
Respond to adrenaline

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6
Q

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

A

Coronary vessels
Dilation
Respond to adrenaline

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7
Q

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

A

Heart muscle
Increase contraction
Respond to noradrenaline

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8
Q

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

A

Systemic Vessles
Constrict
Respond to noradrenaline

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9
Q

What does beta-1 do to increase contraction?

A

Increase calcium current, SR calcium ATPase, SR calcium release

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10
Q

What is the beta 1 pathway?

A

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

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11
Q

What is the alpha 1 pathway?

A
Gq
beta&gamma activate PLC PIP2 - DAG & IPS
PKC activated
Increase pH
Increase myofilament calcium sensitivity
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12
Q

What is the normal myocyte pH?

A

7.1

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13
Q

How much does beta stimulation increase force?

A

20%

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14
Q

How much is calcium transit increased by beta stimulation?

A

400%

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15
Q

What is endothelin 1?

A

21 aa peptide

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16
Q

Where is ET-1 derived from?

A

Blood vessel endothelium, endocardial and endothelial cells, fibroblasts

17
Q

What is Ang II?

A

8 aa peptide

18
Q

What does Ang II do when infused systemically?

A

Decreases cardiac contractility

19
Q

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

A

Increase contraction

20
Q

Where are Ang II and ET-1 both produced?

A

Heart endocardium

21
Q

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

A

Stretch and other growth mediators

22
Q

What do Ang II and ET-1 activate?

A

PKC and PKA

23
Q

What happens when there is cardiac overexertion of Ang II?

A

Myosin heavy chain promoter, normotensive, hypertrophy - increased mortality

24
Q

What does acute Ang II lead to?

A

Increased pump function

25
Q

What does chronic Ang II lead to?

A

Decreased pump function

26
Q

What does ANF do?

A

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

27
Q

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

A

Atria and ventricles in response to stretch

28
Q

What is the ANF signalling pathway?

A
Guanylyl cyclase
GTP - cGMP
PKG
Decrease calcium current and increase SR calcium ATPase
Relaxation
29
Q

What is IP3 involved in?

A

Transcription and hypertrophy