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c. Given knowledge of the ANS control on heart rate and knowledge that neural in

ID: 3505271 • Letter: C

Question

c. Given knowledge of the ANS control on heart rate and knowledge that neural input from the ANS to the SA node of the heart is tonically active, fill in the table below with your predictions for the effects (use: increase in heart rate, decrease in heart rate, no effect on heart rate) of the ANS agonist drugs on heart rate. Assume you are comparing the drug effect relative to a resting heart rate prior to drug administration.

Agonist drug

Heart rate changes following administration

(Effector tissue is the SA Node)

Alpha-adrenergic

Beta-adrenergic

Muscarinic

d. Explain your answer to the effect of the muscarinic agonist on heart rate.

e. Given knowledge of the ANS control on heart rate and knowledge that neural input from the ANS to the SA node of the heart is tonically active, fill in the table below with your predictions of heart rate changes (use: increase in heart rate, decrease in heart rate, no effect on heart rate) in response to the administration of the antagonist drug. Assume you are comparing the drug effect relative to a resting heart rate prior to drug administration.

Antagonist drug

Heart rate changes following administration

(Effector tissue is the SA Node)

Alpha-adrenergic

Beta-adrenergic

Muscarinic

Nicotinic*

* Think about where these receptors in the ANS are located and what the intrinsic rate of the SA node is (see textbook Chap. 14 for guidance)

f. Explain your answer to the effect of the nicotinic antagonist on heart rate.

Agonist drug

Heart rate changes following administration

(Effector tissue is the SA Node)

Alpha-adrenergic

Beta-adrenergic

Muscarinic

Explanation / Answer

1.alpha adrenergic- no effect

2.beta adrenergeic- increase in heart rate

3.muscarinic-decrease in heart rate

reason- the ach released from vagal stimulation causes decrease in heart rate

antagonist

1.alpha adrenergic- no effect

2.beta adrenergic- decrease heart rate

3.muscarinic- increase heart rate

4.nicotinic- no effect

reason - muscarinic receptors are presentbin heart( not the nicotinic )