- Given knowledge of the ANS control on heart rate and knowledge that neural inp
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Question
- 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
-Explain your answer to the effect of the nicotinic antagonist on heart rate.
Antagonist drug
Heart rate changes following administration
(Effector tissue is the SA Node)
Alpha-adrenergic
Beta-adrenergic
Muscarinic
Nicotinic*
Explanation / Answer
Antagonist Drug
Heart Rate Changes
Alpha – adrenergic
Increase in heart rate
They are also known as alpha blockers which bind to the alpha-adrenergic receptors. This helps in reducing the blood pressure as it prevents the constriction of the arteries and backward movement of the blood via the arteries. They effectively lower the blood pressure but are also known to increase heart rate.
Beta – Adrenergic
Decrease heart rate
The beta blockers are known to reduce blood pressure and it does so by blocking the epinephrine hormones. On taking beta blockers, it leads to slowing of the heart beat and hence reduces blood pressure. It helps the blood vessels to open up and improve blood flow.
Muscarinic
Increase the heart rate
It acts on the activity of the acetylcholine and leads to tachycardia. It improves the atrioventicular conduction and does so by blocking the influence of parasympathetic system on heart.
Nicotinic
Decrease heart rate
It is majorly used for treating hypertensive situation and is known to inhibit acetylcholine which reduces the blood pressure.
The nicotinic antagonists are a treatment which is majorly used as treatment for nicotine. It is a anticholinergic drug which is involved in inhibiting the action of acetylcholine by binding to the nicotinic acetylcholine receptors. It helps in blocking the nicotine receptors and is a possible treatment for nicotine addiction.
Antagonist Drug
Heart Rate Changes
Alpha – adrenergic
Increase in heart rate
They are also known as alpha blockers which bind to the alpha-adrenergic receptors. This helps in reducing the blood pressure as it prevents the constriction of the arteries and backward movement of the blood via the arteries. They effectively lower the blood pressure but are also known to increase heart rate.
Beta – Adrenergic
Decrease heart rate
The beta blockers are known to reduce blood pressure and it does so by blocking the epinephrine hormones. On taking beta blockers, it leads to slowing of the heart beat and hence reduces blood pressure. It helps the blood vessels to open up and improve blood flow.
Muscarinic
Increase the heart rate
It acts on the activity of the acetylcholine and leads to tachycardia. It improves the atrioventicular conduction and does so by blocking the influence of parasympathetic system on heart.
Nicotinic
Decrease heart rate
It is majorly used for treating hypertensive situation and is known to inhibit acetylcholine which reduces the blood pressure.
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