In: Anatomy and Physiology
Which of the following receptors are present on the heart?
β1 (Beta 1) |
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β2 (Beta 2) |
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α1 (Alpha 1) |
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Both β-1 and α-1 |
ANSWER
Beta 1 ( ß1) |
Explanation:
Adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors .These are targets of many catecholamines like norepinephrine and epinephrine produced by the body.Five types of adrenergic receptors (receptors binding epinephrine): α1, α2, β1, β2, and β3.
Beta 1 - Also known as ADRB1 ,which is associated with Gs heterotrimeric G protein that are predominantly present in cardiac tissue. Function : Activation of beta 1 receptor leads to increase in contractile force and heart rate. |
Beta 2 - Also known as ADBR2 , they are expressed mainly in bronchioles of lungs and the arteries of the skeletal muscles.
Function : Cause dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin.
Alpha 1 - Type
of classic postsynaptic alpha receptors . Mainly found on vascular
smooth tissue. Helps in determining arteriolar resistance, venous
capacitance and thus regulating BP.
Function: As alpha receptor is stimulated by epinephrine or norepinephrine, the arteries constrict. This increases the blood pressure and the blood flow returning to the heart.