Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?

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"Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown? A - Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP. B-Epinephrine binds to a cell-surface receptor; the activated receptor catalyzes the conversion of glycogen to glucose. C-Epinephrine diffuses through the plasma membrane; the hormone dimerizes in the cytosol. D-Epinephrine is taken into the cell by endocytosis; glycogen is converted to glucose in the endocytotic vesicle"

Answer:

A - Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP

Explanation:

Epinephrine is a neurotransmitter hormone produced and stored by the adrenal medulla that is released after nerve end stimuli.

Usually adrenaline is released into the bloodstream under stress and arousal. It is common for people to start tachycardia, sweating, and pupil dilation in these situations, responses known as fight or flight reactions. Among the actions of adrenaline in the body, we can mention:

→ Increased heart rate;

→ Increased ventricular contraction force;

→ Arteriolar constriction in the skin and abdominal region;

→ Arteriolar dilation in skeletal muscle;

→ Release of fatty acids from adipose tissue;

→ Stimulation of glycogen breakdown and gluconeogenesis (glucose production from non-glycemic precursors), triggering the release of glucose into the circulation. In this case, adrenaline binds to a cell surface receptor; The activated receptor stimulates the production of the second messenger, cAMP.

Answer: Epinephrine triggers the breakdown of glycogen. Athletic activity leads to the release of epinephrine (adrenaline), a catecholamine derived from tyrosine, from the adrenal medulla. Epinephrine stimulates glycogen breakdown in muscle.

Explanation:

The initial step involves the signal molecules epinephrine and glucagon binding to specific 7TM receptors in the plasma membranes of muscle and liver cells, respectively. Epinephrine binds to the β-adrenergic receptor in muscle, whereas glucagon binds to the glucagon receptor. These binding events activate the α subunit of the heteromeric Gs protein. A specific external signal has been transmitted into the cell through structural changes, first in the receptor and then in the G protein.