MEDICAL PHYSIOLOGY

Detailed explanation-1: -Epinephrine (also known as adrenaline or adrenalin) is a hormone and a neurotransmitter. The model for the action of Epinephrine is shown below. Which of the following best describes a benefit of the many steps involved in a protein kinase cascade? It allows for the activation or inhibition of many enzymes.

Detailed explanation-2: -When activated, adenylyl cyclase converts a large number of ATP molecules into signaling molecules, called cyclic AMP (cAMP). Because cAMP carries the message of the first messenger (epinephrine) into the cell, cAMP is referred to as a second messenger.

Detailed explanation-3: -Which of the molecules are used as second messengers in signal transduction pathways? Adenosine 3’, 5’-cyclic monophosphate (cAMP) acts as a key secondary messanger molecule for various signal transduction pathways.

Detailed explanation-4: -The amino acid-derived hormones epinephrine and norepinephrine bind to beta-adrenergic receptors on the plasma membrane of cells. Hormone binding to receptor activates a G-protein, which in turn activates adenylyl cyclase, converting ATP to cAMP. cAMP is a second messenger that mediates a cell-specific response.

Detailed explanation-5: -Epinephrine activates both Gs and Gi pathways, but norepinephrine activates only the Gs pathway through human beta2-adrenoceptors overexpressed in mouse heart.