Question

*Why is the consequence of epinephrine so different for heart cells and liver cells?*

The epinephrine receptors on the surface of their target cells are different.

The epinephrine receptors are more abundant on the surface of heart cells.

The proteins stimulated by the bound epinephrine receptor are different in heart cells and liver cells.

Different amounts of epinephrine reach each different type of target cell.

Answer 1

The consequence of epinephrine differs between heart cells and liver cells due to cell-specific receptors and signaling pathways. In liver cells, epinephrine triggers a pathway that converts glycogen to glucose, increasing available energy for the fight-or-flight response.

Step-by-step explanation:

The difference in the consequence of epinephrine for heart cells and liver cells is due to the distinct cellular response mediated by different receptors and signaling pathways in each cell type. In liver cells, epinephrine binding to β-adrenergic receptors activates a G-protein, which then activates adenylyl cyclase, converting ATP to cAMP. cAMP serves as a second messenger to mediate a cell-specific response—initiating the conversion of glycogen into glucose, thereby increasing blood glucose levels. This specific pathway involves the phosphorylation of enzymes involved in glucose metabolism and ultimately leads to an increase in glucose available to muscles, providing energy for the fight-or-flight response.