Mechanism of Hormone Action

The video explains how hormones in the human endocrine system recognize and act on their target cells through specific receptors. It distinguishes between steroid and non-steroidal hormones, detailing their mechanisms of action. Steroid hormones, like estrogen, are lipid-soluble and act by entering cells and influencing gene expression. Non-steroidal hormones, such as epinephrine, are lipid-insoluble and rely on transmembrane receptors and second messengers like cAMP to exert their effects. The video also touches on how these processes are regulated and the impact of external factors like toxins.

What ensures that hormones act only on their specific target cells?

• The presence of specific hormone receptors

• The temperature of the body

• The size of the hormone molecules

• The speed of hormone circulation

Where are the receptors for steroid hormones like estrogen typically located?

• On the mitochondria

• On the cell surface

• In the cytoplasm or nucleus

• In the bloodstream

What is the role of the hormone-receptor complex in the action of steroid hormones?

• It deactivates the hormone

• It transports the hormone out of the cell

• It activates specific genes

• It breaks down the hormone

Which of the following acts as a second messenger in the action of epinephrine?

• ATP

• cAMP

• DNA

• RNA

What enzyme is activated by cAMP in the action of non-steroidal hormones?

• Adenylyl cyclase

• Glycogen synthase

• Protein kinase A

• Phosphodiesterase

How is the effect of cAMP reversed in the cell?

• By the enzyme phosphodiesterase

• By decreasing ATP levels

• By activating more receptors

• By increasing hormone concentration

What effect does the cholera toxin have on intestinal cells?

• It enhances protein synthesis

• It blocks hormone receptors

• It increases cAMP production

• It decreases cAMP production