16. The Endocrine System

For a nerve impulse to travel from one neuron to another, the signal must be transmitted across a synapse. At the synapse, the axon releases a neurotransmitter that then diffuses across the synapse and activates receptors on the subsequent dendrite. While this is an example of a nervous signal using a neurotransmitter, the action of neurotransmitter at a synapse is also sometimes considered an example of what other type of signaling?

Epinephrine (also known as adrenaline) is produced by your adrenal cortex during stressful situations. The adrenal cortex is part of the adrenal gland, located just superior to the kidneys. One of the targets for adrenaline is the heart, where it increases the heart rate. Based on this description, what type of signaling molecule is adrenaline?

Between the statements below, which one correctly describes a significant difference between how the endocrine and nervous systems function?

True or False: if false, choose the answer that best corrects the statement.

Target cells can be defined as cells that possess a receptor that binds a particular hormone.

Ghrelin is a hormone produced in the stomach with target cells in the anterior pituitary. Its release is associated with feelings of hunger, and its release is lowest immediately after eating. Considering this, why do you think the stomach is not usually considered as an organ of the endocrine system?

Which statement below correctly identifies the difference between the endocrine system and other body systems?

Insulin operates by activating a receptor on the outside of the target cell. Based on your knowledge of hormone types, do you expect insulin to be an amino acid-based hormone or a steroid hormone, and why?

Why do steroid hormones use a transport protein?