Question 1

Which of the following best describes a neurohormone?

Accepted Answer

A chemical messenger produced by neurons, released into the blood via extracellular fluid, and acts on distant target cells.

Question 2

Which of the following is an example of a neurohormone?

Accepted Answer

Antidiuretic hormone (ADH)

Question 3

A lipophobic chemical messenger is most likely to have its receptor located:

Accepted Answer

On the plasma membrane of the target cell

Question 4

Which of the following best explains why lipophilic messengers can have longer-lasting effects than lipophobic messengers?

Accepted Answer

Lipophilic messengers activate gene transcription after binding to intracellular receptors, leading to prolonged changes in cell function.

Question 5

A patient is given a drug that blocks all G-protein-linked receptors. Which of the following effects would most likely be observed?

Accepted Answer

Impaired signal transduction for many lipophobic messengers, leading to reduced cellular responses to neurotransmitters and hormones

Question 6

Which of the following statements about receptor specificity is correct?

Accepted Answer

Each receptor is specific to a particular messenger, allowing only certain messengers to bind and elicit a response.

Question 7

Which of the following best describes the difference between paracrine and endocrine signaling?

Accepted Answer

Paracrine signals act on neighboring cells within the same tissue, while endocrine signals are released into the bloodstream to act on distant targets.

Question 8

A mutation causes a hormone receptor to be permanently located in the cytosol, regardless of the hormone's chemical properties. Which hormone would be most affected by this mutation?

Accepted Answer

A lipophobic hormone such as epinephrine

Question 9

Which of the following is a correct sequence of events for a lipophobic messenger acting on a target cell?

Accepted Answer

Messenger binds to membrane-bound receptor → Activates second messenger system → Alters cell function

Question 10

Which of the following best explains why steroid hormones can cross the plasma membrane?

Accepted Answer

They are lipophilic and can diffuse through the lipid bilayer.

Question 11

A researcher is studying a new hormone that binds to a receptor in the nucleus and alters gene expression. Based on this information, which property is most likely true of this hormone?

Accepted Answer

It is lipophilic and can diffuse through the plasma membrane.

Question 12

Which of the following is a correct example of functional classification of messengers?

Accepted Answer

Hormones can be either lipophilic or lipophobic and act on distant target cells.

Question 13

Which of the following best describes the role of interneurons in the nervous system?

Accepted Answer

They connect afferent and efferent neurons within the central nervous system, integrating information.

Question 14

A patient has a defect in ligand-gated ion channel receptors. Which of the following physiological processes would be most directly affected?

Accepted Answer

Rapid synaptic transmission in neurons

Question 15

Which of the following equations best represents the relationship between a chemical messenger (M), its receptor (R), and the formation of the messenger-receptor complex (MR)?

Accepted Answer

$$M + R \rightarrow MR$$

Question 16

A scientist discovers a new signaling molecule that is hydrophilic, acts locally, and binds to receptors on the plasma membrane. Which type of signaling molecule is this most likely to be?

Accepted Answer

Paracrine signal

Question 17

Which of the following best explains why a single target cell can respond differently to two different messengers?

Accepted Answer

The cell expresses multiple types of receptors, each specific to a different messenger.

Question 18

Which of the following is a correct statement about the organization of neurons in the nervous system?

Accepted Answer

Axons in the central nervous system are grouped into tracts or pathways.

Question 19

A patient is exposed to a toxin that prevents the release of neurotransmitters from presynaptic neurons. Which of the following would most likely occur?

Accepted Answer

Decreased communication between neurons, leading to impaired nervous system function

Chemical Messengers and Receptor Properties in Physiology

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