Question 1

Which of the following best describes the concept of homeostasis in human physiology?

Accepted Answer

The maintenance of a constant internal environment despite external changes.

Question 2

A patient is experiencing rapid changes in blood glucose levels. Which type of control system is primarily responsible for the immediate regulation of this parameter?

Accepted Answer

Neural control system

Question 3

Which of the following is an example of antagonistic control in homeostatic regulation?

Accepted Answer

Sympathetic and parasympathetic nervous systems regulating heart rate in opposite directions.

Question 4

During signal transduction, what is the primary function of a second messenger?

Accepted Answer

To amplify the signal inside the cell after the first messenger binds to the receptor.

Question 5

A neuron is exposed to a neurotransmitter that opens potassium ($K^+$) channels. What is the most likely effect on the neuron's membrane potential?

Accepted Answer

The neuron becomes hyperpolarized and less likely to fire an action potential.

Question 6

Which of the following best explains why action potentials are conducted in only one direction along an axon?

Accepted Answer

Voltage-gated sodium ($Na^+$) channels become inactivated after opening, creating a refractory period.

Question 7

Which of the following statements about graded potentials is correct?

Accepted Answer

Graded potentials lose strength as they move through the cell due to current leak and cytoplasmic resistance.

Question 8

A patient with hyperkalemia (elevated plasma $K^+$) is at risk for which of the following changes in neuronal excitability?

Accepted Answer

The resting membrane potential becomes less negative, making neurons more likely to depolarize.

Question 9

Which of the following best describes the process of saltatory conduction?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing conduction speed.

Question 10

Which of the following is a correct statement about the specificity of neural versus endocrine control systems?

Accepted Answer

Neural control is more specific than endocrine control.

Question 11

A ligand binds to a receptor and triggers a cascade that results in the release of intracellular calcium ($Ca^{2+}$). Which of the following is a likely outcome of this signaling event?

Accepted Answer

Activation of protein kinases and changes in enzyme activity.

Question 12

Which of the following best explains the concept of signal amplification in cell signaling?

Accepted Answer

A single ligand-receptor interaction can result in the production of many second messenger molecules.

Question 13

Which of the following is true regarding the duration and speed of neural versus endocrine responses?

Accepted Answer

Neural responses are faster and shorter in duration than endocrine responses.

Question 14

A drug acts as an antagonist at a specific receptor. What is the most likely effect of this drug?

Accepted Answer

It blocks the action of the natural ligand at the receptor.

Question 15

Which of the following best describes the role of Schwann cells in the peripheral nervous system?

Accepted Answer

They form myelin sheaths around axons, increasing the speed of action potential conduction.

Question 16

Which of the following equations best represents the Nernst equation for calculating the equilibrium potential for an ion?

Accepted Answer

$E_{ion} = \frac{61}{z} \log \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$

Question 17

Which of the following scenarios best illustrates the concept of up-regulation in cell signaling?

Accepted Answer

A cell increases the number of receptors on its surface in response to low levels of a hormone.

Question 18

During the rising phase of the action potential, which of the following occurs?

Accepted Answer

Sodium ($Na^+$) moves into the cell down both its concentration and electrical gradients.

Question 19

Which of the following is a characteristic of graded potentials but NOT action potentials?

Accepted Answer

They can vary in amplitude depending on the strength of the stimulus.

Question 20

A patient is given a drug that increases the permeability of neuronal membranes to sodium ($Na^+$). What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential becomes less negative (depolarizes).

Physiology 116: Exam Reflection and Critical Thinking Assignments

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