Q: Which equation correctly represents the calculation of plasma osmolarity?

$$\text{Plasma Osmolarity} = 2 \times [\text{Na}^+] + \frac{[\text{Glucose}]}{18} + \frac{[\text{BUN}]}{2.8}$$

Question 1

Which of the following best describes the role of negative feedback in maintaining homeostasis in the human body?

Accepted Answer

It reverses the direction of change in a variable, bringing it back toward the set point.

Question 2

A patient presents with hyponatremia (low plasma sodium). Which of the following physiological responses would you expect as the body attempts to restore homeostasis?

Accepted Answer

Increased aldosterone secretion to promote sodium reabsorption in the kidneys.

Question 3

Which of the following is the correct order of events in a typical negative feedback loop?

Accepted Answer

Stimulus → Sensor → Integrator → Effector → Response

Question 4

Which equation correctly represents the calculation of plasma osmolarity?

Accepted Answer

$$	ext{Plasma Osmolarity} = 2 	imes [	ext{Na}^+] + \frac{[	ext{Glucose}]}{18} + \frac{[	ext{BUN}]}{2.8}$$

Question 5

A patient is experiencing hyperkalemia (elevated plasma potassium). What effect would this have on the resting membrane potential of neurons?

Accepted Answer

It would depolarize the membrane, making neurons more excitable.

Question 6

Which of the following best describes the function of voltage-gated sodium channels during the action potential?

Accepted Answer

They open during depolarization to allow sodium to enter the cell.

Question 7

Which of the following is a correct statement about the cellular location of receptors for lipid-soluble messengers?

Accepted Answer

They are located in the cytoplasm or nucleus.

Question 8

A patient with diabetes insipidus has a deficiency of antidiuretic hormone (ADH). Which of the following would you expect to find in this patient?

Accepted Answer

Decreased water reabsorption in the kidneys and dilute urine.

Question 9

Which of the following best explains the effect of up-regulation of receptors on a cell?

Accepted Answer

The cell increases the number of receptors, becoming more sensitive to the messenger.

Question 10

Which of the following is the primary mechanism by which glucose is transported into most body cells?

Accepted Answer

Facilitated diffusion via GLUT transporters.

Question 11

A patient is exposed to a cold environment. Which physiological response is most likely to occur as part of homeostatic regulation?

Accepted Answer

Shivering to increase heat production.

Question 12

Which of the following best describes the role of the integrator (control center) in a feedback system?

Accepted Answer

It compares the sensor input to the set point and initiates a response.

Question 13

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

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{out}}{[	ext{ion}]_{in}} ight)$$

Question 14

Which of the following is a characteristic of facilitated diffusion?

Accepted Answer

It moves substances down their concentration gradient using membrane proteins.

Question 15

During the repolarization phase of an action potential, which ion movement is primarily responsible?

Accepted Answer

Efflux of potassium ions ($$	ext{K}^+)$$

Question 16

Which of the following best describes the effect of a hypertonic solution on a red blood cell?

Accepted Answer

The cell will shrink due to water leaving the cell.

Question 17

Which of the following is a correct example of a positive feedback mechanism in the human body?

Accepted Answer

Release of oxytocin during childbirth to intensify uterine contractions.

Question 18

A patient with severe dehydration is likely to have which of the following changes in plasma osmolarity and urine output?

Accepted Answer

Increased plasma osmolarity and decreased urine output.

Question 19

Which of the following best describes the process of signal transduction for a water-soluble hormone?

Accepted Answer

The hormone binds to a membrane receptor, activating a second messenger system.

Question 20

Which of the following is the most immediate effect of opening voltage-gated potassium channels during an action potential?

Accepted Answer

Repolarization of the cell membrane.

Anatomy & Physiology I: Course Structure, Learning Outcomes, and Key Concepts

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