Homeostasis MCQs - MCQtimes.com

Homeostasis

Which of the following statements about positive feedback and homeostasis is correct?

They are regulation mechanisms that control most fluctuations in the internal environment of the body.

The response to the stimulus serves to exaggerate the feedback effect.

This type of feedback response only involves an effector not a specific stimulus receptor site.

This feedback mechanism involves adjustments at the organ level but not at the cellular level.

Positive feedback causes the stimulus to increase in magnitude which in turn elicits a more exaggerated response.

Author: rikazzz Comment

Homeostasis

As blood glucose concentration rises, what homeostatic response would the body produce?

Insulin would be released to cause blood glucose to fall.

Glucagon would be released to cause blood glucose to fall.

Insulin would be released to cause blood glucose to rise.

Insulin and glucagon would be released to cause blood glucose to rise.

Homeostasis tends to result in a response that opposes the detected change. So something would be done to arrest the rise in glucose concentration. Insulin is the hormone that causes cells to absorb glucose from the blood.

Author: rikazzz Comment

Homeostasis

What is meant by fluid balance in the body?

Avoiding dehydration

Avoiding overhydration

Replacing the losses via sweating during exercise with balanced electrolyte drinks

Ensuring that water inputs are equal to water losses

Unless water intake via food, drink, metabolic production and intravenous infusion exactly matches losses via sweat, respiration, faeces and urine, etc., the body will either dehydrate or “swell up” with water retention.

Author: rikazzz Comment

Homeostasis

Homeostasis refers to maintaining:

A constant internal body environment through negative feedback

Body conditions relatively constant within a narrow range through negative and positive feedback

Adequate concentrations of respiratory gases

Blood glucose level within the healthy range

The maintenance of body conditions through feedback which is usually negative but is positive in some rare situations.

Author: rikazzz Comment

Homeostasis

What is meant by acid-base balance?

The ability to maintain body solutions as neither acidic nor basic.

The body’s ability to maintain the solutions in the three main compartments at pH 7.4.

The situation where the concentration of hydronium ions equals the concentration of hydroxide ions.

Any excess acid entering or being produced by the body is removed by buffer systems.

The buffers in the body operate to maintain the pH of its aqueous solutions at close to 7.4 (not pH 7.0 as implied by choices A and C). Excess acid is excreted via the lungs and kidneys.

Author: rikazzz Comment

Homeostasis

The term “homeostasis” is described by which one of the following statements? The body’s ability to:

Respond to a stimulus or stress in such a way as to enhance the stress

Maintain a relatively constant internal temperature

Respond to a stimulus or stress in such a way as to reduce the stress

Maintain a relatively constant internal environment

Choice A refers to positive feedback. Choice C refers to negative feedback. Choice B is an example of homeostasis.

Author: rikazzz Comment

Homeostasis

When blood sodium ion concentration moves close to the lower limit of normal (137 mmol/L), what would the body do to maintain homeostasis?

More aldosterone would be released to cause more reabsorption of Na+ from the filtrate.

Additional aquaporins would be inserted in the nephron tubule to allow more water to pass into the filtrate.

More aldosterone would be released to cause more reabsorption of K+ from the filtrate.

Water would move into the intracellular compartment to increase the osmotic concentration of blood.

Homeostasis almost always results in a response that opposes the detected change. Aldosterone promotes the reabsorption of Na+ from the filtrate; this would slow the decline in the blood’s sodium concentration. The other three choices are wrong.

Author: rikazzz Comment

Homeostasis

As the osmotic concentration of blood increases, what homeostatic response would the body produce?

The glomerular filtration rate would increase.

The feeling of thirst would increase so that a liquid with low osmolarity is ingested.

The rate of release of ADH would decrease.

The feeling of satiety would increase so that a low osmolarity liquid is less likely to be ingested.

Homeostasis tends to result in a response that opposes the detected change. So something would be done to reverse the rise in osmotic concentration of blood. Drinking water would do this. The other three choices would not oppose the rise in osmotic concentration.

Author: rikazzz Comment

Homeostasis

Some of the body’s homeostatic responses rely on “negative feedback”. Which of the following happens in negative feedback?

The body ignores changes in a physiological variable that are directed towards the set point for that variable.

The body ignores changes in a physiological variable that are directed away from the set point for that variable.

The body’s response acts to oppose the change in the physiological variable.

The body’s response acts to enhance the change in the physiological variable

“Negative” refers to the response being in the opposite direction to the stimulus. Thus if a variable is increasing, then the body’s response is to produce a change that causes the variable to decrease. The body does not “ignore” stimuli.

Author: rikazzz Comment

Homeostasis

Which of the following would be a negative feedback response by the body to hyperthermia?

Shivering

Sweating

Vasoconstriction of blood vessels in the dermis

An increase in metabolic rate

Hyperthermia is an increase on body temperature above 38 °C. Negative feedback would be a response that opposed the temperature rise. Allowing perspiration to evaporate from the skin would cool the skin and lead to a decrease in body temperature. The effect of the other choices would be to increase body temperature.

Author: rikazzz Comment