MCAT Biology : Hormone Mechanisms and Effects

Study concepts, example questions & explanations for MCAT Biology

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Example Questions

Example Question #81 : Endocrine System

What two hormones have opposite effects?

Possible Answers:

Cortisol and cortisone

Insulin and epinephrine

Calcitonin and parathyroid hormone

Angiotensin I and angiotensin II

Estrogen and progesterone

Correct answer:

Calcitonin and parathyroid hormone

Explanation:

Calcitonin decreases blood calcium levels, while parathyroid hormone increases blood calcium levels.

Example Question #681 : Systems Biology And Tissue Types

All of the following hormones exhibit periods of spiked concentration in the mestrual cycle EXCEPT __________.

Possible Answers:

FSH

prolactin

estrogen

LH

progesterone

Correct answer:

prolactin

Explanation:

FSH, LH, estrogen, and progesterone all increase around ovulation to make an environment in the uterus that will be healthy if fertilization occurs. Prolactin promotes milk production at the end of pregnancy and while a mother is breast feeding a child.

Example Question #682 : Systems Biology And Tissue Types

Antidiuretic hormone (ADH) is released from the posterior pituitary in response to increased plasma osmolarity. It acts on the kidney nephrons to increase water permeability in the distal convoluted tubule and collecting duct. This allows for greater water reabsorption from the filtrate, and results in higher body fluid volume.

Which of the following would NOT be reasonably associated with increased levels of ADH?

Possible Answers:

Increased arterial pressure.

Decreased volume of urine.

Increased solute concentration in the urine.

High levels of atrial naturitic hormone.

Correct answer:

High levels of atrial naturitic hormone.

Explanation:

Release of ADH would not be associated with release of atrial naturitic hormone. ADH increases blood pressure, while atrial naturitic hormone decreases blood pressure.

Example Question #21 : Hormone Mechanisms And Effects

Recall that parathyroid hormone (PTH) is a peptide hormone secreted by the parathyroid glands that serves to increase serum calcium.

Which of the following is not a mechanism by which PTH increases serum calcium?

Possible Answers:

Increased absorption of vitamin D from skin

Increased osteoclast absorption of calcium from bone

Increased calcium uptake from gut

Increased calcium reabsorption by kidneys

Correct answer:

Increased absorption of vitamin D from skin

Explanation:

Parathyroid hormone (PTH) does not enhance absorption of vitamin D through the skin.

It does, however, act independently on the bones, kidneys, and gut, to increase blood calcium. Interestingly, cancer cells in various types of cancers (breast and lung) can secrete parathyroid hormone-related protein (PTHrP), which acts similarly to PTH and can cause hypercalcemia (high serum calcium) in cancer patients.

Example Question #701 : Biology

If an individual with type I diabetes injects themselves with too much insulin, which of the following would be a possible result?

Possible Answers:

Hypoglycemia

Hypocalcemia

Hypercalcemia

Hyperglycemia

Increased urine glucose levels

Correct answer:

Hypoglycemia

Explanation:

Insulin functions to decrease blood glucose levels, causing cells to take up glucose from the blood. If someone takes too much insulin it would result in hypoglycemia, or decreased blood glucose levels. Insulin has no effect on calcium levels. Glucose is rarely found in the urine and can be a sign of extremely high blood glucose levels, or hyperglycemia.

Example Question #21 : Hormone Mechanisms And Effects

What happens to the levels of FSH and LH in a human female, once her ovaries have begun to atrophy during menopause?

Possible Answers:

Levels of FSH and LH both decrease

 

FSH levels increase, while LH levels decrease

Levels of FSH and LH both increase

FSH levels decrease, while LH levels increase

Correct answer:

Levels of FSH and LH both increase

Explanation:

This question requires knowledge of the negative feedback loop between the anterior pituitary hormones (FSH and LH) and the sex hormones (estrogen and progesterone). Prior to menopause, FSH and LH production is inhibited by estrogen production in the ovaries. When ovarian estrogen production decreases, during menopause, FSH and LH levels increase uninhibited.

Example Question #692 : Systems Biology And Tissue Types

A patient goes to his doctor for a normal check-up, and the doctor sees that he ihas very high levels of Na+ and Cl- in his blood.  He runs some tests, and determines that:

Possible Answers:

The patient has high blood pressure caused by underproduction of aldosterone.

The patient has high blood pressure caused by no production of aldosterone.

The patient has high blood pressure caused by overproduction of aldosterone.

The patient has low blood pressure caused by overproduction of aldosterone.

The patient has low blood pressure caused by underproduction of aldosterone.

Correct answer:

The patient has high blood pressure caused by overproduction of aldosterone.

Explanation:

Aldosterone functions to make the collecting duct and distal convoluted tubule in the kidneys to make them more permeable to Na+, Cl–, K+, and H+. When Na+ and Cl– are reabsorbed, water follows them into the blood, thus increasing total blood volume and raising blood pressure.

Example Question #691 : Systems Biology And Tissue Types

An increase in aldosterone will __________.

Possible Answers:

increase water secretion

decrease blood volume

decrease blood osmolarity

increase antidiuretic hormone (ADH) release

decrease sodium reabsoprtion

Correct answer:

increase antidiuretic hormone (ADH) release

Explanation:

An increase in aldosterone will cause an increase in sodium reabsoption, an increase in blood osmolarity, an increase in antidiuretic hormone (ADH) release, an increase in water reabsoption, and an increase in blood volume.

Example Question #701 : Biology

A patient has a condition where the adrenal cortex is unable to be stimulated by adrenocorticotropic hormone (ACTH). Based on this condition, which of the following is true?

Possible Answers:

The patient will have low blood pressure

Sodium levels will be elevated in the blood

Aldosterone secretion will increase

Cortisol secretion will increase

Correct answer:

The patient will have low blood pressure

Explanation:

Addison's disease is a disorder in which the adrenal cortex is unable to be stimulated by adrenocorticotropic hormone (ACTH). The adrenal cortex is responsible for the secretion of aldosterone and cortisol. Aldosterone is responsible for the increased reabsorption of sodium and increased excretion of potassium, leading to water retention. This process helps raise the blood pressure. Since aldosterone is not being adequately produced in a patient with Addison's disease, the patient's blood pressure will be lower than normal.

Example Question #91 : Endocrine System

Which of the following is not a function of estrogen?

Possible Answers:

Increases fat storage

Binds to a DNA hormone response element

Promotes postpartum lactation

Triggers the onset of ovulation

Correct answer:

Promotes postpartum lactation

Explanation:

Estrogen is a very versatile hormone that regulates several biological processes, including structural roles (such as increasing fat stores and developing female reproductive organs) and reproductive roles (such as promoting ovulation and preparing the uterine lining to support a fertilized egg). In order for estrogen to have such diverse effects, it enters the cell and binds to the estrogen receptor. The estrogen-receptor complex translocates to the nucleus and binds to hormone response elements (also call estrogen response elements) to activate target gene expression. Finally, although estrogen plays a role in the differentiation and formation of the milk duct system, following birth estrogen levels are dramatically reduced because high levels of estrogen inhibit lactation.

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