maintaining a stable internal environment typically requires

ATI RN

ATI Anatomy and Physiology Online Practice

1. Maintaining a stable internal environment typically requires

A. positive feedback mechanisms.
B. an unstable outside environment.
C. decreased atmospheric pressure.
D. negative feedback mechanisms.

Correct answer: D

Rationale: The correct answer is 'negative feedback mechanisms.' In biological systems, negative feedback mechanisms help maintain homeostasis by counteracting any deviations from the set point. They work to stabilize internal conditions and keep them within a narrow range. On the other hand, positive feedback mechanisms amplify changes and are not involved in maintaining stability. Choice B, 'an unstable outside environment,' is incorrect as internal stability is independent of external conditions like weather. Choice C, 'decreased atmospheric pressure,' is also incorrect as it does not directly relate to internal homeostasis.

2. Which of the following hormones is secreted by the posterior pituitary gland?

A. Growth hormone
B. Luteinizing hormone
C. Adrenocorticotropic hormone
D. Antidiuretic hormone

Correct answer: D

Rationale: The correct answer is D: Antidiuretic hormone. Antidiuretic hormone (ADH), also known as vasopressin, is produced by the hypothalamus and stored in the posterior pituitary gland. It plays a key role in regulating the body's water balance by controlling the amount of water reabsorbed by the kidneys. Choices A, B, and C are incorrect because Growth hormone is produced by the anterior pituitary gland, Luteinizing hormone is produced by the anterior pituitary gland, and Adrenocorticotropic hormone is produced by the anterior pituitary gland.

3. An obstetrician tells a 42-year-old patient that she can have a healthy baby, but that she is of 'advanced maternal age.' The patient is so upset that she fails to listen to the rest of the doctor's advice, goes home in a huff, and immediately dyes her hair.

A. the age of the sperm.
B. the age of her eggs.
C. her risk of developing diabetes.
D. her cholesterol level, not her appearance.

Correct answer: B

Rationale: The correct answer is 'the age of her eggs.' As women age, the quality of their eggs decreases, leading to a higher risk of chromosomal abnormalities and infertility. This decline in egg quality is why advanced maternal age is associated with a higher risk of certain pregnancy complications. Choices A, C, and D are incorrect because the primary concern in this context is related to the age-related changes in a woman's eggs, not sperm, diabetes risk, or cholesterol levels.

4. In negative feedback mechanisms, changes away from the normal state

A. stimulate changes in the same direction
B. inhibit all body reactions
C. stimulate changes in the opposite direction
D. stimulate a reduction in all body requirements

Correct answer: C

Rationale: In negative feedback mechanisms, changes away from the normal state stimulate changes in the opposite direction. This is a fundamental concept in biological systems where the response to a stimulus opposes the initial change, helping to maintain homeostasis. Choice A is incorrect because negative feedback does not stimulate changes in the same direction. Choice B is incorrect because negative feedback does not inhibit all body reactions, but rather specific responses. Choice D is incorrect because negative feedback does not stimulate a reduction in all body requirements, but rather adjusts specific functions to restore balance.

5. What is assimilation?

A. changing absorbed substances into different chemical forms
B. breaking down foods into nutrients that the body can absorb
C. eliminating waste from the body
D. an increase in body size without a change in overall shape

Correct answer: A

Rationale: Assimilation is the process of changing absorbed substances into different chemical forms. It occurs after nutrients from food are absorbed into the bloodstream and used by the body. Choice B, breaking down foods into nutrients that the body can absorb, refers to the process of digestion rather than assimilation. Choice C, eliminating waste from the body, describes the process of excretion. Choice D, an increase in body size without a change in overall shape, does not accurately define assimilation.