which structure in the brain regulates sleep and wakefulness

HESI A2

HESI A2 Anatomy and Physiology Quizlet

1. Which structure in the brain regulates sleep and wakefulness?

A. Hypothalamus
B. Thalamus
C. Pineal gland
D. Cerebellum

Correct answer: C

Rationale: The pineal gland, located in the brain, is responsible for regulating sleep and wakefulness by secreting the hormone melatonin. Melatonin plays a crucial role in controlling the sleep-wake cycle, with higher levels at night inducing sleepiness. The hypothalamus (Choice A) regulates various physiological processes but is not primarily responsible for sleep-wake cycles. The thalamus (Choice B) is involved in relaying sensory information but not specifically in regulating sleep. The cerebellum (Choice D) plays a role in coordination and motor control rather than sleep regulation.

2. What are the chemical messengers that control growth, differentiation, and metabolism of specific target cells called?

A. Hormones
B. Neurons
C. Glands
D. Second messengers

Correct answer: A

Rationale: Hormones are signaling molecules produced by glands in multicellular organisms. They travel through the bloodstream to specific target cells where they regulate various physiological processes, including growth, differentiation, and metabolism. Neurons (choice B) are nerve cells that transmit nerve impulses and are not responsible for controlling growth, differentiation, or metabolism. Glands (choice C) produce and release hormones but are not the chemical messengers themselves. Second messengers (choice D) are molecules involved in intracellular signal transduction, not the primary chemical messengers controlling growth, differentiation, and metabolism. Therefore, hormones (choice A) are the correct answer as they match the description provided in the question.

3. How does the lymphatic system work with the circulatory system?

A. The circulatory system produces red blood cells for the lymphatic system.
B. Lymph draws excess fluid from the cells and deposits it into the blood vessels.
C. The heart regulates the production of lymph in the lymph glands.
D. White cells from the lymphatic system eliminate excess red blood cells.

Correct answer: B

Rationale: The lymphatic system works with the circulatory system by draining excess fluid and waste products from the spaces between cells, known as interstitial fluid. This excess fluid, now called lymph, is then transported back into the blood circulation through lymphatic vessels. This process helps maintain fluid balance in the body and supports the circulatory system in regulating blood volume and pressure. Choice A is incorrect because the circulatory system does not produce red blood cells for the lymphatic system. Choice C is incorrect as the heart does not regulate lymph production in lymph glands. Choice D is incorrect as white cells from the lymphatic system do not eliminate excess red blood cells. Therefore, the correct answer is B, as lymph draws excess fluid from the cells and deposits it into the blood vessels, aiding in maintaining proper fluid balance and supporting the circulatory system.

4. What is the main component of the cell membrane?

A. Proteins
B. Carbohydrates
C. Lipids
D. Nucleic acids

Correct answer: C

Rationale: The main component of the cell membrane is the phospholipid bilayer, which is primarily composed of lipids. Lipids form a barrier that separates the interior of the cell from the external environment, providing structural integrity and regulating the passage of substances in and out of the cell. Proteins are also essential components of the cell membrane, serving various functions such as transport, signaling, and cell recognition. Carbohydrates are present in the form of glycoproteins and glycolipids on the cell membrane surface, contributing to cell-cell recognition. Nucleic acids are not a primary component of the cell membrane.

5. Where does primary peristalsis occur?

A. Esophagus
B. Stomach
C. Nervous system
D. Small intestine

Correct answer: A

Rationale: Primary peristalsis occurs in the esophagus. Peristalsis is the coordinated muscular contractions that propel food through the digestive tract. In the esophagus, primary peristalsis is the involuntary wave-like contractions that push food from the mouth to the stomach. It is the natural and automatic process that occurs to facilitate the movement of food during digestion. The stomach (choice B), nervous system (choice C), and small intestine (choice D) are not the primary sites where peristalsis occurs in the digestive system.