HESI A2
Anatomy HESI A2
1. What structure links the nasopharynx to the middle ear?
- A. Larynx
- B. Pharyngeal muscles
- C. Eustachian tube
- D. Bronchus
Correct answer: C
Rationale: The Eustachian tube is the structure that connects the nasopharynx to the middle ear. It functions to equalize pressure between the middle ear and the atmosphere, protecting the eardrum from damage and aiding in the drainage of fluid from the middle ear. This connection is essential for maintaining proper ear function and health. The larynx (Choice A) is not the correct structure that links the nasopharynx to the middle ear. Pharyngeal muscles (Choice B) are involved in swallowing and do not directly link the nasopharynx to the middle ear. The bronchus (Choice D) is part of the respiratory system and is not connected to the middle ear.
2. How does a sagittal section divide the body?
- A. Into right and left regions
- B. Into upper and lower regions
- C. Into front and back regions
- D. Between the dorsal and ventral cavities
Correct answer: A
Rationale: A sagittal section divides the body into right and left regions. This type of section runs longitudinally from front to back, separating the body into right and left halves. Sagittal sections are crucial for understanding the anatomical structure and orientation of various body parts. Choices B, C, and D are incorrect because a sagittal section specifically divides the body into right and left portions, not upper and lower regions, front and back regions, or between the dorsal and ventral cavities.
3. If an impulse is traveling from a sense receptor toward the spinal cord, it is traveling along what type of neuron?
- A. Motor neuron
- B. Sensory neuron
- C. Interneuron
- D. Bipolar neuron
Correct answer: B
Rationale: The correct answer is B: Sensory neuron. A sensory neuron is responsible for carrying impulses from sensory receptors to the spinal cord. These neurons transmit information about external stimuli from the periphery to the central nervous system for processing and response. Choice A, Motor neuron, is incorrect as motor neurons carry signals from the central nervous system to muscles and glands, enabling movement and secretion. Choice C, Interneuron, is incorrect as interneurons act as connectors between sensory and motor neurons, primarily facilitating communication between the two. Choice D, Bipolar neuron, is incorrect as bipolar neurons are specialized sensory neurons found in some sensory organs like the retina of the eye and the olfactory epithelium.
4. Which hormone is involved in regulating the sleep-wake cycle?
- A. Insulin
- B. Melatonin
- C. Cortisol
- D. Thyroxine
Correct answer: B
Rationale: The correct answer is B: Melatonin. Melatonin, produced by the pineal gland, is the hormone involved in regulating the sleep-wake cycle. It plays a crucial role in signaling the body that it is time to sleep and is influenced by light exposure. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, helping in waking up. Choice A, Insulin, is involved in regulating blood sugar levels, not the sleep-wake cycle. Choice C, Cortisol, is a stress hormone that helps regulate metabolism and immune response but is not primarily involved in the sleep-wake cycle. Choice D, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in regulating the sleep-wake cycle.
5. Which type of muscle tissue is found in the walls of hollow organs?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. Striated muscle
Correct answer: C
Rationale: Smooth muscle tissue is found in the walls of hollow organs such as the intestines, blood vessels, and bladder. It contracts involuntarily, allowing for functions like peristalsis in the intestines and regulation of blood flow in blood vessels. Skeletal muscle (Choice A) is attached to bones, cardiac muscle (Choice B) is found in the heart, and striated muscle (Choice D) refers to both skeletal and cardiac muscles due to their striped appearance, but neither of these types are typically found in the walls of hollow organs.
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