HESI A2
HESI A2 Anatomy and Physiology Practice Exam
1. Which hormone is produced by the pineal gland?
- A. Corticosteroid
- B. Oxytocin
- C. Prolactin
- D. Melatonin
Correct answer: D
Rationale: Melatonin is the hormone produced by the pineal gland. It plays a crucial role in regulating the sleep-wake cycle and is instrumental in maintaining the body's circadian rhythm. Melatonin production is triggered by darkness and inhibited by light, aiding in signaling the body when it is time to sleep. Corticosteroid, oxytocin, and prolactin are hormones produced by other glands in the body and are not associated with the pineal gland. Therefore, they are incorrect choices for this question.
2. Which cellular structure is responsible for producing energy?
- A. Nucleus
- B. Mitochondria
- C. Ribosome
- D. Golgi apparatus
Correct answer: B
Rationale: Mitochondria are the organelles responsible for producing energy in the cell through a process called cellular respiration. They are often referred to as the powerhouses of the cell due to their role in generating ATP, the cell's energy currency. The nucleus is not involved in energy production but houses the cell's genetic material. Ribosomes are responsible for protein synthesis, not energy production. The Golgi apparatus is involved in processing and packaging proteins for secretion, not energy production.
3. Which hormone regulates the sleep-wake cycle?
- A. Melatonin
- B. Insulin
- C. Cortisol
- D. Thyroxine
Correct answer: A
Rationale: Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. Its secretion is influenced by light exposure, with levels typically rising in the evening to promote sleep and falling in the morning to encourage wakefulness. Insulin is involved in regulating blood sugar levels, not the sleep-wake cycle. Cortisol plays a role in the body's stress response and circadian rhythm but is not the primary hormone regulating sleep-wake cycles. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle.
4. How do the muscular and skeletal systems collaborate to facilitate movement?
- A. Muscles attached to tendons contract to bend the skeleton at the joints.
- B. The hard bones of the skeleton protect the voluntary muscles of the limbs.
- C. The cardiac muscles produce calcium that is needed for sturdy bones.
- D. Smooth muscles on internal organs leach excess minerals from the bones.
Correct answer: A
Rationale: The muscular system and the skeletal system collaborate to facilitate movement. Muscles are connected to bones through tendons and contract to generate movement at the joints. When muscles contract, they exert force on the bones, resulting in actions like bending the arm or leg. This coordinated effort between muscles and bones is crucial for various activities such as walking, running, and grasping objects. Choices B, C, and D are incorrect because they do not accurately describe the interaction between the muscular and skeletal systems. The skeletal system's primary role is to provide structural support and protect internal organs, while cardiac muscles are responsible for heart function and not bone strength. Smooth muscles are found in internal organs and are not involved in leaching excess minerals from bones.
5. What is the function of hemoglobin in red blood cells?
- A. To fight infections
- B. To transport oxygen
- C. To carry carbon dioxide
- D. To store oxygen
Correct answer: B
Rationale: The correct answer is B: 'To transport oxygen.' Hemoglobin in red blood cells plays a crucial role in transporting oxygen. It binds to oxygen in the lungs and carries it to the body's tissues and organs for cellular respiration. Choices A, C, and D are incorrect because hemoglobin's primary function is to bind and transport oxygen, not to fight infections, carry carbon dioxide, or store oxygen.
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