which muscle is responsible for breathing

HESI A2

Anatomy HESI A2 Practice Test

1. Which muscle is responsible for breathing?

A. Diaphragm
B. Intercostal muscles
C. Rectus abdominis
D. Pectoralis major

Correct answer: A

Rationale: The diaphragm is the primary muscle responsible for breathing. It is a large, dome-shaped muscle located at the base of the chest cavity. When it contracts, it flattens, increasing the volume of the chest cavity and causing inhalation. When it relaxes, it returns to its dome shape, decreasing the volume of the chest cavity and causing exhalation. The intercostal muscles, located between the ribs, assist the diaphragm in breathing by expanding and contracting the chest cavity. The rectus abdominis and pectoralis major are not directly involved in the process of breathing.

2. Where would you be likely to find a Schwann cell?

A. In the digestive system
B. In the nervous system
C. In the skeletal system
D. In the muscular system

Correct answer: B

Rationale: Schwann cells are a type of neuroglia found in the peripheral nervous system. They are responsible for producing the myelin sheath around axons of neurons, which helps with the conduction of nerve impulses. Therefore, Schwann cells are typically found in the nervous system. Choices A, C, and D are incorrect because Schwann cells are specifically associated with the nervous system and are not found in the digestive, skeletal, or muscular systems.

3. What is the role of the liver in detoxification?

A. To secrete bile
B. To store glucose
C. To convert toxins into less harmful substances
D. To produce insulin

Correct answer: C

Rationale: The correct answer is C. The liver's primary function in detoxification is to convert harmful toxins into less harmful substances. This process helps in safeguarding the body from the adverse effects of toxins and is essential for maintaining overall health. Choices A, B, and D are incorrect because secreting bile, storing glucose, and producing insulin are functions of the liver unrelated to detoxification.

4. What is the primary function of the kidneys in the urinary system?

A. To filter waste from the blood
B. To produce urine
C. To regulate blood pressure
D. To absorb nutrients

Correct answer: A

Rationale: The correct answer is A: 'To filter waste from the blood.' The primary function of the kidneys in the urinary system is to filter waste products and excess substances from the blood, forming urine, which is then excreted from the body. Kidneys play a crucial role in maintaining the body's overall balance by filtering out waste, regulating fluid levels, and helping in the elimination of toxins. Choices B, C, and D are incorrect because while the kidneys do produce urine, regulate blood pressure, and help in nutrient absorption indirectly, their primary function is the filtration of waste from the blood.

5. What is the function of the medulla oblongata in the brain?

A. To control breathing and heart rate
B. To regulate body temperature
C. To coordinate voluntary movements
D. To process sensory information

Correct answer: A

Rationale: The correct answer is A: To control breathing and heart rate. The medulla oblongata is a vital part of the brainstem responsible for regulating essential functions such as breathing, heart rate, and blood pressure. These functions are crucial for maintaining life, and the medulla oblongata plays a key role in ensuring the body's survival. Choices B, C, and D are incorrect because regulating body temperature is primarily controlled by the hypothalamus, coordinating voluntary movements is associated with the cerebellum and motor cortex, and processing sensory information is related to the thalamus and sensory cortex, not the medulla oblongata.