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. Which of the following statements best describes endocrine glands?

A. They secrete chemicals into the blood
B. They secrete enzymes into ducts
C. They produce sweat
D. They produce saliva

Correct answer: A

Rationale: Endocrine glands are ductless glands that release hormones directly into the bloodstream. These hormones are then carried to target organs and tissues throughout the body, where they regulate various physiological functions. The statement 'They secrete chemicals into the blood' accurately describes the function of endocrine glands. Choices B, C, and D are incorrect because endocrine glands do not secrete enzymes into ducts, produce sweat, or produce saliva. These functions are typically associated with exocrine glands, sweat glands, and salivary glands, respectively.

3. 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.

4. What is the meaning of endocytosis?

A. The cell engulfs solid particles.
B. The cell engulfs liquid material.
C. The cell expels solid particles.
D. The cell releases liquid material.

Correct answer: A

Rationale: Endocytosis is a cellular process where the cell engulfs and internalizes solid particles by forming vesicles. It is a mechanism used for nutrient uptake, cell signaling, and maintaining cellular homeostasis. Options B, C, and D describe processes that are opposite to endocytosis. Choice B is incorrect because it describes pinocytosis, which is the process of engulfing liquid material. Choice C is incorrect as it describes exocytosis, the process of expelling material from the cell. Choice D is incorrect as it describes the process of releasing liquid material from the cell. Therefore, the correct answer is A.

5. Which organ system is primarily responsible for preventing water loss?

A. The nervous system
B. The integumentary system
C. The lymphatic system
D. The urinary system

Correct answer: B

Rationale: The correct answer is B: The integumentary system. The integumentary system, which includes the skin, is primarily responsible for preventing water loss from the body. The skin acts as a barrier that helps regulate moisture and prevent excessive water loss through a process known as transepidermal water loss. The nervous system (choice A) is responsible for transmitting signals throughout the body, the lymphatic system (choice C) is responsible for the immune response and fluid balance, and the urinary system (choice D) is responsible for filtering blood and producing urine, but they do not primarily prevent water loss like the integumentary system.