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 small intestine in digestion?

A. Breaking down fats
B. Absorbing nutrients
C. Secreting digestive enzymes
D. Storing bile

Correct answer: B

Rationale: The correct answer is B: Absorbing nutrients. The small intestine plays a crucial role in digestion by absorbing nutrients. It is where the majority of nutrient absorption occurs, allowing digested food to pass into the bloodstream for distribution to the body's cells. Choice A (Breaking down fats) is incorrect because the breakdown of fats primarily occurs in the small intestine with the help of bile from the liver and enzymes from the pancreas. Choice C (Secreting digestive enzymes) is incorrect because while the small intestine does produce some digestive enzymes, its primary role is absorption. Choice D (Storing bile) is incorrect as the storage of bile occurs in the gallbladder, not the small intestine.

4. Which of the following HDL cholesterol levels might warrant regular testing?

A. 70 or higher
B. 60
C. 50
D. 40

Correct answer: A

Rationale: An HDL cholesterol level of 70 or higher is considered high and beneficial for heart health. Individuals with high HDL levels are usually at lower risk of heart disease. Therefore, a level of 70 or above would warrant regular testing to monitor and maintain heart health. Choices B, C, and D are lower levels of HDL cholesterol, which are not typically considered high enough to warrant regular testing as they may not provide the same level of heart health benefits.

5. How does the endocrine system work with the reproductive system?

A. The reproductive system transforms minerals into useful nutrients.
B. The endocrine system determines the sex of the embryo.
C. The reproductive system controls the growth of secondary sex organs.
D. The endocrine system produces chemicals that regulate sexual function.

Correct answer: D

Rationale: The correct answer is D. The endocrine system plays a vital role in the regulation of sexual functions within the reproductive system. It produces hormones that are responsible for various functions, such as the development of secondary sex characteristics, production of gametes (sperm and egg cells), and the regulation of the menstrual cycle. These hormones are crucial for the proper functioning and coordination of the reproductive system, ensuring the successful reproduction and maintenance of reproductive health. Choices A, B, and C are incorrect because the reproductive system is not primarily responsible for transforming minerals into nutrients, determining the sex of the embryo, or controlling the growth of secondary sex organs. These functions are mainly regulated by the endocrine system in coordination with the reproductive system.