HESI A2 Anatomy and Physiology 2023

Correct Answer: B

Rationale: The correct answer is B: White blood cells. White blood cells, also known as leukocytes, are primarily responsible for fighting infections by detecting and destroying pathogens. Red blood cells (A) carry oxygen, platelets (C) aid in blood clotting, and plasma (D) is the liquid component of blood carrying nutrients and waste. White blood cells play a crucial role in the immune system's defense against infections, making them the correct choice.

Correct Answer: B

Rationale: The correct answer is B: Hinge joint. The knee joint is classified as a hinge joint because it primarily allows movement in one plane, similar to a door hinge. This type of joint permits flexion and extension movements, which are the main actions of the knee. The other choices are incorrect because: A: Ball and socket joint allows for multi-directional movement, such as the hip joint. C: Pivot joint allows for rotation around an axis, like the joint between the radius and ulna bones in the forearm. D: Saddle joint allows for movements in two planes, like the joint at the base of the thumb.

Correct Answer: B

Rationale: During the fight-or-flight response, the body needs to prepare for immediate action. Adrenaline, also known as epinephrine, is the hormone released by the adrenal glands in response to stress or danger. Adrenaline triggers physiological changes such as increased heart rate, blood flow to muscles, and heightened awareness to help the body react quickly. Insulin is involved in regulating blood sugar levels, not the fight-or-flight response. Thyroxine plays a role in metabolism, while cortisol is released in response to stress but is not the primary hormone involved in the fight-or-flight response.

Correct Answer: B

Rationale: The correct answer is B: Skeletal muscle. Skeletal muscle is voluntary as it is under conscious control, allowing us to move our body voluntarily. Cardiac muscle (A) is involuntary and found in the heart. Smooth muscle (C) is also involuntary and found in internal organs. Striated muscle (D) is a general term that can refer to both skeletal and cardiac muscle, but not all striated muscles are voluntary. Therefore, B is the correct answer as it specifically refers to the type of muscle tissue that is under voluntary control.

Correct Answer: B

Rationale: The correct answer is B: To produce bile. The liver produces bile, which is essential for the digestion and absorption of fats in the small intestine. Bile emulsifies fats, breaking them down into smaller droplets for easier digestion by enzymes. This process aids in the absorption of fat-soluble vitamins and fatty acids. Choice A (To store glucose) is incorrect because the liver primarily regulates blood glucose levels by storing glycogen and releasing glucose as needed. Choice C (To detoxify harmful substances) is incorrect as the liver's main function in detoxification is carried out by enzymes in the liver cells, not directly related to the digestive system. Choice D (To absorb nutrients) is incorrect as the liver doesn't directly absorb nutrients. Instead, it processes and stores nutrients after absorption by the small intestine.