HESI A2 Anatomy and Physiology 2023

Correct Answer: A

Rationale: The correct answer is A: Left ventricle. The left ventricle is the largest and strongest chamber of the heart because it is responsible for pumping oxygen-rich blood to the entire body. It has thicker muscle walls compared to other chambers to generate enough force to push blood through the body's systemic circulation. The left atrium receives oxygenated blood from the lungs, but it does not pump blood out of the heart. The right ventricle pumps blood to the lungs for oxygenation and is not as strong as the left ventricle. The right atrium receives deoxygenated blood from the body and sends it to the right ventricle. Therefore, the left ventricle is the correct answer due to its crucial role in systemic circulation and its muscular structure.

Correct Answer: B

Rationale: The correct answer is B: Hinge joint. The elbow joint is a hinge joint because it allows movement in one plane, similar to a door hinge. It primarily allows flexion and extension movements. A ball and socket joint (A) allows a wider range of motion in multiple planes. A pivot joint (C) allows rotation around a central axis. A saddle joint (D) allows movement in multiple directions with a greater range of motion compared to a hinge joint.

Correct Answer: C

Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata is located in the brainstem and is responsible for regulating essential functions such as heart rate and breathing. It contains vital centers that control autonomic functions, including the cardiovascular and respiratory systems. The medulla receives inputs from various sensory receptors and sends signals to the heart and lungs to maintain homeostasis. The other choices are incorrect because: A: Cerebrum is primarily responsible for higher brain functions such as thinking and voluntary movements. B: Cerebellum is involved in coordination and balance, not in regulating heart rate and breathing. D: Hypothalamus plays a role in regulating body temperature, hunger, and thirst, but not specifically in controlling heart rate and breathing.

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: The correct answer is B: Amygdala. The amygdala is a key structure in the brain responsible for processing emotions, particularly fear and pleasure. It plays a crucial role in emotional responses and memory formation related to emotions. The frontal lobe (choice A) is primarily involved in decision-making and reasoning. The parietal lobe (choice C) is responsible for sensory processing and spatial awareness. The occipital lobe (choice D) is mainly involved in visual processing. Therefore, the amygdala is the correct choice for processing emotions due to its specific functions related to emotional responses.