Anatomy HESI A2 Practice Test

Correct Answer: C

Rationale: Platelets play a crucial role in blood clotting, known as hemostasis. Step 1: When a blood vessel is damaged, platelets adhere to the site to form a temporary plug. Step 2: Platelets release chemicals that attract more platelets and help in clot formation. Step 3: This clotting process prevents excessive bleeding. Choice A is incorrect as oxygen is primarily carried by red blood cells. Choice B is incorrect as fighting infections is mainly done by white blood cells. Choice D is incorrect as nutrient transport is mainly carried out by the plasma in the blood.

Correct Answer: A

Rationale: The correct answer is A: Parathyroid gland. When under stress, hormones like cortisol and adrenaline are released primarily from the adrenal cortex and the hypothalamus-pituitary-adrenal (HPA) axis. The posterior pituitary releases oxytocin and vasopressin, which are not directly related to stress response. The parathyroid gland, on the other hand, regulates calcium levels in the blood and is not directly involved in the stress response.

Correct Answer: A

Rationale: The primary function of the hypothalamus is to regulate body balance and thermoregulation. It maintains homeostasis by controlling various physiological processes such as body temperature, blood pressure, and electrolyte balance. It also plays a role in regulating hormonal functions through the pituitary gland. Choices B, C, and D are incorrect because hunger, thirst, sleep, circadian rhythms, and voluntary movements are primarily controlled by other brain regions such as the amygdala, pineal gland, and motor cortex, respectively.

Correct Answer: A

Rationale: The correct answer is A: They secrete chemicals into the blood. Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. This allows the hormones to travel throughout the body to target organs and tissues. Choices B, C, and D are incorrect because endocrine glands do not secrete enzymes into ducts (B), produce sweat (C), or produce saliva (D). These functions are typically associated with exocrine glands that have ducts for secretion.

Correct Answer: B

Rationale: The correct answer is B: Mouth. Digestion begins in the mouth where food is mechanically broken down by chewing and chemically broken down by enzymes in saliva. This initial process prepares food for further digestion in the stomach and small intestine. The stomach (A) primarily functions to further break down food through acid and enzymes. The small intestine (C) is where the majority of nutrients are absorbed, not where digestion begins. The esophagus (D) is responsible for transporting food from the mouth to the stomach, but it does not participate in the actual digestion process.