Which of the following statements best describes endocrine glands?

Correct Answer: B

Rationale: The correct answer is B: 'They secrete chemicals into the blood.' Endocrine glands release hormones directly into the bloodstream to regulate various body functions. This process helps in maintaining homeostasis and coordinating different physiological processes within the body. Choice A is incorrect as endocrine glands do not absorb chemicals from the blood; instead, they release hormones. Choice C is incorrect as endocrine glands do not filter chemicals from the blood; they secrete hormones. Choice D is incorrect as endocrine glands do not absorb chemicals from the lymphatic system; they release hormones into the bloodstream.

Correct Answer: B

Rationale: The correct answer is the Urethra. The urethra is a structure that plays a role in both the male reproductive system, by carrying semen, and the urinary system, by carrying urine. It serves as a common pathway for both reproductive and excretory functions in males. The Testes (Choice A) are part of the male reproductive system but not the urinary system. The Prostate (Choice C) is also part of the male reproductive system but not the urinary system. The Penis (Choice D) is primarily involved in the male reproductive system as the organ that delivers semen during sexual intercourse.

Correct Answer: B

Rationale: Erythropoiesis specifically refers to the process of producing red blood cells (erythrocytes) in the bone marrow. Hematopoiesis is the broader term that encompasses the production of all types of blood cells, including red blood cells, white blood cells, and platelets. Phagocytosis is the process by which cells engulf and digest particles, while thrombopoiesis is the production of platelets. Therefore, the correct answer is B as it directly relates to the production of red blood cells.

Correct Answer: D

Rationale: During stress, hormones are released from the adrenal cortex, posterior pituitary, and hypothalamus to help the body respond. The parathyroid gland, however, is not typically involved in the stress response by releasing hormones. The posterior pituitary releases hormones like oxytocin and vasopressin, the hypothalamus secretes corticotropin-releasing hormone (CRH) and vasopressin, while the adrenal cortex releases cortisol and aldosterone in response to stress. Therefore, the correct answer is 'Parathyroid.'

Correct Answer: B

Rationale: The central nervous system consists of the brain and spinal cord, which are responsible for processing and coordinating information. The retina is part of the eye, while the heart is part of the circulatory system. Therefore, the correct answer is 'Spinal cord' as it is not part of the central nervous system.