Correct Option
The correct option is
A-3, B-1, C-4, D-2
Explanation
The endocrine system comprises ductless glands that secrete hormones directly into the bloodstream. These chemical messengers regulate critical physiological functions, including metabolism, growth, blood sugar levels, and reproductive development.
Analysis of Pairs
- A. Thyroid - 3. Thyroxine: The thyroid gland, located in the neck, secretes thyroxine (T4). This hormone is primarily responsible for regulating the basal metabolic rate (BMR) of the body, influencing protein synthesis and energy consumption.
- B. Pancreas - 1. Insulin: The pancreas acts as a heterocrine gland (both exocrine and endocrine). Its endocrine component, the Islets of Langerhans, contains beta cells that secrete insulin. Insulin lowers blood glucose levels by facilitating the uptake of glucose by cells.
- C. Adrenal - 4. Adrenalin: The adrenal glands are located on top of the kidneys. The adrenal medulla secretes adrenalin (epinephrine), often called the "emergency hormone." It prepares the body for "fight or flight" responses by increasing heart rate, blood pressure, and glucose availability.
- D. Testis - 2. Testosterone: The testes are male gonads that produce androgens, primarily testosterone. This hormone regulates spermatogenesis and the development of male secondary sexual characteristics.
Key Takeaway
Thyroxine (Thyroid) controls metabolism; Insulin (Pancreas) regulates blood sugar; Adrenalin (Adrenal) manages acute stress responses; and Testosterone (Testis) governs male reproductive traits.