Question

name any three endocrine glands in human body and briefly write functions of each

Answer 1

The three endocrine glands and their functions are as follows:

1. Pineal Gland

• Location − Dorsal side of forebrain
• Secretes melatonin that regulates 24-hour (diurnal) rhythm of the body such as sleep-wake cycle, body temperature, etc.
• Melatonin also regulates metabolism, pigmentation, and menstrual cycle.

2. Thyroid Gland

• Location − Two lobes of thyroid gland are located on either side of trachea.
• Isthmus − Thin flap of connective tissue interconnecting the thyroid glands
• Composition − Follicles + Stromal tissues

• Follicular cells synthesize two hormones:

  • Tetraiodothyronine or thyroxine (T₄)
  • Triiodothyronine (T₃)

• Functions:

  • Regulates BMR (Basal Metabolism Rate)
  • Supports the process of RBC synthesis
  • Maintains water-electrolyte balance
  • Secretes thyrocalcitonin which regulates blood calcium levels

3. Parathyroid Gland

• Location − Four parathyroid glands are present on back side of thyroid glands.
• Secretes − Parathyroid hormone (PTH)
• Secretion of PTH is regulated by circulating level of calcium ions.

• PTH is a hypercalcemic hormone. It increases blood calcium levels by

  • dissolution/demineralization from bones
  • reabsorption of Ca²⁺ by renal tubules
  • Ca²⁺ absorption from digested food