Correct Option
The correct option is (a) 1 only.
Explanation
Growth Hormone (GH), also known as somatotropin, is a peptide hormone essential for stimulating growth, cell reproduction, and cell regeneration in humans and other animals. It plays a crucial role in human development.
Statement-wise Analysis
- Statement 1 is Correct: Growth hormone is secreted by the anterior lobe of the pituitary gland (adenohypophysis). It acts on many tissues throughout the body to promote growth and metabolism.
- Statement 2 is Incorrect: The development of secondary sexual characters is primarily regulated by sex hormones (testosterone in males and estrogen/progesterone in females), which are secreted by the gonads (testes and ovaries). Growth hormone is responsible for somatic growth (bones, muscles, and tissues) and metabolic processes, not sexual maturation.
- Statement 3 is Incorrect: The secretion of growth hormone is controlled by the hypothalamus, not the thyroid gland. The hypothalamus releases Growth Hormone-Releasing Hormone (GHRH) to stimulate GH secretion and Somatostatin to inhibit it.
Key Takeaway
Growth Hormone (GH) is secreted by the anterior pituitary gland and is regulated by the hypothalamus. Its primary function is to stimulate somatic growth and metabolism, distinct from sex hormones which regulate sexual characteristics.