Long answer question
What is adenohypophysis? Name the hormones secreted by it?
Adenohypophysis: It is an outgrowth from the roof of the buccal cavity. This outgrowth is called Rathke’s pouch. It grows upwards towards the brain. It is the larger lobe of the pituitary gland. It is a highly cellular and vascular part of the pituitary gland. It contains various types of epitheloid secretory cells, acidophils, basophils, chromatophores. It is further divided into three parts - Pars distalis, pars tuberalis, and pars intermedia. Pars intermedia is poorly developed in human beings. It is a small reduced part lying in the cleft between the anterior and posterior lobe. It secretes Melanocyte Stimulating Hormone (MSH) in some lower vertebrates. MSH stimulates the dispersion of melanin granules in melanocytes and is responsible for skin pigmentation.
The pituitary gland located just below the hypothalamus.
Hormones secreted by anterior pituitary:
i. Somatotropic Hormone (STH) / Somatotropin / Growth Hormone (GH): The secretion of GH is high till puberty later its secretion becomes low. However, it is continuously secreted throughout life for repair and replacement of body tissue or cells.
a. It stimulates the growth of the body and the development of all tissues.
b. It accelerates protein synthesis and cell division.
c. It stimulates the release of growth hormone.
ii. Thyroid Stimulating Hormone (TSH) / Thyrotropin:
It stimulates the thyroid gland to produce the hormone thyroxine.
iii. Adrenocorticotropic Hormone (ACTH) / Adrenocorticotropin:
a. It stimulates the adrenal cortex to produce its hormones.
b. It maintains the functioning of the adrenal cortex.
iv. Prolactin / Luteotropin/ Mammotropin: The secretion of this hormone is regulated by PIF (Prolactin inhibiting factor) of the hypothalamus.
a. Activates the growth of mammary glands during pregnancy (mammotropin).
b. Stimulates milk production and secretion of milk (lactogenic) by the mammary gland after childbirth.
a. Follicle Stimulating Hormone (FSH): In males, it stimulates the development of seminiferous tubules. In females, it stimulates the growth of ovarian follicles.
b. Luteinizing hormone (LH): LH induces the ruptured follicles to develop into corpus luteum and for the production of progesterone FSH and LH are responsible for the stimulation of ovaries to produce estrogen.
c. ICSH: In males, it stimulates the testes to produce the androgen called testosterone. Testosterone is responsible for the development of secondary sexual characters.