Location : The thymus gland is a lobular structure located between the lungs and behind sternum on the ventral side of aorta.
Hormone : Secretes thymosin hormone. Thymosin is a peptide hormone.
Functions of the hormones :
1. It plays a major role in the differentiation of T-lymphocytes which provide cell-mediated immunity.
2. It promotes the production of antibodies.
(1) Adrenocorticotrophin hormone (ACTH) : It stimulates the adrenal gland to release different hormones. It is synthesized and secreted by the anterior pituitary or the pars digitalis region of pancreas.
(2) Thyroid stimulating hormone (TSH) : It stimulates thyroid gland to secrete various hormones. It is released by the anterior pituitary.
Gonadotrophin hormone : These are hormones which stimulate the gonadal activity. It is of two types :
(1) Follicle stimulating hormone (FSH) : It stimulates gonads to form gametes. It is present in both the sexes. In males it regulates spermatogenesis and in females it also stimulates ovary to produce oestrogens and stimulates the growth and development of the ovarial follicles.
(2) Luteinizing hormone : In males the LH results in thesynthesis and secretion of the androgens from the testis.
In females LH induces the ovulation.
Adrenal medulla : It is the centrally located tissue that lies inner to cortex. It secretes following two hormones :
1. Norepinephrine : It controls heart beat, contraction of arteries, breathing etc. at normal time.
2. Epinephrine : It is released at the time of emergency. It has the following effects.
(a) It increases heart beat and breathing.
(b) It constricts the arteries so that more blood may go into muscles.
(c) It dilates pupil.
(d) It oxidises more food so that more energy is produced.