intermedia, pars distalis and pars tuberalis. The neurohypophysis is otherwise known as pars nervosa. . .
Hypothalamus Hypothalamus is a small cone shaped structure that projects downward from the brain ending into the pituitary stalk. It interlinks both the nervous system and endocrine system. Though pituitary gland is known as master endocrine glands that controls the other endocrine glands, but it is, in turn controlled by the hypothalamus. Hypothalamus contains groups of neurosecretory cells.
It produces neurotransmitters which regulate the secretions of the pituitary (Figure11. ). The hormones produced by the hypothalamus act either as a releasing hormone or as an inhibitory hormone. In the basal region of the brain, the hypothalamic hypophyseal portal blood vessel connects hypothalamus and anterior pituitary.
It allows hypothalamic hormones to control anterior pituitary secretion. The posterior pituitary is connected with hypothalamus by a nerve bundle called hypothalamic hypophyseal axis . It produces nerve signal that control the posterior pituitary secretion. Hypothalamus maintains homeostasis, blood pressure, body temperature, cardio and fluid electrolyte balance of the body.
Table11. The major hypothalamic hormones and their functions S.No. Hormones Functions . Thyrotropin releasing hormone (TRH) Stimulates the secretion of TSH .
Gonadotropin releasing hormone(GnRH) Stimulates the secretion of FSH . Corticotropin releasing hormone (CRH) Stimulates the secretion of ACTH . Growth hormone releasing hormone(GHRH) Stimulates the secretion of GH . Prolactin releasing hormone (PRH) Stimulates the secretion of Prolactin .
Luteinizing hormone releasing hormone (LHRH) Stimulates the secretion of LH . MSH releasing hormone Stimulates the secretion of MSH . Growth hormone-inhibiting hormone (GHIH) Inhibits the secretion of GH . Prolactin inhibiting hormone (PIH) Inhibits the secretion of Prolactin .
MSH inhibiting hormone Inhibits the secretion of MSH XI Std Biology-Zoology Chapter- The anterior lobe of pituitary secretes six tropic hormones such as growth hormone (GH), thyroid stimulating hormone (TSH), adreno corticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH), luteotropic hormone (LTH) and melanocyte stimulating hormone (MSH) (in lower animals only). The posterior lobe of pituitary secretes the hormones namely vasopressin and oxytocin. Figure. .
Hypothalamus and pituitary gland Hormones of Adenohypophysis