Hypothalamus 

The hypothalamus is the basal part of the diencephalon, forebrain and it regulates a wide spectrum of body functions. It contains several groups of neurosecretory cells called nuclei which produce hormones. 

HYPOTHALAMUS- RELEASING HORMONES

(1) Growth hormone-releasing factor [GHRF]

Stimulates the secretion of growth hormone.

(2) Thyrotropic releasing factor [TRF/TSHRF] 

It stimulates the secretion of TSH.   

(3) Gonadotrophin releasing hormone or factor[GnRH] 
  • Follicle-stimulating hormone-releasing factor [FSHRF] 
  1. It stimulates the secretion of FSH.
  • Luteinizing hormone-releasing factor [LHRF]
  1. It stimulates the secretion of LH

(4) Prolactin release factor [PRF] 

Stimulates the secretion of Prolactin 

(5) Melanocyte release factor [MRF/MSHRF] 

Stimulates the secretion of MSH 

(6) Adrenocorticotrophic releasing hormone (CRH) 

Stimulates the secretion of ACTH


HYPOTHALAMUS- INHIBITING HORMONES


(1) Growth hormone inhibitory factor [GHIF]

It inhibits the secretion of GH. 

(2) Melanocyte inhibitory factor [MIF] 

It inhibits the secretion of MSH.

(3) Prolactin inhibitory factor [PIF] (Dopamine) 

It inhibits the secretion of Prolactin.   


PITUITARY GLAND 

ORIGIN:- Ectodermal.
POSITION:- The pituitary gland is located in a bony cavity called Sella tursica and is attached to the hypothalamus by a stalk called the infundibulum. It is divided anatomically into an adenohypophysis and a neurohypophysis.



ADENOHYPOPHYSIS

The anterior part of the pituitary gland.    

HORMONES OF ADENOHYPOPHYSIS

  1. Growth hormone/ Somatotrophic hormone(GH/STH)
  2. Prolactin/Lactotrophic hormone(PRL/LTH)
  3. Adrenocorticotrophic hormone(ACTH)
  4. Thyrotrophic hormone (TSH) 
  5. Follicle stimulating hormone(FSH) 
  6. Luteinising hormone(LH) 


GROWTH HORMONE/SOMATOTROPHIC HORMONE(GH/STH)

Stimulates growth of bone, cartilage,  and soft tissues. Stimulates metabolism of proteins fat and carbohydrates.  
  • Effect on growth:-
(i) Promotes elongation of bones 
(ii) GH promotes mitosis & increases the number of cells in many visceral organs e.g. liver 
(iii) GH stimulates the growth of muscle and cartilage.


  • Effect on metabolism:- 
  1. Fat: It Increases lipolysis. Under the influence of the growth hormone fat is used for energy in preference to carbohydrates and protein. 
  2. Carbohydrate:- It decreases uptake of glucose in the cells as a result of which blood glucose level increases. So it is also called Diabetogenic Hormone. 
  3. Protein: It increases amino acid uptake by the cells of the liver & muscles & helps in protein synthesis


 PROLACTIN / LACTOTROPHIC HORMONE(PRL/LTH)

Regulates the growth of mammary glands and the formation of milk. Responsible for lactation after delivery. The hormone of maternity. 

ADRENOCORTICOTROPHIC HORMONE (ACTH)

Stimulates the synthesis and secretion of steroid hormones from the adrenal cortex. (Mainly Glucocorticoids)

THYROTROPHIC HORMONE(TSH)

Stimulates thyroid gland for synthesis and secretion of thyroid hormone (Thyroxine)

FOLLICLE-STIMULATING HORMONE(FSH)

  • In males, FSH and Androgen (secreted from testes) both regulate spermatogenesis and the normal functioning of Seminiferous tubules. 
  • In females, FSH stimulates the growth and development of ovarian follicles In females, FSH stimulates the growth and development of ovarian follicles.

Luteinizing hormone(LH) 

• In males, LH stimulates the synthesis and secretion of hormones called Androgens from testes
• In females, LH induces ovulation of fully mature follicles ( Graffian follicles) and maintains the corpus luteum.


    NEUROHYPOPHYSIS



HORMONES OF POSTERIOR PITUITARY GLAND

  1. OXYTOCIN OR PITOCIN OR BIRTH HORMONE
  2. VASOPRESSIN OR PITRESSIN OR ADH

OXYTOCIN OR PITOCIN OR BIRTH HORMONE 

• Stimulates uterine contraction during the time of childbirth. 
• Stimulates milk ejection from the mammary gland. 
• In male humans it causes contraction in smooth muscles of the reproductive tract.

VASOPRESSIN OR PITRESSIN OR ADH

Mainly acts on kidney and stimulates reabsorption of water by distal tubules and thereby reducing loss of H2O through urine (Diuresis)and hence is called an Anti-Diuretic Hormone (ADH)

Disorder due to hyposecretion of Vasopressin (ADH)

Diabetes insipidus

• Micturiting dilute urine several times a day. 
• Excessive thirst (Polydipsia). 
• Excessive dehydration.

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