Subtopic: The Pituitary Gland

The Pituitary Gland

• Loca­tion: Sel­la tur­si­ca (bony cav­i­ty)
• Attach­ment: Attached to the hypo­thal­a­mus by a stalk.
• Struc­ture: Divid­ed into two parts:
  • Ade­no­hy­poph­ysis (Ante­ri­or Pitu­itary)
  • Neu­ro­hy­poph­ysis (Pos­te­ri­or Pitu­itary)

Adenohypophysis (Anterior Pituitary)

• Sub­di­vi­sions:
  • Pars dis­tal­is
  • Pars inter­me­dia (almost merged with pars dis­tal­is in humans)
• Hor­mones secret­ed by Pars Dis­tal­is:
  • Growth Hor­mone (GH)
    • Over-secre­tion: Gigan­tism (abnor­mal growth)
    • Under-secre­tion: Pitu­itary dwarfism (stunt­ed growth)
    • Excess in adults: Acromegaly (severe dis­fig­ure­ment, espe­cial­ly of the face)
  • Pro­lactin (PRL)
    • Func­tion: Reg­u­lates mam­ma­ry gland growth and milk for­ma­tion.
  • Thy­roid Stim­u­lat­ing Hor­mone (TSH)
    • Func­tion: Stim­u­lates thy­roid hor­mone syn­the­sis and secre­tion.
  • Adreno­cor­ti­cotroph­ic Hor­mone (ACTH)
    • Func­tion: Stim­u­lates glu­co­cor­ti­coid (steroid hor­mone) syn­the­sis and secre­tion from the adren­al cor­tex.
  • Luteiniz­ing Hor­mone (LH) — Gonadotrophin
    • Males: Stim­u­lates andro­gen syn­the­sis and secre­tion from the testes.
    • Females: Induces ovu­la­tion and main­tains the cor­pus luteum.
  • Fol­li­cle Stim­u­lat­ing Hor­mone (FSH) — Gonadotrophin
    • Males: Reg­u­lates sper­mato­ge­n­e­sis (with andro­gens).
    • Females: Stim­u­lates ovar­i­an fol­li­cle growth and devel­op­ment.
• Hor­mone secret­ed by Pars Inter­me­dia:
  • Melanocyte Stim­u­lat­ing Hor­mone (MSH)
    • Func­tion: Reg­u­lates skin pig­men­ta­tion by act­ing on melanocytes.

Neurohypophysis (Posterior Pituitary)

• Func­tion: Stores and releas­es hor­mones syn­the­sized by the hypo­thal­a­mus.
• Hor­mones stored and released:
  • Oxy­tocin
    • Func­tion: Stim­u­lates smooth mus­cle con­trac­tion.
      • Females: Uter­ine con­trac­tion dur­ing child­birth and milk ejec­tion.
  • Vaso­pressin (Anti-diuret­ic Hor­mone — ADH)
    • Func­tion: Acts on the kid­neys to increase water and elec­trolyte reab­sorp­tion, reduc­ing water loss through urine.
    • Impair­ment: Dia­betes Insipidus (dimin­ished abil­i­ty to con­serve water, lead­ing to water loss and dehy­dra­tion).

Gem­i­ni