ENDOCRINE SYSTEM-BIOLOGY- TNPSC,TET,RRB,SSC SCIENCE (GK) STUDY MATERIAL

ENDOCRINE SYSTEM ENDOCRINE GLANDS

Hypothalamus

  • part of fore-brain, secretes neurohormones,
    which effect the release of hormones from
    pituitary.
  • Acts as the thermostat.
    PITUITARY GLAND
  • smallest endocrine gland.
  • Somatotrophicharmone: Its hypersecretion
    leads to acromegaly in adults and gigantium
    in children. Its hyposecretion leads to
    dwarfness in children.
  • Gonadotrophic harmone (GTH) : Stimulates
    the primary sex harmones
  • Lactogenic hormone: Initiates milk
    production in the pregnant females.
  • Thyrotrophic hormone: regulation of thyroid
    secretion.
  • Adrenocorticotrophic hormone (ACTH)
  • Diabetogenic or Metabolic Hormone:
  • Oxytocin or Pitocin: smooth muscle
    contractions, helps in the secretion of milk.
  • Vasopressin or ADH (Anti-Diuretic
    Hormone): Hypoactivity leads to Diabetes. THYROID GLAND
  • It is the largest endocrine gland located in
    the neck between the trachea and larynx.
    Controls BMR (Basal Metabolic Rate) it is
    1600 Kcal/day
    Secretes:
  • Thyroxine: Hypoactivity in children leads to
    cretinism.
  • A diet, poor in iodine which is insufficient
    for the synthesis of thyroxin, leads to simple
    goiter.
  • Its hyperactivity leads to increased metabolic
    activities
  • Thyrocalcitonin – controls the amount of
    calcium in the body.
    Hashimoto Disease:thyroid gland is destroyed. It
    is known as suicide of the thyroid.
    PARATHYROID GLAND
  • Secretes Parathormone, which is also known
    by the name of Collip’s Hormone.
  • It influences calcium and phosphorus
    metabolism (Ca level = 12 mg/100 ml of
    blood)
  • Removal of this gland leads to death due to
    tetany (cramps, tremors and convulsions in
    muscles)
  • Hyperactivity withdraws calcium from bones
    THYMUS GLAND
  • near the heart.
  • thymine
  • formation of antibodies
    PANCREAS
  • It is an exocrine as well as an endocrine
    gland. Its endocrine part is known as Islets
    of Langerhans.
  • Beta cells secrete Insulin which controls the
    amount of sugar in the blood. Its
    hyposecretion leads to Diabetes Mellitus.
  • Alpha cells secretes Glucagon which
    increases blood sugar level.
  • Gamma cells secrete Somatostatin which
    controls the functioning of alpha and beta
    cells.
    ADRENAL GLANDS
  • 2, on each kidney. Sugar metabolism, Salt
    retention, Sex hormone and Source of energy
  • Outer cortex and inner medulla.
  • Adrenaline or epinephrine 3F Gland
    GONADS
  • in addition to producing, sperms and ova,
    also produce hormones.
    TESTES
  • Its interstitial cells (Leydig’s cells) secrete
    testosterone
  • Deficiency leads to sterility (eunuchoidism)
    OVARIES
  • Follicular cells producesOestrogen which
    controls the female secondary sexual
    characters.
  • Corpus luteum secretes Progesterone which
    is essential for the completion of each
    menstrual cycle.
  • Relaxin at the end of gestation period, and
    helps in eas birth by relaxing the uterus and
    ligaments of the pelvic girdle.
Read More  தன்வினை, பிறவினை, செய்வினை, செயப்பாட்டு வினை வாக்கியங்களைக் கண்டெழுதுதல்

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