ENDOCRINE SYSTEM

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ENDOCRINE SYSTEM

• A. FUNCTION - Controls the body using hormones
  Important for
• 1) metabolism
• 2) stress
• 3) reproduction

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• B. HORMONES
• 1) Steroids, amino acids,polypeptides,
  glycoproteins
• 2) Mechanisms of action
• a) introduction
• b) proteins
• c) steroids
• d) thyroxine

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• C. ORGANS
• 1) Hypothalamus
• a) nervous - endocrine interface
• b) hormones

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• 2) pituitary gland (hypophysis) - below
  hypothalamus. 2 portions, anterior and
  posterior (adeno and neurohypophysis). Master
  gland.

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• a) anterior pituitary (adenohypophysis)
  produces 6 major hormones
• 1) thyrotropin (troph to feed or
  nourish) TSH. Stimulates the thyroid
  to increase in size and activity.

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• 2) adrenocorticotrophic hormone (ACTH)
  - stimulates the adrenocortex to increase
  in size and activity.

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• 34) gonadotrophic hormones (2)
• a) follicle stimulating hormone (FSH)
  - stimulates follicles. In males,
  stimulates production of sperm.
• b) luteinizing hormone (LH) -
  ovulation in females. In males,
  stimulates interstitial cells in testes
  (ICSH) to produce testosterone.

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• 5) prolactin - stimulates milk
  production in women, possible
  electrolyte regulation in men.

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• 6) somatotropin - growth hormone,
  stimulates growth and maintains
  tissues. Abnormalities
• a) gigantism
• b) acromegaly
• c) dwarfism
• d) abuse in athletes

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• b) pars intermedia - melanocyte
  - stimulating hormone (MSH)
• 1) skin color in animals
• 2) beta-endorphin

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• b) posterior pituitary (neurohypophysis)
  stores and releases 2 major hormones.
  1) antidiuretic hormone (ADH) - retains
  H2O. Lack of ADH causes diabetes insipidus.
• 2) oxytocin - labor and milk letdown.
  Social functions? Unknown function in
  males.

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• 3) thyroid gland
• a) metabolic hormones
• 1) Thyroxine (T4)
• 2) Triiodothyronine (T3)

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• b) Thyrocalcitonin - lowers blood calcium
  levels by stimulating osteoblasts.

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• c) Abnormalities
• 1) hypothyroidism - decreased metabolic
  rate, cretinism in infants.
• 2) goiter - enlargement of the thyroid.
  Endemic goiter due to lack of iodine.
• 3) hyperthyroidism - increased
  metabolic rate, exophthalmia. Graves
  disease is one possible cause.

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• 4) parathyroid glands - 4 glands, dorsal
  surface of the thyroid.
• a) parathyroid hormone (PTH,
  parathormone) stimulates osteoclasts,
  changes vit. D to dihydroxychole- calciferol
  (calcitriol), raises blood calcium levels.

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• 5) Adrenal glands - above the kidneys,
  divided into the medulla and the cortex.

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• a) adrenal medulla - releases
  epinephrine and norepinephrine.

Epinephrine Norepinephrine
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• b) adrenal cortex - produces 3 groups of
  hormones
• 1) mineralocorticoids - primarily
  aldosterone. Ischemic kidneys produce
  renin, stimulates formation of
  angiotensin, stimulates AC to produce
  aldosterone, stimulates kidneys to retain
  sodium.

aldosterone
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• 2) glucocorticoids - primarily cortisol
  (hydrocortisone). Prepares body for
  stress. Mobilizes nutrients, decreases
  protein synthesis, stabilizes lysosomes,
  constricts blood vessels.

Cortisol (hydrocortisone)
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• 3) androgens (male sex hormones)-
  stimulates libido in females.
• 4) abnormalities
• a) masculinization of females.
• b) Addisons disease caused by
  failure of the adrenal cortex.
• c) Cushings syndrome from excess
  cortisol.

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• 6) pancreas - Endocrine functions in Islets
  of Langerhans. 2 major hormones glucagon
  and insulin.

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• a) glucagon - from alpha cells. Released
  when blood glucose levels fall, causes
  breakdown of glycogen (glycogenolysis).

Glucagon
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• b) insulin - beta cells produce. Released
  when blood glucose levels rise lowers
  blood glucose levels by bringing transporters
  to membrane. Causes glycogenesis, decreased
  use of triglylcerides, stimulates protein
  synthesis

Insulin
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• c) Diabetes mellitus, an increase in blood
  glucose. Two different diseases type I
  (juvenile onset) and type II (adult
  onset).

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• 1) type I - young people usually under
  25. An autoimmune disease, body destroys own
  beta cells. Less than 10 of
  diabetics, requires insulin or
  ketoacidosis and death result. Too
  much insulin can cause insulin shock.

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• 2) type II - usually adults (over 40),
  though there has been surprising increase
  children. Generally obese, more than 90 of
  diabetics. Have insulin tolerance. Oral
  medications used to stimulate insulin
  production and insulin sensitivity.

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• 3) Advances
• a) pumps
• b) inhalants, oral insulin
• c) electric glucose testers
• d) transplants
• e) gene therapy

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• 7) pineal gland - near midbrain,
  produces melatonin. Controls seasonal
  breeding in animals. In humans important
  for sleep-wake cycles. Puberty?
  Increased light decreases hormone.

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• 8) Thymus - just below sternum. Large in
  children, atrophies in adults. Produces
  thymosin, stimulates immune system.

Thymosin
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• 9) gonads - ovaries in women produce
  estrogens and progesterone, testes in men
  produce testosterone.

Testosterone
Estrogens Progesterone
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• 10) Autocrines - hormone like molecules
  derived from arachidonic acid.
• a) prostaglandins
• b) leukotrienes

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ACROMEGALY
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Hypothyroidism
Cretinism
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