• Hormones: chemicals released by cells that affect cells in other parts of the body

Endocrine Hormones: chemicals secreted by endocrine glands directly to the blood

  • Exocrine glands secret substances through ducts, where as endocrine glands secret directly into the blood
  • The nervous system enables the body to adjust quickly to the environment; the endocrine system is designed to maintain control over longer periods of time (an example is growth hormones)
  • The pituitary gland is often referred to as the “master gland” because it exercises control over other endocrine glands; functions as the control centre along with the hypothalamus
  • A) hypothalamus and posterior lobe of pituitary- posterior lobe stores and released hormones (like oxytyocin; initiates strong uterine during labour ) which have been produced by the hypothalamus

B) Hypothalamus and anterior lobe of pituitary- anterior lobe produces own hormones; richly supplied with nerved from the hypothalamus. Hypothalamus regulates release of hormones from the anterior pituitary.

HormoneTargetPrimary Function
Thyroid Stimulating Hormone (TSH)Thyroid Gland
  • Stimulates release of thyroxine from thyroid
  • Thyroxine regulates cell metabolism
Growth HormoneMost cells
  • Promotes growth
OxytyocinUterus, mammary glands
  • Initiates strong contractions
  • Triggers milk release in lactating females
Antidiuretic hormone (ADH)Kidneys
  • Increases water reabsorption by kidneys

When blood sugars are high, Insulin is released, increasing permeability of cells to glucose. Glucose is converted to glycogen within the liver, thereby restoring blood sugar levels. Glycagon is released when blood sugars are low, promoting the conversion of liven glycogen into glucose, thereby restoring blood sugar levels

  • The cause of Diabetes is insufficient production or use of insulin; when the body is unable to produce any insulin or enough insulin, or is unable to use properly the insulin it does make. Some of the effects of Diabetes include: large excretions of urine, thirst, and low energy levels.
  • Type One diabetes: occurs when the pancreas is unable to produce insulin because of the early degeneration of the beta cells in the islets of Langerhans; usually diagnosed in childhood; must take insulin to live

Type Two Diabetes: associated with decreased insulin production or ineffective use of the insulin that the body does produce; usually diagnosed in adulthood; can be controlled with diet, exercise, or oral drugs known as sulphonamides (found to stimulate islets of Langerhans to function in adults; does not work with type one)

HormoneLocation of ProductionEffects
InsulinIslets of Langerhans (pancreas)
  • Increases permeability of cells to glucose; increases glucose uptake
  • Allows for the conversion of glucose to glycogen
  • Brings about a decrease in blood sugar
GlucagonIslets of Langerhans (pancreas)
  • Promotes the conversion of glycogen to glucose
  • Brings about an increase in blood sugar
Epinephrine (adrenaline)Adrenal medulla
  • Promotes the conversion of glycogen to glucose
  • Bring about an increase in blood sugar
  • Brings about an increase in heart rate, and cell metabolism
CortisolAdrenal cortex
  • Promotes the conversion of amino acids to glucose
  • Promotes the breakdown of fats to fatty acids
  • Decreases glucose uptake by the muscles (not by  brain)
  • Brings about  increase in blood sugar in response to stress
  • When metabolic rates decrease
    • Receptors in the hypothalamus are activated
    • Nerve cells secrete thyroid-releasing hormones (TRH) , which stimulates the pituitary to release thyroid stimulating hormones (TSH)
    • Thyroid stimulating hormone is carried by the blood to the thyroid gland, which, in return releases thyroxin
  • Thyroxin raises metabolism by  stimulating increased sugar utilization in the body cells
  • Iodine is actively transported from the blood into the follicle cells of the thyroid, and plays a important role in both hormone components
HormoneLocationFunction
TestosteroneInterstitial cells (testes)Stimulates spermatogenesis, Influences the development of secondary male sexual characteristics at puberty, Associated with sex drive
EstrogenFollicle cells (ovary)Inhibits growth of facial hair, Initiates secondary female characteristics, Causes thickening of the endometrium
ProgesteroneCorpus luterm (ovary)Inhibits ovulation, Inhibits uterine contractions, Stimulates the endometrium

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