The Endocrine System

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The Endocrine System

• .hormonal control of homeostasis

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Compare Nervous /hormonal
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Functions of Endocrine System
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Mechanism of action
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The Major Endocrine Glands
Pineal Body
Pituitary
Parathyroids
Thyroid
Thymus
Adrenals
Pancreas
Testes
Ovaries
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The Anterior Pituitary Trophic Hormones

• Thyrotrophin (the Thyroid Stimulating Hormone
  -TSH)
• Regulates the activity of the thyroid gland

• Adrenocorticotrophin (ACTH)
• Regulates the function of the adrenal cortex of
  the adrenal glands

• Gonadotrophins
• a) Follicle Stimulating Hormone (FSH)
• Lutenising Hormone (LH)
• Regulate the reproductive organs (gonads)

• FSH ?
• regulates the development of ovarian follicles
  and secretion of oestrogen

• FSH ?
• regulates the production of sperm in men

• LH ?
• stimulates ovulation and formation of the corpus
  luteum that secretes oestrogen and progesterone.

• LH ?
• Stimulates testosterone secretion in the male

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The Anterior Pituitary Other Hormones

• Prolactin
• Enlarges the mammary glands and stimulates milk
  production
• HYPERSECRETION - over production of milk and
  enlargement of breasts (also occurs in men)
• HYPOSECRETION - under production or no production
  of milk

• Human Growth Hormone (HGH)
• Regulates growth during pregnancy.
• HYPERSECRETION causes gigantism
• HYPOSECRETION causes dwarfism

• Melanocyte Stimulating Hormone (MSH)
• Stimulates the production and release of melanin
  by melanocytes in skin (basal layer).
• HYPERSECRETION - unnaturally dark skin
• HYPOSECRETION - prone to sunburn

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The Posterior Pituitary Hormones

• Oxytocin
• Regulates the release of milk in lactating women
• Induces uterine contractions in labour
• Has a role in orgasm and inducing 'pair
  bonding'ie. Love!)

Vasopressin Anti Diuretic Hormone (ADH) Regulates
the body fluids HYPERSECRETION - high blood
pressure HYPOSECRETION- low blood pressure
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The Thyroid Hormones

• Thyroxine
• Increases the metabolic rate
• HYPERSECRETION - Hyperthyroidism -
• HYPOSECRETION - Hypothyroidism

• Thyronine
• Reduces the metabolic rate

The Parathyroid Hormones

• Calcitonin
• Lowers blood calcium and phosphorus levels
• maintains dense bones by inhibiting osteoclast
  activity.
• HYPERSECRETION - leads to low blood calcium
  levels

• Parathormone
• Increases blood calcium and phosphorus levels by
  stimulating osteoclast activity, enhancing
  calcium reabsorption (kidneys) and enhances
  absorption of calcium in the intestines
• HYPERSECRETION - Softened bones from lack of
  calcium
• HYPOSECRETION - Low blood calcium levels

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The Pancreatic Hormones

• Insulin
• Lowers blood glucose levels by increasing glucose
  transport into the body cells and increasing
  glycogen synthesis in liver and muscle cells
• HYPERSECRETION - Hypoglycaemia
• HYPOSSECRETION - Hyperglycaemia
• low levels of insulin leads to diabetes mellitus
  type 2 (NIDDM), no insulin leads to diabetes
  mellitus type 1 (IDDM)

• Glucagon
• Raises blood glucose levels by inhibiting glucose
  uptake and liberating glucose stored as glycogen.

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The Thymus Hormones

• Thymic Factor (TF) Thymic humoral factor (THF)
• Involved in the activation of T lymphocytes
  (T-cells)
• HYPOSECRETION - increased susceptibility to
  disease

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The Adrenal Hormones

• Adrenal Cortex
• Aldosterone
• Increase reabsorption of mineral salts (sodium
  etc) in the renal tubules
• HYPOSECRETION - Addison's Syndrome (dehydration,
  weight loss, hypoglycaemia, hypotension)

• Adrenal Medulla
• Adrenaline (aka epinephrine or nor-adrenaline)
• Affects the heart breathing centre of brain
  arterioles of skin and digestive tract muscles
  of the gut, muscles of the body, liver.
• Secreted during fear, fight, flight response to
  danger
• HYPERSECRETION - stress / anxiety disorders,
  digestive disorders, CV disorders, skin
  disorders, immune weakening etc

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The Pineal Hormones

• Seratonin
• Regulates Mood, sexuality and body rhythms
  (responds to sunlight)
• HYPERSECRETION - ecstasy
• HYPOSECRETION - depression, Seasonal Affective
  Disorder (SAD)

• Melatonin
• Regulates sleep/wake or circadian rhythms
• Stimulated by darkness and inhibited by light

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The Gonads

• Testes
• Testosterone
• Regulates the production and maturation of sperm
  
• Responsible for the secondary male sexual
  characteristics

• Ovaries
• Progesterone
• Prepares the endometrium for implantation and
  pregnancy

• Oestrogen
• Matures the ovum for release
• Responsible for the secondary female
  characteristics