Download Endocrine System

The Endocrine System
 The
Endocrine System is the set of hormone
secreting glands within the body.
 An Endocrine gland is a ductless organ and
makes and secretes specific chemical messengers
into the blood.
 An Exocrine gland secretes directly or by a duct
to the outside of the body e.g. sweat gland,
salivary gland
 The pancreas is both an endocrine and exocrine
gland (Islets of Langerhans secrete insulin)
 A Hormone is a chemical messenger, secreted by
a endocrine gland into the blood which alters the
effect of a specific tissue.
Hormone
Gland
Function
ADH / Growth
Hormone
Pituitary
Increases water re-absorption by the
kidney / bone elongation
Thyroxine
Thyroid
Regulates Metabolism, growth and
development
Adrenalin
Adrenals
Raises heart rate, breathing rate, blood
pressure and blood glucose levels
Insulin
Pancreas
Uptake of glucose from blood.
Oestrogen
Ovaries
Endometrium Formation, female
secondary sexual characteristics
Testosterone
Testes
Sperm Production, male secondary
sexual characteristics
Melatonin
Pineal
Sleep Pattern, Ovulation, Sexual
Maturity
 NS
is fast acting, ES is slower (growth)
 NS
is electrical, ES is chemical.
 NS
has fast transmission, ES is slow (blood)
 NS
is short lived response, ES is long lasting.
 NS
affects local, ES has widespread affect.
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The Pituitary gland is located in the hypothalamus (front
of the brain) and is the most important part of the
endocrine system.
The Pituitary gland has two parts, the anterior and
posterior.
The Anterior part produces two hormones, ADH and
Oxytocin.
ADH is involved in water level control in the blood.
Oxytocin controls lactation (milk let down) and is
released from the pituitary when an animal is suckled.
The Posterior part of the Pituitary produces a number of
important hormones.
These include FSH (Follicle Stimulating Hormone), LH
(Luteinizing Hormone), Prolactin and Growth
Hormones.
The Pituitary also releases hormones which control the
Adrenal and Thyroid glands.
 The
thyroid glands are found on the trachea.
 The main hormone produced is called
thyroxine.
 This hormone controls the growth and
development of animals.
 Iodine is required for its production.
 Lack of thyroxine causes deformation and
retardation.
 The glands swell if not enough hormone is
produced – this is called goitre in humans.
 These
are located on either side of the thyroid.
 They produce two hormones: Parathormone
and Calcitonin.
 These hormones control the level of calcium,
magnesium and phosphate in the body.
 The
Thymus A very small gland located on the
neck.
 Has some involvement in the production of
lymphocytes (white blood cells), which are
involved in immune response.
The Pancreas produces insulin.
 It is produced in the pancreas in the Islets of
Langerhans.
 Insulin is required for the intake of glucose in cells
and prevents the excess breakdown of glycogen.
 If insulin is lacking, one outcome is the passing of
glucose in the urine.
 This is called diabetes mellitus.
 This can cause coma because the brain needs
glucose.
 Synthetic Insulin is now available for diabetics.
 It must be injected because if it was eaten it would be
digested.

The adrenal glands are found near the kidney.
They produce over fifty different hormones which
are vital for life.
 Hydrocortisone is produced in the adrenal glands
and is required to control blood pressure and
controls the loss of blood.
 Adrenalin is secreted from the adrenal glands
during stress.
 It redirects blood to the head and increases the
heartbeat.
 It makes the individual more acute to their
surroundings.
 It is usually secreted when frightened.
 Another hormone called non-adrenalin, turns off the
effects of adrenalin.
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 The
gonads are the sex glands - the testes
and ovaries.
 The hormones produced are involved in
the reproductive systems of the animal.
 These include testosterone, oestrogen
and progesterone.
 These hormones will be looked at in more
detail in Animal Reproduction.