Download THE ENDOCRINE SYSTEM

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Communication system that uses chemicals
called hormones to send messages through
the body.
Works with the nervous system
Substance secreted into blood stream by a
gland
Acts on a target organ elsewhere in the body
Alter cellular activity, so have ability to alter
metabolic rate
Classified as
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Steroids
Proteins
Brain controls secretion of endocrine glands
which regulates function of internal organs
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Secrete directly into the
bloodstream
Do not have ducts
Hypothalamus
Part of nervous system
Regulates the pituitary
gland
Produces releasing and
inhibiting hormones
2. Pituitary Gland
 Located at base of brain
 Divided into 2 lobes
 Called the master gland
3. Pineal Gland
 Located in centre of brain
 Secretes melatonin
 Sleep/awake hormone
4. Thyroid Gland
 Just below larynx
 Has two lobes
 Secretes thyroxine and calcitonin
5.Parathyroid Glands
 Four tiny glands in posterior wall of thyroid
 Secretes parathyroid hormone ( PTH )
6.Thymus
 Upper thorax behind sternum
 Protects the body from infection
 Produces thymosin
7. Pancreas
 Is both endocrine and exocrine gland
 Mainly a digestive gland
 Secretes insulin and glucagon from groups of
cells called Islets of langerhans
8. Adrenal Gland
 Attached to upper part of kidneys
 Secretes aldosterone which is involved in
control of blood pressure
 Secretes cortisol enabling body to cope with
stress
 Secretes DHEA which stimulates male
secondary sexual characteristics
 Secretes adrenaline at times of emotional or
physical stress
9. Gonads
 The sex glands
 Ovaries in female
 Testes in male
 Hormones excreted are progesterone,
oestrogen and testosterone
 These hormones maintain the reproductive
system and develop sexual characteristics
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Secrete their products into ducts which open
onto a surface
Examples are
Sweat glands
Salivary glands
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Most common endocrine disease
Caused by disturbance of hormonal control and
level of glucose in blood
Type 1 starts in childhood but can occur when
older
Autoimmune disease
Person’s immune system destroys insulin
produced by pancreas
High level of glucose, ( hyperglycaemia ), causes
person to have polyuria and thirst ( polydipsia )
Treated with insulin
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Type 2
Usually appears at later age
Often associated with obesity, can run in
families
Problem is lack of insulin
Can be treated often with weight reduction
and dietary changes
Some people require medication