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UNIT 9: ENDOCRINE SYSTEM
(CHEMICAL COORDINATION)
(MADER, 2010:
CHAPTER 40 p. 736 – 752)
ENDOCRINE GLANDS
The nervous system and the endocrine
system work together
 To regulate the activities of the other
systems in the body.
 Both systems use chemical signals when
they respond to changes.
 But they have different means of
delivering the signals

Differences between the CNS and the
endocrine system
Central nervous
system
Endocrine system
Transmits electrical
impulses
Impulse send through
neurons through
neurotransmitters
Fast reaction
Reaction doesn’t last a
long time
Transmits chemical
biological messengers
Transmits message
through bloodstream by
means of hormones
Slow reaction
Reaction lasts a long time
ENDOCRINE GLANDS
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Endocrine system consist of different endocrine glands in the
body.
Endocrine glands are ductless .
And produce and secrete hormones.
That are transported through the blood in the blood vessels
of the body.
Towards a specific target organ where it has a specific
function.
The target cells only respond to specific hormones secreted
by specific endocrine glands.
If the cell can respond to the hormone, the hormone and the
recepter proteins bind together as a key fits into a lock.
EXOCRINE GLANDS

Exocrine glands have ducts and secrete
chemicals like enzymes into these ducts
which takes it to the lumen of organs or
to the outside of the body.
HORMONES (CHEMICAL SIGNALS)
Hormones are biological chemical messengers that help
cells, body parts and even individuals to communicate
with one another.
• Most hormones are proteins, but the steroids are fats.
• Hormones can inhibit or stimulate a reaction.
• Hormones are temperature, pH and substrate sensitive
and specific. (proteins).
•
ENDOCRINE GLANDS
1. HYPOPHYSIS
2. THYROID
3. ADRENAL GLAND
4. PINEAL GLAND
5. PARATHYROID GLAND
6. THYMUS
7. PANCREAS
8. GONADS
ENDOCRINE GLANDS
HYPOTHALAMUS AND PITUITARY
GLAND

The hypothalamus controls the glandular secretions
of the pituitary gland (hypophysis)
HYPOPHYSIS
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Attached to a stalk onto the hypothalamus.
Consist of a posterior- and anterior pituitary.
Posterior- produce and secrete the following
hormones: ADH and Oxytocin.
Anterior- produce and secete the following
hormones: TSH, ACTH, prolactin, growth hormone,
FSH and LH.
Posterior pituitary gland hormones:
ADH and Oxytocin

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ADH: Regulate the water reabsorption through the
kidneys by changing the permeability of the renal
tubules.
Oxytocin: Stimulates the uterus wall to contract
during the process of giving birth and stimulates
milk production during pregnancy.
How ADH functions
Anterior pituitary gland hormones:
TSH
ACTH
prolactin
growth hormone
FSH
LH.
TSH (THYROID STIMULATING
HORMONE)
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Stimulates the thyroid gland to secrete thyroxin.
Function by means of a negative feedback reaction.
ACTH (Adrenocorticotropic hormone)

Stimulates the adrenal cortex to produce
glucocorticoid that is released during stress.
PROLACTIN

Control milk production in females
Growth hormone

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Promotes skeletal and muscular
growth.
It stimulates the rate at which amino
acids enter cells and protein
synthesis occurs.
It promotes fat metabolism as
opposed to glucose metabolism.
DISORDERS CAUSED BY THE
UNDERSECRETION OF GROWTH
HORMONE
PITUITARY DWARFISM
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When a too little GH
has been produced
during childhood.
Normal proportions but
small stature.
Low blood pressure.
Can be rectified by
injecting the child with
growth hormone
DISORDERS CAUSED BY THE
OVERSECRETION OF GROWTH
HORMONE
GIANTISM
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If too much GH have
been produced during
childhood.
Excessive growth of
muscles and bones.
Usually have diabetes.
Much taller than normal
children/adults.
Disorder of GH : ACROMEGALY

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Caused by
overproduction of GH
in adults.
Enlargement of bones
in the face, fingers and
toes as a person ages.
FEEDBACK MECHANISMS CAUSED BY
HORMONE ACTION

NEGATIVE FEEDBACK MECHANISM
FSH (follicle stimulating hormone)
and LH

Stimulates the gonads (testis and ovaries) to
produce sex hormones and gametes.
THYROID GLAND
STRUCTURE OF THYROID GLAND
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Located in the neck around
the trachea.
Red – high blood volume
2 lobes connected by
isthmus.
Uses Iodine to produce the
hormone thyroxin
Thyroxin production is
stimulated by TSH secreted
by the Hypophysis
Also secretes the hormone
calcitonin
FUNCTIONS OF THYROXIN
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Increase the metabolic rate of a person.
No specific target organ, they stimulate all cells of
the body to metabolize at a faster rate.
Promotes the metabolism of glucose so that more
energy is released.
DISORDERS OF THE THYROID
GLAND
SIMPLE GOITER
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Disorder caused by the lack
of Iodine in the diet.
Without iodine the thyroid is
unable to produce thyroxin
and continued anterior
pituitary stimulation causes the
gland to enlarge.
CONGENITAL HYPOTHYROIDISM
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Retarded growth during
infancy.
Body is short and stocky
with mental retardation
Disorder of Thyroid Gland:
Exophthalmic goiter
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This goiter is due to an overactive thyroid
gland
The eyes of a person protrudes because of
edema in the eye socket tissue
Person is hyperactive, nervous, irritable,
suffers from insomnia.
Sweat excessively and is heat sensitive.
Enlarged thyroid can be surgically removed
and treated with radioactive iodine.
FUNCTIONS OF CALCITONIN
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Regulates the Calcium level in the blood.
Calcitonin brings about the deposit of calcium in the
bones when the level of calcium in the blood is too
high.
When the blood calcium level lowers to normal, the
release of calcitonin by the thyroid is inhibited.
This lower level of calcium in the blood, stimulates
the release of parathyroid hormone (PTH) by the
parathyroid glands.
PARATHYROID GLAND
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4 parathyroid glands are located on the thyroid.
Secretes the hormone: Parathyroid Hormone (PTH)
PTH corrects a low blood calcium level
PTH promotes the release of calcium by the bones
PTH promotes the reabsorption of calcium from the
kidneys
PTH brings about the activation of Vitamin D.
DISORDERS OF THE PARATHYROID
GLAND
TETANY
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Insufficient PTH
secreted.
Dramatic drop in
blood calcium
levels.
The body shakes
from continuous
muscle
contraction
HYPERPARATHYROIDISM
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The blood calcium
level becomes
abnormally high.
Bones become soft
and fragile.
Person irritable
and prone to get
kidney stones
CALCITONIN AND PTH –
ANTAGONISTIC HORMONES
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These 2 hormones (Calcitonin and PTH) are
antagonistic.
Both hormones work together regulate the blood
calcium level.
When the blood calcium level is high – the thyroid
gland secretes calcitonin.
When the blood calcium level is low – the
parathyroid gland releases PTH
ADRENAL GLAND
STRUCTURE
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Located ontop of the
kidneys.
Consist of an inner part the
adrenal medulla and and
outer part called the
adrenal cortex.
The adrenal medulla secretes
2 hormones: adrenalin and
nor-adrenalin.
FUNCTIONS OF ADRENALIN AND
NOR-ADRENALIN
ADRENALIN and NORADRENALIN
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Brings about all the bodily changes
that occur when an individual reacts to
an emergency situation.
Effect of this hormone is short term.
Released during fright, anxiousness
and anger.
Increase heart rate.
Increase blood flow and blood
pressure.
Muscles absorb glucose for energy to
react.
More blood (oxygen) to brain.
Actions of the digestive system
inhibited.
Pupils dilate to observe clearly
MALFUNCTION OF THE ADRENAL
CORTEX
ADDISON DISEASE
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Bronzing of the skin
Excess amount of ACTH.
This lead to a buildup of
melanin.
CUSHING SYNDROME
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Excess cortisol in blood
Sub-cutaneous fat
deposits.
PANCREAS
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The pancreas consist of
exocrine tissue with ducts that
produce and release digestive
juice (pancreatic sap) into the
duodenum, and endocrine
tissue without ducts that
secrete hormones directly into
the bloodstream.
The endocrine tissue is know as
the Islets of Langerhans and it
secretes two hormones: Insulin
and glucagon (antagonistic
hormones).
FUNCTIONS OF INSULIN IN THE
PANCREAS
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If blood sugar (glucose) level is high.
Insulin is secreted.
Insulin stimulates the uptake of glucose by the cells
(liver, muscle and adipose)
In the liver and muscles it is stored as glycogen.
Muscle cells break it down for energy.
Fat cells convert it to glycerol for the forming of fat.
Therefore insulin lowers the blood sugar level.
FUNCTIONS OF GLUCAGON
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When the blood sugar
level is low.
Glucagon is secreted
into the blood.
Glucagon stimulates the
liver cells to convert
glycogen into glucose
for energy production.
Therefore glucagon
raises the blood sugar
level.
DIABETES MELLITUS
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Type 1 Diabetes:
Pancreas is not
producing insulin
Islets of Langerhans
damaged.
Glucose accumulate in
blood.
Coma results if not
treated with insulin
injections.
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Treatment of
Diabetes:
Self study
TESTIS AND OVARIES
HORMONES PRODUCED BY THE
OVARIES
HORMONES PRODUCED BY THE
TESTIS
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Testis produce testosterone
(male sex hormone)
Stimulates the formation
of male traits during
puberty
Stimulates oil and sweat
glands.
Stimulates hairloss
(baldness)
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Ovaries produce estrogen and
progesterone (female sex
hormones)
Estrogen stimulates growth of the
uterus and vagina during
puberty and secondary sexual
female traits.
Stimulate egg production and
preparation of the uterus for
pregnancy.
Progesterone prepare the uterus
wall for possible implantation of
an embryo.
Effects of testosterone on males
Effects of estrogen and
progesterone in females