The endocrine system coordinates activities through chemical messengers called hormones. It consists of endocrine glands that secrete hormones directly into the bloodstream. The hypothalamus and pituitary gland regulate many other endocrine glands. The thyroid gland regulates metabolism through thyroxine and calcitonin regulates calcium levels. The parathyroid glands work with the thyroid to maintain calcium homeostasis through PTH. The adrenal glands produce hormones like adrenaline for the fight-or-flight response. The pancreas regulates blood sugar through insulin and glucagon. The gonads produce sex hormones like testosterone and estrogen.

1. UNIT 9: ENDOCRINE
SYSTEM
(CHEMICAL
COORDINATION)
(MADER, 2010: CHAPTER 40 p. 736 –
752)

2. 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

3. Differences between the CNS and
the endocrine system
Central nervous
system
Endocrine system
Transmits electrical
impulses
Transmits chemical
biological messengers
Impulse send through
neurons through
neurotransmitters
Transmits message
through bloodstream
by means of hormones
Fast reaction Slow reaction
Reaction doesn’t last a
long time
Reaction lasts a long
time

4. ENDOCRINE GLANDS
 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

5. 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.

6. • 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
HORMONES (CHEMICAL
SIGNALS)

7. ENDOCRINE GLANDS
1. HYPOPHYSIS
2. THYROID
3. ADRENAL GLAND
4. PINEAL GLAND
5. PARATHYROID GLAND
6. THYMUS
7. PANCREAS
8. GONADS

8. ENDOCRINE GLANDS

9. HYPOTHALAMUS AND
PITUITARY GLAND
 The hypothalamus controls the glandular
secretions of the pituitary gland (hypophysis)

10. HYPOPHYSIS
 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.

11. Posterior pituitary gland
hormones: ADH and Oxytocin
 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.

12. How ADH functions

13. Anterior pituitary gland
hormones: TSH
ACTH
prolactin
growth hormone
FSH
LH.

14. TSH (THYROID STIMULATING
HORMONE)
 Stimulates the thyroid gland to secrete
thyroxin.
 Function by means of a negative feedback
reaction.

15. ACTH (Adrenocorticotropic
hormone)
 Stimulates the adrenal cortex to produce
glucocorticoid that is released during stress.

16. PROLACTIN
 Control milk production in females

17. Growth hormone
 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.

18. DISORDERS CAUSED BY THE
UNDERSECRETION OF
GROWTH HORMONE
 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
PITUITARY DWARFISM

19. DISORDERS CAUSED BY
THE OVERSECRETION OF
GROWTH HORMONE
 If too much GH have
been produced during
childhood.
 Excessive growth of
muscles and bones.
 Usually have
diabetes.
 Much taller than
normal
children/adults.
GIANTISM

20. Disorder of GH :
ACROMEGALY
 Caused by
overproduction of
GH in adults.
 Enlargement of
bones in the face,
fingers and toes as
a person ages.

21. FEEDBACK MECHANISMS
CAUSED BY HORMONE ACTION
 NEGATIVE FEEDBACK MECHANISM

22. FSH (follicle stimulating
hormone) and LH
 Stimulates the gonads (testis and ovaries) to
produce sex hormones and gametes.

23. THYROID GLAND
 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
STRUCTURE OF THYROID
GLAND

24. FUNCTIONS OF THYROXIN
 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.

25. DISORDERS OF THE THYROID
GLAND
 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.
 Retarded growth
during infancy.
 Body is short and
stocky with mental
retardation
SIMPLE GOITER
CONGENITAL
HYPOTHYROIDISM

26. Disorder of Thyroid Gland:
Exophthalmic goiter
 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.

27. FUNCTIONS OF CALCITONIN
 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.

28. PARATHYROID GLAND
 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.

29. DISORDERS OF THE
PARATHYROID GLAND
 Insufficient PTH
secreted.
 Dramatic drop
in blood
calcium levels.
 The body
shakes from
continuous
muscle
contraction
 The blood
calcium level
becomes
abnormally high.
 Bones become
soft and fragile.
 Person irritable
and prone to get
kidney stones
TETANY
HYPERPARATHYROID
ISM

30. CALCITONIN AND PTH –
ANTAGONISTIC HORMONES
 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

31. ADRENAL GLAND
 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.
STRUCTURE

32. FUNCTIONS OF ADRENALIN
AND NOR-ADRENALIN
 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
ADRENALIN and NOR-
ADRENALIN

33. MALFUNCTION OF THE
ADRENAL CORTEX
 Bronzing of the skin
 Excess amount of
ACTH.
 This lead to a buildup
of melanin.
 Excess cortisol in
blood
 Sub-cutaneous fat
deposits.
ADDISON DISEASE CUSHING SYNDROME

34. PANCREAS
 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).

35. FUNCTIONS OF INSULIN IN THE
PANCREAS
 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

36. FUNCTIONS OF GLUCAGON
 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.

37. DIABETES MELLITUS
 Type 1 Diabetes:
 Pancreas is not
producing insulin
 Islets of Langerhans
damaged.
 Glucose accumulate
in blood.
 Coma results if not
treated with insulin
injections.
 Treatment of
Diabetes:
 Self study

38. TESTIS AND OVARIES
 Testis produce
testosterone (male sex
hormone)
 Stimulates the
formation of male traits
during puberty
 Stimulates oil and
sweat glands.
 Stimulates hairloss
(baldness)
 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.
HORMONES PRODUCED BY
THE TESTIS
HORMONES PRODUCED BY
THE OVARIES

39. Effects of testosterone on
males
Effects of estrogen and
progesterone in females