The document discusses the endocrine system and hormones. It defines hormones as chemical messengers produced by endocrine glands that travel through the bloodstream and affect target organs. The main endocrine glands are the pituitary, thyroid, adrenals, pancreas, ovaries, and testes. The pituitary gland is called the "master gland" as it controls the other endocrine glands through releasing tropic hormones. Hormones maintain homeostasis by allowing physiological processes to function in a coordinated manner. Imbalances in hormones can lead to disorders like gigantism, dwarfism, hyperthyroidism, hypothyroidism, and diabetes.

1. BIOLOGY FORM 5
CHAPTER 3
COORDINATION & RESPONSE PART 2

2. LEARNING OBJECTIVESLEARNING OBJECTIVES
3.3 Analysing the role of hormones in humans
LEARNING OUTCOMESLEARNING OUTCOMES
 state what a hormone is,
 state what the endocrine system is,
 state why the endocrine system is necessary,
 state physiological processes not directly regulated by the
nervous system,
 describe how the endocrine system complements the nervous
system,
 describe briefly coordination involving both the nervous system
and endocrine system, in a “fight or flight” situation
 state the effects of hormonal imbalance,
 state the use of hormone in medicine

3. HORMONAL
CONTROL:
THE ENDOCRINE
SYSTEM

4. A chemical communication system is
made up of at least two types of cell:
one cell:
produces & releases
the hormone ⇒
message released
second cell with
receptor:
receives message ⇒
target cell activated

5. Receptors are SPECIFIC

6. A Gland is:
 a structure which secretes a specific
chemical substance or substances

7. A Gland secretes chemicals
into:
Some other part
of the body
The bloodstream

8. Glands in the body are:
secrete an enzymesecrete an enzyme
into ainto a ductduct
 secrete hormonessecrete hormones
 have no duct (ductless)have no duct (ductless)
 have a rich blood supplyhave a rich blood supply
Exocrine
gland
EndocrineEndocrine
glandgland

9. What is a hormone?
 a chemical which is produced by an
endocrine gland, travels in the bloodstream
and has an effect on the target organ

10. • The blood stream
transports hormones
throughout the body.
• Each hormone acts
on a certain type of
tissue called its target
tissue.

11. Endocrine System
• Made up of endocrine
glands and hormones
• The glands are
ductless
• The glands release
hormones directly into
the blood stream

12. Endocrine Glands

13. Pituitary
Thyroid
Adrenal
Pancreas
Ovary
Testes
Position of the main endocrine glands in the human

14. Test: Name The Endocrine
Organs

15. The main human endocrine glands
and their secretions.

16. The hypothalamus and the pituitary gland
– Control much of the endocrine system
Pituitary
gland
Hypothalamus
Pituitary gland = master gland
because it controls the other endocrine glands

17. The Pituitary Gland
is a small red-grey gland
weighs about 0.5g [size of a pea]
hangs from the base of the brain
by a short stalk
is a link between the nervous
system and many endocrine
glands

18. Hypothalamus
• Controls the pituitary
gland
• Receives information
from the nervous
system

19. The hypothalamus collects
information from:
1. other regions of the
brain
2. blood vessels passing
through it
What does the
hypothalamus do
with
this information?

20. How does the pituitary gland respond?
By releasing
hormones,
which directly or
indirectly
regulate the activity of
all other endocrine
glands

21. What parts of the body does the pituitary
gland affect?

22. • Makes hormones which are stored & released
from the posterior pituitary gland
• Controls the release of hormones from the
anterior pituitary gland and
HYPOTHALAMUS

23. The Posterior Pituitary
Gland: does not synthesise any hormones but
stores and releases two hormones:
ADH
(antidiuretic hormone
or vasopressin)
Oxytocin

24. Hypothalamus & Posterior Pituitary Gland

25. Recap:
Hormones are
stored in and
released from the
posterior pituitary
are
Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Anterior
pituitary
Posterior
pituitary
HORMONE ADH Oxytocin
TARGET Kidney tubules Mammary glands,
uterine muscles
1. ADH
2. OXYTOCIN

26. Functions of Oxytocin:
 contraction of the
uterus during birth
 ejection of milk
from the nipple
Target: Uterus & mammary glands

28. Antidiuretic hormone (ADH)
– Target: kidney
– Enhances water reabsorption in
in the kidneys

29. Function of ADH: Increased permeability
to water by:
Distal
convoluted
tubule
Collecting
tubule

30. Anterior Pituitary Gland
– true endocrine gland
– Produces both tropic and nontropic hormones
Note: Tropic hormones from the hypothalamus
control release of hormones from the anterior pituitary

31. Hormones Released
by the
Anterior Pituitary:
 TSH
 ACTH
 LH
 FSH
 Prolactin
 Growth Hormone
Tropins
orTrophic
hormones

32. Tropic Hormones of
Anterior Pituitary Gland
• The four tropic hormones are
– Follicle-stimulating hormone (FSH)
– Luteinizing hormone (LH)
– Thyroid-stimulating hormone (TSH)
– Adrenocorticotropic hormone (ACTH)

33. 1. Follicle-stimulating hormone (FSH)
– Target: Gonads
– stimulates the development of follicles in
ovaries (female) & spermatogenesis (males)
Tropic Hormones of
Anterior Pituitary Gland

34. 2. Luteinizing hormone (LH)
– Target: gonads
– controls ovulation, development of
the corpus luteum, secretion of
oestrogen & progesterone
(females)
– secretion of testosterone (males)
Tropic Hormones of
Anterior Pituitary Gland

35. OVULATION

36. 3. Thyroid-stimulating hormone (TSH)
– Target: thyroid gland
– Stimulates the thyroid gland to release thyroxine
Tropic Hormones of
Anterior Pituitary Gland

37. 4. Adrenocorticotropic hormone (ACTH)
- Target: adrenal gland
- Stimulates the adrenal cortex to release hormones.
Tropic Hormones of
Anterior Pituitary Gland

38. Nontropic Hormones
• The nontropic hormones produced by the
anterior pituitary include
Prolactin
• Target: mammary gland
• Prolactin stimulates lactation in mammals

39. Nontropic Hormones
Growth hormone (GH)
• Target: Bones & soft tissues
• stimulates the elongation of bones in the body.
Growth Hormone (GH) and insulin like growth
factor 1 (IGF-1) are important hormones that
help you grow. They also keep muscles and
bones strong, fat levels down and your energy
levels up.
GH is produced by the pituitary gland and sent
in the blood. GH makes another hormone
called IGF-1. This is made all over the body but
mostly in the liver.

40. RECAP

41. 52
The role of the hypothalamus in
regulating the secretion of hormones
from the pituitary gland
HypotHalamus
Anterior
pituitary
Posterior
pituitary
ADH oxytocin
Kidney tubules Smooth muscle in the
uterus
Adrenal
cortex Thyroid Ovaries, testes Bones, tissues Mammary
glands

42. GROWTH HORMONE
IMBALANCE

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Excess GH during childhood - Gigantism
Tallest man 8 feet 11 inches.

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Excess GH as an adult - Agromegaly
Hands, bones, feet ,
cheeks, jaws thicken

46. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Low GH at childhood-dwarf
Under secretion of growth hormone during childhood.
Physical growth retarded but
mental growth normal

48. Thyroid Gland
• Located in the neck in
front of the trachea
• Thyroid gland releases
iodine-containing
hormone thyroxine.

50. Negative Feed Back Mechanism

52.  Hyperthyroidism, excessive
secretion of thyroxine can cause
Graves’ disease in humans
Hyperthyroidism
10

53. Lack of thyroxine
during childhood
Cretinism
- mentally &
physically retarded
Hypothyroidism
During adulthood-
Myxedema-
Low metabolic rate,
sluggish, low heart
rate/body
temperature.

54. Hypothyroidism
 Goiter
 Lack of iodine in diet
 enlargement of thyroid gland.

55. Goiter

57. Hyperthyroidism
 a condition in which the thyroid
gland makes too much thyroid
hormone. The condition is often
called overactive thyroid.
Symptoms
Fatigue
Goiter
Hair loss
Hand tremor
Heat intolerance
Increased appetite
Increased sweating
Irregular menstrual
periods in women
Nervousness
Palpitations
Restlessness
Sleep problems
Weight loss (or weight
gain)

58. Adrenal Gland
KidneysKidneys
Adrenal glandsAdrenal glands• Location: on top of
kidney
• Hormone: Adrenaline
• Function: Raises
blood sugar level and
increases heart beat
and breathing rates.

59. Cortex
Medulla
Two regions
in the adrenal
glands:
• made up of two glands:
the
adrenal medulla and the
adrenal cortex

60. ADRENAL GLAND
• Adrenal medulla -
secretes adrenaline and noradrenaline
*Adrenaline prepares body in a
fight /flight (Increases the blood sugar level,
heart & respiratory rate, metabolic rate,
constricts blood vessels.
• Adrenal cortex -
secretes aldosterone
Aldosterone controls reabsorption of sodium
ions in the kidneys.

61. Adrenaline, the emergency
hormone

62. Adrenaline prepares the body for
action
Muscles need ENERGY to contract!!Muscles need ENERGY to contract!!

63. Which process releases energy?
glucose + oxygen carbon
dioxide
+ water + energy
glucose
oxygen
muscle energy
How can MORE glucose + oxygen
reach the muscle?

64. Effects of adrenaline
Heart beat increases
Breathing rate
increases

65. Effects of adrenaline
 Arteries to muscles widen
What is the effect of this?

66. 5 litres of blood in an adult
If more blood
flows to muscles
less must flow to
other organs.
Which?

67. Gut & Skin get less blood
 As arteries narrow
A person becomes pale
when afraid. Why?

68. Glycogen
Glucose in the blood increases
Glycogen is converted
to glucose
Effects of adrenaline

69. The pancreas:
 is described as both an endocrine
and an exocrine gland because:
Produces both enzymes and hormones.
 is richly supplied with blood:
to carry hormones towards the target
organs

70. Islets of Langerhans
• Location: Pancreas
• Produces Hormones:
Insulin & Glucagon

71. Pancreas
 Glucagon
 Is produced by alpha cells
 Converts glycogen to glucose
 Insulin
 Is produced by beta cells
 Converts glucose to glycogen

72.  Insulin lowers blood glucose by increasing the
rate of glucose uptake and utilization
 Glucagon raises blood glucose by increasing
the rates of glycogen breakdown and glucose
manufacture by the liver
Insulin and glucagon

74. Control of blood sugar

76. Diabetes Melitus
• Undersecretion of
insulin.
• High blood sugar

77. Question:
Give a biological explanation for the following
situation:
A diabetic person received an insulin shot after
intake of a meal rich in carbohydrates. (2)
A diabetic person does not
produce insulin. The insulin
injected helps the person to
reduce the sugar level in the
blood back to normal.

79. Ovary
• Hormone: Oestrogen
Function: Develop
secondary sexual
characteristics in females.
• Hormone: Progesterone
Function: thickening of
endometrium wall for
implantation of foetus

80. Testes
• Hormone: Testosterone
• Function:
1. Stimulate sperm production (spermatogenesis)
2. Development of secondary sexual characteristics

82. Negative feedback control:
 produces an effect which is the opposite of
what has been happening before
 e.g. if body temperature rises, sweat is
produced to cool it down
 is important to keep conditions constant in
the body

83. Control of blood sugar as an
example of:
N O R M
E x c e s s
D e f ic ie n c y
C o r r e c tiv e
m e c h a n is m
C o r r e c tiv e
m e c h a n is m
N O R M
N e g a tiv e
f e e d b a c k
N e g a tiv e
f e e d b a c k

84. Differences between nervous and
endocrine co-ordination.
Nervous Chemical
Information passes as
electrical impulses
along nerve fibres
Information passes as a
chemical substance
through the
bloodstream
Rapid transmission Slow transmission
Response is immediate
Response is usually slow
e.g. growth
Response is short-lived Response is long-lasting
Response is very exact
Response is usually
widespread

85. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Testosterone causes an increase in muscle and
bone mass
– And is often taken as a supplement to cause
muscle growth, which carries many health risks
Figure 45.14

86. HORMONES IN MEDICINE
 Insulin injection for treatment of diabetes
mellitus
 Growth hormone for treatment of dwarfism
 Thyroxine for treatment of hypothyroidism

87. Summary
A hormone is a chemical messenger with
the
following properties:
it travels in the blood;
it has an effect at a site different from the
site where it is made, called the target;

88. Summary
it fits precisely into receptor molecules in the
target like a key in a lock – it is therefore
specific for a particular target;
it is a small soluble organic molecule;
it is effective in low concentrations.

91. THE
ENDOCRINE
SYSTEM
THE END

92. THE END