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
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
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
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
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
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
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
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
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.
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
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)
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?
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
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
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.
78.
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
81.
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
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.