Download HORMONES

HORMONES
The Endocrine system
• The foundations of the endocrine system
are hormones and glands.
• The major glands that make up the human
endocrine system include the:
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hypothalamus
pituitary gland
thyroid
adrenal glands
pancreas
reproductive glands (which include the ovaries
and testes)
What is a gland?
• A gland is a group of cells that produces and
secretes, or gives off, chemicals.
• A gland selects and removes materials from the
blood, processes them, and secretes the finished
chemical product for use in the body
• There are two types of glands:
– Endocrine Gland: on the other hand, release more than 20
major hormones directly into the bloodstream
– Exocrine Gland: Such as the sweat and salivary glands,
release secretions in the skin or inside the mouth
Endocrine system - Overview
Pituitary Gland: (pronounced: puh-too-uhter-ee) called the "master gland" because it
makes hormones that control several other
endocrine glands
Thyroid: (pronounced: thy-royd) Produces
hormones that control the rate at which
cells burn fuels from food to produce
energy
Adrenal: (pronounced: uh-dree-nul)
Triangular glands which cover the top of
each kidney. The glands produce
adrenaline and other hormones.
Pancreas: (pronounced: pan-kree-us)
produces and secretes digestive
enzymes such as insulin and glucagon
The Endocrine System
Testes (Or Ovaries): Produce hormones
that are related to sex, reproduction and
sexual development (Puberty)
What are Hormones?
• The chemicals that are produced from the
endocrine glands are called hormones.
• Hormones regulate functions such as
growth and development, water balance,
sexual reproduction and the rate of
chemical reactions in the cell.
Endocrine
system:
Hormones
How Hormones work
• Hormones travel all around your body but only act on
specific target cells.
• Target cells only respond to particular hormones.
• This is because hormones have specific shapes which
fits chemically into a receptor on the target cell.
• However hormones in blood are at very low
concentrations, making them difficult to extract and
isolate.
Why Hormones?
Fast Control
Slow Control
• Both the nervous system and the endocrine system
are involved in response and control.
• While the nervous system responds quickly,
hormones take time.
• It can take minutes, hours or days before a hormone
reaches its peak concentration in the blood.
Why Hormones? continued
• This can be beneficial since not all
responses need to be fast.
• When a hormone affects a cell, the
response is usually long lasting.
• If hormones acted quickly then a
continuous supply of the would be needed.
• Hormones provide the ideal mechanism to
control
longer-term
activities
like
reproduction, growth and development.
Example: Small Brain, Big
Testicles
Small Brain
Big Brain
• A team of American scientists have discovered that if
a male animal has big testicles, the more likely it has
a small brain.
• Testicles use a large amount of energy to produce
sperm and the hormone testosterone.
• The brain requires a large amount of energy too and
the body doesn’t have enough for both.
Response from both systems
Something Scary
Causes you to become
Frightened
• The nervous system sends a rapid response when you
are frightened to cause an immediate and brief
reaction.
• The endocrine system releases Adrenalin which
causes the following:
• Increases breathing rate
• Dilates your pupils
Diverts blood to your muscles
Increases your alertness
The Pituitary is the “Master” gland
1. Name five (5) endocrine glands found in the human body.
2. What do endocrine glands do?
3. What happens to hormones after they have done their job?
4. Name one hormone produced for each of the glands named in
question one.
5. When is adrenaline produced ?
6. List four (4) different changes that adrenaline causes in the
body.
7. What is the role of insulin in the body? Where is it produced?
8. Name two (2) examples of ‘sex hormones’. List three (3)
changes that these can cause.
10. What hormone is responsible for controlling your body rhythms
such as sleeping?
Case Study
The table below shows the blood glucose (sugar)
levels of two people after they each consumed 50g
of glucose in a can of drink.
Blood glucose level (mg/100 mL)
Time after drinking
glucose solution
(minutes)
0
15
30
45
60
75
90
105
120
Matthew
Elly
86
110
140
115
90
80
84
85
85
85
125
170
190
210
210
200
180
145
Instructions
1.
Plot Matthew and Elly’s data in one graph, putting time on the
horizontal axis.
2.
The hormone insulin is secreted from the pancreas. It causes glucose to be
removed from the blood and stored in the liver as glycogen. In diabetes,
either the pancreas does not manufacture enough insulin (Type I Diabetes)
or the body does not respond to the insulin produced (Type 2 Diabetes).
Which of these two people do you think may have diabetes? Explain your
answer.
3.
Why do you think the non-diabetic person’s blood glucose levels fall?
4.
Why do you think the diabetic person’s blood glucose levels fall? (Think
about the role of glucose in the body.)
5.
People with type 1 diabetes inject insulin to make up for their body’s
inability to produce it. Injected insulin takes about an hour to start
working. When do you think the diabetic person should have injected
insulin? Explain your answer.