B11 Hormonal Coordination

Question 1

What is the endocrine system?

Answer 1

The endocrine system is composed of glands which secrete chemicals
called hormones directly into the bloodstream. The blood carries the
hormone to a target organ where it produces an effect. Compared to the nervous system the effects are slower but act for longer.

Question 2

What is the pituitary gland and what does it do?

Answer 2

The pituitary gland in the brain is a ‘master gland’ which secretes
several hormones into the blood in response to body conditions. These
hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.

Question 3

Identify the following on a diagram of the human body. (Back of card)

Answer 3

• pituitary gland
• pancreas
• thyroid
• adrenal gland
• ovary
• testes.

Question 4

What do the pancreas monitor?

Answer 4

Blood glucose concentration.

Question 5

How do the pancreas combat high blood sugar?

Answer 5

If the blood glucose concentration is too high, the pancreas produces
the hormone insulin that causes glucose to move from the blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage.

Question 6

How does Type 1 diabetes function?

Answer 6

Type 1 diabetes is a disorder in which the pancreas fails to produce
sufficient insulin. It is characterised by uncontrolled high blood glucose
levels and is normally treated with insulin injections.

Question 7

How does Type 2 diabetes function?

Answer 7

In Type 2 diabetes the body cells no longer respond to insulin produced
by the pancreas. A carbohydrate controlled diet and an exercise regime
are common treatments. Obesity is a risk factor for Type 2 diabetes.

Question 8

How do you treat Type 1 diabetes?

Answer 8

Injections of insulin before mealtimes. This insulin takes glucose to be converted to glycogen in the liver, where if needed it can be converted back into glucose to make blood glucose concentration rise again.

Question 9

How do you treat Type 2 diabetes?

Answer 9

Sometimes insulin injections, but often normal blood glucose levels can be restored with three simple steps:

• Losing weight
• Regular exercise
• Diet low in carbohydrates.

There are also drugs for Type 2 diabetes which help insulin work better on body cells, increase pancreas insulin production and reduce the amount of glucose absorbed by the intestines.

Question 10

How do you cure Type 1 diabetes?

Answer 10

Type 1 diabetes can be cured by:

• Pancreas transplant
• Transplanting pancreatic cells from dead to living volunteers.

Question 11

How do the pancreas combat low blood sugar?

Answer 11

If the blood glucose concentration is too low, the pancreas
produces the hormone glucagon that causes glycogen to be converted
into glucose and released into the blood.

Question 12

Why is the release of glucagon an example of negative feedback?

Answer 12

Blood sugar is low, so glucagon is high - the opposite occurs.

Question 13

What does a negative feedback system attempt to accomplish?

Answer 13

Negative feedback systems work to maintain a steady level of a certain substance. If a factor in the internal environment increases/decreases, changes take place to reduce/increase it to its original level.

Question 14

What are examples of a negative feedback system?

Answer 14

• Release of glucagon
• Release of insulin
• Thyroxine

Question 15

What does a negative feedback loop look like?

Answer 15

RECEPTORS DETECT CHANGE - RESPONSE LOWERS/RAISES LEVELS - IDEAL LEVEL - LEVELS FALL/RISE - RECEPTORS DETECT CHANGE
The cycle continues in a loop.

Question 16

What does thyroxine do?

Answer 16

Thyroxine from the thyroid gland stimulates the basal metabolic rate. It
plays an important role in growth and development. Thyroxine levels are controlled by negative feedback. It’s made by iodine from your diet in the thyroid gland.

Question 16

What does adrenaline do?

Answer 16

Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.

Question 17

What is the basal metabolic rate?

Answer 17

How quickly substances are broken down and built up - how much oxygen your tissues use, for example.

Question 18

What are some osmotic changes in bodily fluids?

Answer 18

Water leaves the body via the lungs during exhalation.
Water, ions and urea are lost from the skin in sweat.
There is no control over water, ion or urea loss by the lungs or skin.
Excess water, ions and urea are removed via the kidneys in the urine.

Question 19

What happens if osmotic changes are not functioning properly?

Answer 19

If body cells lose or gain too much water by osmosis they do not
function efficiently.

Question 20

How are amino acids excreted from the body?

Answer 20

The digestion of proteins from the diet results in excess
amino acids which need to be excreted safely. In the liver these amino
acids are DEAMINATED to form ammonia. Ammonia is toxic and so it is
immediately converted to urea for safe excretion.

Question 21

How do the kidneys function?

Answer 21

The kidneys produce urine by filtration of the blood and SELECTIVE REABSORBTION of useful substances such as glucose, some ions and
water.

Question 22

How are water levels controlled?

Answer 22

The water level in the body is controlled by the hormone ADH
which acts on the kidney tubules. ADH is released by the pituitary
gland when the blood is too concentrated and it causes more water
to be reabsorbed back into the blood from the kidney tubules. This is
controlled by negative feedback. This process will result in a small amount of very concentrated, dark urine.

Question 23

How can kidney failure be treated?

Answer 23

People who suffer from kidney failure may be treated by organ transplant or by using kidney dialysis.

Question 24

How does a dialysis machine work?

Answer 24

• Arterial blood leaves the arm and is pumped into the machine
• Blood thinners are applied to prevent blood clotting
• Blood enters the machine
• waste products diffuse through dialysis PPM (Urea, salts). Dialysis fluid has same concentration as normally concentrated blood so not too many salts are lost.
• Clean blood flows through bubble trap to exterminate any bubbles
  -Blood flows back into arm

Question 25

What does testosterone do?

Answer 25

Testosterone is the main male reproductive hormone produced by the
testes and it stimulates sperm production.

Question 26

What hormones are needed in the menstrual cycle?

Answer 26

Several hormones are involved in the menstrual cycle of a woman.
* Follicle stimulating hormone (FSH) causes maturation of an egg in the
ovary. Stimulates the ovaries to produce oestrogen.
* Luteinising hormone (LH) stimulates the release of the egg.
* Oestrogen causes the uterus lining to develop. Inhibits the release of FSH and stimulates the release of LH.
* Progesterone maintains the lining of the uterus and inhibits the release of both FSH and LH

Question 27

What are all the methods of contraception?

Answer 27

• oral contraceptives that contain hormones to inhibit FSH production
  so that no eggs mature
• injection, implant or skin patch of slow release progesterone to inhibit
  the maturation and release of eggs for a number of months or years
• barrier methods such as condoms and diaphragms which prevent the
  sperm reaching an egg
• intrauterine devices which prevent the implantation of an embryo or
  release a hormone
• spermicidal agents which kill or disable sperm
• abstaining from intercourse when an egg may be in the oviduct
• surgical methods of male and female sterilisation

Question 28

How does IVF work?

Answer 28

In Vitro Fertilisation (IVF) treatment.
* IVF involves giving a mother FSH and LH to stimulate the maturation
of several eggs.
* The eggs are collected from the mother and fertilised by sperm from
the father in the laboratory.
* The fertilised eggs develop into embryos.
* At the stage when they are tiny balls of cells, one or two embryos are
inserted into the mother’s uterus (womb).

Question 29

What are the negatives of IVF?

Answer 29

Although fertility treatment gives a woman the chance to have a baby of
her own:
* it is very emotionally and physically stressful
* the success rates are not high
* it can lead to multiple births which are a risk to both the babies and
the mother.

Question 30

Why do plants produce hormones?

Answer 30

Plants produce hormones to coordinate and control growth and
responses to light (phototropism) and gravity (gravitropism or
geotropism). Unequal distributions of auxin cause unequal growth rates
in plant roots and shoots.

Question 31

What do gibberellins do?

Answer 31

They are important in initiating seed germination, ending seed dormancy, promoting flowering and can increase the size of fruit making them grow better.

Question 32

What does ethene do?

Answer 32

Ethene controls cell division and ripening of fruits.

Question 33

What are uses for auxin?

Answer 33

Auxins are used:
* as weed killers
* as rooting powders
* for promoting growth in tissue culture.

Question 34

What are uses for gibberellins?

Answer 34

Gibberellins can be used to:
* end seed dormancy
* promote flowering
* increase fruit size.