These notes are perfectly designed to help students in the nervous system topics and also a little bit of diabetes and controlling blood sugar levels and the best thing of all is the past papers exam questions which are really useful and helps students in that specific topic.
By definition, homeostasis is keeping a constant internal environment. It involves
balancing bodily outputs and inputs.
Automatic control systems in the body help to maintain temperature, water and
carbon dioxide levels. This ensures that cells can work at their optimum (best)
level.
Negative feedback controls are also used in homeostasis. The negative
feedback systems act to cancel out a change such as a decreasing temperature.
Temperature control:
The temperature of the body should be maintained at 37oC – this is because
many of the body’s enzymes work best at this temperature; it is their optimum.
When the body gets too hot:
- Heat stroke can happen – the skin becomes cold and slimy and your pulse
rate is fast, yet weak
- Dehydration can happen – this is where too much water is lost
Both of these can lead to death if not properly treated.
Sweating is used as a defence mechanism to avoid overheating. Sweating
increases the transfer of heat to the surrounding environment. The evaporation
of sweat requires body heat to transfer the (liquid) sweat into water vapour
(gas).
When we get too cold, in very low temperatures, hypothermia can set in. This
causes violent shivering and a slowed pulse – it can be fatal if not treated
quickly.
The hypothalamus is part of the brain that monitors the
temperature of the blood in your body.
The actual reaction to temperature extremes (too cold /
too hot) is controlled by the hormonal and nervous
systems, which trigger vasodilation or
vasoconstriction.
Vasoconstriction is the constriction
(narrowing) of small blood vessels in the
skin. It causes less blood flow and less
heat transfer.
Vasodilation is the dilation (widening) of
small blood vessels in the skin. This
causes more blood to flow near the
surface of the skin, resulting in more
heat transfer.
, Staying in Balance – Revision Pack
Controlling blood sugar levels:
Hormones are chemicals that travel to target organs to regulate the functions of
organs and cells. Insulin is an example of a hormone; it is produced in the
pancreas and lowers blood glucose levels when they get too high. When your
body lacks insulin diabetes is caused.
Hormone reactions are lower than nervous reactions as hormones travel in the
blood.
There are two types of diabetes:
Type of diabetes Cause Method of Control
1 Person’s pancreas does Insulin injections at
not produce any insulin mealtimes.
2 Occurs later in life and Controlled diet
linked with being
overweight. Person’s
body produces too little
insulin or their body
doesn’t react to the
insulin
Insulin converts excess glucose into glycogen, which is stored in the liver. This
helps to regulate the blood sugar level.
The insulin dosage for people with Type 1 diabetes will vary according to the
person’s diet and amount of activity.
For example, when we do strenuous activity we need more glucose in our blood
for energy, so a lower insulin dose would be needed for someone with Type 1
diabetes.
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