HOMEOSTASIS

Test Yourself: Homeostasis

Test Yourself: Homeostasis

  • The body is constantly removing waste products to prevent them from building up; homeostasis
  • The kidneys ensure that water and ions are balanced in the body by filtering the blood.
  • Kidney failure is when both kidneys stop working.
  • Kidney dialysis uses a dialysis to filter the blood through dialysis fluid.
  • A kidney transplant is a more long-term solution however the donor kidney might be rejected by the body.
  • The thermoregulatory centre in the brain controls the temperature of the body.
  • Receptors in the skin pick up any external changes in temperature.
  • The concentration of glucose in the blood is monitored by the pancreas which produces the hormone insulin.
  • Type 1 diabetes is a condition which is caused by the pancreas not being able to produce enough insulin. Suffers use insulin injections to control their glucose blood level.

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TEST IT!

1. On a hot day more water is lost from the body than on a cold day.

a) Name two ways water is lost from the body?

i. __________________________________________
ii. __________________________________________

b) Why is it good to get rid of water when the body is too hot?

2. It is important for the body that it maintains a balance of water in the cells. How is this achieved on a hot day? Choose two ways below.

i. The amount of water in the urine decreases

ii. The amount of water in the faeces increases

iii. The amount of water eaten or drunk increases

iv. The amount of water being exhaled decreases

3. The glucose level in our blood changes very quickly when we eat. In an experiment a volunteer was given two slices of white bread and her blood glucose level was recorded over a period of 100 minutes. She was then given two slices of wholemeal bread and her blood glucose was again recorded over a period of 100 minutes.

a) Which bread would cause her blood sugar level to increase the most?

b) Which bread would be best for someone suffering from diabetes and why?

4. The kidneys are very important for regulating the concentration of certain substances in the blood stream.

a) In a healthy person no glucose is found in the blood. How does the kidney prevent glucose being excreted in the urine?

b) The table below shows the concentration of substances in a healthy person and one with kidney disease.

Substance

Concentration (grams per dm3)

Healthy urine

Kidney disease urine

GlucoseProteinAmino acidsMineral ionsUrea

0

0

0

20

18

0

5

0

20

18

Why do you think there are differences in the urine samples?

c) One cure of kidney disease is to have a kidney transplant. What are the advantages and disadvantages of this method compared to kidney dialysis?

ANSWERS

a)

i. Sweating

ii. Urination

b) The body is cooled down as the water evaporates from the skin.

  1. i. and iii.

a) The white bread.

b) The wholemeal bread because it contains less carbohydrates which are broken down in the body into sugars.

a) When the kidneys filter the blood they reabsorb all the glucose.

b) In kidney disease the kidneys are not able to reabsorb all the protein molecules and so some are lost in the urine.

c) The main advantage of a kidney transplant is that it’s a better long term solution than kidney dialysis for which a patient has to go into hospital every eight days. The main disadvantage is that the body could reject the donated kidney as it does not recognise it as part of the body. However, anti-rejection medicines can be taken but probably will need to be taken for the rest of that person’s life.