GCSE Biology

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Author:
ghoran
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157919
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GCSE Biology
Updated:
2012-06-09 06:07:03
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homeostasis
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  1. Why do we need homeostasis?If there was not a constant___(i)___ environment, our ___(ii)___ would not work properly. That would mean that nothing would operate properly and we would ___(iii)___.
    (Marks available: 3)
    • (i) internal
    • (ii) enzymes
    • (iii) die
  2. When there is too little water in the body, a sequence of events occurs. Fill in the missing words to complete the process:Too little water in blood.Detected by___(i)___.More___(ii)___ released into blood by the ___(iii)___.___(iv)___ reabsorbs more water.Less ___(v)___ produced.Blood water level not reduced further
    (Marks available: 5)
    • (i) hypothalamus
    • (ii) adh
    • (iii) pituitary gland
    • (iv) kidney
    • (v) urine
  3. Name the organs of the body that are involved in homeostasis
    • hypothalamus
    • pituitary gland
    • liver
    • kidney
    • lungs
    • pancreas
    • skin
  4. internal conditions that are controlled include
    • the water content of the body
    • ion content
    • temperature
    • blood sugar levels
  5. The hypothalamus monitors
    water, temperature and the level of carbon dioxide in the blood.
  6. The pituitary gland secretes a number of hormones - a key one is
    ADH, which is important in regulating the water content of the body.
  7. The liver helps to control
    glucose content of the body by storing it as glycogen. It is also involved in temperature regulation, acting as the bodys furnace by increasing the rate of respiration when we are cold.
  8. The lungs are involved by
    getting rid of carbon dioxide from the body.
  9. The pancreas is involved in maintaining a
    constant amount of glucose in the body through the actions of glucagon and insulin.
  10. The muscles of the body can help to maintain a
    stable body temperature as muscular activity and shivering help to generate heat.
  11. The kidney is involved in controlling
    the amount of water in the body.
  12. The skin is the largest organ and has a central role in maintaining a
    constant temperature
  13. What is Homeostasis?
    Homeostasis means keeping a constant internal environment
  14. What is Homeostasis?
    • Homeostasis means keeping a constant internal environment
    • it is carried out around the whole body. Homeostasis reaches from every cell up to whole organs and systems.
  15. what has to be controlled
    • A cool way to remember these 6 things is by learning this...
    • When (Water)
    • Shall (Sugar)
    • I (Ions)
    • Clean (CO2)
    • The (Temperature)
    • Utensils (Urea)
  16. why does the level of carbon dioxide in our body need to be controlled
    Extra carbon dioxide must be removed, otherwise the body becomes too acidic.
  17. how do we loose carbon dioxide
    It is lost mainly in the air we breathe out, but a small amount is lost in the urine.
  18. what is urea and why must the level of it in our body be contolled
    This is the waste chemical produced when we digest amino acids in the liver. It is poisonous and so must be removed
  19. how do we remove urea
    This is done mainly through the urine, although some is lost through our sweat.
  20. If the right balance of ions is not kept
    our cells can become shrivelled, swollen or even burst
  21. Important ions include -------------------------------------------------------------------------------------------------------------- hese are controlled through --------------------------------------------------------------------------------------------------------------
    • sodium, potassium, hydrogen and phosphate
    • our urine and the amount of water we drink. We also lose some, like sodium ions, through our faeces and our sweat.
  22. Having enough glucose for respiration plus adequate stores of glycogen is critical. If the blood glucose level falls to low we will
    die
  23. Without keeping the right amount of water we would
    die
  24. ...... of our body is water
    70%
  25. what organ controls water
    kidney
  26. why do we need to control temperature
    The enzymes that control every chemical reaction in our body work best at their optimum temperature of 37 degrees Centigrade. If our body cells get too hot or too cold they would die. So would we!
  27. The skin is described as the biggest organ in the body. An average person has about 2 square metres of skin. It is important because
    it keeps our water in, has a layer of fat to keep us warm and is tough enough to keep out microbes that might cause disease. It is also a great place for nerve receptors.In addition to all of this, the skin has some interesting mechanisms to help control temperature. It can alter blood flow, hair position and the amount of sweating.
  28. What happens when your temperature starts to move away from the normal 37 degrees? Too hot?
    • When we get too hot the hypothalamus sends impulses to the skin which cause 3 things to happen:
    • Our hairs lie flat: so letting more heat out.
    • We sweat: the evaporation of this cools us down
    • More blood goes through the skin: this acts like a radiator to radiate out heat.
  29. What happens when your temperature starts to move away from the normal 37 degrees? Too cold?
    • If we get too cold the hypothalamus sends other impulses so that the reverse happens:
    • Our hairs stand up: this traps a layer of air which acts like an insulator.
    • We stop sweating: this stops the heat loss by evaporation.
    • less blood goes through the skin: the skin will appear paler and colder
  30. Temperature control is important for the normal operation of enzymes and cells.The brain has a key role in co-ordinating this function
    near the bottom of the brain is a place called the hypothalamus, which monitors a number of key things in the body, including temperature.When the hypothalamus detects a change in the temperature of the blood it sends impulses down neurones to the skin.
  31. Too Little WaterThe chemical messenger between the brain and the kidney is the hormone ADH, Anti-Diuretic Hormone.The important parts of the process involve:
    • The hypothalamus in the brain, which detects the lower blood water content.The pituitary gland at the base of the brain, which releases the hormone ADH.The kidney, which reabsorbs the water.
    • In order to get back to the normal level of water in the blood we absorb more water from the digestive system, feel thirsty, and so drink more.
  32. We have two kidneys, which are in your lower back just where your belt goes. Their job is to
    lean the blood by filtering out unwanted material such as urea, excess water, salt andions.
  33. What the kidney doesOne job that they are involved in is
    reabsorbing excess water so that we don't dry out
  34. When there is too little water in the body the following sequence of events occurs:
    • he hypothalamus in the brain, which detects the lower blood water content.
    • The pituitary gland at the base of the brain, which releases the hormone ADH.The kidney
    • which reabsorbs the water
    • less urine produced
    • blood water level not reduced further
  35. too much water in blood
    • detected by hypothalamus
    • less ADH released into the blood by the pituitary gland
    • kindney reabsorbs less water
    • more urine is produced
    • noraml blood water level is reached
  36. our blood sugar level is controlled by two hormones which are produced by the pancreas
    • they are insulin and glucagon
    • insulin converts glucose to glycogen
    • glucagon converts glycogen to glucose

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