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GCSE Biology > Homeostasis > Flashcards

Homeostasis Flashcards

1
Q

What does homeostasis mean?

A

Keeping your internal environment constant.

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2
Q

What 5 things does homeostasis include monitoring and controlling?

A
  1. Waste materials.
  2. Body temperature.
  3. Water content
  4. Ion content.
  5. Blood glucose levels.
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3
Q

What 2 waste materials have to be removed from the body?

A
  1. Carbon dioxide.

2. Urea.

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4
Q

How is carbon dioxide produced?

A

By respiration.

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5
Q

How is carbon dioxide removed from the body?

A

Via the lungs when we breathe out.

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6
Q

How is urea produced?

A

In the liver by the breakdown of amino acids.

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7
Q

How is urea removed from the body?

A

By the kidneys. It is temporarily stored in the bladder and then excreted as urine.

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8
Q

What temperature should the body be kept constant at?

A

37^oC

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9
Q

What 3 things does the thermoregulatory centre in the brain do?

A
  1. Monitors and controls body temperature.
  2. Has receptors that monitor the temperature of the blood flowing through the brain.
  3. Receives information (impulses) from temperature receptors in the skin.
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10
Q

Why do people sweat?

A

To cool the body. When it is hot, more water is lost by your body, so more water has to be taken in as drink or in food to balance this lost.

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11
Q

What two things does the body do when it is hot to regulate body temperature?

A
  1. Sweat.

2. Skin appears flushed.

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12
Q

Why does skin appear flushed when it’s hot?

A

Because there is an increased blood flow beneath its surface.

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13
Q

What 2 things happen if core body temperature is too high?

A
  1. Blood vessels supplying skin capillaries dilate (widen) to increase blood flow and heat loss.
  2. Sweat glands release more sweat, which cools the skin as it evaporates.
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14
Q

What 2 things happen if core body temperature is too low?

A
  1. Blood vessels supplying skin capillaries constrict (narrow) to reduce blood flow and heat loss.
  2. Muscles start to shiver, causing heat energy to be released by respiration in cells.
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15
Q

What is the main function of the kidneys?

A

To maintain the concentrations of dissolved substances in the blood.

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16
Q

What three things do the kidneys do?

A
  1. Regulate the amount of water in the blood.
  2. Regulate the amount of ions in the blood.
  3. Remove all urea in the form of urine.
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17
Q

How do water and ions enter the body?

A

When you eat and drink.

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18
Q

Why does the level of water and ions need to be maintained?

A

Because too much water moving into or out of the cells may damage them.

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19
Q

What three processes occur in the kidneys?

A
  1. Ultra filtration.
  2. Selective reabsorption.
  3. Excretion of waste.
20
Q

What do blood vessels carry through the kidneys?

A

Blood.

21
Q

What is ultra filtration?

A

When lots of water and all the small molecules are squeezed out of the blood, under pressure, into tubules in the kidney.

22
Q

What is selective reabsorption?

A

When all the sugar, plus any ions and water needed by the body, are reabsorbed back into the blood from the tubules.

23
Q

What is excretion of waste?

A

When excess water, ions and all lof the urea pass to the bladder in the form of urine, where it’s stored before being released from the body.

24
Q

How can failed kidneys be treated?

A
  1. Using a dialysis machine.

2. By having a kidney transplant.

25
Q

How does a dialysis machine work?

A
  1. Blood flows through a dialysis machine.
  2. The blood is separated from the dialysis fluid by partially permeable membranes.
  3. The membranes allow urea, and any excess substances, to pass from the blood into the dialysis fluid.
  4. Concentrations of dissolved substances in the blood are restored to their normal levels.
26
Q

What is in dialysis fluiid?

A

The same concentration of useful substances as blood. This ensures glucose and essential mineral ions aren’t lost through diffusion.

27
Q

How often should dialysis be carried out?

A

At regular intervals to maintain the patient’s health.

28
Q

What does a kidney transplant involve?

A

A diseased kidney being replaced with a healthy one from a donor.

29
Q

What is the main problem with kidney transplants?

A

The donor kidney might be rejected by the recipient’s immune system. There are antigens on the surface of cells. The recipient’s antibodies may attack the antigens on the donor organ because they don’t recognise them as being part of the recipient’s own body.

30
Q

What 2 things can be done to prevent rejection of the transplanted kidney in a kidney transplant?

A
  1. A donor kidney with a tissue-type similar to that of the recipient is used (this is best achieved if the donor is a close relative.
  2. The recipient is treated with drugs that suppress the immune system.
31
Q

What are the two main functions of the pancreas?

A
  1. To monitor and control blood sugar levels.

2. To secrete the hormone insulin.

32
Q

What does insulin do?

A

It allows glucose to move from the blood into the cells.

33
Q

What other organ does the level of insulin in the pancreas affect?

A

The liver.

34
Q

What happens if a person’s pancreas doesn’t produce enough enough insulin?

A

A person’s glucose concentration may rise to a high level. This is called Type 1 diabetes.

35
Q

How can type 1 diabetes be controlled?

A
  1. By careful management of diet and exercise.

2. By injecting insulin into the blood.

36
Q

How is human insulin made?

A

Via genetic engineering, quickly and cheaply using bacteria.

37
Q

How does insulin work?

A

It converts glucose into glycogen, which is stored in the liver. A second hormone called glucagon is made in the pancreas when blood glucose levels fall too low. This cause glycogen to be converted into glucose and be released into the blood.

38
Q

What reaction happens between glucose and insulin?

A

Glucose glycogen

39
Q

What is glucose needed for?

A

To provide energy for the body.

40
Q

What happens if blood sugar level is too high?

A
  1. Thirst.
  2. Hunger.
  3. Need to urinate.
  4. Blurred vision.
  5. Dizziness.
  6. Nausea.
41
Q

What happens if blood sugar level is too low?

A
  1. Hunger.
  2. Weakness.
  3. Inability to concentrate.
  4. Dizziness.
  5. Convulsions.
  6. Loss of consciousness.
42
Q

Which part of the brain monitors body temperature?

A

The thermoregulatory centre.

43
Q

Where is insulin made?

A

Pancreas.

44
Q

What is urea?

A

Broken down amino acids.

45
Q

Where is urine stored?

A

In the bladder.

46
Q

If a person’s kidney fails, what type of machine can be used to filter their blood?

A

Dialysis machine.

GCSE Biology (5 decks)

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