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AQA GCSE - Biology > 3.3 Homeostasis > Flashcards

3.3 Homeostasis Flashcards

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1
Q

What is homeostasis?

A

Maintenance of a constant internal environment

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2
Q

Why is homeostasis important? Which components?

A

Body temperature: enzymes
Blood sugar levels: respiration and blood pressure
Water: cell size
pH: enzymes

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3
Q

What waste products are removed from our body?

A

Carbon dioxide

Urea

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4
Q

How and why are the two waste products removed?

A

Carbon dioxide: breathed out via the lungs because it makes carbonic acid lowing the pH of our blood affecting enzymes

Urea: made in the liver from the breakdown of excess amino acids, removed by the kidneys in urine, temporarily stored in the bladder
Because it is toxic

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5
Q

What is negative feedback?

A

A deviation from the norm initiates corrective mechanisms to restore the norms

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6
Q

How is water obtained in the body?

A

When eating and drinking

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7
Q

How do we lose water?

A

Sweat
Breathing out
Urine

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8
Q

What can too much or too little water do to out cells?

A

Damage them causing them to burst or shrivel

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9
Q

What do kidneys do?

A

Filter the blood excreting substances you don’t want and keep substances the body needs

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10
Q

How is blood brought to the kidney?

A

Via the renal artery

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11
Q

What is a nephron?

A

Microscopic filtering units

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12
Q

What is the first stage of the kidney producing urine?

A

Filtering the blood:
The Glomerulus separates the larger molecules - red blood cells, white blood cells and carbon dioxide
From the smaller molecules - water, ions, urea, glucose and amino acids
The bowman’s capsule collects the filtrate of smaller molecules and they can pass through the renal tubial

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13
Q

What is the second stage of the kidney producing urine?

A

Reabsorbing all the sugar:
In the proximal convoluted tubal glucose and amino acids are reabsorbed by active transport as they ate against a concentration gradient

Lots of mitochondria and ribosomes- for energy and proteins (they carry certain molecules across a membrane)

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14
Q

What is the third stage of the kidney producing urine?

A

Reabsorbing dissolved ions needed:
In the loop of Henle some ions are reabsorbed by active transport
But other salts are left behind to balance what the body needs

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15
Q

What is the fourth stage of the kidney producing urine?

A

Reabsorbing as much water as the body needs:
In the distal convoluted tubal a diuretic hormone is released by the pituitary gland leading to increased reabsorption of water via osmosis

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16
Q

What is the fifth stage of the kidney producing urine?

A

Releasing urea, excess ions and water:
In the collecting duct the molecules left are water, salt and urea forming urine to be temporarily stored in the bladder leaving via the ureter

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17
Q

What can Kidney failure be treated with?

A

Kidney dialysis
Or
Kidney transplant

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18
Q

What does dialysis do?

A

Remove the blood from you body then clean out the urea before sending it back

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19
Q

What is an anticoagulant used for in dialysis? Example of drug?

A

Prevents blood clotting

Heparin

20
Q

What is an air trap used for in dialysis?

A

Gets rid of air bubbles preventing air embolisms (blood vessels blockages due to air bubbles)

21
Q

What is done to maximise amount of urea moved in the dialysis fluid?

A

The dialysis fluid flows in the opposite direction to the blood

22
Q

How is urea removed in dialysis?

A

Urea moves out of the blood via diffusion as there is no urea in the dialysis fluid creating a concentration gradient

23
Q

How do you not lose useful molecules in dialysis?

A

The fluid contains the same concentration of glucose and mineral ions as the blood so there is no no net movement of the substances needed by the body

24
Q

How often is dialysis done?

A

Carried out regularly

Changes from person to person

25
Q

What are some similarities between dialysis and a nephron?

A

Both remove urea

Red blood cell and white blood cells don’t leave the blood

26
Q

What are some differences between dialysis and a nephron?

A

Glucose is removed and then reabsorbed by active transport from the blood in the nephron

27
Q

What are the advantages of dialysis?

A

Prevents you feeling ill
Available to all kidney patients
No immunosuppressant drugs

28
Q

What are the disadvantages of dialysis?

A 
Time consuming
Affects your daily life
Expensive 
Go to hospital al lot
Can't eat salt and protein in between
29
Q

What does a kidney transplant do?

A

Enables a diseases kidney to be replaced with a healthy one from a donor (dead or living)

30
Q

What are antigens?

A

Proteins on the surface of cells

31
Q

Why can kidneys be rejected?

A

Antigens on someone else’s kidney will be different to the recipients antigens
White blood cells see the new kidney as a foreign object
They produce antibodies to attack the foreign antigens

32
Q

How do we prevent rejection of a kidney?

A

They kidney must be a good tissue match

Immunosuppressant drugs must be taken to suppress your immune system

33
Q

What are the advantages of a kidney transplant?

A

No longer need dialysis
Lead a more normal life
Overall it’s cheaper for the NHS

34
Q

What are the disadvantages of a kidney transplant?

A 
Immunosuppressant drugs have to be taken
Vulnerable to common infections
Waiting for an organ can be years 
Shortage of donors
The kidney will only last 8-9 years on average
Surgery carries risks
35
Q

How is thermoregulation monitored in the body?

A

It’s detected by thermoreceptors of the thermoregulatory centre in the brain

It monitors the temperature of blood flow through the brain

36
Q

What is the core temperature of must humans?

A

37 degrees

37
Q

What responses does your body do if you are too hot?

A

Sweat: heat evaporates
Vasodilation: Capillaries dilate and increased blood means more heat lost at the surface
Hairs lie flat: heat isn’t insulated
Fanning yourself or finding shade

38
Q

What responses does your body do if you are too cold?

A

Shivering: rapid muscle contractions of skeletal muscles increase respiration increasing heat energy to blood
Vasoconstriction: capillaries constrict limiting blood at the surface
Hairs on end: insulates heat
Goosebumps
Huddle: reduces surface area exposed

39
Q

What is glucose monitored by?

A

The pancreas

40
Q

What is happens if you have high levels of glucose concentration in your blood?

A

The hormone insulin is released

Allowing glucose to move from the blood into the cells

41
Q

What other ways can glucose by removed from the blood stream?

A

Increased rate of respiration
Convert glucose to glycogen
Convert glucose into fat
Increase amount taken into the cells

42
Q

Where is glucose converted into glycogen?

A

The liver

43
Q

What is happens if you have low levels of glucose concentration in your blood?

A

The hormone glucagon is released

This caused glycogen to be converted back into glucose

44
Q

What other ways can glucose be added to the blood stream?

A

Break down fats

45
Q

What is Type 1 diabetes?

A

A disease where a persons blood glucose is too high because the pancreas doesn’t produce enough insulin

46
Q

How do you control type 1 diabetes?

A

Careful attention to diet and exercise

Injections of insulin

47
Q

What new methods are being tried to treat diabetes?

A

Pancreas transplants
Embryonic stem cells
Transplanting pancreas cells

AQA GCSE - Biology (25 decks)

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