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BIOLOGY IGCSE > EXCRETION > Flashcards

EXCRETION Flashcards

1
Q

What is excretion?

A

The removal of the waste substances of metabolic reactions, toxic materials and substances in excess of requirements.

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2
Q

What are excretory organs?

A

Lungs
Kidneys
liver

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3
Q

What is produced by the breakdown of respiration?

A

CO2

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4
Q

How is CO2 removed?

A

It is carried away by the blood and removed in the lungs.

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5
Q

Why must CO2 be removed?

A

It dissolves in water easily to form an acidic solution which can lower the pH of cells

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6
Q

What can an acidic atmosphere cause?

A

It can reduce the activity of enzymes in the body which are essential for controlling the rate of metabolic reactions.

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7
Q

What happens to most of the food molecules absorbed into the blood?

A

They are carried to the liver for assimilation

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8
Q

What is assimilation?

A

When food molecules are converted to other molecules that the body needs.

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9
Q

What is fibrinogen needed for?

A

Blood clotting

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10
Q

What happens to excess amino acids?

A

They are broken down in a process called deamination

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11
Q

What does deamination involve?

A

The actions of enzymes to split up the amino acid molecules.

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12
Q

What happens to the part that contains carbon?

A

It is turned into glycogen and stored

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13
Q

What happens to the part that contains nitrogen?

A

Is removed and turned into ammonia

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14
Q

What happens to the ammonia produced?

A

Converted to urea which is less toxic

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15
Q

What happens to the urea?

A

It is dissolved in the blood and is taken to the kidney to be excreted as urine.

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16
Q

Where are the kidneys located?

A

Back of the abdomen

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17
Q

What functions does the kidney have?

A

Regulate water content in the blood

Excrete waste products of metabolism and substances of excess requirements

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18
Q

What is osmoregulation?

A

Regulate water content in the blood

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19
Q

What does the kidney tissue consist of?

A

Many capillaries and thousands of tiny tubules called renal tubules( nephrons) held together with connective tissue

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20
Q

What color is the cortex?

A

Dark outer region

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21
Q

What part is the medulla?

A

Lighter inner zone

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22
Q

What is the renal pelvis?

A

Where the ureter joins the kidney

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23
Q

Where is blood filtered and where is urine produced?

A

In the nephrons

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24
Q

Where does each nephron begin?

A

In the cortex of the kidney

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25
Q

Where do the tubules join up?

A

In the pelvis to join up with the ureter

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26
Q

Where does the ureter lead to?

A

To the bladder where urine is stored

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27
Q

What is the glomerlus?

A

Knot of capillaries that branch of the renal artery and lead to each nephron

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28
Q

Where does the glomerlus sit?

A

Inside a cup shaped structure called the Bowman’s capsule

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29
Q

What happens as the capillaries get narrower in the glomerulus?

A

Increase in the pressure on the blood

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30
Q

What does the pressure of the blood cause?

A

Causes small molecules including water and most substances dissolved in the blood to be squeezed out of the capillaries and into the Bowman’s capsule

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31
Q

What does the filtrate contain?

A

Water, salt, glucose and urea

32
Q

Which molecules are too big to pass through?

A

protein molecules and blood cells

33
Q

What is the first substance to be reabsorbed?

A

Glucose

34
Q

Where is glucose reabsorbed?

A

In the proximal convoluted tubule.

35
Q

How is glucose absorbed?

A

By active transport

36
Q

What are nephrons surrounded by?

A

Capillaries where useful substances from filtrate are reabsorbed and passes into the blood

37
Q

Where does the remaining filtrate continue?

A

through the hoop of henle

38
Q

What happens at the loop of Henle?

A

Necessary salt and water are reabsorbed back into the blood by diffusion and osmosis.

39
Q

What happens to the remaining liquid?

A

Continue through the distal convoluted tubule to the collecting duct where water is reabsorbed into the blood according to the body’s demand.

40
Q

What is the ADH?

A

Anti diuretic hormone

41
Q

What happens to the urine?

A

Flows out of the kidney through the ureter and into the bladder

42
Q

What does the urine contain?

A

this contains urea and salts in water.

43
Q

Where is water reabsorbed at?

A

Loop of Henle and collecting duct

44
Q

Where is salts reabsorbed at?

A

Loop of Henle

45
Q

Where is glucose reabsorbed at?

A

First convoluted tubule

46
Q

What factors affect the volume and concentration of urine?

A

Water intake
temperature
Exercise

47
Q

How does water intake affect the volume and concentration of urine change?

A

More fluids drunk means more water will be removed so a large quantity of urine is produced

48
Q

How does temperature affect the volume and concentration of urine change?

A

The higher the temperature the more water is lost in sweat and so less will appear in urine

49
Q

How does exercise affect the volume and concentration of urine change?

A

More exercise done the more water is lost in sweat and so less will appear in urine

50
Q

Why is water and salt concentration controlled?

A

To keep the concentrations the same inside the cells as around them.

51
Q

How does osmoregulation help the cells?

A

Protects the cells by stopping too much water from entering or leaving by osmosis.

52
Q

How is water lost from the body?

A

Sweat

Water vapour from when we exhale

53
Q

Why might a kidney not work?

A

Accident or disease

54
Q

What are two treatments of kidney failure?

A

Dialysis

Kidney transplant

55
Q

What is kidney dialysis?

A

This the artificial method of filtering the blood to remove toxins and excess substances

56
Q

What does the dialysis machine act as?

A

An artificial kidney

57
Q

What does the kidney dialysis machine do?

A

To remove most of the urea and maintain the water and salt balance of the blood

58
Q

Where is the unfiltered blood taken from in dialysis?

A

Artery in the arm

59
Q

Where is the filtered blood returned in dialysis?

A

In the vein

60
Q

What are the blood and dialysis fluid separated by?

A

A partially permeable membrane

61
Q

What does the dialysis fluid contain?

A

A glucose concentration similar to normal level in blood
A concentration of salts similar to a normal level in blood
No urea

62
Q

What happens because the dialysis fluid has no urea in it?

A

A large concentration gradient is formed meaning the urea diffuses across the partially permeable membrane

63
Q

What happens because the dialysis fluid has a glucose concentration equal to the normal sugar level?

A

No net movement of glucose

64
Q

What happens because the dialysis fluid has a salt concentration equal to the blood?

A

No net movement

65
Q

How long does dialysis take?

A

3- 4 Hours

66
Q

What is added to the machine?

A

An anticoagulant is added to the blood to prevent the blood from clotting and slowing the flow.

67
Q

What is kidney transplant?

A

Implanting a kidney from an organ donor into the patient’s body.

68
Q

Benefits of kidney transplant

A

More freedom
Diets are less restrictive
use of dialysis machines is expensive
long term solution

69
Q

Disadvantages to kidney transplants

A

Donors don’t have the same antigens on cell surfaces- organ rejection
You have to take immunosuppressant drugs which have side effects
Tissue typing can lead to long waits
There are not enough donors.

70
Q

What does kidney dialysis remove?

A

Urea, ammonia, water

71
Q

Where is the concentration of urine determined?

A

Medulla

72
Q

Explain the function of the renal capsule

A

This is where ultrafiltration occurs. The high blood pressure assists molecules to diffuse into the glomerulus. Protein and blood cells are too big to go through but substances such as glucose are able to pass through

73
Q

What is the renal capsule?

A

The glomerulus and Bowman’s capsule

74
Q

Where does filtration occur?

A

In the glomerulus

75
Q

Describe how urea is transported in the blood to the kidney

A

Dissolved in plasma

76
Q

What does Bowman’s capsule do?

A

Collects the filtrate

77
Q

Where does reabsorption take place?

A

In the proximal convoluted tubule

BIOLOGY IGCSE (16 decks)

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