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BIOLOGY IGCSE > EXCRETION > Flashcards

EXCRETION Flashcards

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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
Where do the tubules join up?
In the pelvis to join up with the ureter
26
Where does the ureter lead to?
To the bladder where urine is stored
27
What is the glomerlus?
Knot of capillaries that branch of the renal artery and lead to each nephron
28
Where does the glomerlus sit?
Inside a cup shaped structure called the Bowman's capsule
29
What happens as the capillaries get narrower in the glomerulus?
Increase in the pressure on the blood
30
What does the pressure of the blood cause?
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
31
What does the filtrate contain?
Water, salt, glucose and urea
32
Which molecules are too big to pass through?
protein molecules and blood cells
33
What is the first substance to be reabsorbed?
Glucose
34
Where is glucose reabsorbed?
In the proximal convoluted tubule.
35
How is glucose absorbed?
By active transport
36
What are nephrons surrounded by?
Capillaries where useful substances from filtrate are reabsorbed and passes into the blood
37
Where does the remaining filtrate continue?
through the hoop of henle
38
What happens at the loop of Henle?
Necessary salt and water are reabsorbed back into the blood by diffusion and osmosis.
39
What happens to the remaining liquid?
Continue through the distal convoluted tubule to the collecting duct where water is reabsorbed into the blood according to the body's demand.
40
What is the ADH?
Anti diuretic hormone
41
What happens to the urine?
Flows out of the kidney through the ureter and into the bladder
42
What does the urine contain?
this contains urea and salts in water.
43
Where is water reabsorbed at?
Loop of Henle and collecting duct
44
Where is salts reabsorbed at?
Loop of Henle
45
Where is glucose reabsorbed at?
First convoluted tubule
46
What factors affect the volume and concentration of urine?
Water intake temperature Exercise
47
How does water intake affect the volume and concentration of urine change?
More fluids drunk means more water will be removed so a large quantity of urine is produced
48
How does temperature affect the volume and concentration of urine change?
The higher the temperature the more water is lost in sweat and so less will appear in urine
49
How does exercise affect the volume and concentration of urine change?
More exercise done the more water is lost in sweat and so less will appear in urine
50
Why is water and salt concentration controlled?
To keep the concentrations the same inside the cells as around them.
51
How does osmoregulation help the cells?
Protects the cells by stopping too much water from entering or leaving by osmosis.
52
How is water lost from the body?
Sweat | Water vapour from when we exhale
53
Why might a kidney not work?
Accident or disease
54
What are two treatments of kidney failure?
Dialysis | Kidney transplant
55
What is kidney dialysis?
This the artificial method of filtering the blood to remove toxins and excess substances
56
What does the dialysis machine act as?
An artificial kidney
57
What does the kidney dialysis machine do?
To remove most of the urea and maintain the water and salt balance of the blood
58
Where is the unfiltered blood taken from in dialysis?
Artery in the arm
59
Where is the filtered blood returned in dialysis?
In the vein
60
What are the blood and dialysis fluid separated by?
A partially permeable membrane
61
What does the dialysis fluid contain?
A glucose concentration similar to normal level in blood A concentration of salts similar to a normal level in blood No urea
62
What happens because the dialysis fluid has no urea in it?
A large concentration gradient is formed meaning the urea diffuses across the partially permeable membrane
63
What happens because the dialysis fluid has a glucose concentration equal to the normal sugar level?
No net movement of glucose
64
What happens because the dialysis fluid has a salt concentration equal to the blood?
No net movement
65
How long does dialysis take?
3- 4 Hours
66
What is added to the machine?
An anticoagulant is added to the blood to prevent the blood from clotting and slowing the flow.
67
What is kidney transplant?
Implanting a kidney from an organ donor into the patient's body.
68
Benefits of kidney transplant
More freedom Diets are less restrictive use of dialysis machines is expensive long term solution
69
Disadvantages to kidney transplants
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
What does kidney dialysis remove?
Urea, ammonia, water
71
Where is the concentration of urine determined?
Medulla
72
Explain the function of the renal capsule
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
What is the renal capsule?
The glomerulus and Bowman's capsule
74
Where does filtration occur?
In the glomerulus
75
Describe how urea is transported in the blood to the kidney
Dissolved in plasma
76
What does Bowman's capsule do?
Collects the filtrate
77
Where does reabsorption take place?
In the proximal convoluted tubule

BIOLOGY IGCSE (16 decks)

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