Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology OCR > 5.2 Excretion > Flashcards

5.2 Excretion Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is excretion?

A

The removal of metabolic waste from the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is metabolic waste?

A

A chemical produced by the metabolic processes in the cells, and can be toxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does waste need to be excreted?

A

At high concentrations, waste can:

  • Inhibit enzyme activity
  • Become toxic
  • Affect pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name 3 excretory products.

A
  • Carbon Dioxide
  • Nitrogenous waste e.g. urea
  • Other compounds such as bile pigments in faeces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is egestion?

A

The elimination of faeces from the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the main excretory organs?

A
  • Lungs
  • Liver
  • Kidneys
  • Skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do the lungs excrete?

A

Carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is bilirubin?

A

A bile pigment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is urea transported?

A

Dssolved in blood plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the main role of the kidneys?

A

To remove urea from the blood and make urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is the skin involved in excretion?

A

Sweat released through the skin contains salts, urea, water, uric acid and ammonia, which are all excretory products.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In what form is carbon dioxide transported in the blood?

A

Hydrogen carbonate ions

HCO 3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which enzyme promotes carbonic acid dissociation?

A

Carbonic anhydrase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is carbonic acid formed in erythrocytes?

A

Carbon dioxide + water > carbonic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is an acidic pH in red blood cells bad?

A

It changes the tertiary structure of haemoglobin, reducing its affinity for oxygen (haemoglobinic acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to carbon dioxide that is not converted to hydrogencarbonate ions?

A

It combines directly with haemoglobin, forming carbaminohaemoglobin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens if the blood pH drops a small amount?

A

Change is detected by the respiratory centre in medulla oblongata, which makes breathing rate increase to remove the excess carbon dioxide (CO2 causes more H+ to be produced)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is respiratory acidosis?

A

When blood pH drops below 7.35 and can cause headaches, confusion etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Urea is less _____ and less ______ than ammonia

A

Toxic and soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why does the body not excrete excess amino acids?

A

The body can’t store them, and it would be wasteful to excrete them without releasing their energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a hepatocyte?

A

A specialised liver cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of the hepatic artery?

A

To provide oxygenated blood for aerobic respiration in hepatocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of the hepatic portal vein?

A

To take deoxygenated, digestive product rich blood from the digestive system into the liver.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is bile?

A

Bile is a secretion from the liver which has functions in digestion (emulsifies lipids, neutralises stomach acid).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Bile is made in the _____ and stored in the _____.

A

Made in liver, stored in gall bladder.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the function of the bile duct?

A

To carry bile from the liver to the gall bladder.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How are bile pigments made?

A

They are produced by the breakdown of red blood cells in the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why do hepatocytes have loads of peroxisomes?

A

Peroxisomes contain powerful enzymes which breakdown toxins and poisons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Where is glycogen stored?

A

The liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does a Kuppfer cell do?

A

It’s a specialised macrophage which breaks down old red blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the livers main roles?

A

Breakdown of excess amino acids and detoxification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Why must nitrogenous substances be removed from the body?

A

They can’t be stored, and in excess they can be damaging

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is deanimation?

A

The removal of the nitrogen containing amino group from an amino acid making ammonia and organic keto acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the use of organic keto acid?

A

They can be respired to make ATP, or converted to carbohydrates and stored as glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is urea made of?

A

Ammonia + Carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What part of the ornithine cycle occurs in the mitochondria?

A

Ornithine> Citruline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why can’t ammonia be excreted directly?

A

It’s too toxic and soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is detoxification?

A

The breakdown of harmful substances into less harmful compounds that can be excreted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How is ethanol detoxified in the liver?

A

Ethanol> Ethanal> Acetic acid

40
Q

What is liver cirrhosis?

A

Excess alcohol causes liver cells to die and scar tissue blocks blood flow

41
Q

Why must paracetamol be broken down?

A

An excess amount in the blood can lead to liver and kidney failure

42
Q

Why must excess insulin be broken down?

A

In excess it can cause problems with blood sugar

43
Q

Where in the digestive system does the hepatic portal vein bring blood from?

A

Small intestine

44
Q

What are liver lobules?

A

Cylindrical structures made of hepatocytes that are arranged in rows, radiating from the centre outwards.

45
Q

What connects the hepatic artery and hepatic portal vein to the central vein?

A

Capillaries called sinusoids

46
Q

How is the bile duct connected to the central vein?

A

Canalculi tubes

47
Q

What is the main function of the kidney?

A

To excrete waste products from the body, e.g. urea

48
Q

How does blood enter the kidney?

A

The renal artery

49
Q

From outwards to inwards, what is the kidney structure?

A

Renal capsule, cortex, medulla, pelvis

50
Q

What are nephrons?

A

Long tubules with a bundle of capillaries

51
Q

Where does ultrafiltration take place?

A

Glomerulus and Bowmans capsule

52
Q

What is the difference between the afferent and efferent arteriole?

A

Afferent- takes blood to the glomerulus

Efferent- takes blood away from glomerulus

53
Q

Why does the efferent arteriole have a smaller diameter than the afferent arteriole?

A

To increase the pressure, which forces liquid and molecules out of the capillary and into the Bowmans capsule

54
Q

What layers must a molecule pass through to get into Bowmans capsule?

A

The capillary endothelium, the basement membrane, and the podocyte/Bowmans capsule epithelium

55
Q

Why is the proximal convoluted tubule convoluted?

A

To increase the surface area for diffusion

56
Q

Where does selective reabsorption take place?

A

Proximal CT, Loop of Henle, Distal CT, collecting duct

57
Q

What is completely selectively reabsorbed into the blood from the glomerular filtrate?

A

Glucose and amino acids

58
Q

What is mostly reabsorbed (but dependant on conditions)?

A

Water and ions

59
Q

What is reabsorbed in the Proximal convoluted tubule?

A

Most water, and all glucose and amino acids

60
Q

How does selective reabsorption of glucose and amino acids work?

A

Na+ pumped out of cell, then diffuse back in with cotransport protein which brings back glucose and amino acids

61
Q

What is the purpose of the loop of Henle?

A

To decrease the water potential of the tissue fluid in medulla, by removal of water and addition of ions

62
Q

What happens in the descending limb of loop of Henle?

A

Water is removed by osmosis, and Na+ and Cl- diffuse in

63
Q

What happens in the ascending limb of the loop of Henle?

A

Na+ and Cl- pumped out

64
Q

What happens in the distal convoluted tubule?

A

K+ pumped in by active transport

65
Q

What does ADH do?

A

Increase the collecting ducts permeability to water by aquaporins, so more water is reabsorbed.

66
Q

What happens in the collecting duct?

A

Water gradually lost to decrease the water potential, but it remains above that of the surrounding tissue (allowing max water to be reabsorbed)

67
Q

What is the equation for deamination?

A

Amino acid + Oxygen > Keto acid + Ammonia

68
Q

What does the ornithine cycle require to start?

A

ATP and Carbon Dioxide

69
Q

What is the equation for the formation of urea?

A

Ammonia + Carbon Dioxide > Urea + Water

70
Q

What is the equation for the reaction that catalase catalyses?

A

Hydrogen peroxide > Water + Oxygen

71
Q

Where does detoxification occur in hepatocytes?

A

The smooth endoplasmic reticulum

72
Q

What enzyme catalyses ethanol > ethanal ?

A

Ethanol dehydrogenase

73
Q

What enzyme catalyses ethanal > ethanoic acid?

A

Ethanal dehydrogenase

74
Q

What are fenestrations?

A

Pores between capillary endothelium

75
Q

What is osmoregulation?

A

The control of water potential in the body, by controlling salt and water levels

76
Q

Where is ADH secreted from?

A

Posterior lobe of pituitary gland

77
Q

Where are osmoreceptors found?

A

Hypothalamus

78
Q

What is hypertension?

A

High blood pressure

79
Q

What is acute kidney failure?

A

Fast development, short acting, easily treatable

80
Q

What is chronic kidney failure?

A

Slow developing, long acting, hard to treat

81
Q

What are the treatments for kidney failure?

A

Haemodialysis, peritoneal dialysis, kidney transplant

82
Q

What is the peritoneum?

A

The layer of tissue lining the abdominal cavity

83
Q

What do pregnancy tests test for?

A

HCG

84
Q

Osmoregulation is an example of _________ feedback.

A

Negative

85
Q

In haemodialysis, where is blood added back to the body?

A

Vein

86
Q

Describe peritoneal dialysis.

A
  • Dialysis fluid put into body through catheter and left in peritoneal cavity
  • Takes around an hour, happens multiple times a day
87
Q

How do pregnancy tests work?

A

Monoclonal antibodies with blue bead test for HCG in urine

88
Q

What 4 ways are the cells lining the proximal convoluted tubule specialised?

A
  • Plasma membrane is highly folded to form microvilli
  • Cotransport proteins are in the plasma membrane
  • Membrane close to the capillary has microvilli and Na/K pumps
  • Many mitochondria
89
Q

Which part of the nephron is impermeable to water?

A

Ascending loop of Henle

90
Q

What mechanism does the loop of Henle create?

A

The countercurrent multiplier mechanism

91
Q

What does the countercurrent multiplier mechanism do?

A

Helps to reabsorb water back into the blood

92
Q

What are osmoreceptors?

A

Receptor cells in hypothalamus which monitor the water potential of the blood

93
Q

What is water potential?

A

The tendency of water to move from one place to another.

94
Q

What is the effector to control the body’s water content?

A

The kidneys

95
Q

What are aquaporins?

A

Vesicles containing water permeable channels

96
Q

How does the cell membrane remove water permeable channels in the collecting duct?

A

It folds in on itself to create more new vesicles that remove water permeable channels.

A Level Biology OCR (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions