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Biology > The kidney > Flashcards

The kidney Flashcards

1
Q

What is homeostasis?

A

The control of the constant internal environment. AND
negative feedback returns things to a set point

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2
Q

What are the two types of effectors?

A

Muscles and glands

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3
Q

What is positive feedback?

A

When the effector increases the change, we are not trying to get back to a set point

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4
Q

What is negative feedback?

A

When the effector decreases the change, we are trying to get back to a set point

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5
Q

How is CO2 produced and how is it excreted?

A

Created in respiration, excreted when breathing out by the lungs

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6
Q

How is H2O produced and how is it excreted?

A

Created in respiration, excreted when breathing out by the lungs

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7
Q

How is creatine produced and how is it excreted?

A

Created by muscle tissue breakdown, excreted in urine by the kidney

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8
Q

How is uric acid produced and how is it excreted?

A

Created by breaking down nucleic acids, excreted in urine by the kidney

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9
Q

How is urea produced and how is it excreted?

A

Created by sweating, excreted in sweat via the skin

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10
Q

How are bile pigments produced and how are the excreted?

A

Created by haemoglobin breakdown, excreted in faeces by the liver

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11
Q

What are 3 other ways water is excreted?

A

As a metabolic waste product
As tears/saliva
Egested in faeces

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12
Q

What is the function of the kidney?

A

Excretion: removing nitrogenous waste
Osmoregulation: control of water potential of the body fluids

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13
Q

How is urea produced

A

Protein goes to the liver where it is broken down to amino acids. Amino acids are deaminated producing ammonia which is converted into urea.

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14
Q

What is deamination?

A

The removal of NH2 group

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15
Q

Why does ammonia have to be converted into urea?

A

Ammonia is toxic in high concentrations

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16
Q

How does blood enter the kidney?

A

Via the renal artery

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17
Q

How does blood leave the kidney?

A

Via the renal vein

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18
Q

How many nephrons per kidney?

A

1 million

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19
Q

What is the role of the nephron and what happens in it?

A

Nephron filters blood and exchange of materials occurs before urine is produced

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20
Q

What are the two halves of the nephron called and where are they located?

A

Top half is cortex, bottom half is medulla

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21
Q

How does blood enter the nephron?

A

Afferent arteriole

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22
Q

How does blood leave the nephron?

A

Efferent arteriole

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23
Q

What are the 3 stages that happen in the nephron?

A

Ultrafiltration
Selective absorption
Reabsorption of water

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24
Q

Outline the process of ultrafiltration

A

Blood enters afferent arteriole and goes towards glomerular capillaries within the bowmans space. High pressure in these capillaries forces small molecules through fenestrate (pore) - basement membrane - filtration slits into the bowmans capsule.

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25
Q

What contains the filtration slits and what are the gaps between them called?

A

Filtration slits are held within the podocyte and the gaps are called pedicels.

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26
Q

Why is there high pressure in the capillaries?

A

Because the diameter of the afferent arteriole is bigger then the efferent

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27
Q

What is ultrafiltration?

A

High pressure filtration

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28
Q

What molecules cannot filter into bowmans capsule and leave via the efferent arteriole to be reabsorbed into blood?

A

Large molecules like blood cells and proteins

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29
Q

What small molecules filter through?

A

Salts, water, urea, amino acids, glucose

30
Q

What is the blood called once in bowmans capsule?

A

Glomerular filtrate

31
Q

What is the glomerular filtration rate?

A

The rate at which fluid passes from blood into the capillaries

32
Q

What are the 3 layers of bowmans space?

A

Wall of capillaries which contains the fenestrate
Basement membrane
Wall of bowmans which has the podocytes

33
Q

Outline the process of selective reabsorption

A

Reabsorption of small molecules back into the blood.

34
Q

Where does selective reabsorption occur?

A

Proximal convoluted tubule

35
Q

How are the small molecules reabsorbed in the PCT?

A

Urea-diffusion
Water- osmosis
salts- active transport
Glucose/amino acids- Co-transport
Sodium- electro chemical gradient

36
Q

What are the features of the proximal convoluted tubule which allows reabsorption

A

Many mitochondria for active transport
A large SA because of microvilli
Tightly held membrane so that nutrients cannot seep back into glomerular filtrate

37
Q

Does the pct allow most absorption?

A

Yes and it is also the widest part of the nephron

38
Q

Explain reabsorption of water

A

There is a low wp between the thick ascending limb and thin descending limb because its a very conc space. This causes water to move into the space via osmosis from the glomerular filtrate moving down the descending limb. As glomerular filtrate moves up the ascending limb Na/Cl ions are pumped by active transport into the space between the two limbs which is why the space has a low wp.
Glomerular filtrate then travels to distal convoluted tubule where it is very dilute because Na/Cl has left, filtrate travels to collecting duct where water moves out by osmosis because the medulla outside is more concentrated. Whats left goes to the pelvis

39
Q

Where does reabsorption of water happen?

A

Loop of henle

40
Q

What are the features of the ascending and descending limb?

A

Ascending limb is 100% impermeable to water, and contains loads of mitochondria to produce atp to pump ions into space between.
Descending limb is 100% permeable to water to allow water to move into space via osmosis.

41
Q

Where is the most concentrated space in the nephron?

A

The apex

42
Q

Where in the nephron ultrafiltration and selective reabsorption happen?

A

Cortex

43
Q

Where does reabsorption of water happen?

A

Medulla

44
Q

What does the collecting duct have that allows water to move out by osmosis?

A

Aquaporins

45
Q

Why is the pct different to dct and collecting duct?

A

The distal convoluted tubule and collecting duct can vary what is reabsorbed the pct cant do this.

46
Q

Why would not all the glucose be reabsorbed?

A

Not enough insulin produced by pancreas
Or type 2 diabetes

47
Q

What would the loop of henle look like in an animal that lives in a hot climate?

A

It would be longer to allow more reabsorption of water because the wp in medulla would be lower

48
Q

What is the loop of henle function?

A

To maintain the sodium ion gradient, so more water can be absorbed

49
Q

What is hypoglycaemia and some symptoms

A

Low blood sugar/glucose in blood is low.
Dizzy, confused, shaky, sweaty
HypO=lOw

50
Q

What is hyperglycaemia and some symptons?

A

High blood sugar/glucose in blood is high.
Dehydration, large urine passed out.
Hyper=high

51
Q

What is metabolic water?

A

Water that is released from metabolic reactions

52
Q

How is the concentration of body fluids controlled when there is high solutes/low water.

A

High solutes in blood detected by osmoregulators in hypothalamus. This enables the lobe of the posterior pituitary gland to release higher/more anti-diuretic hormone. The adh travels in the blood to collecting duct and distal convoluted tubule. The adh makes the collecting duct and dct more permeable, more water is absorbed. A lower volume of more concentrated urin is produced. Medulla has a low wp.

53
Q

How is the concentration of the body fluids controlled when there is low solutes in blood?

A

low solutes in blood is detected by osmoregulators in the hypothalamus, this causes the lobe of the posterior pituitary gland to release ADH which travels in the blood to collecting duct and DCT making their walls less permeable, less water is absorbed and a larger volume of less concentrated urine is produced.

54
Q

What are the causes of kidney failure?

A

Diabetes: high conc of glucose causes the glomerular capillaries to let protein into glomerular filtrate which causes scarring.
High blood pressure.
Infections
Accidents

55
Q

Explain haemodialysis

A

External dialysis, blood is taken from an artery in the arm and runs through a selectively permeable membrane in a dialysis machine. This allows unwanted molecules to be filtered out. Blood is returned to a vein and heparin can be added to stop coagulation.

56
Q

What does the blood contain that is put back into the body?

A

Proteins, platelets and blood cells

57
Q

How many times does haemodialysis happen?

A

A few hours several times a week

58
Q

When is dialysis used?

A

When both kidneys do not function like they should

59
Q

Explain ambulatory/ peritoneal dialysis

A

Internal dialysis, dialysis fluid is drained through a catheter into the abdomen. The peritoneum has a good supply of capillaries and acts as a membrane removing unwanted molecules into the dialysis fluid.
After 40 mins fluid is drained, process has to be repeated 4 times a day.

60
Q

What is the advantage of internal dialysis?

A

Patient can carry on with life, like can move when its happening

61
Q

What should patients stay away from when on dialysis?

A

Avoid drinking, eating bananas and tomatoes to stop the build up of potassium ions as potassium ions build up in the blood during dialysis

62
Q

Explain the function of loop of henle in osmoregulation

A

Loop of henle has a thin ascending limb and a thick descending limb. The ascending limb is 100% impermeable to water and the descending is 100% permeable to water. Glomerular filtrate moves down descending limb and water moves out by osmosis to low wp space, the glomerular filtrate moves up the ascending limb which pumps Na+ via active transport out.
Loop of henle operates by a counter-current system and the apex is the most conc point.

63
Q

What is transamination?

A

Using an enzyme to transfer an amino group to alpha gluarate which makes an amino acid

64
Q

Why arent animals efficient at transamination?

A

Because they make nitrogenous waste/ammonia which is toxic in high conc and has to be converted to urea and excreted.

65
Q

How do plants do transamination?

A

They combine ammonium ions from the soil with alpha gluarate to make amino acids which are transported by the phloem.
Plants do not make nitrogenous waste, they use all the nitrogen needed so are more efficient at transamination.

66
Q

What do aquatic organisms excrete their nitrogenous waste as?

A

Ammonia directly into the water

67
Q

What do birds/insects/reptiles excrete their nitrogenous waste as?

A

As uric acid, this is a very solid substance so its good at water retention

68
Q

Describe the cortical nephron

A

Has a short loop of henle which is mostly in the cortex.
Aquatic animals/humans have a cortical nephron as they don’t have a high risk of dehydration so less water needs to be absorbed.

69
Q

Describe the Juxtamedullary nephron

A

Has a longer loop of henle which is mostly in the medulla.
The bowmans capsule is closer to the medulla.
Mammals living in arid environments will have these because it allows for more absorption of water as there is a lower wp in medulla.

70
Q

What is the one desert animal that doesn’t have a juxtamedullary nephron and what does it have instead?

A

The kangaroo rat.
It is very metabolically active so it can maintain a steep ion gradient in the medulla without the need for a long loop of henle.
Produces small vol of conc urine

71
Q

How do desert animals conserve their H20?

A

Use respiration to oxidise their food stores to make metabolic water
Live underground as it is cooler during the day

72
Q

What is an xerocole?

A

An animal which gets all its water from metabolic water

Biology (26 decks)

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