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Biology GCSE > Homeostasis + The Kidneys > Flashcards

Homeostasis + The Kidneys Flashcards

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0
Q

What is homeostasis?

A

The maintenance of internal body conditions. E.g. Temperature

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0
Q

What happens when you are too hot? (2)

A

Sweating

Vasodilation

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1
Q

What is thermoregulation?

A

The process that allows the human body to maintain its core internal temperature

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2
Q

What is sweating?

A

Sweat glands cause sweat to evaporate on the skin, cooling the blood, using up energy

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3
Q

What is vasodilation?

A

When the muscles in the arteries dilate letting more blood through to the capillaries nearer the skin. This causes the heat to radiate from the blood in the capillaries and the skin to turn red

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4
Q

How does conservation of heat occur when you are too cold? (2)

A

Vasoconstriction

Hair erector muscles

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5
Q

What is vasoconstriction?

A

When the muscles in the arteries constrict, causing less blood to flow near the skin, not letting the heat radiate, keeping it nearer the core of your body, keeping you warmer

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6
Q

What do hair erector muscles do?

A

When the hair on the body rises, trapping air, causing less heat to radiate. Occurs mainly in furry animals (cute ones)

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7
Q

How is heat generated when you are too cold? (1)

A

Shivering

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8
Q

What is shivering?

A

Rapid contraction and relaxation of muscles causing rapid respiration, producing more heat

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9
Q

What is the hypothalamus?

A

It is the processing centre in the brain that controls body temperature

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10
Q

How does the hypothalamus help thermoregulation?

A

Temperate receptors in the skin detect changes in the external temperature
They pass this information to the hypothalamus which also has temperature receptors to detect changes in the temp of blood
The hypothalamus automatically triggers changes in the effectors (sweat glands and muscles) to ensure a constant body temperature

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11
Q

Where in the brain is the hypothalamus?

A

Just above the brain stem

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12
Q

What is the pituitary gland and what does it do?

A

It is a gland that contains anti-diuretic hormones and it controls blood water level by triggering uptake of water in the kidneys

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13
Q

Why does ADH kick in and give an example of when this would happen

A

When your body is short of water eg when you are sweating heavily on a hot day and not drinking enough

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14
Q

Describe the cycle of ADH from the brain to the kidneys

A

Loss of water means more concentrated blood
This is detected by the hypothalamus
Hypothalamus sends a signal to your pituitary glands to release more ADH
ADH travels in the blood stream to the kidneys

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15
Q

What does ADH do when it reaches the kidneys?

A

At the kidney tubules, it causes the collecting ducts to become more permeable to water so that more water moves back into the blood
This makes urine more concentrated so that the body loses less water and the blood becomes more dilute

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16
Q

What happens when your water levels return to normal?

A

The ADH gets switched off and the kidney tubules will then reabsorb water

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22
Q

What happens when you have high blood sugar?

A

Insulin is released

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23
Q

What organ releases insulin?

A

The pancreas

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24
Q

What do your kidneys do?

A

Filter your blood
Help maintain homeostasis
Remove urea from your blood
Remove excess water from your blood and conserve it when needed
Remove excess salt from your blood but conserve when needed

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25
Q

How does insulin decrease the levels of blood sugar?

A

It causes sugar to move from the blood to storage cells so there is less sugar in the blood and therefore a lower blood sugar

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26
Q

What does insulin change glucose to?

A

Glycogen, which is stored for when it is needed

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27
Q

What happens when there is too much glycogen?

A

It becomes stored as Adipose tissue (fat)

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28
Q

What happens when there is a low blood sugar level?

A

Glucagon is released and coverts the stored glycogen into glucose which goes into the blood

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29
Q

What are the kidneys main function in the body?

A

To filter the blood.

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30
Q

What specifically do kidneys do when filtering your blood?

A

They filter the blood by removing urea, excess water and mineral ions but conserve them when necessary.

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31
Q

Why do the kidneys filter the blood?

A

To maintain homeostasis.

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32
Q

How do they maintain homeostasis?

A

Selectively reabsorbing everything your body needs, such as:
Glucose and amino acids and mineral ions and water.

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33
Q

How do the kidneys reabsorb amino acids and glucose?

A

Kidneys should reabsorb all glucose and amino acids, it will do this by a combination of diffusion and active transport depending on the concentration of glucose or amino acids in the blood.

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34
Q

How do the kidneys reabsorb water and mineral ions?

A

By diffusion.

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35
Q

Learn structure of kidney and how to label it.

A

Kk bbz

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36
Q

What is the ureter?

A

A tube through which urine passes from the kidney to the bladder.

37
Q

What is the urethra?

A

A tube through which urine passes to outside your body.

38
Q

What is a sphincter?

A

Rings of muscle which control the opening and closing of the bladder.

39
Q

What is the pelvis?

A

Control chamber where the urine arrives from the collecting ducts.

40
Q

What is the renal artery?

A

Brings blood to the kidney from the heart.

41
Q

What is the renal vein?

A

Carries blood from the kidney.

42
Q

What is the cortex?

A

On the outside of the pyramids, file with capillaries.

43
Q

What is the medulla?

A

Collection of pyramids containing the loops of Henle from the nephrons.

44
Q

What is the glomerulus?

A

A group of blood capillaries, the site of diffusion. (Ultrafiltration)

45
Q

What is bowmans capsule?

A

First part of the nephron where the filtrate is collected

46
Q

What is the proximal convoluted tubule?

A

The first site of reabsorption.

47
Q

What comes after the proximal convoluted tubule?

A

The loop of Henle Innit.

48
Q

Describe the process of ultrafiltration

A

Blood enters each kidney by a renal artery under high pressure because of the pumping of the heart. This divides into smaller arteries. The arteriolar supply blood to the capillaries of the glomerulus. A blood vessel with a smaller diameter carries blood away from the glomerulus causing a resistance flow. This means the pressure of the blood in the arteriolar leading to the glomerulus is very high, causing water and small molecules in blood plasma are forced through capillary walls into Bowman’s capsule. Proteins and blood cells don’t go through. Filtrate contains water, amino acids, fatty acids, glycerol, vitamins, mineral salts and urea.

49
Q

What is the distal convoluted tubule?

A

The second site of reabsorption, the last chance.

50
Q

What is the collecting duct?

A

Site of water reabsorption controlled by ADH.

51
Q

What is ultrafiltration?

A

Filtration of the blood under high pressure

52
Q

Where does ultrafiltration happen

A

glomerulus, filtrate enters bowmans capsule

53
Q

What is selective reabsorption?

A

the kidneys must reabsorb the molecules which are needed, while allowing those molecules which are not needed to pass out in the urine. Therefore, the kidneys selectively reabsorb only those molecules which the body needs back in the bloodstream.

54
Q

Where does selective reabsorption occur?

A

The proximal convoluted tubules

55
Q

Why is selective reabsorption useful?

A

Prevents loss of nutrients in urine.

56
Q

What does the remaining filtrate after selective reabsorption have?

A

water, urea and excess mineral salts.

57
Q

How is glucose moved in selective reabsorption and why?

A

By active transport and so all is reabsorbed.

58
Q

Why are the convoluted tubules shaped like they are?

A

The surface area is increased so it takes longer for the nutrients to move and more is reabsorbed.

59
Q

Where does water reabsorption occur?

A

The collecting duct.

60
Q

What does ADH do?

A

Controls water reabsorption.

61
Q

What happens in water reabsorption ?

A

Filtrate enters the collecting duct and becomes urine. Amount of water reabsorbed depends on intake of water diet and amount of water lost by body.

62
Q

When will the amount of ADH secreted increased?

A

When you exercise or sweat.

63
Q

Why is water reabsorption important?

A

Cells become turgid and burst if too much water, this is called LYSIS. If too little water cells become flacid and don’t carry out processes this is called CRENATION when they shrink.
Plasmolysed – a plant cell that has lost water causing the cell membrane to be pulled away from the inside of the cell wall.

64
Q

How does water move in and out of cells?

A

Osmosis

65
Q

What is diuresis?

A

The flow of urine from the body

66
Q

What is ADH?

A

A hormone secreted when your body is short of water.

67
Q

Process of ADH secretion

A

As you lose water your blood becomes more concentrated.
Detected by hypothalamus in brain.
Hypothalamus sends a signal to pituitary glands to release more ADH.
ADH travels in blood stream to kidneys.
At kidney tubules it causes the collecting ducts to become more permeable to water so that more water moves back into the blood.
Urine is made more concentrated so body loses less water and blood gets more dilute.

68
Q

What is dialysis?

A

Is essentially an artificial kidney, a form if treatment that replicates many kidney functions.

69
Q

Who needs dialysis?

A

People with kidney failure.

70
Q

How is dialysis set up?

A

A needle linked to a machine inserted into a blood vessel and blood passes through a machine with partially permeable membrane:another side is dialysis fluid. The concentration of substances allows unwanted things to go and wanted things to stay.

71
Q

How does blood enter the kidneys?

A

Through the renal artery straight from the aorta. This means the blood is at a high pressure. Then the blood is filtered and passes out through each renal vein to the vena cava.

72
Q

On a kidney diagram where is the renal artery/vein?

A

Artery on top

Vein below.

73
Q

What is the maintenance of water and salt content known as?

A

Osmoregulation

74
Q

Other than water and salt levels, temperature and blood sugar levels, what else does homeostasis regulate in the body?

A

Levels of co2 in your blood and blood pH.

75
Q

Why does someone with diabetes have glucose in their urine?

A

Because people with diabetes can’t produce enough insulin. There is excess glucose in their blood. Because there is excess, it is not reabsorbed and is released in the urine.

76
Q

Why does the rate of sweating change when a person does exercise?

A

When you exercise, the muscles respire more. Energy is released as heat energy, causing your body temperature to increase. To prevent the body from overheating, your rage of sweating will increase because when the sweat evaporates off the skin, it releases to heat energy, cooling you down

77
Q

Example method to measure the rate of sweating

A

Measure the mass of clothing before and after running for ten minutes. Sweat is absorbed in the clothes so mass should increase. Repeat to get the mean.

78
Q

When is there no net exchange of carbon dioxide or oxygen

A

When the rate of respiration = the rate of photosynthesis

79
Q

Give an example of nitrogenous waste?

A

Urea and ammonia, they contain nitrogen

80
Q

Definite excretion

A

The removal of metabolic waste

81
Q

In a kidney diagram, with the medulla and cortex, where is the renal artery and vein?

A

The renal artery is on top of the renal vein, both coming out from the left

82
Q

Give a summary of what happens in the nephron:

A

Part of the plasma leaves the blood in the bowmans capsule due to ultrafiltration and enters the nephron. The filtrate consists of water and small molecules. As the fluid passes along the nephron, all the glucose is absorbed back into the blood in the proximal convoluted tubule, along with most of the sodium and chloride ions. In the rest of the tubule, more water and ions are reabsorbed, and some diluted like ammonium are secreted into the tubule. The final urine contains urea at a much higher concentration that in the blood and controlled quantities of water and ions.

83
Q

What does the loop of henle do?

A

It is involved with concentrating the fluid in the tubule by causing more water to be reabsorbed into the blood.

Biology GCSE (18 decks)

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