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Biology - Real One > B3.3 - Maintaining Internal Environments > Flashcards

B3.3 - Maintaining Internal Environments Flashcards

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1
Q

What is homeostasis?

A

The maintenance of a constant internal environment

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2
Q

What temperature does your body work best at?

A

Your body works best at 37°C as this is the optimum temperature for your enzymes

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3
Q

What can happen if you get too cold? (Core body temperature)

A

Exposure to extreme cold can reduce core body temperature

This causes enzyme reactions to occur too slowly

This means that Respiration does not release enough energy and your cells begin to die

If your core body temperature drops below 35°C you are at risk of hypothermia

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4
Q

What can cause the body to ‘overheat’?

A

Exercise

Exposure to very high temperatures

Some infections

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5
Q

What can happen if your core body temperature becomes too high?

A

If your core body temperature rises above 40-42°C your enzymes can denature and so body reactions cannot occur.

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6
Q

What is the name of the system that controls your body temperature?

A

The thermoregulatory system in your brain

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7
Q

How is body temperature controlled.

A

The thermoregulatory system in your brain is responsible for regulating body temperature.

It relies on signals received from from receptor cells in your skin (to monitor the external temperature) and from internal receptor cells (to monitor the temperature of your blood).

When a change in temperature is detected, your brain causes different parts of the body to respond, by sending impulses to effectors.

These responses return the body back to its normal temperature

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8
Q

What happens when you get too hot?

A
  • body hairs lower so the hair on your skin lies flat
  • sweat glands produce sweat
  • blood vessels supplying capillaries near the surface of your skin widen (vasodilation)
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9
Q

Why do body hairs lower/ lie flat when you get too hot?

A

It prevents an insulating layer of air being trapped around the body.

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10
Q

Why do sweat glands produce sweat when you get too hot?

A

(Sweat is made from Water, salt and urea)

As the water in sweat evaporates energy is transferred by heating from your body to the environment. This reduces your temperature.

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11
Q

Why do the blood vessels supplying capillaries near the surface of your skin widen when you get too hot?

A

It increases blood flow through the capillaries, increasing heat loss by radiation.

This is vasodilation

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12
Q

What happens when you get too cold?

A
  • body hairs rise
  • sweat glands stop producing sweat
  • blood vessels supplying capillaries near the surface of your skin narrow (vasoconstriction)
  • shivering
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13
Q

Why do body hairs rise when you get cold?

A

This insulates the body as it traps a layer of air close to the skin

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14
Q

Why do blood vessels supplying capillaries near the surface of your skin narrow?

A

It reduces blood flow through the capillaries and so reduces heat loss.

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15
Q

Why do you shiver when you are cold?

A

Shivering occurs when your muscles contract and relax quickly.

This makes your cells respire more quickly, transferring extra energy by heating.

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16
Q

Why do your blood sugar levels rise after meals?

A

After you eat, the glucose released by digestion passes into the bloodstream.

This causes blood sugar levels to rise

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17
Q

Why do blood sugar levels drop after exercise?

A

When you exercise, more glucose in needed as the body needs to transfer more energy.

This causes blood sugar levels to drop

This can prevent cells from respiring effectively

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18
Q

What can happen if blood sugar levels are high for a long period of time?

A

Body systems can become damaged.

Especially nerves and blood vessels.

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19
Q

What is insulin?

A

It is the hormone that stimulates the liver to turn glucose into glycogen, decreasing blood sugar levels

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20
Q

What happens if there is too much glucose in the blood (blood sugar levels are high)?

A

If blood sugar levels are too high this is detected by the pancreas which releases the hormone insulin.

Insulin travels in the blood to the liver.

Insulin stimulates the liver to turn glucose into glycogen by a series of enzyme controlled reactions.

Glycogen is then stored in the liver.

As there is now less glucose in the blood, the blood sugar level falls.

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21
Q

What is glucagon?

A

It is the hormone that stimulates the liver to turn glycogen into glucose increasing blood sugar levels

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22
Q

What happens if the blood glucose concentration is too low (blood sugar levels are low)?

A

The pancreas releases GLUCAGON

Glucagon makes the liver change glucagon back into glucose

This is then released into the blood, increasing blood sugar levels

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23
Q

What is diabetes?

A

It is a medical condition that effects a persons control of blood sugar levels

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24
Q

Is diabetes curable?

A

No but it can be controlled

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25
Q

What is type 1 diabetes?

A
  • they cannot produce insulin
  • the persons own immune system has destroyed the pancreatic cells that make insulin
  • (normally begins in childhood)
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26
Q

How can type 1 diabetes be controlled?

A

Regular injections

Balanced diet

Exercise regularly

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27
Q

What is type 2 diabetes?

A
  • they cannot effectively use insulin
  • do not produce enough insulin or the persons body cells don’t respond properly to insulin.
  • occurs later in life
  • has been linked to obesity
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28
Q

How can type 2 diabetes be controlled?

A

Regulating a persons carbohydrate intake through their diet and matching this to their exercise levels

  • sometimes insulin injections are given
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29
Q

How do water and salts enter your body

A

Through food and drink

Water is also produced as a result of respiration

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30
Q

How do water and salts leave the body (how are they removed)?

A

Through sweating

In urine

Water also leaves your body as water vapour when you exhale

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31
Q

What is excretion?

A

The removal of waste products

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32
Q

Why is it important that water levels in your blood plasma remain constant

A
  • If too much water is present it will move into your blood cells, causing them to swell and burst. (Lysis)
  • if too little water is present (or if there is too much solute) water will diffuse out of your blood cells causing them to shrink
33
Q

What is lysis?

A

The rupture of the cell membrane

34
Q

What is urine?

A

It is a solution containing water, urea and other waste substances

35
Q

What is the kidney?

A

It is an organ which filters waste substances out of the blood and produces urine

36
Q

What is the bladder?

A

It is an organ which stores urine until it is removed from the body

37
Q

Where is urea produced?

A

In the liver

38
Q

What is the renal artery?

A

It brings blood containing urea and other substances in solution to the kidney

39
Q

What is the renal vein?

A

It carries blood away from the kidney, after urea and other substances have been removed from the blood

40
Q

What is the ureter?

A

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

41
Q

What is the urethra?

A

A tube through which urine passes to the outside of your body

42
Q

How is urine produced?

A

Small molecules including water glucose urea and salts pass into tubules inside the kidney,
(Blood cells are too large so remain within the capillaries)

Then the kidneys put back any useful substances into the blood, including all of the glucose, any salts the body needs and some water. This is known as selective reabsorption.

Urine contains a mixture of urea excess salts and excess water

43
Q

What does the amount of using you produce depend on?

A

It depends on the amount of water you take in with the amount you lose through breathing and sweating

44
Q

What happens to the amount of urine if you don’t drink enough water

A

If you don’t drink enough water your kidneys produce very little urine.

Water is saved for your body’s use.

Instead you would produce a small amount of concentrated urine which would appear dark yellow.

45
Q

What happens to the amount of urine if you don’t drink enough water ?

A

If you take in lots of water the kidneys produce lots is urine so therefor Excess water is lost from the body.

You will instead produce a large amount of dilute urine which will appear almost colourless.

46
Q

What are the three observable sections of the kidney?

A
  1. Capsule
  2. Cortex
  3. Medulla
47
Q

What is the capsule ?

A

It is the outer membrane of the kidney. It helps to maintain the kidneys shape and protect it from damage.

48
Q

What is the cortex?

A

It is the outer part of the kidney?

49
Q

What is the medulla?

A

It is the inner part of the kidney

50
Q

What is a tubule?

A

It is a small tube

51
Q

What are nephrons?

A

They are structures in the kidney that filter the blood

52
Q

Approximately how many nephrons does each kidney contain?

A

1 million nephrons

53
Q

Where is the top of the nephron found?

A

In the cortex

54
Q

Where is the bottom of the nephron found?

A

In the medulla

55
Q

How do substances enter the kidney?

A

Blood enters the kidney under high pressure from the renal artery. Thus contains many branches, each of which leads to a glomerulus. Each glomerulus contains a knot of capillaries.

The blood vessels narrow at the exit to the glomerulus which increases the blood pressure here. The increased blood pressure forces small molecules including water glucose salts and urea out through the capillary wall into the Bowman’s Capsule.

56
Q

Why do large molecules remain in the bloodstream.

A

They are too large to fit through the capillary wall so they remain in the bloodstream.

57
Q

What happens during selective reabsorption

A

As the filtrate moves through the nephron tubule all of the glucose is reabsorbed as well as some of the water and any salts needed by the body.

58
Q

What happens after selective reabsorption ?

A

The filtrate passes through the loop of Henlé and the collecting ducts.

These structures regulate the amount of salt and water in the body by reabsorbing extra water and salt if needed.

59
Q

What happens during excretion?

A

The waste solution (urine) collects in the collecting duct.

It travels to the bladder before it is removed from the body

60
Q

What does ADH stand for?

A

Anti-diuretic hormone

61
Q

What is ADH?

A

It is a hormone that controls the amount of water reabsorbed in the kidney

62
Q

How does the body control how much urine is produced?

A

The volume of urine produced is controlled through a negative feedback loop.

Your hypothalamus detects the water potential of your blood as it passes through the brain. It responds by secreting the hormone ADH from the pituitary gland.

ADH travels in the bloodstream to the kidney where it makes the walls of the collecting ducts more permeable to water. This means more water is reabsorbed into the blood.

63
Q

What happens to the amount of urine if blood water potential is too low?

A

More ADH is produced.

This results in more water reabsorbed from the nephron into the bloodstream.

Less water is lost from the body so a small volume of concentrated urine is produced

64
Q

What happens to the amount of urine if blood water potential is too high?

A

Less ADH is produced

Less water is being reabsorbed from the nephron into the bloodstream.

More water is lost from the body

A large amount of dilute urine is produced

65
Q

Why does insulin have to be injected?

A

It is a protein

If it was taken orally it would be digested

66
Q

How much water should you drink each day?

A

2L

67
Q

Why might you need to drink more water?

A

If you

take part in strenuous exercise

Are exposed to high temperatures

This is because these activities increase the rate of water loss through sweating.

68
Q

What is the thirst response?

A

A nervous impulse that triggers the body to take in more water

69
Q

What triggers the thirst response?

A

A reduction in the water potential of your blood plasma

An increase in salt concentration

70
Q

What happens if you do not take in more fluids (after the thirst response)?

A

You will become dehydrated.

71
Q

What is dehydration

A

It is the condition where you have not taken enough water into your body

72
Q

What are symptoms of dehydration

A
  • dark concentrated urine
  • headaches and dizziness
  • a lack of energy

If a person remains dehydrates the kidneys and liver may suffer permanent damage

73
Q

What happens if you take in too much water?

A

It causes the water potential of your blood plasma to rise above the water potential of your cells.

74
Q

What happens if a large volume of water is consumed rapidly?

A

Water will move by osmosis into your cells. This can cause these cells to burst.

The concentration of sodium in the blood plasma also drops. This can lead to muscle cramps, confusion and seizures.

75
Q

What are sports drinks used for?

A

Rehydration

76
Q

What are the three groups of sports drinks?

A

Hypertonic

Hypotonic

Isotonic

77
Q

What are hypertonic sports drinks?

A

They contain high levels of glucose and salts

78
Q

What are hypotonic sports drinks

A

Contain low levels of glucose and salts

79
Q

What are isotonic sports drinks?

A

They contain ion concentrations equal to those in blood plasma

Biology - Real One (10 decks)

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