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Biology Paper 2 > B12 Homeostasis in action > Flashcards

B12 Homeostasis in action Flashcards

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1
Q

What happens to the blood flow to the skin when vasodilation takes place?

A

Increases, more energy transferred to the surroundings

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2
Q

In which two parts of the body would you find thermo-receptors?

A

Skin and hypothalamus

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3
Q

Which 4 response occur if we become too cold?

A
  1. Vasoconstriction of blood vessel
  2. No sweat is produced
  3. Shivering
  4. Hair stands up
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4
Q

Vasodilation of blood vessels

A
  • capillaries get wider so a larger amount of blood can flow near the skin surface.
  • heat is lost to the environment
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5
Q

Vasoconstriction of blood vessels

A
  • capillaries get smaller so less blood can flow near the skin surface.
  • heat is kept near to the body
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6
Q

Which waste products do we need to remove from our bodies?
Where do they come from?
How are they removed?

A

Carbon dioxide:
- produced by body cells during respiration
- removed through exhalation/ through the lungs

Urea:
- deamination in the liver forms ammonia (toxic) which is converted into urea
- filtered out the blood by the kidney and passed out the body in urine produced by the kidney

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7
Q

What happens if the concentration of carbon dioxide is too high?

A

It forms an acidic solution which could cause enzymes to denature

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8
Q

What happens if the concentration of urea is too high?

A

It is poisonous.

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9
Q

Function of the renal artery

A

Brings blood containing urea and other substances in solution to the kidney

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10
Q

Function of the renal vein

A

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

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11
Q

Explain how urea leaves the body.

A
  • blood enters the kidney via the renal artery
  • blood leaves the kidney via the renal vein
  • the waste products gather
  • the waste products leave via the ureter
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12
Q

Function of bladder

A

Stores urine

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13
Q

Function of ureter

A

Carries urine from the kidneys to the bladder

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14
Q

Function of the kidney

A

Filters the blood

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15
Q

Why do the red blood cells not get filtered out of the blood?

A

They are too large.

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16
Q

Why does urea need to be removed from the blood?

A

In high concentrations, it becomes poisonous.

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17
Q

Why do the kidneys have a large blood supply?

A

So that urea can be removed from all of the blood before the concentration builds up

18
Q

How is glucose transported back into the blood?

A

Diffusion and active transport

19
Q

Which reaction in the body produces water?

A

Respiration

20
Q

The role of ADH (antidiuretic hormone) in water regulation - high/low ADH

A

High ADH - increases permeability of kidney tubule, more water reabsorbed by the kidneys, less urine
Less ADH - decreases permeability of kidney tubule, less water reabsorbed by the kidneys, more urine

21
Q

What is ultrafiltration?

A
  • The process in the kidney by which urea, salt and glucose etc. is extracted from the blood.
  • When the blood passes through the top of the nephron, it enters the glomerulus, a network of tiny capillaries.
  • This causes the pressure to increase and a fluid is pushed through the walls of the vessels. Blood cells and large proteins do not pass through the capillaries as they are too large. Most of the useful products enter the filtrate e.g. sodium, amino acids, glucose, so needs to be reabsorbed.
  • This is a process called selective reabsorption.
22
Q

Selective reabsorption

A

Sodium, amino acids and glucose (useful products) are reabsorbed from the filtrate back into the blood

23
Q

Controlled and not controlled methods of maintaining water and mineral balance

A

NO CONTROL - water leaves the lungs and water, mineral ions, and urea lost by sweat
CONTROL - urea, excess water, and excess mineral ions removed via kidneys

24
Q

Where is ADH produced?

A

Pituitary gland

25
Q

Describe how the amount of water in the bloodstream is controlled by the kidneys.

A
  • Pituitary gland releases ADH
  • Changes permeability of nephron/tubule
  • Water reabsorbed
26
Q

No control, maintaining water and mineral ion balance examples

A
  • Water leaves the lugs every time you exhale
  • Water, mineral ions and urea are lost through the skin as sweat
27
Q

Control, maintaining water and mineral ion balance examples

A
  • Urea, excess water, and excess mineral ions are removed from the blood via the kidneys, then excreted in the urine
28
Q

Problems with the kidneys

A
  • Damaged due to injury
  • Polycystic kidneys (genetic)
  • Bacterial infections
  • Kidney failure
29
Q

Two types of kidney treatment

A
  • Dialysis
  • Kidney transplant
30
Q

What is dialysis?

A

The function of the kidney is carried out artificially

31
Q

Why is the glucose concentration the same in the dialysis fluid as in the blood?

A

So that there is no net movement of glucose out of the blood by diffusion

32
Q

How does a dialysis machine work?

A
  • Arterial blood leaves the arm
  • Blood passes through blood thinners to prevent clotting
  • Blood and dialysis fluid enters the dialysis machine
  • In the dialysis machine the blood flows between partially permeable membrane (permeable to ions and waste substances)
  • Dialysis fluid carrying waste products and urea is removed
  • Clean blood flows through bubble trap to get rid of any bubbles
  • Clean blood returns to a vein in the arm
33
Q

How does dialysis ensure that urea is removed?

A

No urea in the dialysis fluid ensures that there is a large concentration gradient so diffusion will happen at a faster rate

34
Q

Why are blood thinners added?

A

To prevent blood clotting

35
Q

Disadvantages of dialysis

A
  • Time-consuming
  • Can become really ill in between visits
36
Q

Transplants

A
  • Donor needs to be same blood group and tissue type as a recipient: can be live (relative), or from a victim of road accident, stroke or heart attack
  • Involves operation (risks)
  • Transplant may be rejected by the immune system
  • Medicines given to suppress the immune system (immunosuppressant drugs)
37
Q

What is the function of skin?

A
  • Protection
  • Temperature control
  • Receptors for touch
38
Q

What effect does hairs standing on end have on the body temperature?

A

Traps a thin layer of air to provide insulation

39
Q

How is temperature regulated?

A
  • The hypothalamus receives nerve impulses from heat and cold thermo-receptors in the skin
  • There are also receptors in the hypothalamus called central thermo-receptors, these detect changes in blood temperature
40
Q

Negative feedback loop to show how temperature is regulated

A
  • Body temperature rises
  • Receptors detect stimuli
  • Body responses triggered
  • Capillaries widen, lots of sweat is produced, hairs lie flat, no shivering
  • Body temperature falls
  • Body temperature falls
  • Receptors detect stimuli
  • Body responses triggered
  • Capillaries constrict, no sweat is produced, hairs pulled erect, shivering occurs
  • Body temperature rises

Biology Paper 2 (10 decks)

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