homeostastis

Question 1

what is homeostasis

Answer 1

the maintenance of constant internal conditions

Question 2

Normal body temperature?

Answer 2

37 degrees celsius

Question 3

where is the thermoregulatory system

Answer 3

The thermoregulatory centre is in the hypothalamus of the brain

Question 4

what is the use of thermoreceptors in the skin

Answer 4

they send impulses to the thermoregulatory centre sending information on skin temperature

Question 5

what happens when youre core body temperature rises

Answer 5

This is detected by the thermoreceptors in the hypothalamus

Impulses are sent out from the hypothalamus to the body

blood vessels that supply the skin surface - capillaries - open wide - lets more blood flow through

Skin warms, so more energy is transferred to surroundings, cooling the body

Sweat glands produce more sweat and energy is used to evaporate it off. In humid conditions when it can’t evaporate, it is hard to cool down

Question 6

what is vasodilation

Answer 6

vaso - vessels dilation - getting wider

Question 7

What happens when core body temperature falls

Answer 7

1. impulses are sent from the hypothalamus to the body
2. vasoconstriction occurs
   vasoconstriction = blood vessels that supply the skin cappillaries constrict (close up). This reduces blood flow through the capillaries and so reduces energy loss in the form of heat
3. Sweat production is reduced or stopped –> reduces the amount of energy lost from water evaporating
4. Skeletal muscles contract and relax rapidly –> causes shivering
   Muscle contractions need a lot of respiration, which is an exothermic process, so this raises body temperature

Question 8

what is vasoconstriction

Answer 8

vasoconstriction = blood vessels that supply the skin cappillaries constrict (close up).

Question 9

Why is CO2 bad?

Answer 9

CO2 produces an acidic solution –> this can be harmful as it affects the pH of the environment of enzymes, affecting their function

Question 10

How is CO2 removed?

Answer 10

1. CO2 diffuses out of the cell (where it is made via respiration) down a concentration gradient
2. Diffuses from the blood to the air in alveoli
3. This air is excreted when you exhale
   A side effect of this is that water is also lost when moist air is breathed out.

Question 11

what is urine?

Answer 11

Urine = urea dissolved in water

Question 12

what is urea?

Answer 12

Urea = the waste product of deamination

Question 13

what is deamniation?

Answer 13

Deamination = the process of excess amino acids being broken down in the liver

Question 14

Why does urea need to be excreted?

Answer 14

Urea is poisonous –> if it accumulates, it will greatly damage cells

Question 15

How is urea removed?

Answer 15

1. Urea passes from the liver cells to the blood
2. Filtered out of the blood by the kidneys
3. Passed out of the body in urine, produced by the body with any excess water and salt

Question 16

When is urea produced?

Answer 16

. when excess protein is eaten
2. muscle tissues are worn out
- Deamination occurs as excess protein cannot be stored
Process where water/minerals/urea loss cannot be controlled:
1. Sweat - lose water, mineral, urea
2. Water leaves the lungs when you exhale

Question 17

Process where water/minerals/urea loss cannot be controlled?

Answer 17

1. Sweat - lose water, mineral, urea
2. Water leaves the lungs when you exhale

Question 18

what is selective reabsorortion

Answer 18

This process where the body determined the varying amount of water or mineral ions reabsorbed is called selective reabsorption

Question 19

wha size molecules that can be filtered through the kidney

Answer 19

ALL small molecules are filtered out of the blood

Question 20

what process must happen for reabsorption to happen

Answer 20

for ALL of the glucose to be reabsorbed back into the blood, diffusion AND active transport must take place

Question 21

what happens when the body is dehydrated (urine)?

Answer 21

When the body is dehydrated, a lot of water molecules are also reabsorbed back into the blood
If a lot of water is reabsorbed, this would result in very concentrated urine

Question 22

what happens when the body is hydrated

Answer 22

when the body is hydrated a lot more water molecules will not be reabsorbed into the blood
This means that the urine would be dilute

Question 23

what is the use of the kidneys

Answer 23

ALL small molecules are filtered out of the blood, in the kidneys
Then, useful molecules, such as glucose, are reabsorbed back into the blood

Question 24

what do osmoreceptors do

Answer 24

Osmoreceptors detect the concentration of solutes in the plasma –> this tells it how high or low water levels are

Question 25

what happpens if the blood becomes too concentrated

Answer 25

If blood becomes too concentrated:
1.the pituitary gland releases lots of ADH into the blood
2.ADH binds to the kidneys and causes the kidney tubules to reabsorb a lot more water
3.Results in a small volume of concentrated urine

Question 26

what happens if the blood becomes too dilute

Answer 26

If blood becomes too dilute:
1.the pituitary gland releases less adh into the blood
2.ADH binds to the kidneys and causes kidney tubules to reabsorb less water
3.this results in a larger dilute amount of urine released

Question 27

what happens in dialysis (4 points)

Answer 27

blood of the patient is removed for cleaning
Anti-coagulant prevents any blood clots
new dialysis fluid is placed in the machine for fresh blood the dialysis fluid contains the right amount
of useful solutes so that when the blood passes through no diffusion occurs and no useful substances from the blood are lost
the dialysis machine also contains a semi-permeable membrane so it ensures that the substances that need to be filtered
are filtred
4. this process repeats so for every new batch of fresh blood dialysis fluid is removed and replaced

Question 28

name 4 disadvantages of dialysis

Answer 28

Disadvantages of Dialysis:
You have to follow a carefully controlled diet
You have to spend long regular hours connected to it
As the next session approaches, the patient may tired
Over time it gets more difficult to keep the balance

Question 29

what are the risks of kidney transplant

Answer 29

The risk with this: the patient’s immune system’s antibodies will attack the antigens on the donor organ

Question 30

what are ways we can reduce the risks of kidney transplants

Answer 30

match organ donor with a similar tissue type to the patient

recipient is given immunosuppressants for the rest of their life –> this means that the patient’s immune system won’t reject the organ

Question 31

what is a disadv of immunosuppressants

Answer 31

a disadv of immunosuppressants = prevenys patients from dealing effectively with infectious diseases (they can become more seriously ill from minor illnesses like the common cold because they won’t really have a proper immune system)

Question 32

how long does an average kidney last

Answer 32

The average transplanted kidney lasts 1 year - at the end the patient goes back to dialysis and waits for a new kidney

Question 33

what is one disadv of longterm dialysis

Answer 33

Long term dialysis is much more expensive than transplant and causes serious damage to the body
a kidney transplant means an almost normal life, however you need to constantly take immunosuppressants