Topic 6 - Homeostasis

Question 1

why do conditions in the body need to be kept steady?

Answer 1

so cells can function properly

Question 2

what two conditions in the body need to be kept steady?

Answer 2

water content - there needs to be a balance between the water you gain and the water you lose
body temperature - you need to get rid of excess heat when you’re hot, but retain heat when you’re cold

Question 3

what is homeostasis?

Answer 3

the maintenance of a constant internal environment

Question 4

how is water lost from the body?

Answer 4

as sweat, in breath and as urine

Question 5

why does the body maintain a certain temperature?

Answer 5

to keep the enzymes in your body at the optimum temp (37 degrees)

Question 6

how does the body maintain a certain temperature?

Answer 6

a part of the brain is sensitive to blood temperature and receives messages from temperature receptors in the skin. based on these signals, your CNS can activate the necessary effectors to make sure the body temperature is just right.

Question 7

what happens in the skin when the body is too hot?

Answer 7

1. lots of sweat is produced - when it evaporates energy is transferred from the skin to the surroundings
2. blood vessels close to the surface widen (vasodilation) - it allows more blood to flow near the surface to transfer more energy to the surroundings
3. hairs lie flat

Question 8

what happens in the skin when the body is too cold?

Answer 8

1. very little sweat is produced
2. blood vessels close to the surface constrict (vasoconstriction) - it allows less blood to flow near the surface to transfer less energy to the surroundings
3. shivering - increases rate of respiration transferring more energy to warm the body
4. hairs stand on end to trap an insulating layer of air

Question 9

why do smaller organisms cool down quicker?

Answer 9

they have bigger surface area to volume rations, so there is more area for heat to transfer across. this means they gain/lose heat quickly