Biology Unit 2 revision notes - Homeostasis

Homeostasis
BIOLOGY REVISION…read more

THE BASICS
The word "homeostasis" literally means
'staying the same'
It is the word used to describe how animals
maintain a constant internal environment
There are three key areas in our bodies that are
controlled by homeostasis
- Temperature
- Water balance
- Blood sugar level…read more

HOW TEMPERATURE IS CONTROLLED
Controlled by the thermoregulatory centre in the
brain
Should stay at 37 degrees celcius
If its too high:
- you sweat
- your hairs lay flat
- your veins rise to the surface
If its too low:
- your hairs stand up
- you shiver
- your veins constrict…read more

HOW WATER BALANCE IS
CONTROLLED
Controlled by the kidneys
If its too high:
- you sweat
- you urinate more
- your urine is concentrated
If its too low:
- your urine is clear
- you feel thirsty
- you dehydrate…read more

HOW BLOOD SUGAR LEVEL IS
CONTROLLED
Controlled by the pancreas
Should stay between 4-6mm
If it is too high:
- more insulin is produced
- liver converts excess glucose into insoluble
glycogen
If it is too low:
- more glucagon is produced
- liver converts stored insoluble glycagon into
soluble glucose
Insulin and Glucagon are hormones…read more

UREA AND CARBON DIOXIDE
These are the two main waste products your body
produces
They are both poisonous and can cause lots of
damage if they are not removed
Urea is created in the liver when excess amino acids
are broken down and filtered out of the blood by
the kidneys and then it is removed through urine
Carbon dioxide is produced during cellular
respiration and removed through breathing…read more