B2-4 How do our bodies keep a healthy water balance? Flashcards
What is homeostasis?
It is the balancing of inputs and outputs to maintain a constant internal environment.
Why is this important?
Because our cells need the right conditions to function properly.
How is this done?
It involves both nervous and hormonal communications systems.
What do all our automatic control systems have in common?
Three main components that work together - receptors, processing centres and effectors.
Receptors
detect the change in environment
Processing centres
receive information and pass information on to conduct a response
Effectors
produce the response
What is the mechanism used to keep our internal environment stable?
negative feedback
What is negative feedback?
When levels get too high or low e.g. water/temperature, body uses negative feedback to bring it back to normal. It is a cycle - happens automatically.
Write down an example:
- Receptor detects a HIGH level
- PC receives info
- Effector produces response to get a LOW level
CYCLE - Receptor detects a LOW level
- PC receives info
- Effector produces response to get a HIGH level
Why is balancing water levels really important?
Your body needs to maintain the concentration of its cell contents at the correct level for cell activity.
Inputs
Drinks, food and respiration
Outputs
Sweating, breathing, faeces and urine.
What do kidneys do?
They help balance substances in the body.
How do they do this?
The do this by changing the amount of urine you make.
-On a hot day, if you lose a lot of water through sweat, your kidneys make a smaller volume of urine, but with the same waste levels - it will be more concentrated.
How can the concentration of blood be affected?
Depending on concentration, your body makes more or less urine.
- Excess sweating
- not drinking enough water
- eating salty food
ALL increase blood concentration, meaning your kidneys will re-absorb more water into the body.
How is the concentration of water controlled?
By the hormone ADH
Control system for water balance
A negative feedback system - Receptors in the brain detect any change in concentration in the blood plasma.
What happens when concentration is too high?
ADH is released into the bloodstream from the pituitary gland in the brain.
What happens when concentration is too low?
NO ADH is released.
Less ADH?
More urine, less re-absorbed
More ADH?
Less urine, more re-absorbed
Too much water?
Less ADH
Water content too low?
More ADH
How does alcohol affect ADH production?
Suppresses ADH production - more dilute urine, leads to dehydration - headaches, tiredness.
How does ecstasy affect ADH production?
Increases ADH production - less urine, more water absorbed into the body, could lead to water overflow which leads to BRAIN DAMAGE AND DEATH.
