Biology- Homeostasis And The Nervous System Flashcards
What is homeostasis?
The regulation of internal conditions of a cell or organism in response to internal and external changes
Why is homeostasis important.
Because it keeps conditions constant for optimal enzyme action and cell functions
What does homeostasis include the control of
- blood glucose concentration
- body temperature
- water and ion levels
What does the automatic control systems involve
- electrical responses using the nervous system
- chemical responses using hormones
What do all control systems include
- specialised cells called receptors
- coordination centres such as the brain and spinal cord
- effectors (muscles or glands)
What do receptors do
They detect stimuli (changes in environment) such as change in blood glucose level
What do coordination centres do
They receive and process information from the receptors
What do the effectors do
Carry out responses that restore optimum levels
What does the nervous system enable humans to do
They allow humans to react to their surroundings and coordinate their behaviour
How does the body react to a stimuli (non-conscious)
1) the pain stimulus is detected by the receptors
2) impulses from the receptor pass along a SENSORY NEURONE to the central nervous system (cns)
3) an impulse then passes through a RELAY NEURONE
4) a MOTOR NEURONE carries an impulse to the EFFECTOR
5) the EFFECTOR responds
Are neurones directly connected to eachother
No, when an electrical impulse reaches a SYNAPSE a chemical is released which diffuses across the gap
Required practical: investigating reaction time
1) the experimenter holds a metre ruler vertically from the end
2) the subject has their fingers and thumb a small distance apart either side of the ruler on the 50cm line
3) the experimenter lets go of the ruler and the subject has to trap it
4) the distance the ruler travels is noted down
5) the subject then drinks caffeine and waits for 20 minutes then repeats the experiment
