Homeostasis Flashcards
Central nervous system
Brain
Spinal chord
Stimulus…
Receptor, coordination, effector, response
Nerve cell
Neurone
Bundle of neurones
Nerve
How do synapses work?
Chemical transmitters are released
They diffuse across the gap
They bind to the receptors in the membrane
A new impulse starts
Reflex arc
stimulus receptor sensory neurone relay neurone motor neurone effector response
what happens to the eye in bright light?
- circular muscles contract
- pupil becomes smaller
what happens to the eye in dim light?
- radial muscles contract
- pupil becomes larger
looking at distant objects:
- ciliary muscles relax
- suspensory ligaments pull tight
- the lens goes thin
looking at near objects:
- ciliary muscles contract
- suspensory ligaments slacken
- the lens becomes fat
where are hormones produced?
in glands
where is ADH produced?
in the pituitary gland
what is the role of ADH?
controls water content
what are the effects of ADH?
increases the permeability of the kidney tubules to water
where is adrenaline produced?
in the adrenal glands
what is the role of adrenaline?
readies the body for a ‘fight or flight’ response
what are the effects of adrenaline?
increases heart rate, blood flow to muscles and blood suger level
where is insulin produced?
in the pancreas
what is the role of insulin?
helps control the blood sugar level
what are the effects of insulin?
stimulates the liver to turn glucose into glycogen for storage
what are the three characteristics of nerves?
- very fast message
- act for a very short time
- act on a very precise area
what are the three characteristics of hormones?
- slower message
- act for a long time
- act in a more general way
homeostasis definition
homeostasis is the maintenance of a constant internal environment
what are the three ways that water is lost from the body?
- through the skin as sweat
- via the lungs in breath
- via the kidneys as urine
