14 Coordination and response Flashcards
what travels along neurons?
electrical impulses
What does the CNS consist of?
the brain and spinal cord
What does the PNS consist of?
nerves outside of the brain and spinal cord
/
nerve cells that carry information to or from the CNS
role of the nervous system
coordination and regulation of body functions
reflex action
automatically and rapidly integrating and coordinating stimuli with the responses of effectors
reflex arc order
stimulus –> receptor –> sensory neurone –> motor neurone –> effector –> response
synapse
a junction between two neurones
events at a synapse
- an impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap
- the neurotransmitter molecules diffuse across the gap
- neurotransmitter molecules bind with receptor proteins on the next neurone
- an impulse is then stimulated in the next neurone
how many directions do impulses travel in?
One direction, the synapses ensure that the impulses travel in one direction
describe the structure of a synapse
prescence of vesicles containing NT molecules, the synaptic gap and receptor proteins
sense organs
groups of receptor cells responding to specific stimuli: light. sound, touch, temperature and chemicals
cornea
Clear area of the sclera, it refracts light
iris
Muscles which alter the size of the pupil, controlling the amount of light entering the eye
lens
focuses light on to the retina
retina
contains light receptors, some sensitive to light of different colours
optic nerve
Carries impulses between the retina and the brain
pupil
Small hole at the centre of the iris through which light enters the eye
fovea/yellow spot
a part of the retina that is directly opposite to the pupil and contains only cone cells.
- responsible for good visual acuity (good resolution)
blind spot
where the optic nerve leaves the retina so it lacks receptor cells
pupil reflex in dim light
radial muscles of the iris contract
circular muscles of the iris relax
pupil is dilated (more light can enter the eye)
pupil reflex in bright light
radial muscles of the iris relax
circular muscles of the iris contract
contracted pupil (less light can enter the eye)
accomodation to view objects which are near
ciliary muscles: contract
Suspensory ligaments: slackened
Muscle tension on lens: low
Lens shape: thicker and rounder (fat)
accomodation to view objects which are distant
ciliary muscles: relax
Suspensory ligaments: stretched
Muscle tension on lens: high
Lens shape: flatter (thin)
number of rods and cones in the retina
120 millions rods and 7 million cones
where are the rods and cones most concentrated?
rods are most concentrated in the outer edges of the retina
cones are most concentrated in the fovea
where do rods and cones work best in?
rods work best in dim light
cones work best in bright light
function of rods and cones
- greater sensitivity of rods for night vision
- three different kinds of cones, absorbing light of different colours, for colour vision
hormone
a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
what hormone does the adrenal glands secret?
adrenaline
what hormone does the pancreas secret?
insulin
what hormone do the testes secrete?
testosterone
what hormone do the ovaries secrete?
oestrogen
what are the flight or flight reponses during adrenaline secretion?
- increased breathing rate
- increased heart rate
- increased pupil diameter
where is glucagon secreted?
pancreas
Compare nervous and hormonal control, limited to speed of action and duration of effect
The effects of hormones take longer than the nervous system, but they last longer.
role of adrenaline in the control of metabolic activity
a) increasing the blood glucose concentration
b) increasing heart rate
what does insulin do
it decreases blood glucose concentration
role of rod cells
detect light in low intensity and passes impulse to optic nerve (3)
