homeostasis and response - RESPONSE Flashcards
nervous system, the eye, the brain
NS
what do eyes detect
light - light receptors
NS
what do ears detect
sound and orientation - sound/balance receptors
NS
what does the nose detect
smell - smell receptors
NS
what does the tongue detect
different tastes - taste receptors
NS
what does skin detect
temperature and pressure - touch, pressure, temperature receptors
NS
what are the two types of nervous system
central - brain + spinal chord
periphery - nerves and sense organs
NS
what is a nerve
an organ containing a bundle of nerve cells
–> they carry electrical messages called impulses throughout the day
NS
peripheral nervous system
- neurons are wired together through the body
- neurons (carrying messages as electrical impulses) move from one to another to keep the body functioning
- limited ability to repair themselves - nerve cells cannot be repaired or damaged
NS
what are the 3 main nerve cells
- sensory neuron
- relay neuron
- motor neuron
they come in many shapes and sizes depending on what their function is
NS
what is the function of the 3 main nerve cells
sensory N - carries signals from outer part of body (periphery) into the central nervous system
motor N - carries signals from the central nervous system to the outer parts of your body (muscles, skin, glands)
relay N - connects various neurons within the brain & spinal cord (relays info basically)
NS
what is the purpose of receptors
- they sense the environment (chemicals, light , sound, touch)
- they encode this info into electrochemical messages transmitted by sensory neurons
NS
how does information flow from neurons (explain)
information flows from 1 neuron to another across a synapse.
synapse - a small gap separating neurons
the electrical impulse is converted into a chemical signal which crosses the gap
sensory . .. . . neuro . . . . . . relay
neuron . . . transmitters. neuron
–> . .. . . . . . . .. . –> . . .. . .. –>
–> - electrical impulse
———->|
NS
describe the steps of a
conscious action/voluntary response
voluntary response involves a person’s brain making conscious decisions - response is fast since the brain processes info quickly and impulses travel quickly
1 - receptors in your skin detect a stimulus
2 - impulse is carried by SENSORY NEURONS to the spinal cord
3 - relay neuron carries signal to the brain
4 - brain decides to move away hand
5 - the impulse is sent by MOTOR NEURONS to the hand muscles via spinal cord
stimulus –> receptor –> sensory neuron –> co-ordinator –> motor neuron –> response
NS
describe the steps of reflex actions
conscious action may be too slow to prevent harm
so the body bypasses the brain and produces a quicker response
1 - sensory neurons send electrical impulses to relay neurons (in the spinal cord)
2 - they connect sensory neurons to motor neurons
3 - motor neurons send electrical impulses to an effector
4 - the effector produces a response (muscle contracts to move hand away)
receptor –> sensory neuron –> relay neuron –> motor neuron –> effector response
TE
function of optic nerve
carries impulse from retina –> brain
TE
function of sclera
tough outer layer for protection - holds eye in place
TE
function of cornea
transparent region of sclera at the front of the eye
refracts light - bends it as it enters eye
TE
function of iris
muscles in the iris regulate the amount of light reaching the retina
TE
function of ciliary muscles and suspensory ligaments
changes the shape of lens to focus light rays on the retina
TE
how does light intensity change the iris’ muscles
low light intensity - radial muscles in iris contract and pupils become larger
high light intensity - circular muscles contract and pupil becomes smaller
TE
the retina
- made up of 2 light sensitive receptor cells - cones & rods
- cones - sensitive to colour
- rods - sensitive to low light intensity and allow us to see very dim light (1000x more sensitive than cones)
- receptor converts light into electrical energy of a nerve impulse
TE
explain short-sightedness
the light focuses before the retina - focus is too forwards - long eye
you cannot see objects at long distances
it occurs when the eyeball is too long for the strength of the lens OR when the cornea is too sharply curved
when producing an image, it falls short of the retina
it can be corrected by a concave lens - diverges light
TE
explain long-sightedness
the light focuses after the retina - focus is too far back - short eye
you cannot see objects at short distances
it occurs when the lens is too weak because it is not thick enough OR the eyeball is too short OR when the cornea is not curved enough
when producing an image, it falls behind the retina
it can be corrected by a convex lens - converges light
TE
looking at a distant object..
- flat (pancake) lens
- ciliary muscles relax
- suspensory ligaments contract
