Coordination Flashcards
How does response occur
Stimulus (change in surrounding ), receptor organ detects change in environment , contraction of muscles of the effector organ brings the response
How does saliva respond to smell of food
Nose is the receptor then glands secrete saliva
What is the link between stimulus and response
Nervous system where information in nerve cells is transmitted by nerve impulses.
What is the role of the receptor
Detect the stimulus by changing its energy into the electrical energy of nerve impulses e.g. Eat converts sound energy into nerve impulses . This is called transduction , all receptors are transducers of energy
What is the name for a nerve cell
A neurone
What is the CNS
Brain and spinal cord , impulses from receptors pass along nerves containing sensory neutrons until they teach the brain and spinal cord
What do motor neurones do
Transmitt impulses to muscles and glands
What are dendrons
Part of the CNS for motor neurones , outside CnS for sensory . Cytoplasmic extensions which in turn from finer extensions called dendrites
What are synapses
Junctions
Axon
Longest extension of the neurone , carries impulses to the effector organs . At the end of the axon it divides into many nerve endings which connect with a muscle at a synapse called the nerve muscle junction . Signals from nerve impulses transmitted across the nerve muscle junction causing the muscle to contacts .
Sheath
Covers the axon and made of myelin which insulates the axon preventing short circuits with other axons and speeds up conduction of impulses
Sclera and cornea and iris and pupil
Outer coat of the eye , at the front becomes the cornea which let lights into the eye . Behind cornea is the iris which has a hole called the Pupil that lets light through but is black to stop light escaping from the inside of the eye
Choroid
Underneath sclera . Contains pigment which stops light being reflected around inside the eye .
Retina
Intermost layer of the bAck of the eye where light energy is transduced into electrical energy of nerve impulses . Retina contains rods and cones that react to light producing impulses in sensory neurones that pass impulses to the brain through the optic nerve , can’t distinguish between different colours in dim light as cones can’t work . Cones are concentrated at centre of retina called gives and give a sharper image than rod
Lens
Light is refracted and inverted then the brain interprets the image the right way round
How does the iris work
Changes the amount of light entering the eye by changing the size of the pupil . Contains circular muscles that form a ring shape in the iris and radial muscles.
What happens in bright light
Stimulus light intensity , retina is the receptor , sensory neurones in the optic nerve go to an unconious part of the brain , motor neurones in the nerve to the iris cause in bright light circular muscles contact and radial muscles relax so pupil constricts , dim light circular muscles relax radial muscles contract and the pupil dilates . This is a reflex action as too bright light would damage rods and cones and too dim light would not form an image
What is the blind spot
No image as this is where optic nerves leaves the eye so no rods and cones