12. coordination and response Flashcards
stimuli
changes in the environment that can be detected by organisms
receptors
cells or groups of cells that detect stimuli
effectors
parts of the body that respond to a stimulus
coordination
ensuring that the actions of different parts of the body work together
nerve
a group of neurone axons lying together
neurone
a cell that is specialised for conducting electrical impulses rapidly
motor neurone
a neurone that transmits electrical impulses from the central nervous system to an effector
axon
a long thin fibre of cytoplasm that extends from the cell body of a neurone
dendrites
short fibres of cytoplasm in a neurone
nerve impulse
an electrical signal that passes rapidly along an axon
CNS central nervous system
the brain and spinal cord
PNS peripheral nervous system
nerves outside the brain and spinal cord
sensory neurone
a neurone that transmits electrical impulses from a receptor to the central nervous system
relay neurone
a neurone that transmits electrical impulses within the central nervous system
reflex arc
a series of neurones that transmit electrical impulses from a receptor to an effector
reflex action
a means of automatically and rapidly integrating and coordination stimuli with the responses of effectors
synaptic gap
a tiny gap between two neurones at a synapse
synapse
a junction between 2 neurones
neurotransmitter
a chemical stored in vesicles at the end of neurones which can be released to diffuse across the synaptic gap and set up an electrical impulse in the next neurone
receptor proteins
proteins on the membrane of the seconds neurone at a synapse which have a complimentary shape to the molecules of neurotrasmitter
sense organ
a group of receptor cells that are able to respond to a specific stimulus
retina
a tissue at the back of the eye that contains receptor cells that respond to light
optic nerve
the nerve that carries electrical impulses from the retina to the brain
blind spot
the part of the retina where the optic nerve leaves and there are no recpetor cells
fovea
the part of the retina where cone cells are very tightly packed and light is focused
rods
receptor cells in the retina that responf to dim light but do not detect colour
cones
receptor cells in the retina that are sensitive to light of different colours but only function in bright light
iris
the coloured part of the eye that contains muscles that alter the size of the pupil
pupil
a circular gap in the middle of the iris
iris reflex
an automatic response to a change in light intensity
antagonistic muscles
a pair of muscles whose contraction has opposite effects
cornea
a transparent layer near the front of the eye which refracts light rays entering the eye
lens
a transparent structure in the eye which changes shape to focus light rays onto the retina
accommodation
changing the sha[e of the lens to focus on objects at different distances from the eye
suspensory ligament
strong inelastic fibres that hold the lens in position
ciliary muscle
a circle of muscle surrounding the lens and joined to it by the suspensory ligament
hormones
chemicals that are produced by a gland and carried in the blood, which alter the activities of their specific target organs
adrenaline
a hormone secreted by the adrenal glands which prepares the body for fight or flight
tropism
a growth response by a plant in which the direction of growth is related to the direction of the stimulus
phototropism
a response in which part of a plant grows towards or away from the direction from which light is coming
gravitropism
a response in which part of a plant grows towards or away from gravity
auxin
a plant hormone made in the tips of shoots which causes cells to elongate
