Coordination and response Flashcards
Electrical impulses travel along
neurones
Mammalian nervous system consist of
The central nervous system (CNS) consisting of the brain and the spinal cord
The peripheral nervous system (PNS) consisting of the nerves outside of the
brain and spinal cord.
Role of the nervous system is
coordination and regulation of body functions.
Reflex arc:
receptors detect stimulus and generate impulse, it travels to sensory
neurone, then relay neurone, then to motor neutron, then to the effector.
A reflex action
a means of automatically and rapidly integrating and coordinating
stimuli with the responses of effectors (muscles and glands).
synapse
A junction between two neurones
Structure of synapse include:
presence of vesicles containing neurotransmitter molecules
Synaptic gap/cleft
receptor protein
Events at a synapse:
An impulse stimulates the release of neurotransmitter molecules from vesicles
into the synaptic gap.
The neurotransmitter molecules move from their region of higher concentration to their region of lower concentration down their concentration gradient across the gap
Neurotransmitter molecules bind with receptor proteins on the next neuron
An impulse is then stimulated in the next neuron.
Synapses ensure that
impulses travel in one direction only.
Sense organs
groups of receptor cells responding to specific stimuli: light,
sound, touch, temperature and chemicals.
cornea function
refracts light
iris function
controls how much light enters the pupil
lens function
focuses light on to the retina
retina function
contains light receptors, some sensitive to light of different colours
optic nerve function
carries impulses to the brain
As light intensity increase,
diameter of pupil decrease so that less light enters the
eye and prevent damage. The antagonistic muscles, circular muscles contract and
radial muscles relax.