14.1-2 Nervous Control
14.1 Nervous control in humans
Describe a nerve impulse as an electrical signal that passes along nerve cells called neurones
Describe the human nervous system in terms of:
the central nervous system consisting of brain and spinal cord
the peripheral nervous system
coordination and regulation of body functions
Identify motor (effector), relay (connector) and sensory neurones from diagrams
Describe a simple reflex arc in terms of receptor, sensory neurone, relay neurone, motor neurones and effector
Describe a reflex action as a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
Define a synapse as a junction between two neurones
Supplement:
Distinguish between voluntary and involuntary actions
Describe the structure of a synapse, including the presence of neurotransmitter containing vesicles, the synaptic cleft and neurotransmitter receptor molecules
Describe how an impulse triggers the release of a neurotransmitter from vesicles into the synaptic gap and how the neurotransmitter diffuses across to bind with receptor molecules, in the membrane of the neurone after the synaptic gap, causing the impulse to continue
State that in a reflex arc the synapses ensure that impulses travel in one direction only
State that many drugs, e.g. heroin, act upon synapses
14.2 Sense organs
Define sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
Identify the structures of the eye, limited to cornea, iris, pupil, lens, retina, optic nerve and blind spot
Describe the function of each part of the eye, limited to:
cornea – refracts light
iris – controls how much light enters pupil
lens – focuses light onto retina
retina – contains light receptors, some sensitive to light of different colours
optic nerve – carries impulses to the brain
Explain the pupil reflex in terms of light intensity and pupil diameter only
Supplement:
Explain the pupil reflex in terms of light intensity and antagonistic action of circular and radial muscles in the iris
Explain accommodation to view near and distant objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light
State the distribution of rods and cones in the retina of a human
Outline the function of rods and cones, limited to greater sensitivity of rods for night vision and three different kinds of cones absorbing light of different colours for colour vision
Identify the position of the fovea.