Nervous control, reflexes and the eye

Learning objectives

Describe the human nervous system as the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves), which together coordinate and regulate body functions

Identify sensory, relay and motor neurones and describe a simple reflex arc (receptor, sensory neurone, relay neurone, motor neurone and effector) as a means of automatically and rapidly coordinating a response to a stimulus

Describe the structure of a synapse (synaptic gap, vesicles containing neurotransmitter and receptor proteins) and the events that carry an impulse across it, and explain why synapses ensure impulses travel in one direction only (Extended)

Describe sense organs as groups of receptor cells that respond to specific stimuli (light, sound, touch, temperature and chemicals), and identify the cornea, iris, pupil, lens, retina, optic nerve and blind spot of the eye (and at Extended the fovea) and state their functions

Describe the pupil reflex in bright and dim light, and at Extended explain it in terms of the antagonistic action of the circular and radial muscles of the iris

Explain accommodation for near and distant objects in terms of the ciliary muscles, suspensory ligaments, the shape of the lens and the refraction of light, and describe the distribution and functions of rods and cones in the retina (Extended)