Chapter 1: Stimuli & Responses

Brain & Spinal Cord

> 12 CARNIAL NERVES connecting the brain to the sensory and internal organs 31 SPINAL NERVES connecting the spinal cord to the skeletal muscles

> detects stimuli send information in form of impulses produce appropriate responses

Stimulus>Affector>BRAIN>Effector>Response

Affector> Effector>Spinal cord

• Involving medulla oblongata (heartbeat) • Involving spinal cord( withdrawing hand when touches smtg hot

Muscle that changes the thickness of the eye lens through contractions and relaxations

transparent and elastic convex lens which focuses light onto the retina

strong layer that maintains the shape of the eye and protects it

black layer prevents reflection supply oxygen and nutrients to the eye

contains photoreceptors (> detects light > produces nerve impulses)

part of retina that is most sensitive to light as it has many photoreceptors

nerve fibers which carry nerve impluses from the retina to the brain to be interpreted

part of retina which is not sensitive to light as there are no photoreceptors and an exit point for all optic nerve fibers

transparent jelly-like substance which maintains the shape of the eyeball and focuses light onto retina

transparent menbrane > protects front part of sclera

transparent fluid > maintains the shape of the eyeball and focuses light into the eye

> opening in the centre of the iris controls the quantity of light entering the eye

> the coloured part controls the size of the pupil

> transparent layer refracts and focuses light onto retina

strong fibers which hold the eye lens in its position

> sensitive to the colous of light intensities

> sensitive to the colour of light under bright conditions

collects and directs SOUND WAVES into the ear canal