animal coordination key terminology

Accommodation

Accommodation

Changes taking place in the eye which allow it to focus on objects at different distances

Axon

Long extension of a neurone that carries nerve impulses in a direction away from the cell body

Blind spot

Area of retina where optic nerve leaves the eye, so it doesn’t contain any cells and so no image is detected

Cataract

Cloudy patches develop in the lens

Central Nervous System (CNS)

Brain and spinal cord, they coordinate the response of effectors

Choroid

dark layer of tissue below the sclera of the eye that contains blood vessels and pigment cells

Ciliary muscle

ring of muscle around the lens of the eye that alters the shape of the lens during accommodation

Cones

Light sensitive cells that work in bright light and can detect colour

Coordination centre

Areas of body (brain, spinal cord, pancreas) that receive and process information from receptors

Cornea

Transparent part at the front of the eye that allows light to enter. Refracts light as it enters the eye.

Dark adaption

how the eye recovers its sensitivity in the dark after bright light exposure

Dendrites

Fine extensions of the dendrons of a neurone

Effector

Organ that brings about a response (muscle or gland)

Eye

Sense organ containing receptors sensitive to light intensity and colour

Fovea

region at the center of the retina of the eye where there’s a high concentration of cones

Iris

Coloured part of the eye visible from the front. Circular and Radial muscles help change size of pupil

Myelin sheath

Covering made of lipid material that surrounds an axon. Nerve cells that have a myelin sheath are described as myelinated

Nerve impulse

Tiny electrical signal that passes down a nerve cell. Caused by movements of ions in and out of axon

Nerves

Cells that link to sense organs, transmit electrical impulses

Neuromuscular junction

Synapse of a nerve cell on a muscle

Neurone

Nerve cell

Neurotransmitter

Chemical released at the end of a neurone by arrival of nerve impulse. It diffuses across the synapse causing a new impulse in the following neurone

Pupil

Hole in centre of Iris that allows light to enter the eye

Receptor

A cell or organ that detects a stimulus

Reflex action

Rapid, automatic, involuntary response to a stimulus

Reflex arc

Nerve pathway of reflex action

Retina

Inner, light sensitive layer at the back of the eye

Rod

Light sensitive cell in the retina which works in dim light, can’t detect colour

Sclera

Tough outer coat of the eye

Stimulus

Change in surroundings that produces a response

Synapse

Junction between 2 neurons

Voluntary actions

Under conscious control and nerve cell pathways from the brain are linked to motor neurones