MyEdSpace Module 6 : Organisms Respond

6.1 Stimuli, both internal and external, are detected and lead to a response

Neurone

A specialised cell that transmits electrical impulses

CNS

Central nervous system (brain + spinal cord)

Reflex arc

The pathway followed by nerve impulses during a reflex action

Sensory neurone

Carries impulse from receptor to CNS

Relay neurone

Found in the CNS, connects sensory and motor neurones

Motor neurone

Carries impulse from CNS to effector.

Effector

Muscle or gland that brings about a response.

Pacinian Corpuscle

A pressure receptor in the skin that responds to mechanical stimuli

Mechanoreceptor

A receptor that responds to mechanical pressure or distortion.

Stretch-mediated sodium ion channel

A type of channel protein that opens when the cell surface membrane is deformed

Generator potential

A small depolarisation in a membrane that can trigger an action potential

Action potential

An electrical impulse generated if the generator potential reaches threshold

Photoreceptor

A receptor that detects light (rods and cones in the retina) and converts light energy into an electrical impulse.

Retinal Convergence

Multiple rod cells synapse with a single bipolar neurone

Visual Acuity

Sharpness or clarity of vision

Spatial Summation

When several weak stimuli from different sources combine to reach the threshold for an action potential