Responding to stimuli and reflexes

Why do we need nervous system

The nervous system helps us react to changes around us, this keeps us safe and helps us survive.

Reflex action

A fast, automatic, and involuntary response to a stimulus

Stimulus

A thing that changes environmental change such as pain

Difference between reflexes and stimulus

Responding to stimuli = involves thinking and choice but much slower (voluntary).

Reflexes = are automatic and protective and much faster (involuntary).

Receptors

A cell or organ that detects a stimulus

Effectors

A muscle that carries out a response to a stimulus.

Impulse

An electrical signal that travels along a neurone.

CNS (Meaning and definition)

(Central nervous system) Made up of the brain and spinal cord; coordinates responses.

Sensory Neurones

Carries impulses from receptors to the central nervous system

Synapse

The small gap between two neurones where messages are passed by chemicals called neurotransmitters.

Neurotransmitter

A chemical that transmits nerve impulses across a synapse.

Relay neurones

Found in the CNS; connects sensory and motor neurones.

Motor neurones

Carries impulses from the CNS to effectors

Order of events when feeling pain (Stimulus)

(Start) Stimulus
Receptors neurones (located in the 5 senses)
Sensory neurones (located in the spinal cord)
Relay neurones (located inside the skull)
Brain
Motor neurones (located in the muscles)
Effectors neurones
(End) Response