nervous communication the squeaquel Flashcards
what are reflexes
A reflex is where the body responds to a stimulus without making a conscious decision to respond.
why do reflexes happen so fast
Because you don’t have to spend time deciding how to respond, information travels really fast
from receptors to effectors.
what do simple reflexes help
So simple reflexes help organisms to protect the body because they’re rapid
what is a reflex arc
The pathway of neurones linking receptors to effectors in a reflex is called a reflex arc.
You need to learn a simple reflex arc involving three neurones — a sensory, a relay and a motor neurone.
for example, what happens in order when a hand responds to heat
• Thermorece p tors in the skin detect the heat stimulus.
• The sensory neurone carries impulses to the relay neurone.
• Th e relay neurone connects to the motor neurone.
• Th e motor neurone sends impulses to the effector
(your biceps muscle).
• Your muscle contracts to with draw your hand and
stop it being damaged.
what happens if there’s a relay neuron involved in the simple arc
If there’s a relay neurone involved in the simple reflex arc then it’s
possible to override the reflex, e.g. in the exam ple above yo ur brain
co uld tell your hand to withstan d the heat.
what are three features of the nervous system communication
Nervous System Communication is Localised, Short-lived and Rapid
what happens when an electrical impulse reaches the end of a neurone
W hen an electrical impulse reaches the end of a neurone, neurotransmitters
are secreted directly onto target cells (e.g. muscle cells) — so the nervous response is localised.
2) Neuro transmitters are quickly removed once they’ve done their job, so the response is short-lived
what allows animals to have a quick stimuli
Electrical impulses are really fast so the response is rapid — this allows animals to react quickly to stimuli.
