Title: Reflex Actions
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
What are Reflexes?
Learning
Objectives
• Automatic responses are known as
reflexes. E.g. Pulling your hand away
when you touch something hot.
What is a
reflex?
Why are
reflexes so
important?
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
What are Reflexes for?
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
• Reflexes help your
avoid danger or
harm. They also
take care of your
basic body
functions like
breathing.
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
How do reflex actions work?
Learning
Objectives
What is a
reflex?
• Reflexes actions involve a reflex arc,
which is an impulse sent from a
sensory neuron to a relay neuron in
the CNS. The impulse is then sent
along a motor neuron to an effector
organ.
Why are
reflexes so
important?
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
How do reflex actions work?
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
How do synapses work?
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
• Your nerves
are not joined
directly to
each other,
there are
junctions
between them
known as
synapses
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
How do synapses work?
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
• E.g. When an impulse from a sensory
neuron arrives at a synapse with a relay
neuron, a chemical messenger is
released. The chemical travels across
the synapse to the relay neuron. This
sets off an electrical impulse that travels
along the relay neuron.
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
How do synapses work?
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
• E.g. When an impulse from a sensory
neuron arrives at a synapse with a relay
neuron, a chemical messenger is
released. The chemical travels across
the synapse to the relay neuron. This
sets off an electrical impulse that travels
along the relay neuron.
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals
Task
Learning
Objectives
What is a
reflex?
Why are
reflexes so
important?
1. In a ...... Arc, the electrical impulse
bypasses the ........ areas of the brain.
The time between the ........ and the
.......... Is as short as possible. Only .......
neurons, .... neurons and ........ neurons
are involved.
2. Draw a flow chart to explain what
happens when you step on a pin.
3. Using the example of a relay and motor
neuron, explain how a synapse works.
Key Words: Reflexes, reflex arc, synapses, relay neuron,
chemicals