2.2 Reflex Actions [Recovered]

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