SB2g, i - The nervous system , Neurotransmission speeds Flashcards
What is a Stimulus?
– change in the environment
What is a Receptor?
– anything that senses a stimulus/change
What is a Effector?
– anything that produces an effect
What is a Neurones?
– nerve cell
What is a electrical impulses ?
– signal
What makes up the Central Nervous System?
brain
spinal cords
nerves / neurons
Name the 3 types of neuron.
Sensory neuron
Motor neuron
Relay neuron
Explain the purpose of the sensory neuron.
to deliver electrical signals from the outer
parts of the body (the glands, muscles, and skin)
into the CNS
Explain the purpose of the Motor neuron.
to carry signals from the CNS to the outside
parts of the body
Explain the purpose of the Relay neuron.
to sends messages from one neuron to another
Name the 6 sections of the neuron structure.
Dendrites
Dendrons
Axon
Myelin sheath
Cell body
Axon terminals
What are Dendrites and what is their function?
they are extensions that connect neurons together
and receive signals from them
State the function of Dendrons.
They Pass impulses from dendrites and cell body
State the function of the Axon.
to Pass impulse from cell body to the axon terminals
What is the Myelin sheath and state its function.
it is the fatty material covering the axon of neurons
Insulates and speeds up the conduction of an
impulse
State the function of the Cell body.
to contains the nucleus and other organelles
State the function of the Axon terminals.
They are extensions that connect neurons together and Axon terminals pass on signals to other neurons
Why don’t relay neurons have a myelin sheath?
Relay neurones do not have myelin sheath as they are small
and do not need insulation to speed up the impulse
What is Reflex?
A reflex action is a action that is automatic , extremely quick and to protect your body
Explain the order of which a response is created.
- Receptor in the skin detects a stimulus
- Electrical impulse generated in sensory neurons which travels to the relay neurons in the spinal cord
- Then moves into motor neurons
- and finally reaches an effector producing a response ( muscle contracts to move hand away)
What is a synapse?
The gap between 2 neurones
How do impulses travel across the synapse?
when a impulse reaches an axon terminal a neurotransmitter substance is released into the gap. this is detected by the next neuron which generates a new impulse
Why are synapses useful? (3)
- they ensure impulses travel in one direction
- they slow down the speed of neurotransmission
- they allow many impulses in many neurons connected to one neuron
