Neurons Flashcards
What is a nerve cell?
The basic unit of the nervous system.
What percentage of neurons in the human nervous system are located in the brain?
80%
What are the main components of a neuron?
- Cell body (soma)
- Dendrites
- Axon
- Myelin sheath
- Nodes of Ranvier
- Terminal buttons
What is the function of dendrites in a neuron?
Carry impulses from other neurons to the cell body.
What is the role of the axon?
Carries impulses away from the cell body down the length of the neuron.
What does the myelin sheath do?
Protects the axon and speeds up transmission of the impulse.
What are the Nodes of Ranvier?
Gaps in the myelin sheath that increase speed by forcing impulses to ‘jump’ across the gaps.
What are terminal buttons?
At the end of axons, involved in communication across the synapse
What are the three main types of neurons?
- Sensory neurons
- Motor neurons
- Relay neurons
What do sensory neurons do?
Carry messages from sensory receptors to the CNS.
What is the primary function of motor neurons?
Carry messages from the CNS to effectors such as muscles and glands.
What is the role of relay neurons?
Connect sensory and motor neurons together.
What is depolarization in a neuron?
The rapid switch from negative to positive charge inside the neuron.
What is an action potential (AP)?
An electrical impulse created when depolarization reaches a certain threshold.
True or False: An action potential is an all-or-nothing event.
True
What is the maximum number of action potentials myelinated neurons can conduct per second?
Up to 500 APs a second.
Fill in the blank: When a neuron is in a resting state, the inside of the cell is _______ charged relative to the outside.
negatively
Fill in the blank: If the threshold for depolarization is not reached, there is _______ AP.
no
