Neurons Flashcards
2 Basic Functions of Cell Body/ Soma
- Cellular Life- responsible for keeping cell alive and supports life of dendrites and axons.
- Plays role of transmission of neural impulses.
Axon Functions
Single long efferent process which conducts nerve impulses away from the cell body to either other neurons, muscles, or glands
Axon Hillock
Where axon attaches to cell body and it’s where nerve impulses arrive
Telodendria
Located at the end of an axon. Contains terminal boutons at the end.
Terminal boutons
Located at the ends of each telodendria. They contain synaptic vessels.
Synaptic Vessicles
These are where transmitters are stored.
Dendrite Function
They are multiple short afferent processes that conduct impulses towards the cell body.
Difference Between Myelin in PNS and Myelin in CNS
PNS: Myelin is made from neurolemmal cells. Many cells provide myelin for a single neuron. They grow around the point of injury so that the neuron can regenerate.
CNS: Made from Oligodendrocytes. One oligo dendrite provides myelin for several neurons. If a neuron gets injured, myelin condenses around the living ones and kicks out the dying one. Neurons in CNS don’t regenerate.
Axons are Covered in What?
Myelin sheath, which is a fatty substance.
Nodes of Ranvier and Function
Nodes of Ranvier are the gaps in the myelin sheath. Neural impulses jump from one to the next instead of traveling straight down. This causes the neural impulses travel quicker.
Meaning of “We Equate the Myelination to Maturation of the Nervous System”
This means that people are not born myelinated. It takes 10-12 years. During this time, neural impulses travel straight down, which makes them slower and not as precise.
3 Types of Neurons
- Unipolar Neuron
- Bipolar Neuron
- Multipolar Neuron
What is a Unipolar Neuron?
It is a single process that then divides into two processes. Afferent and efferent. Located in PNS.
What is a Bipolar Neuron?
Multiple short processes off of one side of the neuron, and multiple processes off the opposite side. One acts as an axon, the other a dendrite. Located in PNS.
What is a Multipolar Neuron?
Has a single axon off one pole and multiple short dendrites off the opposite pole. Located in CNS. (Stereotypical Neuron)
Tracts and Function
Tracts are chains or bundles of neurons in CNS. They only carry one type of information. Either sensory or motor. Can’t do both.
Nerves and function
Nerves are the chains or bundles of neurons in the PNS. They can carry sensory info, motor info, or both. Mixed nerves carry both.
Neuron Transmission Pathway
The neuron has to be adequately stimulated. This generates a transitory electrochemical impulse that travels away from the point of excitation in a wavelike manner. It hops from one node of ranvier to the next, which is called saltatory conduction. This happens until it has reached the terminal point of the axon at which point, a specialized process begins. At the terminal boutons, synaptic vessels release neurotransmitters to the synaptic cleft. Once the neurotransmitters help the electrochemical impulse cross the cleft, the neurotransmitters go away.
Synapse and its Three Parts
Neurons form functional unions with other structures, which are called synapses.
It has three parts: Presynaptic structure, synaptic cleft, and postsynaptic structure.
Excitatory Effect
It’s an increase in stimulation. Neural impulses crosses to the next structure quicker, structure responds faster, and structure responds stronger.
Inhibitory Effect
It’s a decrease in stimulation. The impulse crosses the cleft slower, the structure responds slower, and the structure’s response is dull or muted.
Two Important Rules To Note About Neuron Transmission
- Either the neuron is adequately stimulated, or it’s not.
- Neural transmission happens on a one way street. Once it has started, it won’t stop until it reaches its destination or it is otherwise stopped.
