Communication in the Nervous System Flashcards
Details of the nervous system structure.
What types of cells make up the nervous system?
- nerve cells (neurons)
- glial cells (glia)
Define: Neurons
- the brain’s communication
- they transmit information throughout the nervous system
- held in place by glia
Define: Glial Cells
- provide nutrients, insulation, and protection to neurons
- make up 90% of the brain’s cells
A neuron has 3 main parts:
- dendrites
- cell body
- axon
Define: Dendrite
- receives messages from other nerve cells
- transmits messages toward the cell body
- does preliminary processing of messages
Define: Cell Body
- contains biochemical machinery keeping the neuron alive
- depending on inputs from other neurons, it with transmit (fire) a message to other neurons
Define: Axon
- transmits messages away from the cell body
- divide into branches called axon terminals
Define: Myelin Sheath
-fatty material that surrounds axons
What are the constrictions in the myelin sheath that divide it into sausage-like segments?
Nodes
What are 2 purposes of the Myelin Sheath?
- prevent adjacent cell signals from interfering with eachother
- speeds up conduction of neural impulses
In the PNS, axons and dendrites are collected together into bundles called:
nerves
Most nerves enter or leave __________
the spinal cord
What is the process of producing new neurons from immature stem cells?
Neurogenesis
Define: Stem Cells
- immature cells that renew themselves and have the potential to develop into mature cells
- stem cells from early embryos can develop into any cell type
Why are embryonic stem cells more useful than stem cells from adults?
-because adult stem cells are limited and harder to keep alive
Neurons do not directly touch eachother. They are separated by…
the synaptic cleft
Define: Synaptic Cleft
-where the axon terminal nearly touches the dendrite or the cell body of another neuron
What is a Synapse?
-the axon terminal, cleft, and the covering membrane of the receiving dendrite
How do neurons communicate?
- they speak an electrical and chemical language
- Action Potential is the term of the electrical impulse that initiates message exchange
How does the Action Potential travel through:
- mylenated axons
- non-mylenated axons
mylenated axons
-action potentials “hop” from one node to the next
Non
-the impulse will travel down the axon like a fuse on a firecracker
How is a myelin sheath beneficial in regards to action potential?
nerve impulses travel faster
When does a neurotransmitter get released?
-when a received nerve impulse reaches the axon terminals, synaptic vesicles open and release neurotransmitter chemicals (AKA at the synapse)
Define: Synaptic Vesicles
- tiny sacs at the tip of the axon terminal
- in charge of releasing neurotransmitter molecules
What does a neurotransmitter do?
-alters activity of a receiving neuron
Once released, where do neurotransmitter molecules go?
-they diffuse across the synaptic cleft and bind with receptor sites
Define: Receptor Sites
- in the membrane of the receiving dendrites
- a lock that needs a key
When neurotransmitter binds to a receptor site, the ultimate effect is either…
-excitatory (+) voltage shift
or
-inhibitory (-) voltage shift
Why is inhibition in the nervous system extremely important?
without it, we could not sleep or coordinate out movements
Define: Plasticity
-the brain’s ability to adapt and change in response to experience, by reorganizing and growing new neural connections
(vividly demonstrated in people who have recovered from brain damage, strokes)
