The Nervous System Flashcards
What are the 2 divisions of the nervous system?
Central nervous system and peripheral nervous system
What structures make up the CNS?
The brain and spinal cord
What structures make up the PNS?
All neurons that extend from the brain or spinal column to the other organs and tissues of the body
What are 2 subdivisions of PNS?
Sensory division and Motor division
What are neurons?
The structural units of the nervous system
What do neurons do?
They are cells which communicate by receiving chemical signals, conducting electrical impulses (action potential) and releasing neurotransmitters which send signals between each other and the rest of the body
The body of a neuron is called?
Cell body or Soma.
What do dendrites do?
The receiving part of the neuron
What do axons do?
The sending part of the neuron
Name the insulating layer covering the axon
Myelin sheath
Regions of myelinated axons are also called?
Nodes of Ranvier
What are the functional classification of neurons? (3)
Sensory neurons, interneurons and motor neurons
How long can neurons function?
For a lifetime
What do Glial cells do?
Support and protect neurons in the CNS and PNS. They are up almost half the volume of the nervous system (also called neuroglia)
What are the types of neuroglia of the CNS and what do they do? (4)
Astrocytes - provide structural and metabolic support for neurons (mediate nutrient exchanges between neurons and blood vessels), maintain the blood brain barrier and modulate synaptic transmission
Ependymal cells - produce, monitor and circulate cerebrospinal fluid around the brain and spinal cord.
Microglia - remove cellular debris, waste products and pathogens (waste collectors of the CNS)
Oligodendrocytes - provide structural framework and produce myelin
What are the types of neuroglia of the PNS and what do they do? (2)
Schwann cells - form a sheath around segments of axons of peripheral neurons. Isolates the neurons from contact with the ECF. They form multi-layered myelin sheath around axon segments.
Satellite cells - surround the neuron call bodies with ganglia and regulate the environment around the neurons (like astrocytes in the CNS), supply nutrients, structural support and protection to the neuron they surround.
What does the plasma cell membrane do?
Regulates what can and can’t enter or leave the cell
What causes a channel protein to open/close?
In response to different stimuli: neurotransmitters and other molecules, voltage charade and mechanical charge
True/False: The voltage of the membrane potential at rest is about -70mV
True
What is another name for the electrical signal transmitted with neurons?
Action potential
Are action potentials transmitted fast or slow?
Depends on the size of the axon (bigger is faster) they can reach 432km/h
The junction between two neurons or between a neuron and its target cell or tissue is called?
A synapse
What are the special chemicals called that relay information between neurons?
Neurotransmitters
The action potential happens before or after the neurotransmitter is released from the synaptic junction?
Before
What is it called when ions move in or out of a channel and change the membrane potential in that area?
Graded potential
Negative change in the cell membrane is called?
Hyperpolarisation
Depolarisation makes action potentials more or less likely?
More likely
What voltage must the cell membrane reach to cause an action potential?
-55mV (threshold value)
Positive ions enter the cell when ________ channels open at -55mV
Voltage-gated
How are action potentials and myelin sheaths related?
Myelin sheaths make action potentials travel much faster
How is cellular communication (neurotransmitters) affected?
Drugs
