Neurons & Muscle Movement Flashcards
What is the difference between a tract and a nerve?
Commissure: Bundle of nerve fibers which cross the midline, connects across the midline
Tract: Bundle of nerve fibers in the CNS
In the PNS it is called a nerve,–> not a tract
T or F: The peripheral nervous system contains the brainstem
True
PNS: nerves and the cell bodies associated with them (includes the central canal)
CNS: brain and spinal cord
Autonomic nervous system is the third division
T or F: the central nervous system contains the spinal cord
True: CNS = Brain + Spinal Cord
T or F: the central nervous system contains spinal nerves
False: cranial and spinal nerves are located in the PNS
What is the difference between a ganglion and a nucleus?
Ganglion is a group of neurons in a cluster located in the PNS
E.g. spinal nerves: spinal ganglion
Cranial nerves: cranial nerve ganglia
Nucleus is a group of neurons in a cluster located in the CNS
What is the difference between grey matter and white matter? What makes them these particular colors?
White matter:
- Aggregations of fibers in the CNS, axons of neurons traveling up and down the spinal cord
- Made of fatty myelin
Grey matter:
- Cell bodies (e.g. ganglia, nucleus)
- Where all the synapses are
What is the function of ependyma cells? Where are they located?
Ependyma cells are located in the brain, line the ventricle spaces (brain and spinal cord)
Work to move CSF through the ventricular system
Cilia on the cells help them move the CSF
Choroid plexus secretes the CSF, leaking it into the ventricles and plays a significant role in the blood-brain barrier (type of ependymal cells)
What is the ventricular system?
Spaces in the brain and spinal cord where CSF flows
What is the function of the choroid plexus?
- Secretes CSF
- Lines the inside of the ventricles of the brain
- Plays a significant role in blood-CSF barrier
- Decides what gets input into CSF (in terms of solutes)
- Type of specialized ependymal cell
- Has brush border cells that secrete CSF
What is the “integration zone” of a neuron?
Integration zone refers to the cell body of a neuron.
What is the structure of a neuron which sends information to another neuron?
4 parts:
- Dendrites
- Cell Body
- Axon
- Terminal Boutons
Dendrites
- Extensions from the cell body, usually one or more which receives the input
- Works to RECEIVE sensory information from other neurons/receptors
- Input zone
Cell Body (Soma)
- Made of the soma which contains the nucleus
- Dendrites branch off of this
- SYNTHESIZING center for the neuron
- Integration center
Axon
- Help to transmit information from cell body to the terminal
- Information is sent through action potentials
- Conduction zone
Terminal Boutons
- Output zone
- Axon Terminals
What is the difference between a nerve and a neuron?
Neuron = single cell where information travels in one direction
Nerve fiber = refers to axons of neurons
Nerve is a group of fibers traveling together, information can go in either direction
Non-Neuronal Supporting Cells CNS
Neuroglia
Astrocyte
Microglia
Oligodendrocytes
Neuroglia
Provide structural support (little connective tissue in CNS)
Providing myelin sheaths of axons –> insulators
Control supply of nutrients
Housekeepers: destroy dead neurons
Don’t form synapses!
Are able to divide–> source of tumors in the nervous system
No Action Potentials!
Can’t transmit nerve impulses!
Astrocytes
Recycle NT
Secrete neurotrophic factors (growth factors)
Dictate number of synapses formed on neuronal surfaces
Maintaining appropriate ionic composition of extracellular fluid surrounding neurons (absorb excess potassium and other larger molecules)
Blood brain barrier is regulated by astrocytes
Microglia
- Smallest of the glial cells
- Represent intrinsic immune effector cells of the CNS
- Underly the inflammatory resposne that occurs following damage to the CNS
- Protect against the invasion of microorganisms
Oligodendrocytes
- Form myelin sheaths around the brain/spinal cord axons
- Not continuous
- Bare spots = nodes of Ranvier
- Myelin wraps in multiple layers
- Provide support to axons
Supporting cells in the PNS (2)
Schwann Cells/Lemmocytes:
- Glial cells of the PNS
- Wrap individually around the peripheral shaft of axons
- membrane primairly composed of lipids
- Insulator- speeds transmission rate of AP down axon
Satellite Cells:
- Regulate the microenvironment of PNS
- Function like astrocytes
