Nervous System I: CNS Flashcards
What are the 2 categories of cells in the nervous system?
- Neurons
- Glia (aka. Neuroglia)
What are neurons?
(~ 100 billion): specialized cells for reception, transduction and conduction of stimuli. They rapidly conduct signals (action potentials) from one part of a neuron to another, and these signals are then transmitted to other neurons.
What are Glia (aka. Neuroglia)?
the support cells of the nervous system. They account for ~70% of all cells in the brain.
What is the basic unit/cell of nervous tissue?
neurons
What are the features of neurons?
- DENDRITES (usually many; they receive inputs)
- CELL BODY/SOMA (nucleus and organelles)
- AXON (cell output; may be <1 mm or > 1 metre)
- AXON TERMINALS (often many).
What are the 2 types of axons?
may be myelinated or unmyelinated.
What does myelin act as?
acts as insulation & increases speed
What is the basic role of neurons?
Transmit action potentials from cell to cell through connections called synapses.
How many axons are in a neuron?
only 1
What are the types of glia in the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
What are the types of glia in the PNS?
- Schwann cells
- Satellite cells
What is the role of astrocytes in the CNS?
provide physical and metabolic support, secrete growth factors, limit neurotransmitter diffusion.
What is the role of Oligodendrocytes in the CNS?
myelination of axons.
What is the role of Microglia in the CNS?
immune cells of the brain, activated during inflammation.
Which of the glias is the most abundant?
Astrocytes!
What is the role of the Schwann cells in the PNS?
myelination of axons.
What is the role of the Satellite cells in the PNS?
support cells found within ganglia.
What type of rxn is taking place at the synapse?
a biochemical rxn!
What is the CNS made up of?
brain + spinal cord
What is the PNS made up of?
i. Cranial nerves
ii. Spinal nerves (aka. peripheral nerves)
iii. Associated structures: Ganglia & Mechanoreceptors and proprioceptors
What are the cranial nerves?
12 pairs attached to the brain.
What are the spinal nerves (aka peripheral nerves)?
31 pairs attached to the spinal cord.
What are the associated structures?
• Ganglia
• Mechanoreceptors and proprioceptors
What are ganglia? Include an ex
clusters of nerve cell bodies.
Dorsal root ganglia (sensory) are one example.
What are Mechanoreceptors and proprioceptors?
specialized structures that detect touch, stretch, vibration, joint position. (aka pain, temp, touch, etc.)
What NS are the 2 types of matter apart of?
the CNS
What is gray matter made up of?
is made up of NEURONAL CELL BODIES and DENDRITES (sites of synaptic connections). Glia are also present.
(stain can absorb it)
What particular type of glia are also present in gray matter?
astrocytes!
What is gray matters function?
Relaying and processing of information occurs in the gray matter.
What is the outer surface of the brain that is a layer of gray matter called?
cerebral cortex
What is a collection of gray matter found within the brain called?
a nucleus
Where are synapses mostly found on?
dendrites!
What does white matter consist of?
MYELINATED AXONS and constitutes the “wiring” of the brain.
Why is white matter called “white matter”?
because of the high lipid content of myelin. (white even when unstained)
What does brain function depend on?
connectivity
(damaged white matter will not work/function)
What are axons with similar functions and connections that are organized into bundles may be referred to as (within the white matter)?
tract (bundle of white matter connecting 2 things), fasciculus, pathway, or lemniscus.
What is the corpus callosum? & What does it connect?
is the largest white matter structure in the brain.
It connects the left and right cerebral hemispheres.
What does the CNS consist of?
Consists of the brain and spinal cord.
What are the brains 3 main divisions?
- Forebrain
- Midbrain
- Hindbrain (continuous with the spinal cord)
What is the forebrain? & what does it consist of?
(largest part of the brain)
- Telencephalon (Cerebrum)
- Diencephalon