Cells of Nervous Tissue Flashcards
2 main types of cells of nervous system
NEURONS
- receive stimuli and transmit action potentials
NEUROGLIA
- non-neural cells (don’t send signals)
- support and protect neurons
characteristic structures of the neuron
- SOMA: cell body
- DENDRITES: input
- AXON: output
Trigger zone:
- AXON HILLOCK: axon attachment point to cell body
- INITIAL SEGMENT: start of axon
SCHWANN CELLS: create myelin sheath
in between schwann cells: NODES OF RANVIER
End of axon
- AXON TERMINAL (branches)
- SYNAPTIC END BULB/PRESYNAPTIC TERMINALS (end)
cytoplasm: AXOPLASM
cell membrane: AXOLEMMA
axons that branch off: COLLATERAL AXONS
explain axonal transport
how axons can transmit signals to other neurons or target tissues
- axons create and store SYNAPTIC VESSICLES in presynaptic terminals
- inside vesicles are neurotransmitters
- NTs can inhibit or stimulate post-synaptic cell
- vessicles can move up or down axon (can carry disease like rabies to cell body)
how are neurons classified?
FUNCTIONAL classifications
- SENSORY/AFFERENT
- MOTOR/EFFERENT
- INTERNEURONS or ASSOCIATION NEURONS
STRUCTURAL classifications
- MULTIPOLAR
- BIPOLAR
- UNIPOLAR
Name of neuron moving action potentials towards CNS
Sensory or afferent neruron
Name of neuron moving action potentials away from CNS
Motor or efferent neuron
What are the structural classifications of neurons?
MULTIPOLAR: many dendrites, single axon (most of CNS, all motor)
BIPOLAR: single dendrite, single axon (sensory organs)
UNIPOLAR: cell body off to the side of neuron, attached to axon (found in PNS sensory receptors)
General charcteristics of neuroglial cells
- accounts for >50% of brain mass
- 4 types in CNS
- 2 types in PNS
- unique structure and function
name supporting cells of CNS
- astrocytes
- ependymal cells
- microglia
- oligodendrocytes
Astrocytes
Supporting cell in CNS
- star shaped
- FOOT PROCESSES: cytoplasmic extensions that cover surfaces of blood vessels, neurons
- release chemicals to form TIGHT JUNCTIONS between endothelial cells of capillaries
- BLOOD BRAIN BARRIER: protects against harmful substances
-help form synapses in CNS
Ependymal cells
Supporting cell in CNS
- epithelial
- range from cuboidal to columnar, many are cilliated, have inner microvillus region
- line ventricles and central canal (tube in spinal cord)
- helps forms CHOROID PLEXUS - produces cerebral spinal fluid (CSF)
- cilia help move CSF
Microglia
Supporting cell in CNS
- like astrocytes, but smaller with more processes
- PHAGOCYTIC (inflammatory response) - wrap around foreign objects, eat it up
Oligodendrocytes
Supporting cell in CNS
- smaller than astrocytes, fewer processes
- cytoplasmic extensions create myelin sheath in CNS
- multiple process can wrap around multiple neurons
Supporting cells of the PNS
- Scwann cells
- Satellite cells
Scwann cells
Supporting cell in PNS
- create myelin sheath
- NEUROLEMMA: outer membrane
- only wraps around 1 axon
