Intro to NS but better Flashcards
What does the NS do?
responds to stimuli
transmits impulses
controls every function in the human body
What are the basic functional units of the NS?
neurons
What does the NS tissue consist of?
neurons (signaling)
glial cell (support)
What is the function of a neuron?
respond to stimuli, convey signals, process info
Awareness of self and surrounding, memory, learning, speech, regulation of muscle contraction and gland secretion
Describe the 3 parts of a neuron?
dendrite- receives and transmits impulses to cell body
cell body- receives impulses from dendrties
axon- transmits impulses away from cell body
Describe the neuronal cell body? What do they contain?
part of neuron that contains nucleus
Maintains neurons integrity
What 2 special organelles are contained in the cytoplasm of a neuron?
nissl bodies- ER, in cytoplasm except where axon emerges, produce proteins
neurofibrils- arranged longitudinally, involved in transport
What part of the neuron can have variable length?
axon
Describe unipolar neurons. Where can they be found?
axon is a single protoplasmic process
mainly in spinal nerves, come cranial nerves
cell bodies in ganglia
Describe bipolar neurons. What pathways is it involved in?
axon and 1 dendrite
visual, auditory, and vestibular pathways
Describe multipolar cells. Where can they be found?
axon and multiple dendrites
everywhere else in NS
What are synapses? What do they rely on?
Junction between axonal ending and a muscle cell, gland, or other neuron.
relies on polarization (always travels away from axon)
What are neurotransmitters? What is their function/effect?
manufactured and released by neurons
released into synaptic cleft to affect postsynaptic neurons, muscle or gland cell
excitatory or inhibitory
Describe the excitatory synapses on neurons.
enhances the production of the impulse
Describe the inhibitory synapses on neurons.
hinders production of the impulse
What types of synapses are excitatory synapses involved in?
neuromuscular
neuro-glandular
neuronal
What types of synapses are inhibitory synapses involved in?
neuronal
What is axoplasmic transport? What are its 2 components?
bidirectional movement within the neurons towards and away from the cell body
Anterograde and retrograde
Describe anterograde axoplasmic transport.
cell body nutrients are carried in a forward direction from the cell body to the termination of the axon
away from CB
Describe retrograde axoplasmic transport.
occurs from the distal end of the axon back to the cell body
enable return of used or worn out materials for restoration or degradation
towards cell body
What is the clinical significance of retrograde axonal transport?
it is the route by which toxins and viruses are transported into the CNS from the PNS
Describe the axoplasmic transport mechanism involved in rabies.
virus enter bloodstream
travels into muscles then nerves where it hijacks the retrograde axonal transport system and travels from PNS to CNS
Muscle, nerve, spine, brain
What is the support tissue (macroglia or glia) of the CNS?
astrocytes
oligodendrocytes
What is the support tissue (macroglia or glia) of the PNS?
schwann cells
capsular cells
Describe astrocytes.
most numerous
vascular end feet form blood-brain barrier, electrolyte balance, neurotrophic factors, removal of neurotransmitters from synaptic cleft (CNS)
control passage of materials into CNA via circulatory system
Describe oligodendrocytes.
forms and maintains the myelin sheath (CNS)
Processes wrap around many axons to form tight spiral
surround cell bodies (no myelin)
produces neurotrophic factors tp promotes growth of damaged axons
Describe Schwann cells
forms the myelin sheath (PNS) enveloped only part of one myelinated axon
Describe capsular cells (satellite cells)
Regulate the neuronal environment (PNS)
surround neuronal cell bodies in sensory autonomic ganglia
describe the shape of the astrocytes that aid in its function.
star-shaped cell body with irregular cellular processes
Cover as much space as possible
Describe the blood brain barrier.
permeability control system governing the passage between capillaries and the CNS parenchyma (tissue)
Tight junctions between endothelial cells
Describe the neurotrophic factors of the astrocytes.
promotes growth of developing and damaged axons
necessary for survival
What are astrocytes highly susceptible to?
formation of neoplasms (abnormal mass of tissue as cells divide and grow
how does the amount of glial cells compare to amount of neurons?
glial cells outnumber neurons 50:1
Describe the central nervous system.
brain and spinal cord
receives, processes and acts on info in the environment
Describe the peripheral nervous system.
connects the CNS to areas outside the NS
Connections made via cranial nerves and spinal nerves
Describe the brain (size, development, peripheral extension).
weighs 3lbs
Reaches max size at age 6
Development complete in early 20s
Peripheral extensions are cranial nerves
Describe the spinal cord (location, peripheral extensions)
extends from brain stem through the neck and back
peripheral extension are spinal nerves
Describe afferent pathways. What are the 3 types of senses?
carry info to brain and spinal cord
sensory
general sense: pain, temp, position
visceral: organs
special: 5 senses
Describe efferent pathways. What are the 2 branches?
controls function
Motor: muscles (somatic)
Visceral: glands (autonomic)
Compare the somatic and autonomic nervous system.
Somatic: voluntary control via skeletal muscles
Autonomic: involuntary, smooth muscle etc
What are the 2 division of the autonomic NS?
sympathetic: stress, fight or flight
parasympathetic: active at rest, rest and digest
Describe the 3 stages of the development of the NS.
blastulation: single-layered
gastrulation: multilayered
neurulation: neural tube
What are the 3 layers of cells formed during gastrulation?
ectoderm- outer, skin and NS
Mesoderm- middle layer, muscle
Endoderm- inner, internal organs
Describe the process of neurulation.
Neural plate into neural tube
notochord is source of midline signals
What will occur if there is a development issue at the stage of neurulation?
midline structures of CNS will not develop properly
ex: cleft palates, midline, skull base
Do midline cranial structures affect the eyes?
Yes
Describe the further development that leads to brain formation and CSF after neurulation.
swellings and outpouching form the parts of the brain
fluid-filled cavities develop into ventricles with CSF
Describe the 2 parts of the prosencephalon (forebrain)
telencephalon- cerebrum
diencephalon- deeper structures, optic nerves enter