M1 Study Guide Flashcards
define neuron
nerve cell that receives, processes, and transmits information via electrical and chemical signals
define dendrite
spiny processes that transmit signals to the soma
define soma
cell body of the neuron containing the nucleus and other organelles vital for cell function
define axon
elongated processes that transmit signals away from soma
retrograde axonal transport
Axon brings substances from the synapse to the soma.
Rapid transport:
- Dynein protein binds to substance (worn out organelles, tropic factors necessary for cell function) and walks up the track to soma; uses ATP.
anterograde
Axon brings substances from the soma into and down axon towards synapse.
Rapid transport:
- Kinesin protein binds to substance (usually neurotransmitters) and walks down the “track” in the axon; uses ATP.
Slow transport:
- due to movement of axon cytoplasm and does not require ATP.
- used to transport proteins and structural filaments for use in the axon
define terminal button
site of synapse for axon of a neuron to dendrite, soma or axon of another or multiple neurons
define neurite
extension from a cell body.
ex. dendrite and axon or either
types of neurons
Multipolar: most common in CNS and motor/integrator
- numerous dendrites
- pyramidal cells
Bipolar: special sensory
- one dendrite and axon
Unipolar/pseudo-unipolar: most common in PNS and primary sensory neuron
- dendrite and axon “share” a process
define nerve
group of axons traveling in the PNS.
called tracts in CNS
ganglion vs. nucleus
ganglion: group of cell bodies (soma) in PNS
nucleus: group of cell bodies (soma) in CNS
different between afferent/sensory vs. efferent/motor
signal traveling from periphery (initiating as a receptor, or affector) to central compared to signal traveling from central to periphery where it terminates at an effector (ex. muscle, gland)
what does CNS consist of
brain and spinal cord
what does PNS consist of
cranial nerves and axons or spinal and peripheral nerves and neuromuscular junctions
(aka all nervous system components outside brain and spinal cord)
define axon transport and name the 2 types
movement of organelles, vesicles, and secretory material (ex. neurotransmitters) throughout the neuron, especially in and out of the axon.
anterograde and retrograde
what are the CNS neuroglia
Astrocytes
Microglia
Ependymal
what are the cells involved in myelination of axons
oligodendrocyte (CNS)
neurolemmocytes (Schwann cell): not considered to be true glial cells bc they are found exclusive within PNS
3 parts of nerve structure
- Endoneurium: connective tissue surrounds axon/nerve fiber
- Perineurium: connective tissue surrounds fascicle (collection of axons)
- Epineurium: connective tissue surrounds a nerve (contains fascicles of axons); outside cover of the nerve
neural injury - severe damage or immediate fatal injury
little change in cell morphology and quickly disintegrates
neural injury - less severe injury
swelling of soma, displacement of nucleus, movement of Nissl bodies (ex. RER, polyribosomes) to the periphery.
if the cell survives, it will go back to normal.
if the cell doesn’t survive, cytoplasm will turn dark and followed by disintegration of the organelles and eventually the cell.
what are dead neurons removed by
Removed in CNS by microglia and in PNS by macrophages
what happens in cases of axon injury
Same cell body changes occur as severe and less severe injury.
Axon injuries proximal to the soma are usually more severe for the cell compared to those that are distal.
Distal injuries only affect part of the axon
When does degeneration commence
At birth because some axons are not able to find connections to other neurons.
Continues later in life due to age
What are the 3 layers of meninges, outer to inner, and the qualities of each
- Dura mater: dense, fibrous connective tissue layer that is very adherent to the inside walls of cranium.
- Arachnoid: structurally continuous with the pia and contains a thick fibrous connective tissue layer.
- space between contains spider-web like structures that connect it to the pia - contains cerebrospinal fluid secreted by ependymal cells. - Pia mater: thin, delicate later of connective tissue containing collagen and elastic fibers.
- cerebral vasculature passes through this layer
what are the dural deflections
Falx cerebri: separates right and left cerebral hemisphere.
Tentorium cerebelli: separates occipital lobe from underlying cerebellum.
What are the 3 hematomas
- Epidural: “above” dura
- shearing of artery (middle meningeal artery in pterion most likely culprit).
- high hydrostatic pressure of arterial blood allows for these to progress fast - Subdural: “beneath” dura.
- shearing of vein (ex. emissary veins that pass through the skull and return blood from scalp back to heart more likely involved with this type of hematoma)
- lower hydrostatic pressure in veins compared to arteries - progress much more slowly than epidurals. - Subarachnoid: typically occur secondary to a ruptured cerebral aneurysm within subarachnoid space.
- blood mixes with CSF and will raise intracranial pressure.
what are the 2 parts of the PNS
Somatic - voluntary contol.
Autonomic - involuntary
specific structures and nerve sections of the PNS in general
Neurons: dendrites, axons, soma
Ganglia: somatosensory and autonomic
PNS schema
- Specialized neurons called receptors (affectors) detect stimuli from inside and outside the body and send an electrical signal in response up an afferent pathway towards CNS.
- Electrical signal travels along a chain of neurons through PNS.
- Afferent signals from all over the body enter CNS and are organized in a way that yields our perceptions (correlation of signals) and these perceptions are stored in the CNS as memories.
- As a reaction to our sensory perceptions and memories, CNS sends out efferent electrical signals along neurons.
- Efferent signals travel through neurons in PNS, ending upon muscles and glands (effectors).
- CNS coordinates these different signals to assure the actions of the muscles and glands work together toward a common goal.
how many cranial nerves are there and what are the types (motor/sensory)
12 pairs of cranial nerves:
- 5 motor only
- 3 sensory only
- 4 both
how many pairs of spinal nerves are there and for what section of the spine
31 pairs of spinal nerves:
- 8 pairs cervical
- 12 pairs thoracic
- 5 pairs lumbar
- 5 pairs sacral
- 1 pair coccygeal.
all carry motor and sensory except C1 (motor only) and coccygeal (sensory only)
what are dorsal and ventral roots
dorsal roots: sensory axons of GSA and GVA fibers to CNS
ventral roots: motor axons of GSE and some GVE from CNS
what are GVE fibers and where are they found
convey autonomic info.
only found in ventral roots of the thoracic and upper lumber (thoracolumbar –> sympathetic) and sacral (craniosacral –> parasympathetic) spinal nerves
where is dorsal root ganglion located
(soma of sensory neurons –> pseudounipolar type).
located adjacent to spinal cord and is linked to the cord via the dorsal root of a spinal nerve
