Nerve Histology Flashcards
brain and spinal cord
Central nervous system
cranial, spinal, and peripheral nerves
Peripheral nervous system
Functions under conscious voluntary control
Somatic nervous system
involuntary motor innervation
Autonomic nervous system
3 categories of the autonomic nervous system
- Sympathetic
- Parasympathetic
- Enteric
convey information from receptors to the CNS
Sensory neurons
senosry
Pain, temperature, touch, pressure from body surface
Somatic Afferent
sensory
pain, temperature, touch, pressure from internal organs, mucous membranes, blood vessels, glands
Visceral afferent
convey information from CNS to effector cells
Motor
Motor
voluntary impulses to skeletal muscles
Somatic efferent
Motor
involuntary impulses to smooth muscle, Purkinje fivers, gland
Visceral Efferent
integration of information between sensory and motor (99.9% of neurons)
Interneurons
One axon and 2 or more dendrites
Multipolar
one axon and one dendrite
Bipolar
one process most common is the one in sensory system. Cell body sits in dorsal root ganglion with one peripheral proceed in body surface detection pressure temp changes, etc.
Pseudounipolar
outer most layer
Epineurium
layer surrounding idv bundles of neurons
Perineurium
layer surrounding idv bundles of neurons
Endoneurium
_____ neuron is larger, vascular action potential.
Somatic Motor Neuron larger
____ of neuron increase speed of action potential
Mylination
FASTER with mylenation due to the fatty cell produce by ____ with little spaces in bwtn ineach allowing action potential to jump btwn each preventing constant repolarization and allowing fast traveling.
shwann cells
Contains nucleus
Cell Body
**ribosomes (stack of rER) heavly packed in neurons, **provide enzyme required for neurotransmitter production and cycling along with transporter protiens.
Nissl Bodies
receive stimuli from other neurons or the external environment
* Characterized by spines which are involved in learning and memory formation
Dendrites
Dendrite pruning is indicative of what?
of learning a new pathway methodology etc.
transmit stimuli to other neurons or from CNS to effector cells (muscle, gland, etc.) take info from one area to another. Pass info back and forth.
Axons
molecular motors directing transport from cell body down axon
Transport vesicles full with neurotrasnmiters, along with mitchondira and other protiens
Kinesin and Dynein
from cell body to axon periphery (nucelus products out)
Anterograde transport
from axon terminal to cell body(used vesicles etc. in)
Retrograde transport
Types of synapse
middle ground, a bit more influencial effect
Axosomatic
Types of Synapse
synapse on axon signal is strong. Easy to have huge effect.
Axonomic
Types of Synapse
synapse far from info originating site of action, synapse on dendrite, little effect.
Axodendritic
Slow, progressive neurological disorder
* Characterized by** loss of dopamine cells in substantia nigra and basal ganglia**
* These two areas are impotant for modulation of muscle movement, fine tune movements
Parkinson Disease
Resting tremor
Rigidity
Lack of spontaneous movement, (hard for them to get started),
Slurred speech, slowed thought cramped handwriting
Symptoms of parkinsons
cause is unknown,
Idiopathic PD
cause is encephalitis, toxins (destroy dopimne cells) , neuroleptics, repetitive trauma(ex. Football)
Secondary PD
impulse conduction is achieved by the release of chemical substances (neurotransmitters)
Chemical Synapse
do not require neurotransmitters for function
Synapses are gap junctions between cells directly connected.
Electical Synapse
contains synaptic vesicles. Area btwn 1&2
Pre-synaptic element
space between neurons, neurotransmitter released from neuron travel in between to area 2.
Synaptic Cleft
reacts to neurotransmitters and bind them with respective receptors. Once bound effects neuron; depends on function.
Post synaptic membrane
Excitatory pre-synaptic neuron
release AcH
Inhibitory neuron
releases Gabba
____ causes voltage-gated calcium (the key for passing info along through synaptic vessles) channels
Depolarization
ACh, glutamine, serotonin – open sodium channels causes depolarization and may generate an action potential
Excritory synapse
GABA, glycine – opens chloride channels (into cells, make more (-) ) causes** hyperpolarization and action potentials are harder to generate**
Inhibitory
open membrane ion channels Generally transient
Ionotropic receptors fast
activate G-protein signaling cascades
* Slow action
* Mostly modulation of neuronal activity
Metabotropic receptors
AcH can bind what receptors?
- Inotropic
- Metabotropic
look
Look dont go to in depth
one of neurotransmitter responsible for conveying pain sensation into CNS
Substance P
metabotropic
endogenous opiates, produced in CNS and when released help reduce sensation of pain.
- Enkephalins
- β-endorphin
metabotropic
3 metabotropic neurotranmitters
- Substance P
- Enkephalins
- β-endorphin
How are neurotransmitters degraded?
Via enzumes
* Ach-ase
* Catecolamin-ase
All help stop action potential
What occurs if ACH builds up?
Contiunual muscle contraction; death
____ of NTs are transported back into the presynaptic neuron via **NT specific transport proteins **
80%
Peripheral Neuroglia
produce myelin sheath
* wrapp around perioherl neurons
* block out production of action potential
Schwann Cells
Peripheral Neuroglia
surround cell bodies in peripheral ganglia, control microenvironment around cell body
Satellite Cells
Peripheral Neuroglia
help coordinate nervous and immune system function with the gut
Enteric Neuroglia
Peripheral Neuroglia
found in retina
Mullers Cells
Each shwanna cell produces 1 myline sheath, in bwtn each shwanna cell is a ____ allow s for fast travling of smooth signal
Node of ranvier
Disease laking peripheral myleniation=
Choppy signal
Still embedded in Schwann cells, just not tightly wrapped.
* no increased speed of action potential
Unmyelinated Nerve Fibers
Central Neuroglia
physical and metabolic support of neurons in CNS
Astrocytes
Central Neuroglia
myelin-forming cells of the CNS
Oligodendrocytes
1 can form mylein around many dif neruons
Central Neuroglia
function as immune cells in CNS
* smallest of neuroglial cells
Microglia
Central Neuroglia
- Line the fluid filled cavities of the CNS
- responsible for producing CSF + maintain composition
- **Single layer of cuboidal collumna cells **
Ependymal cells
Types of Astrocytes
found covering the brain, contribute to blood-brain barrier. VERY branched.
Protoplasmic
Types of Astrocytes
found in the inner core of the braine, fewer processes than the other astrocytes
Fiborous
?
Ependymal Cells
were cell bodies are stored
Ganglia
Sympathetic Ganglia
paravertebral) ganglia (the highest of these is the superior cervical ganglion)
Sympathetic trunk
T1-L2
Sympathetic Ganglia
adjacent to origins of large unpaired branches of abdominal aorta), including celiac, superior mesenteric, inferior mesenteric, and aorticorenal ganglia
Prevertebral ganglia
Sympathetic Ganglia
which may be considered a modified sympathetic ganglion (each of the secretory cells of the medulla, as well as the recognizable ganglion cells, is innervated by cholinergic presynaptic sympathetic nerve fibers)
Adrenal Medulla
Parasympathetic Ganglia (cranio-sacral ganglia)
What are the 4 head ganglia?
- Cillialry ganglion (CN3)
- Submandibular (CN7)
- Ptergopalatine (CN7)
- Otic (CN9)
Parasympathetic Ganglia (cranio-sacral ganglia)
near or in wall of organs, including ganglia of the submucosal (Meissner’s GI ) and myenteric (Auerbach’s) plexuses of the gastrointestinal tract
Terminnal Ganglia
cell body is in CNS **(ventral horn **of sympathetic chain ) within CNS
Motor Neurons
cell body is in ganglia which are next to CNS
Dorsal roots of spinal nerves
Associated with CN V, VII, VIII, IX, and X sensory components
Sensory Neurons
Peripheral Nerve Connective Tissue
loose connective tissue surrounding each individual nerve fiber, innermost
Endonuriuem
Peripheral Nerve Connective Tissue
specialized connective tissue surrounding each nerve fascicl(collection of nerve fibers). Middle.
Perineurium
Peripheral Nerve Connective Tissue
Dense irregular connective tissue surrounding a peripheral nerve. Outside covering of entire nerve.
Epineurium
Sensory Receptors
react to stimuli from the external environment
* Temperature, touch, smell, sound, vision
Externoreceptors
Sensory Receptors
react to stimuli from within the body
* Stretch of the alimentary canal, bladder, blood vessels give info about stretch in blood vessels to contract or relax.
Enteroceptors
Sensory receptors
react to stimuli from within the body
* Provide sensation of body position, muscle tone and movement. Walking etc.
Proprioceptors
Controls and regulates the body’s internal environment
Autonomic nervous system
3 divisions of the ANS
- Sympathetic
- Para
- Enteric
ANS
conscious control
Skeletal
ANS
unconsoius control
Autonomic
How many neurons?
From motor, spinal cord to skeletal muscle
- 1 neuron efferent to mylenated skeletal nerve
ONE
ANS
How many neurons for visceral ANS?
** 2 neurons. **
- 1st neuron from spinal cord into mylenated autonomic ganglion,
- 2nd umylenated neuron from ganglion to end goal
presynaptic neurons are located in the thoracic and upper lumbar portions of the spinal cord (thoracic lumbar cell bodies) but autonomic ganglion chain are cervical through sacral
Sympathetic
Presynaptic neurons are located in the brainstem and sacral spinal corad (cranio-sacral)
Parasympathetic
vision, motor, sensory.
Frontal portion is higher though, cognition, and info application
Cerebrum
responsible for coordinated movment and planning, + maintain sense of time
Cerebellum
keeping you alive, BP, HR, breathing
Brainstem
When people die from opiate overdose caused by depression of ____ stop breathing. Die of asphyxiation.
Repiratory cente; brainstem
Get info out.
Spinal cord
brain
Outside, contains nerve cell bodies, site of many synapses. Sends to white matter. Start to run
Gray matter
Brain
axons of nerve cells, associated glial cells, and blood vessels, received, run.
White matter
In the spinal cord where is white matter and grey matter?
- white matter on outside
- gray inside, butterflu shape
Opposite of brain
Dorsal horn receives?
Sensory info
Ventral horn revieves?
Motor info
Connective Tissue of the CNS
outermost layer
* Thick sheet of connective tissue, protective
Dura mater
Connective Tissue of the CNS
middle layer
Delicate sheet adjacent to inner surface of dura mater
Arachnoid matter
Connective Tissue of the CNS
where blood vessels are located and CSF.
Subarachnoid space
Connective Tissue of the CNS
Innermost layer
Directly on surface of brain and spinal cord
thin
Pia Mater
- Complex tight junctions
- Endothelial basal lamina
- Astrocytes homeostasis of water
- Restrict passage of ions and substances to CNS grey/white matter
Blood Brain Barrier
Exlain PNS Response to injury
- Antrograde degeneratironof axon
- Shwann cells recieve no GF, so they undifferentiate (can be reversed)
- Macrophages come and clean
- If injury not bad, axon will regrown and shwanna cells will differnetite and form bands.
Muscle without connection o spinal cord becomes ____ due to lack of activation, and no growth factor secretion by nerve cells to retain size of muscle.
atrophied
Increased growth of axon will increase muscle .
Exlain CNS Response to injury
- Oligodendrictes apoptos follwinf damage
- **Loss of mylin sheefs **
- Microglial come
- Astrocytes from wallaround injury
- Injury results in**overal loss of neuron **
