Week 7 Random Flashcards
Peripheral nervous system subivisions
SENSORY (somatic & visceral)
GSA = external body (ex. touch, pain, temp, or pressure)
SSA = hearing, equilibrium, and vision
GVA = internal organs (strech, pain, temp) * not aware
GVA = taste, smell
MOTOR (somatic & visceral)
GSE = motor of skeletal muscle
SVE =
GVE = sympathetic & parasympathetic (cardiac muscle, smooth muscle, and glands)
CSN composition
PNS composition
CNS consist of spinal cord and brain
PNS includes nerve fibers and ganglia
Two types of nerves associated with PNS
Cranial (12) all different
Spinal (31) similar with composition but different targets
Component
Refers to whether the fiber is motor or sensory and somatic, visceral or special.
Spinal nerve components
General Sensory (GSA) : touch, feel
Viscerosensory (GVA) : streech recepotrs in blood vessels
Somatomotor (GSE) : muscle moving
Visceromotor (GVE) : vasoconstriction, sweat gland muscle, arrector pili
Components abbreviations, names, and function
(SSA)
(GSA)
(GVA)
(SVA)
(GVE)
(GSE)
(SVE)
Special somatosensory (SSA) (vision and balance/hearing)
General somatosensory (GSA) (skin etc.)
General viscerosensory (GVA) (gut, heart, etc.)
Special viscerosensory (SVA) (taste and smell)
Visceromotor (GVE) (autonomic)
Somatomotor (GSE) (muscles from somites)
Branchiomotor (SVE) (muscles from branchial arches)
Where do cranial nerves come from? Types?
Brain and brainstem
Some are motor, some are sensory, and others are mixed
Formation of spinal nerves
Spinal nerves are made from the ventral and dorsal roots of the spinal cord.
Some nerves travel alone (intercostals)
Some nerves merge with adjacent spinal nerves and form a plexus (cervical, brachial, lumber and sacral)
How do you know which side of the spinal cord are you looking at?
Dorsal root has ganglion
Dorsal horn externs further than anterior
Where do motor fibers originate?
Grey matter
* sensory synapse may be in the gray matter
Name of a fiber that comes out of the spinal cord
Rootlet
What rootlets form
Dorsal or ventral root that merges to form spinal nerve
Does the segmental nature of the cord and the rootlets give you an idea that each of the spinal nerves is destined to innervate a particular are of the body?
Is the whole plan well organized and evident during early development?
Yes
What does the spinal nerve branches into?
What are the functions of these branches?
How is the afferent neurons divided?
Peripheral process (toward the organ)
Central process (toward the spinal cord)
Function of dorsal ramus vs. ventral ramus?
Dorsal ramus = motor and sensory to skin of the back and the true back muscles (muscle that do something with back, not necessarily muscle in a back)
Ventral ramus = everything else
Which type of PNS has ganglia?
GVE (parasymphatetic / symphatetic)
* sensory fibers do not have ganglia
Where cell bodies are located for sensory, visceromotor, and somatomotor?
Sensory = Dorsal root ganglion (DRG)
Visceromotor = lateral horn (intermediate grey) T1-L2 symp and S2-4 for para
Somatomotor = ventral horn
Spinal nerves vs. Splanchnic nerve
Spinal nerves do not supply the body cavities, only body wall structures.
Splanchnic nerves and the vagus supply cavities.
Communicating rami
Fibers that connecte spinal nerve and sympathetic chain.
How efferent neuron can be activated?
By afferent neuron
By control from CSN
Dermatome
Skin innervated by a single spinal nerve (specifically the cutaneous branch).
Examples of dermatomes
C2 - back of head
T4 - nipple
T10 - belly
L1 - back legs
Myotome
The group of muscles that a single spinal nerve root innervates
Pattern of innervations to muscle innervation from a single spinal nerve
Level loss
In spinal injury all control is lost below the level.
Periopheral Nerves vs. Spinal Nerves
Nerve that comes off the plexus (periferal) = multiple combinations of spinal nerves
How many neurons are in parasymapthetic / sympathetic division?
2
Preganglionic
Postganglionic
Location of ganglion for sympathetic vs. parasympathetic
Near organ = parasympathetic
Near spinal cord = sympathetic
Which autonomic division is connected to body wall (dermatome)?
Sympathetic
Origin of sympathetic
T1-L2
Origin of parasympathetic
1st neuron in the CNS brainstem
sacral spinal cord S2-4
Parasympathetic innervations
Only innervates viscera in body cavities, glands in the head, the eye and erectile tissues.
Where do GSA fibers have their nuclei?
DRG
Function of Sympathetic Chain
Allows communication with CSN
Spinal nerves are inserted with
Where are the cell bodies located for the cutaneous branches of nerves?
GSA
GVE
GVA?
Are there overlaps between dermatomes?
Yes there is (ignore)
Herniated disk
A herniated disc is a condition in which the annulus fibrosus (outer portion) of the vertebral disc is torn, enabling the nucleus (inner portion) to herniate or extrude through the fibers.
Contusion
a region of injured tissue or skin in which blood capillaries have been ruptured; a bruise
Most important role of symphatetic division?
Control of vasculature
Other: decrease gastric motility / smooth muscle / hair follices
What is the name of the nerve that goes to the body cavity?
Splanchnic nerve
Which branches do not contain parasympathetic nerves?
Branches of spinal branches
What are seven types of cells found in nerve system?
NEUROEPITHELIUM (neutral tube)
Neuroblast -> Neruon
Astroblast -> Protoplasmic Astrocyte
Astroblast -> Fibrous Astrocyte
Oligodendroblast -> Oligodendrocyte
Neuroepithelium -> Epithelium of Choroid Plexus
Neuroepithelium -> Ependyma cells
Ganglion vs. Nucleus
Ganglia (group of neurons outside the CNS)
Nucleus (group of neurons within the CNS)
How many neurons are in a human?
10^9
Functions of Neurons
- receive and integrate stimuli from many sources simultaneously
- translate stimuli to membrane potential
- propagate this membrane potential
- translate this electrical message into neurotransmitter
- deliver neurotransmitter to target cells
Two types of pigmentations in neurons
Lipofuscin: golden brown, probably represents old age (found more in older neurons)
Melanin: a brown black, represents old neurotransmitter? But function not know for sure.
Prominent structures in neurons
Perikaryon (cell body)
Large nucleus with owl-eye nucleolus
nissil bodies = rER
microtubules / neurotubules (24nm)
intermediate filaments / neurofilaments (10nm)
How many axons can be in a neuron?
Only 1
Term that describes impulses in axon
Axonal transport
Five axon components
Contains neurofilaments/neurotubules
- Axon Hilloc (no nissl bodies)
- PInitial Segment (between axon hillock and myelination; site of action potential initiation)
- Axon Proper
Two types of transport in axon
Anterograde transport (kinesin)
Retrograde transport (dynein)
Site of protein synthesis in neuron
Cell body
Dendrites
Increase surface area (dendritic spines) increased during young age later decreased
Lack golgi
Synthesize message
2 unique characteristics of neurons?
Need trophic stimuli (need signal from other cells to survive)
Types of synapses
Axosomatic synapse (synapse with body)
Axodendritic synapse (on dendrite)
Axoaxonic synapse (contacting another axon terminal)
Axospinous synapse (ending on dendritic spine)
Classification neurons by processes
Multipolar (many dendites; most abundant; pryamidal cells - cerebellum; Purkinje cells - cerebrum)
Bipolar (single dendrite opose axon; sensory; retina, olfactory mucosa; inner ear)
Pseudounipolar (split axon; no dendrites; DRG and cranial ganglia)
Unipolar (short single axon and no dendrite; photoreceptors - rods/cones)
Classification of neurons by function
Motor Neurons: excite or inhibit
Sensory Neurons
Interneurons: chaining neurons; interaction
Classificaiton of neurons by postsynaptic neurotransmitter
Cholinergic - acetylcholine / parasympathetic postganglionic
Adrenergic - epinephrine / sympathetic postganglionic
Names, function, and location of neuroglial cells
Fibrous (Astrocytes) | White Matter | Framework & BBB
Protoplasmic (Astrocytes) | Gray Matter | Framework & BBB
Oligodendrocytes | CNS Myelined Nerves | Myelination
Microglia | CNS | Immunity
Ependymocytes (Ependyma) | Ventricle & Central Canal lining | CSF absorption and circulation
Tanycytes (Ependyma) | 3rd Ventricle flood | CSF-> Hypophysal-portal system transport, monitor CSF
Choroidal epithelial cells (Ependyma) | Suface of choroid plexus | CSF production and secretion
What is glia cells?
Supporting cells in the CNS
Astrocytes
largest glial cells
long branched cytoplasmic processes with vascular end feet cover pia mater, blood vessels, and cell bodies
specific intermediate filaments = glial fibrillary acidic protein
protoplasmic - in gray matter, low [GFAP]
fibrous - in white mater, high [GFAP]
can divide
respond to injury by forming gliosis (similar to fibrosis)
Glia limitans
What junction connect endothelial cells in CNS?
Tight (BBB)
Oligodendrocytes
Most numerous
Myelination in CSN
Can myelinate several axons
Schmidt-Lanterman clefts maintain the membrane forming the mylein
Myelination PNS vs. CNS
Schwann cells vs. Oligodendrocytes
CNS (oligo) | PNS (schawnn)
Neuroepithelium | Neural crest
No close association | Close association
Oligo provides multiple axons | Wrapped around one
Inhibit axonal growth | participate in the regenration of injury
astrocyte foot is present in Node of Ranvier | Cytoplasm is trapped in the Node of Ranvier
BOTH INCREASE VELOCITY
Microglia
Derived from monocytes
Smallest and least numerous
Phagocytic during injury
What 4th ventricle connects to?
Central canal
Ependyma chracteristics
Line ventricles
More than “simple cuboidal epithelium”
Connected by macula adherence and zona adherence
Four ventricles
2 latteral
3rd and 4th
Tanycytes
No basement membrane
Long processes go into brain and terminate near blood vessels and hypothalamic cells (neurosecretory).
Conntected by tight junctions.
Ependymal cells attachement
Attached by desmosomes
Choroid Plexus
capillary tufts push up ependyma into the brain ventricles
made up of simple cuboidal cells upon BM responsible for **production and maintenance of CSF **
Schmidt-Lanternman clefts
Allow oligodendrocytes / schwann cells to get nutrients through the “jelly wrap” to the axon that it is myelinating
Communication
Nerve Regeneration
PNS vs. CNS
Schwann cells are capable of mitosis with the subsequent production of a basal lamina and therefor are key to peripheral nerve regeneration. Astrocytes produce gliosis.
Endoneurium Is Not Present in the CNS. Oligodendrocytes Do Not Proliferate. In trauma, astrocytes DO proliferate and form scar tissue
Why CSF circulates?
Because it is under the pressure
Meninges
Scalp
Skull
Dura mater
Subdural space
Arachnoid membrane
Subarachnoid space
Pia mater
Brain
Cells in cerebral cortex
Layer 1 = molecular
Layer 2 = granular
Layer 3 = Pyramindal external (small)
Layer 5 = Pyramidal internal (large)
Cerebellum
- Molecular layer
- Purkinje cells
- Granule cells
Spinal cord structure
Nerve structure (histology)
Axon wrapped in endoneurium
Fassicle wrapped with perineurium
Nerve wrapped with epineurium
How to tell peripheral nerve from connective tissue?
Wavy
Node of Ranvier
Schwann cells hug axon
Fibroblasts do are not covered by layers
Synonym to visceral
Autonomic
Where does paraympathetic does not innervate?
Skin
Adrenal medulla
Two types of motor neurons
**Somatic **(skeletal muscle) (motor neurons in ventral horn of spinal cord or equivalent area of brainstem)
Autonomic (cardiac muscle, smooth muscle, glands)
Parts of PNS
Sensory Neurons
Motor Neurons
Enteric Nervous System
Basic Unit of the Autonomic Nervous System
First Neuron
preganglionic synapse
Second Neuron
postganglionic synapse
Effector cell
Different pathways in PNS