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FTM Exam 2 > DLA 26, 27, 28 & Lecture 35/36: Nerves > Flashcards

DLA 26, 27, 28 & Lecture 35/36: Nerves Flashcards

1
Q

Peripheral Nervous System

Components:

A

Connects CNS–> body/organs

  • Ganglion = collection of cell bodies
  • Peripheral nerve= Collection of axons

Components:

1) Cranial nerves
2) Spinal nerves
3) Ganglia
4) Enteric Plexuses- Digestive
5) Sensory receptor

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2
Q

Functions of Nervous System

A

1) Sensory Function: Info –> Brain/spinal chord
2) Integrative Function: Processes/stores info
3) Motor Function: Activates muscles/glands

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3
Q

Voluntary and Involuntary Control

A

Somatic= Voluntary:
-Body sensation (wall/limbs)–> CNS/motor neurons –> Skeletal muscle

Visceral= Involuntary:
-Body sensation (Organs)–> CNS/motor neurons –> cardiac muscle, smooth muscle, glands

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4
Q

Parts of Neuron

A

1) Cell body/Soma: Nucleus/organelles
2) Dendrite: Carries into into cell body, unmyelinated
3) Axon: Carries info out of cell body, contains mitochondria/microtubules/neurofibrils, myelinated, ENDS AT THE SYNAPTIC END BULB (TERMINAL BOUTON)

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5
Q

Classifications of Neurons by Structure

  • Multipolar
  • Pseudounipolar (unipolar)
  • Bipolar
A

1) Multipolar: Several dendrites + one axon
2) Pseudounipolar (unipolar): One axon that divides in 2
3) Bipolar: one axon + one dendrite

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6
Q

Classification of Neurons by Function:

Motor (Efferent)

Sensory (Afferent)

Interneurons (Integrative)

A

Motor (Efferent):

  • multipolar
  • Somatic: Skeletal muscle
  • Viseral: Smooth cardiac muscles, glands found in organs
  • CNS–> PNS

Sensory (Afferent):

  • Pseudounipolar/bipolar
  • PNS–> CNS
  • CELL BODIES IN DORSAL ROOT GANGLION (DRG)
  • Somatic: 5 senses
  • Visceral: Inflammation, Glands, processes of internal organs, blood vessels, etc

Interneurons (Integrative):

  • Communication between motor and sensory neurons
  • Reflexes
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7
Q

Neuroglial cells Characteristics

Neuroglial cells in CNS

Neuroglial cells in PNS

A
  • Don’t make action potentials
  • Can multiple and divide if injured
  • Insulate and nourish

CNS: (Central neuroglia)

  • Astrocytes
  • Oligodendrocytes
  • Microglia (macrophages)
  • Ependymal cells

PNS: (Peripheral neuroglia)

  • Schwann Cells
  • Satellite Cells
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8
Q

CNS

Components

A
  • Brain and spinal chord
  • White matter= myelinated tracts of axons or nerve cells/glial cells/vessels
  • Gray matter= Neuronal cell bodies/axons/dendrites/glial cells
  • Nucleus: Collection of cell bodies
  • Tract: Collection of axons

Brain:
1) Cerebral hemisphere: Big area, folds=gyri, grooves=sulci, big groove= longitudinal fissure, functions of lobe

2) Thalamus: Relay center for brain
3) Hypothalamus: Homeostasis, growth, reproduction
4) Brainstem: Midbrain, pons, medulla oblongata, Cardio regulation, swallowing, yawning, etc.
5) Cerebellum: Posture, balance, movement

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9
Q

PNS Spinal Nerves

A

-Axons and neurons forming peripheral nerves exiting the spinal chord segments

  • Parasympathetic Nerves = In Cervical and Sacral
  • Sympathetic Nerves= In Thoracic and Lumbar

31 Pairs

  • 8 Cervical (C1-C8)
  • 12 Thoracic (T1-T12)
  • 5 Lumbar (L1-L5)
  • 5 Sacral (S1-S5)
  • 1 Coccygeal (Co1)
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10
Q

PNS Cranial Nerves

A
  • Axons of neurons forming peripheral nerves exiting the cerebral cortex and brainstem
  • Can consist of motor, sensory, and parasympathetic fibers
  • 12 Pairs
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11
Q

Axonal transport

A

-Bidirectional movement of material between the cell body and processes

Anterograde:

  • Kinesin
  • slow or fast
  • Towards synapse

Retrograde:

  • Dynein
  • Fast
  • Towards Cell Body
  • Clinical importance: route used by toxins and viruses to enter nervous system
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12
Q

Sympathetic Ganglia

A

Ganglia = clusters of nerve cell bodies outside of the CNS

  • Craniospinal (DRG, cranial nerves)
  • Pseudounipolar neurons
  • Thick fascicles of fibers alternating with bundles of cell bodies
  • Central axons
  • Pale staining
  • No synaptic connection
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13
Q

Autonomic Ganglia (Nerve fibers)

A

Ganglia = clusters of nerve cell bodies outside of the CNS

  • Sympathetic and Parasympathetic
  • Large cell bodies
  • Random bundles of fibers
  • Multipolar neurons
  • Diffuse nerve fibers between cell bodies
  • Synapsing
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14
Q

Neuroglia of the CNS

A

1) Oligodendrocytes
- Myelinates axons in the CNS
- Larger Nodes of Ranvier (NR)
- One oligodendrocyte for several axons

2) Ependymal cells
-epithelium lining of the CNS cavities
-cuboid to columnar
-have characteristic of fluid transporting/absorbing
cells (cilia, microvilli, basal infoldings)
-found in choroid plexus- modified ependymal cells
that interact with capillaries and secrete

3) Protoplasmic astrocytes
- In the gray matter
- maintain the blood-CSF barrier

4) Fibrous astrocytes
- In white matter

5) Microglia (Macrophages in brain)
- smallest
- phagocytosis of bacteria, injured tissue and debris

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15
Q

Neuroglia of PNS

A

1) Schwann cells
- myelinated neurons in PNS
- Several in one axon
- Provides support for both myelinated and unmyelinated axons in PNS
- clean up debris
- scaffolding for regenerating nerve tissue

2) Satellite cells
- small cuboidal cells
- surrounds the cell body of neurons in PNS
- regulate the perineuronal environment
- electrical insulator, DOES NOT MAKE MYELIN
- Regulate metabolic exchange

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16
Q

Formation of Myelin Sheath

A

1) Schwann cell plasma membrane forms two
distinct polarized domains
-abaxonal plasma membrane
-adaxonal plasma membrane

2) Mesoaxon connects the abaxonal and adaxonal membranes and closes off the extracellular environment
3) Thickness of the myelin sheath is determined by the diameter of the axon regulated by neuregulin (Ngr-1)

17
Q

Myelination

A

-lipid rich layer around axons that facilitate rapid conduction of nerve impulses
-Myelin sheaths contain small amounts of
cytoplasm

Myelinating cells

  • Schwann cells (PNS)
  • Oligodendrocytes (CNS)
18
Q

Myelinated Vs Unmyelinated Nerves

A

Myelinated nerves:

  • they have multiple concentric layers of myelin sheath around one axon
  • The nerves are devoid of myelin at the nodes of Ranvier, axon hillock, and terminal arborizations

Unmyelinated nerves:
-Axon/axons rests in a cleft of Schwann cell
cytoplasm (each with a single mesoaxon)

19
Q

Synapses

Functions, types

A

Function:
-Facilitate transmission of impulses

Types:

1) Electrical
2) Chemical = Release of chemical substances (neurotransmitter)
- Pre/post synaptic membranes
- Synaptic cleft

  • Axodendritic = between axon and dendrite
  • Axosomatic = between axon and soma
  • Axoaxonic = between axon and axon
20
Q

Types of neurotransmitters: How they are made/used and degraded

Acetylcholine

Catecholamines

Serotonin

A

Acetylcholine:

  • Used by cholinergic neurons
  • Degraded by acetylcholinterase

Catecholamines

  • Precursor = tyrosine
  • Used by catecolaminergic neurons in CNS and ENS
  • Removed by COMT, MAO

Serotonin

  • Precursor = tyrophan
  • Used by serotonergic neurons
21
Q

Blood Brain Barrier

Function, components

A

Function
-Protects CNS from imbalances (Ex: electrolytes)

Components:
1) Continuous capillaries: Tight junctions, Continuous basal lamina, no fenestrations in cytoplasmic membrane,

2) Surrounded by foot processes of astrocytes (cover around blood vessel, prevent foreign substance from reaching neuron if tight junctions fail), neuronal processing
3) Part of cerebral cortex
4) Can lose function with brain diseases
5) Some parts of CNS have no barrier (Ex: Circumventricular organs)

22
Q

Multiple Sclerosis

Cause/Symptoms

A
  • Loss of myelin sheath in CNS (Myelin detached from axon and destroyed)
  • Damage to Oligodendrocytes

Stages of demyelinating:
1) Myelin breakdown associated w/ lymphocyte and macrophage infiltration

2) Proliferation of astrocytes: Gradual infiltration of astrocytes into demyelinating area
3) Reduced cellularity, astrocyte reduce in size

23
Q

Guillain-Barre

A
  • Damage to Schwann cells
  • Large accumulation of lymphocytes, macrophages, plasma cells
  • Loss of muscle coordination and sensation
24
Q

Response to injury:

Wallerian Degenration (Anterograde)

  • PNS
  • CNS
A 
Wallerian Degenration (Anterograde)
-Degenerative of axon distal to site of injury

PNS

  • Degeneration takes a few days
  • Dedifferentiation of Schwann cells and alignment

CNS

  • Degeneration takes several weeks
  • Loss of axon contact = cell death

Some retrograde degeneration also occurs = traumatic degeneration

25
Q

Meninges

A

“DAP”

1) Dura mater:
- Outer
- Dense connective tissue
- Vascular
- In the cranium forms the dural venous sinuses
- Innervated

2) Arachnoid mater:
- Loose connective tissue
- Lined by simple squamous epithelium
- Projects into sinus to drain cerebrospinal fluid into the bloodstream
- Avascular (No blood vessels)

3) Pia mater:
- Vascular
- Loose connective tissue
- Lies directly on brain and spinal cord
- Interacts with ependymal cells = choroid plexus

26
Q

The Spinal Cord (CNS)

Grey matter
White Matter
Segments
Features

A
  • Grey matter = inside (Butterfly shaped), Motor neuron cell bodies, dendritic and axonal processes and glial cells, Neuropil
  • White matter = outside (myelin = white bc lipids washed out during staining), Bundled of unmyelinated/myelinated fibers = tracts

Horns/features:

1) Dorsal Horn- (Posterior) Sensory (afferent) Body–>spinal chord
2) Ventral Horn: (Anterior) = Motor neurons/voluntary control
- By ventral grey fissure
3) Lateral Grey Horn- If not ventral/dorsal its this
4) Grey commissure
5) Central canal- contains CSF, ependymal cells line it

Segments:

1) Cervical
2) Thoracic
3) Lumbar
4) Sacral
5) Coccygeal

27
Q

Alpha motor neurons

Characteristics

A
  • Also called golgi Type I neurons
  • In ventral horn (Anterior)

1) Pale staining large nuclei
2) Long axons
3) Nissl bodies (RER, protein synthesis)
- Embedded in neuropil (Everything light and outside of cell)
- Comprised of dendritic and axonal processes, and central glial cells

28
Q

Brain

White matter and grey matter

A

1) White matter = inside
-Tracts: are groups of axons in CNS
carrying out a specific function

2) Grey matter = outside
- Cell bodies arranged in layers
- Nuclei-islands of grey matter

29
Q

Cerebral cortex

Components/functions

A
  • Grey matter = outside
  • 6 layers of grey matter tissue
  • Layer 3 (external pyramidal) and 5 (Ganglionic layer) has pyramidal cells (Pyramid shape and long axons),

Function:
-helps transmit info from one side of brain to another

30
Q

Cerebellum

Components

A

1) Grey matter = outside
- Cell bodies arranged in layers

2) White matter = inside
- Forms tracts
- Axons travel to other places in CNS

Layers:

1) Molecular layer
- Outer most
- Supporting cells (Stelliate and basket cells)

2) Purkinje Cell Layer
- Dendrites that branch in molecular layer
- Has axon that extends into granular layer
- Layer of motor neurons

3) Granule layer
- Inner layer
- Cells: granule cells, type II Golgi cells
- Carries excitatory cells

31
Q

Choroid Plexus

A
  • Invagination of pia mater
  • In ependymal cells
  • Contains fenestrated capillaries (Pores that let larger ions in)
  • covered by simple cuboidal ependymal cells
32
Q

Peripheral Nerves

What is it/what does it do
Connective tissue layers

A
  • Nerve= collection of axons in PNS
  • Carries impulses CNS–>PNS

Covered by connective tissue layers

1) Epineurium
- Outer most layer
- Dense connective tissue
- Vascular

2) Perineurium
- Surrounded by nerve fibers
- Sheath of unique connective tissue cells epithelioid myofibroblasts
- Cells joined by tight junctions
- Can contract with actin microfilament
- Restrict passage of most macromolecules

3) Endoneurium
- thin layer of reticular fibers
- Covers one nerve

33
Q

Response to Injury:

Wallerian Degeneration

Chromatolysis

A

Wallerian Degeneration
-Degeneration of axon distal to site of injury

Chromatolysis
-Loss of Nissl substance from cell

FTM Exam 2 (25 decks)

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