Ant201 Microanatomy Nervous Tissue

Front 1

Anatomically, The nervous system is divided into what two systems, and what do they contain?

Back 1

Central nervous system, consisting of the brain and spinal chord, located in the cranial cavity and spinal canal
Peripheral nervous system. consisting of cranial, spinal, and peripheral nerves that conduct impulses from efferent/motor nerves, and to afferent/sensory nerves, (centered in the CNS), as well as to and from ganglia nerve cell body collections, and specialized nerve endings.

Front 2

Functionally, the nervous sytem is divided into what two systems, and what are their functions?

Back 2

Somatic Nervous System - somatic body parts of the CNS and PNS. Providing sensory and motor innervation to all parts of the body except viscera, smooth muscle, and glands.
Autonomic Nervous system - consisting of autonomic parts of the CNS and PNS. Provides efferent involuntary motor innervation to smooth muscle, the conducting system of the heart, and glands. Provides afferent sesnroy innervation from the viscera (pain and autonomic reflexes).

Front 3

What is the autonomic nervous system divided into?

Back 3

Sympathetic nervous system
Parasympathetic nervous system
and the Enteric Division, which serves the alimentary canal, and can function independently of the other two divisions of the ANS.

Front 4

what are supporting cells in the nervous tissue?
What are these CNS, and in the PNS?

Back 4

supporting cells are nonconducting cells that are in intimate apposition to the neurons. In the CNS they are known as neuroglia or just glia.
In the PNS they are called Schwan cells (insulators) and Satellite cells (PNS ganglia cells functioning in support)

Front 5

What are supporting cells called in nervous tissue of the Enteric division?

Back 5

enteric Glial cells, despite being part of the PNS.

Front 6

What are three functions of supporting cells in nervous tissue?

Back 6

physical support, electrical insulation, and metabolic exchange

Front 7

What are the specific effectors in internal organs effected by the autonomic nervous system, and what do they do?

Back 7

Smooth muscle, whose contraction modifies diameter or shape of tubular or hollow viscera such as blood vessels, gut, gallbladder, and urinary bladder.
Cardiac conducting cells (purkinje fibers) located within the conductive system of the heart where the inherent frequency of depolarization of these fubers regulates the rate of cardiac muscle contraction and can be modified.
glandular epithelium - in which synthesis, composition, and release of secretions can be modified.

Front 8

Explain the differences between the categories of neurons.

Back 8

Sensory neurons - convey impules TO receptors to the CNS and are involved in somatic afferent (pain, temp, touch, proprioception which is nonconscious sensation of pain and placement) from the body, and visceral afferent nerve fibers which transmit similar information from mucous membranes, glands, and blood vessels.
Motor Neurons - convey impulses FROM the CNS or ganglia of effector cells. Processes of these neureons are included in somatic efferent (voluntary movement of skeletal muscle) and visceral efferent (transmit involuntary impulses to smooth muscle, cardia conducting cells 'purkinje fibers', and glands) nerve fibers.
Interneurons - (aka intercalated neurons) form a communicating and integrating network between the sensory and motor neurons. 99% of neurons are connected to this network.

Front 9

What are three classifications for neurons based on processes from the cell body?

Back 9

Multipolar - one axon and two or more dendrites. These are mainly motor neurons and interneurons. Basic impulse transmitter.
Bipolar neurons - have 1 axon and 1 dendrite. These are really only found in the retina of the eye and the ganglia of the vestibuloochlear nerve (cranial nerve VIII) of the ear
and Unipolar - which has a single axon which divides close to the cell body. These are mainly found in the dorsal root ganglia and cranial nerve ganglia as sensory neurons connecting periphery directly to the CNS.

Front 10

What is the origin of the CNS neurons?
What is the origin of the PNS and ANS neurons?

Back 10

CNS neurons are derived from the neuroectodermal cells of the neural tube.
PNS and ANS come from the neural crest.

Front 11

a group of neurons with related function and connections are called a ____.

Back 11

nucelus; these are the morphological and functional equivalents of ganglia in the PNS, but the nuclei are in the CNS.

Front 12

gray matter contains

Back 12

neurons

Front 13

white matter contains

Back 13

myelinated axons (which are formed by oligodendroglia)

Front 14

Name the structures

Back 14

Front 15

Identify the structures.

Back 15

Front 16

cell bodies of motor neurons that innervate striated muscle are located where?

Back 16

the ventral (anterior) horn of the gray matter. This is an efferent neuron, carrying an impulse up to the spinal chord (CNS) from the ventral anterior root, which was from a spinal nerve of that segment of muscle, which was conveyed from the muscle.
Muscle >spinal nerve >root>horn>spinal chord/CNS

Front 17

Where are the cell bodies of sensory neurons located.

Back 17

Sensory neuron cell bodies are located in the ganglia that lie on the dorsal root of the spinal nerve. these pseudounipolar cells are afferent and carry nerve impulses from the periphery (ie. pacinian corpuscle) up to the cell body in the dorsal root ganglion, and then finally transmitting this to the gray matter of the spinal chord.

Front 18

gray matter contains what?

Back 18

neuronal cell bodies and processess.
astrocytes
myoglia
some oligodendroglia
neurons are within nuclei - which requires Cresyl violet, nucelus violet, and myelin sheath blue to see.

Front 19

white matter contains what?

Back 19

myelinated axons. (myelin being formed by oligodenroglia).

Front 20

Identify the matter, and the cell with the arrow, AND describe the features of the cell.

Back 20

Motorneuron
euchromatic nucleus
prominent nucleolus
abundant Nissl substance

Front 21

What cell is found in the CNS but is derived from bone marrow?

Back 21

Microglia is not derived from the neural crest like all of its neighbors, but actually develops from the bone marrow monocyte precursor cells along with other marcophages of the body.

Front 22

Describe the types of glial cells.

Back 22

Oligodendrocytes, small cells that are active in the formation and maintenance of myelin in the CNS.
Astrocytes, morphologically eterogeneous cells that provide physical and metabolic support for the neurons of the CNS. They are fibrous in the white matter, and protoplasmic in the dark matter.
Microglia, inconspicuous cells with small, dark, elongated nuclei that possess phagocytic properties. (formed in the bone marrow instead of neural crest)
Ependymal cells, columnar cells that line the ventricles of the brains and the central canal of the spinal cord.
Choroid Plexus cells, which are not in the text but mentioned in the lecture, and secrete CSF.

Front 23

Back 23

pukinje fibers are in the heart. cells, however, are neurons with very large dendritic sheets.

Front 24

Back 24

Front 25

Back 25

Front 26

The neuron is a highly active cell as evidenced by a prominent nucleolus within a euchromatin nucleus (N). The glial cells nuclei (NN) are not as active and so their cytoplasm is not stained.
What is the box pointing to, what is it made up of, and what does it indicate?

Back 26

Neuronal cytoplasm is typically basophilic.
The basophilia can be seen to occur in clumps called Nissl bodies (NB).
Nissl bodies are made up of RER and polysomes. These bodies reflect the high level of synthesis of membrane and secreted products.

Front 27

dendritic arborization = ____

Back 27

dendritic arborization = dendritic tree

Front 28

Back 28

Front 29

Back 29

Front 30

some neurons, such as the purkinje cells of the cerebellum, have protrusions that are called ___ ___ and are specialed regions of what?

Back 30

dendritic spines; these are specialized forms of synaptic contact.

Front 31

neurons typically have ___ axon(s).

Back 31

one.

Front 32

why do axons not stain with Nissl stains (cresyl violet)?

Back 32

axons do not contain RER or ribosomes, which are the main components of Nissl bodies, (besides polysomes).

Front 33

what are the terminal arborizations of axons called?

Back 33

telodendria.

Front 34

Both microtubules and neurofilaments are found in axons.
Describe each.

Back 34

Microtubules are important as tracks for fast anterograde and retrograde axonal transport.
Neurofilaments predominate, i.e. are more abundant than microtubules, and are believed important in maintaining axonal diameter

Front 35

What are the classifications for axonal transport?

Back 35

Anterograde - to the axon
Retrograde - away from axon
slow transport
fast transport

Front 36

Describe the features of slow axonal transport.

Back 36

anterograde only.
used for structural proteins tubulin, actin, microtubules, neurofilaments. (once they get there they're broken down by high Calcium levels
100x slower than fast transport.

Front 37

Describe the features of fast axonal transport.

Back 37

its 100x fast than slow axonal transport.
it goes both directions, (anterograde and retrograde)
Anterograde - takes membranous organelles and membrane-bound proteins away from cell body and toward axon terminals (like mitochonria, synaptic vessicles, and SER).
Retrograde - takes worn organelles, endocytosed materials like growth factors toxins and viruses away from axon and sends them back to the cell body.

Front 38

What are some of the needs of fast axonal transport?

Back 38

Microtubule dependent
Anterograde component uses kinesin as a motor protein
Retrograde component uses dynein as a motor protein
Substances that disrupt microtubules or that prevent their assembly will prevent or inhibit fast axonal transport
(ie. ricin toxin used by nazis inihibits this process, injection by dipped and sharp tip of umbrella).

Front 39

What is the process shown?

Back 39

Fast Axonal Transport

Front 40

Describe lipofuscin.

Back 40

When retrogradely transported endosomes and multivesicular bodies reach the cell body, they fuse with lysosomes
Material is digested.
Lipofuscin is material that cannot be digested.
Accumulates with age and in some diseases

Front 41

What do rabies, tetanus, and ricin have in common?

Back 41

Each of these have the ability to be transported retrogradedly to the cell body from an axon. Rabies virus binds to acetylcholine receptor of motor neurons innervating infected muscle cells, Retrogradely transported to cell body where it can replicate.
Toxins such as tetanus toxin, a protease, and ricin toxin are retrogradely transported

Front 42

Describe the major types of synapses.

Back 42

Chemical synapses function through the release of neurotransmitters, are the most common, and can either be excitatory or inhibitory.
Electrical synapses involve the quick exchange of ions through gap junctions that allow neurons to act in unison. These are present in some regions of the CNS.

Front 43

List the steps in this process.

Back 43

Front 44

Describe this slide.

Back 44

Front 45

What are fibrous astrocytes involved in?

Back 45

white matter
structural support for tracts of white matter
GFAP - glial fibrillary acidic protein, are bundles of strong intermediate filaments, (present in protoplasmic astrocytes as well but less so)

Front 46

What are protoplasmic astorcytes involved in?

Back 46

gray matter,
thick short bushy processess
less GFAP
secrete growth factors and act as support cells for neurons.
MOST IMPORTANT - they're little feet extend to the basal lamina of the pia mater to form the glia limitans (relatively impermeable barrier surround the CNS - but not the blood-brain barrier)
they do however induce capillaries to form the blood brain barrier

Front 47

What would you use antibodies to GFAP to find?

Back 47

Astrocidic tumor

Front 48

What is the most common type of primary brain tumor?

Back 48

astrocystomas.
80-90% of all glial tumors in adults.
anaplastic over time (less differentiation = malignancy)
blood-brain barrier may be involved with preventing metastasis to other regions of body besides CNS.
8-10 month mean survival

Front 49

What do oligodendrocytes do?

Back 49

myelinate axons similar to schwann cells, but do it in the CNS.
may myelinate 50 axons.
may not myelinate some axons and instead act as satellite cells

Front 50

What disease has these characteristics?
Chronic demyelinating disease of the CNS
Multiple, focal plaques of demylenization
Optic nerve, which is myelinated by oligodendroglia, often affected.
Prevalence 1 in 1000 in USA
Pathogenesis undetermined
May be autoimmune
Antibodies to central myelin
Characterized by remission and relapse
CNS plaques (scars) formed by astrocytes

Back 50

Multiple Sclerosis (MS)
-
Symptoms in declining order of frequency.
Unilateral visual impairment.
Diplopia (double vision).
Paresthesias (pins and needles)
Ataxia (unsteadiness)
Vertigo (dizziness)
Fatigue
Paresis (muscle weakness)
Dysarthria (speech problems)
Mental disturbances

Front 51

when do microglia migrate into the CNS?

Back 51

uring the development of CNS vasculature.

Front 52

When do microglia have a name change?

Back 52

Twice.
When the CNS is injured, the microglial nuclei enlarge and elongate. These cells are then called rod cells by pathologist
Increased damage causes the microglia to become phagocytic. They are then called gitter cells by pathologists.

Front 53

In CNS injury, what usually occurs?

Back 53

Astrocytes react to injury – gliosis (flocking of glial cells)
ends up forming a glial scar that inhibits axonal regeneration.
ALSO, oligodendroglia express protein that prevents axonal growth

Front 54

Fill in the blanks.
The big arrows are asking afferent or efferent.

Back 54

Efferent or motor nerves innervate muscle while afferent send a message from the periphs directly to the CNS.

Front 55

Dorsal root ganglion contain what type of neuron and what do they send?

Back 55

sensory neurons that signal pain and temperature, touch, pressure, vibration and proprioception.

Front 56

Back 56

Front 57

What disease has the following characteristics?
Acute inflammatory polyradiculoneuropathy
Affects PNS myelin only
Usually bilateral, symmetrical, motor weakness
Evidence of T-cells, plasma cells and macrophages around axons
May be an autoimmune disease
Severe cases can lead to death
Most cases resolve in 2-4 weeks.

Back 57

Guillan-Barre´ Syndrome

Front 58

What critical role do schwann cells play in peripheral nerve regneration?

Back 58

become phagocytic while synthesizing essential growth promoting factors and cytokines, that hopefully a sniffing axon will find and penetrate original detached nerve fiber

Front 59

what explain phantom limb pain?

Back 59

tramatic Neuroma, where several months of regeneration and still nerve fibers were not properly re-established, resulting in tangled axonal processess (bushy looking)

Front 60

A 62-year-old man has begun to notice some tingling and numbness in his right face, neck, and upper limb. He also believes he has become weaker in his right upper limb and has begun having difficulty doing fine motor tasks with his right hand.

After seeing a neurologist, who confirms the man’s deficits, he undergoes an MRI of his brain that reveals a 3cm mass in his left cerebral hemisphere. A biopsy is arranged and a malignant CNS tumor is diagnosed.

What is the most common form of primary CNS tumor in adults?

What type of intermediate filaments do the tumor cells express?

What is this man’s prognosis?

Back 60

What is the most common form of primary CNS tumor in adults? astrocytoma

What type of intermediate filaments do the tumor cells express? Glial fibrillary acidic protein (GFAP)

What is this man’s prognosis? 8-10 months survival

Front 61

what is chromatolysis?

Back 61

the dissolution of nissl bodies that usually occurs during the axonal reaction, (occurring after axotomy (axon severed)).

Front 62

What is the axonal reaction?

Back 62

The axonal reaction occurs after axotomy (severed) in an attempt to prevent neuron death. It involved the swelling of the cell, a dissolution of Nissl bodies called chromatolysis, and the nucleus moving to an eccentric position, all within 24-48 hours.

Front 63

Why would actin and tubulin genes be up-regulated in a neuron and synaptic transmitter genes be down regulated?

Back 63

The axonal response, which produces morphological changes in a neuron in an attempt at regeneration.

Front 64

In the axonal response. What happens at the proximal and distal ends of the severed neuron?

Back 64

proximal portion degenerates back to the next node of Ranvier - retrograde degeneration
distal portion begins to degenerate because separated from synthetic machinery of the cell anterograde or Wallerian degeneration

Front 65

What is an axonal growth cone?

Back 65

A motile structure that has a concentration of receptors for neurotrophic factors and laminin. This is in response to being recently severed, and searching for these substances in higher concentration may lead the cone directly to its severed member. (laminin found on basal lamina and schwann cells)