Nervous Tissue

Question 1

Structure of a typical neuron: Cell body

Answer 1

Also called: perikaryon/soma
Portion of the cell with the nucleus and other organelles (Nissl bodies-rER)

Question 2

Structure of a typical neuron: Nerve fibers-Dendrite

Answer 2

1. Unmyelinated extension from a cell body
2. Receive stimulus from the environment
3. Contains cytoplasmic contants

Question 3

Structure of a typical neuron: Nerve fibers- Axon

Answer 3

1. Myelinated neuronal process
2. Output portion
3. Contains microtubules, microfilaments, mitochondria, vesicles with proteins (NTs)

Question 4

Classification of Neurons by Function: Motor-Efferent

Answer 4

1. Conveys impules to effector cells
2. Somatic-voluntary OR
3. Visceral: smooth cardiac muscle
4. Typically multipolar

Question 5

Classification of Neurons by Function: Sensory-Afferent

Answer 5

1. Conveys impules from receptors for integration
2. Somatic: pain, temp, touch, pressure, proprioception
3. Visceral: distention, ischemia, inflammation-Glands, BVs
4. Typically pseudounipolar for general senses
5. Bipolar special senses

Question 6

Classification of Neurons by Function: Interneurons

Answer 6

1. Communication and Integration between sensory and motor neurons (tendon reflexes)
2. Multipolar

Question 7

Axonal Transport definition

Answer 7

Bidirectional movement of material between the cell body and process

Question 8

Axonal Transport Anterograde

Answer 8

1. Towards synapse
2. Kinesin
3. Can be slow or fast
4. Flow of synpatic vesicles, organelles

Question 9

Axonal Transport: Retrograde

Answer 9

1. FAST ONLY
2. Towards the cell body
3. Dynein
4. Flow of recycled membrane vesicles, neuromodulators

Route used by toxins/viruses to enter the nervous system

Question 10

Ganglia

Answer 10

Clusters of nerve cell bodies in the PNS
Sensory ganglia:
1. Carry data into the CNS
2. Location: craniospinal DRG, cranial nerves

Question 11

Autonomic Ganglia

Answer 11

Carry data to smooth muscle, cardiac muscle, and glands
Subclasses of Sympathetic, Parasympathetic, Enteric

Question 12

Sympathetic Ganglia

Answer 12

1. Location: Prevertebral (anterior to the aorta), paravertebral (in the sympathetic chain)
2. Dispersed multipolar cell bodies
3. Random bundles of fibers mingled w/ soma
4. Synapsing occurs BETWEEN neurons

Question 13

Parasympathetic Ganglia

Answer 13

1. Located close to organs-innervated by postsynaptic neurons
2. Cell bodies clumped together
3. Afferent/Efferent nerve fibers present
4. Large-Euchromatic nuclei w/ prominent nucleolus

Question 14

Neuroglia

Answer 14

Non-neuronal support cells
Fx: support, insulate, or nourish neurons
Can be found in both CNS/PNS

Question 15

Schwann Cells

Answer 15

Myelinated neurons in PNS-ONE axon
Fx:
1. Provide support for both myelinated and unmyelinated axons
2. Clean up debris
3. Scaffolding for regeneration of nerve tissue

Question 16

Satellite Cells

Answer 16

1. Small cuboidal cells that surround cell body of neurons in PNS
2. Regulated metabolic exchange
3. Electrical insulator

Does NOT make myelin

Question 17

Demyelinating Disease in the PNS name and key characteristics

Answer 17

Guillain-Barre Syndrome
1. Post-infectious peripheral polyneuropathy
2. Large accumulation of lymphoctyes, macrophages and plasma cells
3. Ascending muscle weakness and loss of coordination.

Question 18

Demyelinating Disease in the CNS name and key characteristics

Answer 18

Multiple Sclerosis
1. Myelin is detached from the axon and destroyed (oligodendrocytes)
3 main histological stages:
1. Plaque formation-myelin breakdown causes lymphocytes and macrophages to come to infected area
2. Proliferation of astrocytes
3. Reduced cellularity, astrocytes reduce in size

Question 19

What is a collection of axons in the CNS called?

Answer 19

Tract

Question 20

What is so unique about th Perineurium?

Answer 20

Sheath of unique connective tissue cells called epithelioid myofibroblasts.

They have contractile propery-numerous actin microfilaments.
Restrict passage to form BNB

BNB=Blood nerve barrier

Question 21

What is the Cerebrum covered by?

Answer 21

PIA mater

Question 22

Connective tissue of the CNS-deep to superficial (3)

Answer 22

THINK “PAD”
1. Pia Mater: lies directly on brain and spinal cord. Interacts w/ ependymal cells to form choroid plexus. LCT
2. Arachnoid Mater LCT. Lined by back to back simple squamous epithelium. Avascular. Projects into the sinus to drain CSF into the blood stream
3. Dura Mater. DCT. Vascular. In the cranium forms the dural venous sinuses. Innervated

LCT=loose connective tissue

Question 23

Astrocytes: Protoplasmic

Answer 23

1. Prevalent in the gray matter
2. Branching cytoplasmic processes
   3.Maintain the blood-CSF barrier

Question 24

Astrocytes: Fibrous

Answer 24

1. Prevalent in white matter
2. Straight cytoplasmic processes

Question 25

Astrocytes: **BOTH types**

Answer 25

1. Contain GFAP to provide structural support/strength to cells 2. Maintain **Blood-brain barrier** 3. Protect bare areas of neurons 4. Support/regulate movement of metabolites/waste

Question 26

Microglia

Answer 26

1. **Smallest** type of central neuroglia 2. Originate from blood cell line 3. **Phagocytic** properties 4. Cytoplasm contains lots of lysosomes, vesicles and inclusion bodies

Question 27

Ependymal Cells

Answer 27

1. **Epithelium lining** of the CNS cavaties-ventricles of the brain, central canal of the spinal cord 2. **Single layer of cuboidal to columnar** 3. Found in choroid plexus: secrete CSF 4. **Well developed apical complexes:** have cilia, microvilli, basal infoldings for transport, absorption, secretion 5.

Question 28

Oligodendrocytes

Answer 28

1. **Myelinate axons in the CNS** 2. One oligodendrocyte myelinates portions of SEVERAL axons 3. Larger nodes of Ranvier-increases efficiency of nerve conduction

Question 29

Brain/Cerebrum: **White Matter/Medulla**

Answer 29

1. Inner core of brain tissue 2. Contains: **Axons (tracts)**-associated with glial cells, BV

Question 30

Brain/Cerebrum: **Gray Matter/Cerebral Cortex**

Answer 30

1. Outer layer/periphery of brain 2. Site of synapses 3. Contains: Cell bodies, axons, dendrites, central glial cells 4. **Nuclei:** collection of nerve cell bodies in the CNS

Question 31

What is the main cell type in the Cerebral Cortex?

Answer 31

Pyramidal Cells Found in layers III, V

Question 32

What are the 6 layers of the Cerbral Cortex?

Answer 32

1. Molecular layer 2. External granular layer 3. External pyramidal cell layer 4. Internal granular layer 5. Ganglionic Layer (internal pyramidal cells) 6. Multiform (polymorphic cell layer)

Question 33

What are the 3 layers of the Cerebellum? | In Grey Matter

Answer 33

1. **Molecular layer** (outer): stellate and basket cells 2. **Purkinje Cell Layer** (middle): single layer of motor neurons 3. **Granular cell layer** (inner): granule cells, type II Golgi cells ## Footnote White matter: Inner core, axons forms tracts to other parts of the CNS

Question 34

Cerebellar Cotex: **Purkinje Cells**

Answer 34

1. Middle layer 2. An apical dendrite that **arborizes** in the molecular layer 3. Single axon that extends into the granular layer ## Footnote Arborizes: branch freely

Question 35

Cerebellar Cortex: **Granule Cells**

Answer 35

1. Located in the innermost layer 2. Project into molecular layer and connect with dendrites of Purkinje cell via parallel fibers in the molecular layer 3. Carry **excitatory signals** to the cerebellum

Question 36

Choroid Plexus

Answer 36

1. **Vascularized structure**: invaginated folds of *pia mater* containing tufts of **fenestrated capillaries** 2. Covered by simple cuboidal ependymal cells 3. Aries from the walls of four ventricles of the brain 4. **RESPONSIBLE FOR CSF production** 5.

Question 37

Tight junctions between the ependymal cells form what?

Answer 37

Blood-CSF barrier

Question 38

Blood-Brain-Barrier Components and importance

Answer 38

Components: 1. **Continuous capillaries** w/ tigh junctions between endothelial cells. *Continuous basal lamina*. NO fenestrations 2. **Foot processes of astrocytes:** surround the basal lamina of the capillaries and neurons 3. **Neuronal processes**: mostly in contact w/ astrocytes

Question 39

Spinal Cord Gray/White Matter

Answer 39

**Gray** Matter: **inner** core, butterfly-shaped. Cell bodies of motor neurons, dendritic and axonal prcoesses and glial cells (neuropil) **White** Matter: Peripheral tissue. Unmyelinated/myelinated fibers form **tracts**

Question 40

Where are each of the neurons present in. Bipolar? Pseudounipolar? Multipolar?

Answer 40

Bipolar: Special senses Pseudounipolar: Ganglion Multipolar: motor/interneurons | Interneurons found in CNS