1) Smooth Muscle

- gut motility, vascular tone

2) Cardiac Muscle

- rate & intensity of contractions

3) Glandular Epithelium

- secretory regulation

1) neurons

2) neuroglia

1) Somatic Nervous System

- Whole body except visceral, smooth muscle, & glands

2) Autonomic Nervous System

- Sympathetic

- Parasympathetic

- Visceral innervation

1) CNS

- brain & spinal cord

- derived from neural tube

2) PNS

- ganglia

- afferent & efferent nerves (MESA)

- derived from neural crest

1) Unipolar

- single process

- rare in vertebrates

2) Multipolar

- multiple processes

- most common

- motor neurons and interneurons

3) Pseudounipolar

- sensory neurons in spinal & cranial ganglia

- single process

4) Bipolar

- 5 senses receptors

- single axon and process

Large soma = long axon/large diameter = faster conduction

Small soma = short axon/small diameter = slower conduction

1) Dominant rER

2) Significant Nissl substance

- basophilic ribosomes and rER

3) Prominent Golgi

- near nucleus

4) Numerous Mitochondria

1) Neurofilaments

2) Microtubules

- larger

1) Proximally

- same as soma

2) Distally

- No Golgi

- Nissl decreases

- Many MT's

*Tapering

*Dendritic Spines

   - increase synaptic area

1) No Nissl

2) Abundant MT's and NF's

3) No ribosomes or rER

4) Can branch (collaterals)

5) Boutons

- Terminal

- En passage

1) Proteins, vesicles, organelles to/from soma to terminals

2) Fast, intermediate, slow

3)Anterograde

- away from soma

- Kinesin

- Fast (400 mm/ day)

- synaptic vesicles and mito

- Slow (1-2 mm/ day)

- proteins & regeneration

4) Retrograde

- towards the soma

- Dynein

- Intermediate (200-300 mm/ day)

- recycling & viral transport

1) Anterograde

2) Retrograde

1) away from soma

2) Kinesin

3) Fast & Slow

- Fast = synaptic vesicles and mito

- Slow = proteins

1) towards soma

2) Intermediate rate

3) Dynein

1) Located in the CNS (although specialized homologues exist in the PNS)
2) Outnumber neurons 10 to 1
3) Each function in a highly specialized way to support and protect neurons
4) Do not form synapses with other cells
5) Generated throughout life (unlike neurons)
6) Four types of neuroglial cells

1) Astrocytes

2) Microglia

3) Oligodendrocytes

4) Ependymal

1) largest neuroglial cell type

2) light staining cytoplasm

3) euchromatic nucleus

4) perivascular endfeet

- processes that expand to contact blood vessels

5) Blood-brain barrier contributor

6) form glial scar after CNS injury

7) GFAP

- glial fibrillar acidic protein (filamentous)

8) Protoplasmic (Gray Matter)

- highly branched

9) fibrous Astrocytes (White Matter)

- fewer branches

1) CNS version of Schwann cells

2) Myelinate multiple axons

3) White and gray matter

4) dark cyto, heterochromatic nucleus

5) symbiotic with neurons

1) Phagocytic

2) Monocyte lineage

3) smallest cell

4) infiltrate sites of injury

1) cuboidal to columnar epithelium lining ventricles of brain and central canal of the spinal cord

2) Basally located nucleus

3) often cililated to move CSF

4) Choroid Plexus is specialized ependymal cells that secrete CSF

1) Dura Mater

2) Arachnoid Mater

3) Pia Mater

1) Tough outer layer, dense fibrous connective tissue

2) Continuous with periosteum of skull/vertebral column

3) Lined by simp. squa. epith. in skull and both surfaces at spinal level

1) Middle layer

2) Delicate and loosely attached to dura mater

3) covered by simp. squam. epith. on both surfaces

4) have trabeculae which bridge the subarachnoid space to loosely connect with pia mater

5) arachnoid villi that extend into dura mater to return CSF to venous sinuses

1) Highly vascularized

2) simp. squam. epith.

3) separated from underlying nervous tissue by only neuroglial cells

1) Folds of pia mater extending into ventricles of the brain

2) ependymal cells

3) highly vascularized with fenestrated capillaries

4) Secretes CSF

- bathes, cushions, nourishes CNS

1) Gray matter on outer surface of cerebral hemispheres

2) Folded into gyri

3) Functions

- initiation of motor responses

- integration of sensory signals

- association, analysis, and consolidation of info to memories

1) Molecular Layer

2) External Granular Layer

- interneurons

3) External Pyramidal Layer

- multipolar efferent neurons

4) Internal Granular Layer

5) Internal Pyramidal Layer

- efferent neurons

6) Multiform Layer

- Marinotti cells (specialized interneuronal cells)

1) Thin layer of gray matter making up surface of cerebellar hemispheres

2) Folded to form folia

3) Functions:

-coordination of skeletal muscle activity
-maintenance of muscle tone
-maintenance of equilibrium and balance

1) Nerves

2) Ganglia

1) Myelinated & Unmyelinated nerves in connective tissue

1) Encapsulated collections of neuronal cell bodies outside of CNS

2) 2 Types

- Autonomic

- Craniospinal

1) Motor ganglia where pre/post ganglionic fibers synapse

2) Located near/on/in organs they innervate

- sympathetic chain

- celiac ganglia

- Meissner's complex (parasympathetic)

3) Multipolar cell bodies

4) Functions:

- visceral motility

- glandular secretion

- control of smooth and cardiac musculature

1) Sensory Ganglia

2) Round, pseudounipolar cell bodies, central nucleus

3) contain the cell bodies of sensory neurons

- transmit information from peripheral
receptors to the CNS

- without synapsing in the ganglia

1) Motor fibers controlling:

- Smooth muscle

- Cardiac muscle

- glands

2) Conveys afferent (sensory) info from organs to CNS

3) Establishes homeostasis of visceral functions

4) 3 Divisions

- Sympathetic

- Parasympathetic

- Enteric

1) "Thoracolumbar outflow"

2) T1-L2 contain pre-ganglionic cell bodies

3) Post-ganglionic cell bodies are in ganglia

4) Stimulates contraction of smooth muscle of blood vessels leading to vasoconstriction

1) "Craniosacral outflow"

2) S2-S4

3) secretomotor function

4) cause vasodilation

1) Ganglia and post-ganglionic neuronal networks of alimentary canal

2) Contains the intramural ganglia located in the walls of viscera and in Meissner’s and Auerbach’s plexi

3) Can function independently of pre-ganglionic input

1) Site of functional contact between neurons

- dendrodendritic in Purkinje layer

2) Neurotransmitters

- Excitatory- causes membrane depolarization

- Inhibitory - causes membrane hyperpolarization

3) Chemical synapses

- generate action potential

- 1/2 ms delay due to NT's secretion and diffusion

4) Electrical synapses

- gap junctions

- direct propagation of action potential

- nearly instantaneous

1) Voltage-gated Ca²⁺ channels

- regulate entry or release (from mito) at axon terminal

1) Has a subsynaptic web

- electron dense region resembling desmosome

1) 20-30 nm

1) Acetylcholine (Ach)

- myoneural junctions (motor end plates)

- all parasympathetic responses

- pre-ganglionic synapses

2) Norepinephrine

- post-ganglionic synapses

3) Amino acids

- glutamic acid (excitatory)

- gamma aminobutyric acid (inhibitory)

- dopamine, serotonin, glycine

4) Endorphins/enkephalins - pain transmission

1) Depolarization wave

2) voltage-gated Ca²⁺ channels open

3) Calcium floods in and synaptic vesicles fuse with membrane

4) By exocytosis NT's released into synaptic cleft

5) NT's bind to receptors on post-synaptic neuron

6) Post-synaptic neuron depolarizes

7) NT's recycled by endocytosis

1) nerve fibers are individual axons of neurons

1) Produced by Schwann Cells (PNS) and oligodendrocytes (CNS)

2) not continuous (Nodes of Ranvier)

3) uniform thickness

4) easily seen with osmium

1) Major dense line

- visible by EM

- fusion sites of inner leaflets of myelinating plasma membranes

2) Intraperiod lines

- visible by EM

- sites of close contact but not fusion of extracellular surfaces of adjacent myelinating cells

3) Clefts of Schmidt-Lantermann

- visible by light microscopy

- in peripheral myelinated nerves

- cone-shaped discontinuities in myelin sheath

- heavy in mito

4) Inner mesaxon

5) Outer mesaxon

1) CNS and PNS

2) Schwann cell cytoplasm covers Node (not always in CNS)

3) axolemma contains many electron dense sodium pumps

1) Type A

- Largest diameter

- thick and myelinated

- long internodes

- high conduction velocity

- reflexive

2) Type B

- medium

- thinner myelin

- moderate velocity

- post-ganglionic autonomics

3) Type C

- thin fiber

- lack myelin

- slowest velocity

- pain

- post-ganglionic sympathetics

1) can be sutured

1) exists across PM of all electrically competent cells

2) K is 20x higher inside; Na is 10x higher outside

3) PM highly permeable to K, diffuses outward

- offset by intracellular Cl (interior is 40-100mV negatively charged compared to exterior of cell)

4) Resting potential actively maintained by Na-K pump exchanging Na for K

1) Movement of negative charges along outside of axon

2) "All or nothing"

1) Excitatory stimulus partially depolarizes portion of postsynaptic membrane

- makes it less - via Calcium increases usually

2) Membrane reaches critical threshold, Na channels open

3) Local reversal of resting membrane potential

- external surface becomes negative

4) Na channels spontaneously close for 1-2 millisec (refactory period)

5) K channels remain open and resting potential is reset

1) diffusion of Na+ ions into the cell laterally beginning at the site of initial synaptic activation

- toward the axon terminal in the target neuron

- orthodromic spread

-is unidirectional as Na+ channel inactivation occurs at/near the soma preventing movement of impulse to cell body (antidromic spread)

-propogation occurs most rapidly in myelinated fibers, which exhibit saltatory conduction (action potential

1) Spinal Cord Injury (SCI)

2) Stroke

3) Multiple Sclerosis (MS)

- autoimmune where CNS myelin is attacked by inflammatory rxns causing plaques of inflammation and demyelination

- young adult females

- causes death of oligodendrocytes

4) Amyotrophic Lateral Sclerosis (ALS - Lou Gherig's)

- extreme skeletal muscle wasting due to loss of motor neurons in spinal cord

- fatal typically due to respiratory failure

- men 50-70 rate is double

- may involve LMN's and UMN's

5) Neuroglial Tumors

- derived from astrocytes, oligodendrocytes, ependymal

- benign oligodendrogliomas

- malignant astrocytomas

3 Layers

- Molecular Layer

- contains unmyelinated fibers from granular layer

- dendritic processes of Purkinje cells

- stellate and basket cells (specialized interneurons)

- Purkinje Cell Layer

- Purkinje cells unique to cerebellar cortex

- Granular Layer

- cerebellar islands/glomeruli

- areas of synapses between axons entering the cerebellum and granule cell dendrites