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54 Cards in this Set

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What layer does nervous tissue develop from?
What are the components of the CNS?
brain & spinal cord
What are the components of the PNS?
spinal, autonomic, enteric nerves; ie, all NERVES lie in the PNS
3 types of nerves
How are the peripheral nerves classified directionally, and what do these classes do?
Sensory - afferent info towards CNS
Motor - efferent info away from CNS
2 types
What are the effectors for peripheral nerves?
Muscle, glands
How are peipheral nerves classified by type of signal?
Somatic, visceral (autonomic)
What are the important features of SOMATIC nerves?
- Conscious perception
- Voluntary
- SINGLE neuron connection from CNS to effector
3 major points
What are the important features of AUTONOMIC nerves?
- Sensory/unconscious (proprioception)
- Involuntary (smooth muscle, cardiac, glands)
- 2 neurons b/w CNS and target
How are the autonomic nerves further divided?
Parasympathetic, sympathetic
What characterizes SYMPATHETIC nerves?
Fight/flight, catabolic, mobilize energy stores -- INCREASED ACTIVITY
Sympathizes with you, to prepare for a tough situation.
What are the characteristics of the parasympathetic division?
Rest and repose, anabolic, tissue growth and repair -- RESTING FUNCTIONS
Antagonizes sympathetic
Contrast the origin of nerve cell bodies in para/sympathetic nerves.
Sympathetic = thoracic + lumbar spinal cord

Parasympathetic = sacral + cervical/cranial
Contrast the 1st synapse location in para/sympathetic nerves.
Sympathetic = Proximal to CNS

Parasympathetic = Proximal to TARGET
What are the 3 types of cells present in nervous tissue?
Neurons, Glia, Support Cells
General function of neurons?
Excitable cells - info transfer
General function/origin of glia?
Non-excitable cells of NEURAL ORIGIN that enhance transmission efficiency
General function of support cells?
Cells from blood vessels AND microglia - NON-NEURONAL ORIGIN
What are microglia?
Immune cells of CNS (phagocytic)
What is Nissl substance
ribosome rich RER found in neuron.
What are the 4 major parts of neurons?
Soma, Dendrites, Axon, Axon terminal
What is the function and an important histological characteristic of DENDRITES?
Receive impulses, conduct towards cell body. NO GOLGI COMPLEXES.
What is the function and an important histological characteristic of AXONS?
Conducts impulses AWAY from cell body. Mitochondria, SER. NO RER! Also contains neurofilaments and microtubules.
Compare the structure and function of NEUROFILAMENTS and MICROTUBULES
NF - Smaller, structural. Intermediate filaments

MT - Larger, for transport. Microtubules.
What does anterograde mean wrt axonal transport?
Towards axon terminal.
What is histologically characteristic about the synaptic cleft?
Numerous vesicles at the axon terminal. Space between 2 cells.
What characterizes neurofilaments?
- Structural, intermediate filaments. small
What characterizes microtubules?
Transport. Larger.
What are the 6 stages in synaptic transmission?
1. Vesicle transport
2. Vesicle loading
3. Depolarization
4. Exocytosis
5. Binding of neurotransmitter
6. Depolarization of target
What occurs during the depolarization phase?
When the signal travels to the axon terminal, the membrane depolarizes, opening Ca2+ channels. The influx of calcium causes the vesicles to fuse with the membrane, releasing their neurotransmitter.
What occurs on neuronal excitation?
K+ exits cell, Na+ and Cl- enter.
What are characteristics of unmyelinated neurons?
- Leak Na+
- Channels must open along entire length
- Slower
How does myelination occur in the PNS?
Schwann cells. Wrap around an individual axon. Discontinuous - nodes of ranvier.
How does myelination occur in the CNS?
Oligodendrocytes; functionally analagous to schwann cells. 1 oligodendrocyte/>60 axons!
What would be expected of a heavily myelinated axon?
Acute pain
What would be expected of a moderately/unmyelinated axon?
Visceral (AUTONOMIC) motor
CHRONIC pain/pleasure
What are the 4 functions of GLIAL cells?
- Biochemical (speeds up neurotransmission)
- Structural (physical support)
- Nutritive (growth/maintenance)
- Immune (scavenge toxins, depris)
What are the types of neuroglial cells?
- Protoplasmic + fibrous astrocytes
- Microglia
- Oligodendrocytes
What are the functions of protoplasmic & fibrous astrocytes?
- Contact blood vessels (blood-brain barrier)
- Maintain local blood flow
- Scavenge IONS - ion homeostasis
What are the staining characteristics of FIBROUS astrocytes?
- Stained by antibody against Glial Fibrillary Acidic Protein (GFAP)
- The above is an intermediate filament
What are the connective tissue coverings in the PNS?
- Endoneurium, perineurium, epineurium
What characterizes the ENDONEURIUM?
- Surrounds individual NERVE FIBERS (axons)
- Mast cells, fibroblasts, macrophages, capillaries
- Contacts basal lamina of Schwann cells.
What are the characteristics of the perineurium?
Middle CT layer. Bundles of nerve fibers.
What are the characteristics of the epineurium?
- Outermost CT layer: DENSE irregular collagenous CT
- Collagen prevents overstretching
- Continuous with dura
What are the 3 connective tissue coverings of the CNS?
- Dura mater, arachnoid membrane, pia mater [PAD]
What characterizes the DURA mater?
- 2 layers of DENSE irregular collagenous CT
- Fibroblasts, osteoprogenitors, CT connected to skull
What characterizes the ARACHNOID SPACE?
- Fibroblasts (gap junctioned), collagen, elastic
What characterizes the PIA MATER?
- Follows brain contours
- Fibroblasts, abundant BLOOD VESSELS
- Macrophages, mast cells, lymphocyts
- Separated from neural tissue by NEUROGLIA
What maintains brain homeostasis?
- Capillary endothelium and ependymal cells.
What is the capillary endothelium?
- Tight lining of blood vessels that maintains BBB
- Does not allow many usually permitted cells out of the blood
- LIPID-soluble substances pass!
- Tight junctions
- Astrocytes cover
What are ependymal cells?
- Continuous layer of cells lining the brain in pia mater
- Synthesize, Secrete, Excrete CSF into subarachnoid space
- Maintain blood-CSF barrier
What is the choroid plexus?
- Folds of pia mater with capillaries that makes CSF
- Blood-CSF barrier
- Actively transports ions
What are arachnoid villi?
- Regions where arachnoid extends to dural venous sinuses
- Returns CSF from subarachnoid space to blood
What is white matter?
Myelinated axons
What is gray matter?
Neuronal cell bodies