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54 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What layer does nervous tissue develop from?
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ectoderm
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What are the components of the CNS?
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brain & spinal cord
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What are the components of the PNS?
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spinal, autonomic, enteric nerves; ie, all NERVES lie in the PNS
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3 types of nerves
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How are the peripheral nerves classified directionally, and what do these classes do?
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Sensory - afferent info towards CNS
Motor - efferent info away from CNS |
2 types
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What are the effectors for peripheral nerves?
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Muscle, glands
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How are peipheral nerves classified by type of signal?
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Somatic, visceral (autonomic)
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What are the important features of SOMATIC nerves?
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- Conscious perception
- Voluntary - SINGLE neuron connection from CNS to effector |
3 major points
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What are the important features of AUTONOMIC nerves?
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- Sensory/unconscious (proprioception)
- Involuntary (smooth muscle, cardiac, glands) - 2 neurons b/w CNS and target |
AUTO-nomic!
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How are the autonomic nerves further divided?
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Parasympathetic, sympathetic
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What characterizes SYMPATHETIC nerves?
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Fight/flight, catabolic, mobilize energy stores -- INCREASED ACTIVITY
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Sympathizes with you, to prepare for a tough situation.
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What are the characteristics of the parasympathetic division?
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Rest and repose, anabolic, tissue growth and repair -- RESTING FUNCTIONS
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Antagonizes sympathetic
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Contrast the origin of nerve cell bodies in para/sympathetic nerves.
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Sympathetic = thoracic + lumbar spinal cord
Parasympathetic = sacral + cervical/cranial |
SLuT
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Contrast the 1st synapse location in para/sympathetic nerves.
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Sympathetic = Proximal to CNS
Parasympathetic = Proximal to TARGET |
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What are the 3 types of cells present in nervous tissue?
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Neurons, Glia, Support Cells
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General function of neurons?
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Excitable cells - info transfer
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General function/origin of glia?
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Non-excitable cells of NEURAL ORIGIN that enhance transmission efficiency
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General function of support cells?
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Cells from blood vessels AND microglia - NON-NEURONAL ORIGIN
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What are microglia?
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Immune cells of CNS (phagocytic)
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What is Nissl substance
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ribosome rich RER found in neuron.
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What are the 4 major parts of neurons?
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Soma, Dendrites, Axon, Axon terminal
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What is the function and an important histological characteristic of DENDRITES?
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Receive impulses, conduct towards cell body. NO GOLGI COMPLEXES.
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What is the function and an important histological characteristic of AXONS?
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Conducts impulses AWAY from cell body. Mitochondria, SER. NO RER! Also contains neurofilaments and microtubules.
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Compare the structure and function of NEUROFILAMENTS and MICROTUBULES
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NF - Smaller, structural. Intermediate filaments
MT - Larger, for transport. Microtubules. |
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What does anterograde mean wrt axonal transport?
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Towards axon terminal.
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What is histologically characteristic about the synaptic cleft?
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Numerous vesicles at the axon terminal. Space between 2 cells.
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What characterizes neurofilaments?
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- Structural, intermediate filaments. small
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What characterizes microtubules?
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Transport. Larger.
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What are the 6 stages in synaptic transmission?
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1. Vesicle transport
2. Vesicle loading 3. Depolarization 4. Exocytosis 5. Binding of neurotransmitter 6. Depolarization of target |
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What occurs during the depolarization phase?
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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.
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What occurs on neuronal excitation?
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K+ exits cell, Na+ and Cl- enter.
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What are characteristics of unmyelinated neurons?
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- Leak Na+
- Channels must open along entire length - Slower |
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How does myelination occur in the PNS?
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Schwann cells. Wrap around an individual axon. Discontinuous - nodes of ranvier.
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How does myelination occur in the CNS?
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Oligodendrocytes; functionally analagous to schwann cells. 1 oligodendrocyte/>60 axons!
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What would be expected of a heavily myelinated axon?
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Fast
Acute pain SOMATIC motor |
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What would be expected of a moderately/unmyelinated axon?
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Slow
Visceral (AUTONOMIC) motor CHRONIC pain/pleasure |
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What are the 4 functions of GLIAL cells?
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- Biochemical (speeds up neurotransmission)
- Structural (physical support) - Nutritive (growth/maintenance) - Immune (scavenge toxins, depris) |
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What are the types of neuroglial cells?
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- Protoplasmic + fibrous astrocytes
- Microglia - Oligodendrocytes |
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What are the functions of protoplasmic & fibrous astrocytes?
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- Contact blood vessels (blood-brain barrier)
- Maintain local blood flow - Scavenge IONS - ion homeostasis |
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What are the staining characteristics of FIBROUS astrocytes?
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- Stained by antibody against Glial Fibrillary Acidic Protein (GFAP)
- The above is an intermediate filament |
GFAP
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What are the connective tissue coverings in the PNS?
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- Endoneurium, perineurium, epineurium
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What characterizes the ENDONEURIUM?
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- Surrounds individual NERVE FIBERS (axons)
- Mast cells, fibroblasts, macrophages, capillaries - Contacts basal lamina of Schwann cells. |
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What are the characteristics of the perineurium?
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Middle CT layer. Bundles of nerve fibers.
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What are the characteristics of the epineurium?
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- Outermost CT layer: DENSE irregular collagenous CT
- Collagen prevents overstretching - Continuous with dura |
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What are the 3 connective tissue coverings of the CNS?
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- Dura mater, arachnoid membrane, pia mater [PAD]
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What characterizes the DURA mater?
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- 2 layers of DENSE irregular collagenous CT
- Fibroblasts, osteoprogenitors, CT connected to skull |
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What characterizes the ARACHNOID SPACE?
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- AVASCULAR
- Fibroblasts (gap junctioned), collagen, elastic |
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What characterizes the PIA MATER?
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- Follows brain contours
- Fibroblasts, abundant BLOOD VESSELS - Macrophages, mast cells, lymphocyts - Separated from neural tissue by NEUROGLIA |
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What maintains brain homeostasis?
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- Capillary endothelium and ependymal cells.
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What is the capillary endothelium?
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- 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 |
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What are ependymal cells?
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- Continuous layer of cells lining the brain in pia mater
- Synthesize, Secrete, Excrete CSF into subarachnoid space - Maintain blood-CSF barrier |
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What is the choroid plexus?
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- Folds of pia mater with capillaries that makes CSF
- Blood-CSF barrier - Actively transports ions |
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What are arachnoid villi?
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- Regions where arachnoid extends to dural venous sinuses
- Returns CSF from subarachnoid space to blood |
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What is white matter?
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Myelinated axons
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What is gray matter?
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Neuronal cell bodies
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