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44 Cards in this Set

  • Front
  • Back
Nerve tissue is distributed throughout the body as an integrated communications network:
Sensory - Discriminative (Afferent)
Motofacient - Secretory (Efferent)
Cognative - Affective
What are the two cell types in nervous tissue?
Neurons and Glial Cells
How is the nervous system topographically divided?
CNS - Brain, spinal cord
PNS - Peripheral nerves, ganglia, cranial and spinal nerves
______________ are specialized for transmitting nerve impulses
supporting cells, called _____________ provide for the maintenance of the chemical environment around neurons, and produce an insulating material called _________________.
Name structure and function:
***Neuron - answer
Functional classifications of neurons:
Efferent or motor neurons carry commands to muscles and glands.
Afferent or sensory neurons are involved in the reception of sensory stimuli.
Interneurons, which constitute the largest class, establish connections among other neurons.
Shape classification of neurons:
Multipolar neurons - one axon and many dendrites.
Bipolar neurons (retina and olfactory) - a dendrite that carries information from the periphery, and an axon that conveys information toward the CNS.
Pseudounipolar neurons (spinal and cranial ganglia) - single axon that branches to send one process to the CNS and one process to the periphery.
What is Nissl substance?
within nerve cell, aggragates of ribosomal RNA
What is the plasma membrane of a nerve called?
Are ribosomes present within the axon?
No, they are absent and therefore rely on the cell body for metabolic needs and neurotransmitter manufacturing
What are the characteristics of the axon hillock?
The axon hillock is characterized by the absence of Nissl substance and the presence of large numbers of microtubules and neurofilaments.
What are axons' main functions?
They conduct action potentials

They transport materials by a process called axoplasmic transport
What is axoplasmic transport?
involves mechanisms by which selected organelles and certain chemical substances are moved along the axon in both directions
Define anterograde vs. retrograde transport:
Anterograde - Cell body along axon

Retrograde - Axon to cell body
What are the main functions of glia?
To serve as supporting elements in the brain.

To form myelin (oligodendrocytes in the CNS and Schwann cells in the PNS), the insulating sheath that covers most large axons

To function as scavengers (microglia), removing debris after injury or cell death

To buffer the extracellular space and take up some neurotransmitters released by neurons during synaptic transmission.

To form part of the blood-brain barrier.
What are the two classifications of glial cells and where are they located?
Microglia - bone marrow-derived macrophages that are scattered throughout the CNS. These cells become phagocytic, cleaning up cellular debris and ingesting damaged myelin.

Macroglia - consist of Schwann cells and satellite cells (PNS), and oligodendrocytes and astrocytes (CNS).
What type of cells do schwann cells cover?
Both myelinated and unmyelinated nerve cells
How many axons can a schwann cell cover?
Although a schwann cell may envelope many axons, it will only myelinate one axon
What does myelination do for a cell?
Increases the speed of conduction
What exists between schwann cells?
Nodes of Ranvier
How many axons can an oligodendrocyte myelinate?
Unlike the schwann cells in the PNS, the oligodendrocytes have multiple processes and are capable of myelinating multiple axons
Where are satellite cells located in nerve cells?
The satellite cells surround nerve cell bodies in both autonomic and sensory ganglia
Describe how astrocytes look:
Star shaped
Many cell processes
What do astrocytes do?
Astrocytes form most of the supporting cells of the CNS.

They participate in:
*The regulation of ionic balance in the extracellular space during the generation of action potentials.

*Aid in the repair of damaged neural tissue

*They participte in the formation of the blood-brain barrier.
Connective tissue is a component of nerve bundles. What are the layers from superficial to deep?
What is the epineurium?
Loose connective tissue with axon bunndles embedded within
What is the perineurium?
Bundles of axons (bounded by endoneurium) are then bundled into perineurium
What is endoneurium?
Connective tissue that surrounds each axon
The meninges of the brain have extensions into the PNS, what are they?
Dura Mater --> Epineurium
Arachnoid --> Perineurium
Pia Mater --> Endoneurium
What are the two types of tissue within the CNS and describe their topographical relationship with each other:
Dark Matter - Cortex of brain, center of spinal cord

White Matter - Bulk of central brain, exterior portions of spinal cord
What is grey matter composed of?
neuron cell bodies, their dendrites and axons, glial cells and blood vessels. Aggregates of neuronal cell bodies are called "nuclei"
What is white matter composed of?
mainly of myelinated axons and glial cells, and provides the routes (nerve tracts) that connect one part of the brain to another
How much of the brain's total volume is devoted to the cerebrum?
Histologically, how is the cerebral cortex (grey matter) arranged?
In layers that follow the contours of the cerebral cortex
The layers of cerebral cortex (grey matter) tend to have different purposes, ie, regions tend to be receivers or senders.

What is it?
Histologically, the cerebral cortex (gray matter) is organized in several layers parallel to the outer surface. The outer layers receive afferent input from other regions of the cerebral cortex and brainstem, while the inner layers send efferent fibers into the white matter.
Within the cerebrum, what type of neurons are mostly present?
Pyramidal (motor) cells

Interneurons (stellate cells)
What is the thalamic nuclei?
integrates information for the cortex, and is involved in maintaining consciousness
What is the basal ganglia?
involved in coordinating muscle action and tone
How is the gray matter of the spinal cord divided?
Divided in concentric laminae (I-X)
What is within the white matter of the spinal cord?
Ascending and descending tracts
What are the horns of the spinal cord for?
posterior or dorsal horn - is associated with afferent (sensory) functions

anterior or ventral horn - contains large motor neurons
What are the two components of the blood-brain barrier?
*Tight surround layer of astrocytes

*Impermeable endothelial cells of the endoneurial capillaries
Where is the blood-nerve barrier not well-developed?
blood-nerve barrier is not well-developed in sensory and autonomic ganglia