Chapter 9: Nerve Tissue Flashcards
Name for nerve cells; respond to environmental stimuli by a reversal of their ionic gradient
Neurons
cells that support and protect neurons
Glial cells
______ nervous system consisting of the brain and the spinal cord
Central (CNS)
_______ nervous system composed of the cranial, spinal, and peripheral nerves
Peripheral
The nervous system develops from the ______ of the three early embryonic layers
Ectoderm
Step 1 of nervous system development: the overlying layer of ectodermal cells thickens as a bending ___ ___
Neural plate
Step 2 of nervous system development: The plate bends further, making the neural ___ and _____
Folds and groove
Step 3 of nervous system development: the neural folds rise and fuse at the midline, converting the groove into the ____ ____
Neural tube
Cells of the the neural ___ give rise to the entire CNS including neurons and most glial cells
Neural tube
Two other names for the cell body of a neuron ___ and ___
Soma and perikaryon
The ___ ___ which contains the nucleus and most of the cell;s organelles and serves as the synthetic to tropic center for the entire neuron
Cell body/soma/perikaryon
The ______, which are the numerous elongated processes extending from the the perikaryon and specialized to receive stimuli from the other neurons at unique sites called synapses
Dendrites
The ____, which is a single long process ending at synapses specialized to generate and conduct nerve impulses to other cells
Axon
_____ neuron has one axon and two or more dendrites; most common classification
Multipolar neurons
_____ neurons have one dendrite and one axon; comprise the sensory neurons of the retina, the olfactory epithelium, and the inner ear
Bipolar neurons
____ or _____ neurons have a single process that splits into two, near the soma, with the longer branch extending to a peripheral ending and the other toward the CNS
Unipolar or pseudounipolar neurons
Sensory neurons are _____, receiving stimuli from receptors throughout the body and convert to the CNS
Afferent
Motor neurons are _____, sending impulses to effector organs such as muscle fibers and glands from the CNS
Efferent
_______ establish relationships among other neurons, forming complex functional networks or circuits in the CNS
Interneurons
In the CNS, most synapses on dendrites occur on dendritic ____
Dendritic spines
Dynamic membrane protrusions along the small dendritic branches
Dendritic spines
Axons originate from a pyramid-shaped region of the perikaryon called the ___ ___, juts beyond which the axolemma has concentrated ion channels that generate the action potential
Axon hillock
Each small axonal branch ends with a dilation called a _____ ____ that contacts another neuron or non-nerve cell at a synapse to initiate an impulse in that cell
Terminal bouton
Organelles and macromolecules synthesized in the cell body move by _______ transport along axonal microtubules via _____ from the perikaryon to the synaptic terminals
Anterograde transport; Kinesin
______ transport from the synaptic terminals to perikaryon via ______ carries certain other macromolecules
Retrograde transport; Dynein
Sites where nerve impulses are transmitted from one neuron to another, or from neurons and other effector cells
Synapses
Small molecules that bind specific receptor proteins to either open or close ion channels or initiate second-messengers cascades
Neurotransmitters
_____ synapse: branched axon terminals associated with and transmit a nerve impulse to another neuron’s cell body (soma)
Axosomatic synapses
_____ synapse: branched axon terminals associated with and transmit a nerve impulse to a dendritic spine
Axodendritic synapses
____ synapse: an axon terminal forms a synapse with an axon terminal of another neuron
Axoaxonic synapses
The fibrous intercellular network of CNS tissue emerging from neurons and glial cells
Neuropil
______ extend many processes, each of which becomes sheetlike and wraps repeatedly around a portion of a nearby CNS axon
Oligodendrocytes
The ____ ____ electrically insulates the axon and facilitates rapid transmission of nerve impulses
Myelin sheath
______ originate from progenitor cells in the embryonic neural tube and are by far the most numerous glial cells of the brain
Astrocytes
Astrocytes extend fibrous processes with expanded ________ feet that cover endothelial cells, capillaries
Perivascular feet
________ mediate the exchange of ions, oxygen, and other molecules; form part of the blood brain barrier; control vasodilation
Astrocytes
Astrocytes form a barrier layer of expanding protoplasmic processes, called the ___ ___ membranes which lines the meninges at the external CNS surface (Pia Matter)
Glial limiting membrane
Form scar tissue in the CNS at sites of damage
Astrocytes
Columnar or cuboidal cells that line the fluid-filled ventricles of the brain and the central canal of the spinal cord
Ependymal cells
______ cells joined tightly together; no basal lamina; attached to neuropil; some areas apical end can have microvilli
Ependymal cells
Consisting of small cell bodies from which radiate many long, branched processes, are less numerous than oligodendrocytes or astrocytes but nearly as common as neurons in some CNS regions
Microglia
______ cells also constitute the major mechanism of immune defense in the CNS, removing any microbial invaders and secreting several immunoregulatory cytokines
Microglial cells
These cells originate from blood monocytes
Microglial cells
____ cells are only found up the PNS and differentiate from precursors in the neural crest
Schwann cells
Form myelin around a portion of only one axon per cell
Schwann cells
Derived from the embryonic neural crest, small ______ cells form a thin, intimate glial layer around each large neuronal cell body in the ganglia of the PNS
Satellite cells
Loose areas of cytoplasm in Schwann cells myelin sheath; uncompacted regions
Schmidt-Lanterman clefts
The major structures comprising the ______ are the cerebrum, cerebellum, and spinal cord
CNS
The main components of ______ matter are myelinated axons and the myelin-producing oligodendrocytes
White matter
_____ matter contains abundant neuronal cell bodies, dendrites, astrocytes, and microglial cells, and is where most synapses occur
Gray matter
In the cerebrum and cerebellum, ______ matter makes up the periphery and ____ matter makes up the center
Grey; white
In the spinal cord, ______ matter makes up the periphery and ____ matter makes up the center
White; grey
Neurons of the _____ cortex function in the integration of sensory informations and the initiation of voluntary motor responses
Cerebral cortex
The main components of the ______ are the nerves, ganglia, and nerve endings
PNS
Btw adjacent Schwann cells on an axon, the myelin sheath shows small ____ ___ ____, where the axon is only partially covered by interlocking Schwann cell processes
Node of Ranvier
