Nervous Tissue Flashcards
functional unit of the nervous system
Neuron
3 basic components of neuron
cell body/soma, axon, dendrites
Multipolar neuron
irregularly shaped cell body-more than 2 cell processes-with one the axon and the other dendrites .(Motor and Interneurons)
Bipolar neuron
1 dendrite and axon (retina, olfactory receptor neurons)
Pseudounipolar neurons
single process close to the cell body divides into 2 branches. One branch extends to the CNS and the other to a peripheral ending
Motor neurons
control effector organs and exocrine and endocrine glands
Sensory neurons
receive sensory stimuli
form links among neurons
interneurons
Receiving surfaces of neurons
dendritic and cell body synaptic sites
name of the “conducting process” in a neuron
axon
Impulse initiating mechanism
the initial segment aka “axon hillock”
On a slide what would neuron look like?
Speherical, large, pale staining, centrally located nucleus with prominent nucleolus
conduct information away from cell body
axons
Plasma membrane of the axon
=the axolemma and cytoplasm = the axoplasm
Axoplasm contains abundant _______ and ________
microtubules and neurofilaments (no ribosomes or Golgi)
Transport of metabolites in the axon may be _______ or ______ (direction)
orthograde(from cell body to nerve endings) or retrograde (nerve ending to cell body)
Cytoplasmic dynein
can transport organelles and vesicles in retrograde direction. Retrograde flow can carry viruses and toxins along the axon into the CNS.
Dendrites
branching cell processes-protrude from the cell body
Do dendrites have myelin sheath
Dendrites have NO myelin sheath
Function of dendrite
transmit information toward cell body
Cytoplasm of dendrites lack _____________
Golgi complex
Large dendrites may have ____ substance
Nissl
Dendritic spines
present on some dendrites with beaded appearance and are specialized for synaptic contact
Contact of one axon with the dendrites
axodendritic synapse
Contact of one axon with cell body
axosomatic synapse
Contact of one axon with another axon
axoaxonic synapse
Contact of one axon with dendritic spine
axospinous
Contact site between dendrites
dendrodendritic
Where are neurotransmitters stored
synaptic vesicles
Synaptic vesicle membrane contains vesicular docking proteins that
attach to membrane docking proteins of presynaptic membrane
What causes exocytosis of neurotransmitters from vesicle
depolarization of axon terminal
Basic function of Neuroglia
function in mechanical and metabolic support of neurons
Examples of neuroglia in CNS
astrocytes, oligodendrocytes, microglia, ependymal cells
Name of neuroglia in PNS
Schwann cells
Name of neuroglia in CNS that contributes to blood brain barrier
astrocytes
Largest of the neuroglial cells
astrocytes; have processes that attach to capillary walls
Where are astrocytes located?
Localized beneath pia of brain and spinal cord
Function of astrocytes
assist in maintenance of electrolyte balance in CNS and nutrient transport to neurons
Ependymal cells
line neural tube and ventricles of the brain; bathed in CSF ;many have motile cilia
microglia
phagocytic cells derived from bone marrow monocytes. condensed elongated nucleus
Oligodendrocytes
In CNS, analogous to Schwann cells of PNS. Produce myelin.(In gray matter-localized close to perikaryons. In white matter-appear in rows among myelinated nerve fibers)
What are two specific types of astrocytes
Protoplasmic astrocytes and Fibrous astrocytes
Protoplasmic astrocytes
Granular cytoplasm. Processes have many short and thick branches. CNS gray matter
Fibrous astrocytes
Long, slender, infrequently branching processes. CNS white matter.
What astrocytes are found in CNS white matter
Fibrous astrocytes
Choroid plexus
Ependymal cells and associated capillary loops that are modified to produce CSF
Schwann cells produce
myelin for myelinated axons in PNS
Schwann cells originate from
neural crest cells
Myelinated nerve fibers
Schwann cell wraps around and form myelin sheath -(lipoprotein complex)
Dark regular lines of myelin
major dense lines
Less regular lines of myelin
interperiod lines
Nodes of Ranvier
spaces between adjacent Schwann cells that appear as gaps in the myelin sheath
Distance between 2 nodes on myelinated nerve fibers
an internode (1 Schwann cell)
Schmidt-Lantermann clefts
Small clefts or fissures in the myelin
Non-myelinated nerve fibers
Axons containing no myelin sheath but are ensheathed by Schwann cells or oligodendrocytes
Schwann cell sheath
neurolemma
Peripheral nerves may be ________ or ________
myelinated or nonmyelinated
Ganglia on slide
ovoid structures encapsulated by dense connective tissue
Nerve ganglion
aggregation of NERVE CELL BODIES outside the CNS
Sensory ganglia
1) dorsal root ganglia 2) ganglia of cranial nerves
Where are autonomic ganglia located
Sympathetic ganglia occur as segmented chain ganglia (sympathetic trunk) and non-segmental collateral ganglia (pre vertebral)
Where are parasympathetic ganglia located?
Scattered throughout body located near organs they innervate
Auerbach’s plexus
parasympathetic ganglion in walls of lower GI tract
Spinal cord
Central mass of gray matter (H-shaped), surrounded by myelinated and non-myelinated nerve fibers
Gray matter consists of a broad anterior horn, a narrow posterior horn joined by a
central commissure
Where are the lateral horns located?
Lateral horns are present in the thoracic and first 2 lumbar segments
The anterior horn contains
large motor neurons which send axons via the ventral spinal roots to skeletal muscles - terminate in motor plates
The posterior horn contains
small nerve cells which receive afferent impulses from sensory nerve cells of the spinal ganglion cells via dorsal spinal roots
Pacini’s corpuscle
nerve ending; lamellated corpuscle with “onion shape”. located in subcutaneous tissue-sense organ stimulated by pressure found in deep layers of skin particularly around finger pads. Transducer which responds to vibration, pressure, and tension
Meissner’s corpuscles
nerve ending; touch receptors numerous in dermal papillae of finger pads. involved in 2-point discrimination
Merkel nerve ending
Merkel cell in skin associated with nerve. pressure and texture sensor. Sustained response to pressure. also involved in 2-point discrimination along with Meissner’s corpuscle
Blood Brain Barrier
Continuous capillaries with occluding junctions + cell processes of astrocytes
What kind of drugs cross Blood Brain Barrier
lipid soluble drugs; substance>500 daltons
