11/21/2014 Microscopic Anatomy Nerve Thomas Poole Flashcards
What is another term for a Schwann cell?
Neurolemmocyte
T/F: A single Schwann cell can cover many axons.
True
What are the progenitors of Schwann cells?
Neural crest cells
What creates the Schmidt-Lanterman clefts?
The leftover cytoplasm in the Schwann cell that gets squeezed into this one space, creating an arrowhead like appearance.
The lipid component of myelin is not preserved by _____ and standard histological preparation.
Formalin fixation
The place where one Schwann cell is adjacent to another is called?
A node of Ranvier
What covers a node of Ranvier?
Interdigitating cytoplasmic processes
If you want lipid to appear on a histo slide, what chemical should be added to your preparation?
Osmium
T/F Nerves may contain both myelinated and unmyelinated fibers.
True
What is the epineurium made of?
Dense irregular connective tissue
Loose connective tissue
The most prominent and visible coat of a nerve is the ____ that forms a longitudinal bundle (fasicle) of axons.
perineurium
How are nerves protected from the outside extracellular environment?
The perineurium is made of several layers of specialized fibroblastic cells (epitheloid myofibroblasts) that form tight junctions with one another. This arrangement provides a barrier to the massage of most macromolecules.
The Schwann cell ensheathed axons are surrounded by a delicate layer of _________ called the endoneurium.
Reticular fibers
What are ganglia?
Peripheral clusters of nerve cell bodies that are surrounded by satellite cells.
T/F: Sensory and autonomic ganglia cannot be distinguished by the light microscope.
False, they can be distinguished at the level of the light microscope
Sensory ganglia are also known as:
dorsal root ganglia (DRG)
T/F: No synapses take place within the sensory ganglia.
True. DRGs contain the cell bodies of pseudounipolar sensory neurons.
How do satellite cells appear around sensory neurons in a sensory ganglion?
Evenly spaced around the neuron, like a chain of pearls.
How does the nucleus appear in a sensory ganglion cell?
In the middle.
Also note: many myelinated nerve fibers in these cells.
The sensory or dorsal root ganglia contain cell bodies of:
pseudounipolar sensory neurons
The autonomic ganglia contain cell bodies of:
multipolar neurons
T/F: Synapses do not occur in autonomic ganglia.
FALSE. Synapses do not occur in sensory ganglia, but DO occur in autonomic ganglia.
In comparison to sensory ganglia, autonomic ganglia appears more _____.
disordered.
What is a main distinguishing feature of autonomic ganglia?
Multiple process coming out of the cell.
Nuclei not in the center.
Smaller neuronal cell bodies than sensory ganglia.
Numerous unmyelinated nerve fibers.
Where do motor neurons terminate?
At the motor endplate
The postsynaptic membrane of a motor neuron contains two very important features. What are they?
- Junctional folds
2. Acetylcholine receptors
Bare axons (free nerve endings) are important for sensations of what?
Hot and cold from the skin, itching, touch and pain
What are the three encapsulated nerve endings?
- Meissner’s corpuscles
- Pacinian corpuscles
- Muscle spindles
Where are Meissner’s corpuscles found?
Dermal papillae of hairless skin
What kind of touch do Meissner’s corpuscles detect?
low-frequency stimuli
Where are Pacinian corpuscles found?
dermis or hypodermis
What are Pacinian corpuscles made of?
Concentric layers of flatted Schwann cells
What kind of stimuli do Pacinian corpuscles detect?
Pressure, vibration due to displacement of capsule lamellae
What is the main function of a muscle spindle?
It is a proprioceptor.
Muscle spindles contain specialized muscle fibers called ____ in a fluid-filled space.
Intrafusal fibers
How do muscle spindles work?
Sensory nerve fibers exiting the capsule send signals about the extrafusal muscle fiber length and relay this information to the spinal cord where it plays a role in reflexes involved in maintaining posture and coordinating walking.
