Final Exam Flashcards
What is the pathway for innervation of skeletal muscle by a motor neuron?
input via axons from other neurons-> cell body -> axon hillock -> initial segment -> collateral branch of axon -> Node of Ranvier -> Effector (skeletal muscle)
What are the types of sensory neurons?
bipolar and pseudounipolar
What are the types of integrative neurons?
pyramidal cell, interneurons, and Purkinje cells
What are the cytological contents of the axon?
mitochondria, microtubules and neurofilaments
What is ante retrograde transport mediated by?
Kinesin
What is retrograde transport mediated by?
Dynein
What is the path of anterograde transport?
from the perikaryon to the periphery
What is the path of retrograde transport?
from axon terminals and dendrites to the perikaryon
What is the mesoaxon?
a pair of parallel plasma membranes of a Schwann cell that marks the point of edge-to-edge contact in myelination.
What is the myelin sheath composed of?
lipid, cholesterol, and proteins
What are Schmidt-Lantermann clefts?
small islands of cytoplasm in the myelin sheath.
What are the satellite cells of PNS?
small cuboidal cells surrounding neurons that provide electrical insulation and metabolic exchange
What are the four types of neuroglia cells in the CNS?
astrocytes, oligodendrocytes, microglia, and ependymal cells
What is the purpose of astrocytes?
proliferate in injury/disease, form blood brain barrier, modulate synapse formation and efficiency, and provide physical support.
What are the types of astrocytes?
Fibrous astrocytes and protoplasmic astrocytes
What is the purpose of oligodendrocytes?
produce CNS myelin (homolog to schwann cells of PNS)
T/F: One oligodendrocyte can produce multiple myelin Sheaths?
T
What is the purpose of microglia?
proliferate and become phagocytic in response to CNS injury or disease
What is the purpose of ependymal cells?
line the ventricles of the brain and central canal of the spinal cord, part of choroid plexus, and possess cilia to move CSF
What is found in the gray matter of the cerebral cortex?
neuronal cell bodies, unmyelinated fibers, and associated neuroglia cells
What is found in the white matter of the cerebral cortex?
myelinated fibers and associated neuroglia cells
What are the layers of the cerebral cortex in order?
molecular layer, external granular layer, external pyramidal layer, internal granular layer, ganglionic layer, and multiform layer
What are the functions of the cerebellum?
coordination of motor impulses, maintenance of muscle tone, and maintenance of equilibrium and balance
The dorsal horn has mainly what type of neurons?
interneurons
The ventral horn has mainly what type of neurons?
motor neurons
The dorsal root has mainly what type of neurons?
sensory neurons
What are the characteristics of autonomic ganglia?
eccentric nuclei, multipolar neurons, post synaptic neurons, no neuronal clusters
What are the characteristics of sensory ganglia?
centrally located nuclei, pseudounipolar neurons, neuronal clusters, no synapses, and lots of satellite cells.
What is the outflow of sympathetic ganglia?
thoracolumbar
What is the outflow of parasympathetic ganglia?
craniosacral
What is the enteric division?
collection of neurons and their processes within the wall of the alimentary canal
How are PNS axons degraded?
axons and myelin degenerate distally (wallerian degeneration) and schwann cells and macrophages clean away debri
How to PNS lesions regenerate?
- formation of bonds of Bungner
- axonal stump thickens and several sprouts form
- Sprouts enter bands of Bungner
- Single sprout persists and grows
- myelin sheaths regnerated
How do nerves in the CNS degenerate?
axons and myelin degenerate (Wallerian) and oligodendrocytes die. Microglia can not remove myelin debris and myelin inhibit axon regrowth.
What are the symptoms of ALS
gradual onset muscle weakness, slurred speech, outbursts of laughing/crying spells
What does ALS attack?
motor neurons
What causes the majority of Spinal cord injuries?
road traffic accidents
What is MS?
autoimmune disorder in which CNS myelin is attacked
What is the cause of MS?
death of oligodendrocytes
What is the joining of the epidermis and dermis called?
conspicuous interdigitations
What are the characteristics of thick skin?
prominent stratum corner, granulosum and distinct lucid. Lacks hair follicles, sebaceous glands and arrector pili muscles
What are the characteristics of thin skin?
less prominent layers, no obvious stratum lucid, contains hair follicles, sebaceous glands, and arrector pili muscles
What is the endocrine function of the skin?
synthesis of Vitamin D from UV light
What are the layers of the epidermis?
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Cells of the stratum lucidum are rich in what?
eleidin (metabolite of keratohyalin)
What is the origin of melanocytes?
neural crest origin
What do melanosomes contain?
tyrosinase
What is tyrosinase?
UV sensitive enzyme involved in melanin synthesis
What are the two forms of melanin?
eumelanin (brownish black pigment) and pheomelanin (reddish yellow pigment)
What causes Addison’s disease?
lack of cortisol from the adrenal cortex that causes over production of ACTH which increases the pigmentation of the skin
What is albinism?
hereditary inability of the melanocytpsto synthesize melanin, which is caused by the absence of tyrosinase activity or the inability of the cells to take up tyrosine.
What is vitiligo?
genetically regulated degeneration and disappearance of entire melanocytes
Where are Langerhan’s cells located?
stratum spinosum