deck_8220520 Flashcards
functional definition of nervous tissue
- enables body to respond to changes in internal and external environments- controls and integrates functional activities of the organs and organ systems
anatomical divisions of the nervous system
CNS = brain and spinal cordPNS = all peripheral nerves outside CNS with associated ganglions and receptors
functional divisions of the nervous system
sensorimotor = afferent; signal from periphery to CNSmotor = efferent; signal from CNS to periphery- somatic = voluntary actions via skeletal muscle- autonomic = control of internal organs via smooth muscle, cardiac muscle, and glandular epithelium
structure of a nerve cell
dendrites: receive nerve impulses; contain microtubules and neurofilaments and free ribosomescell body: nucleus and site of protein productionNissl body = stack of RER responsible for protein productionaxon = single nerve fiber which transmits impulses to distal end; may have lipid-rich myelin sheath; contain microtubules and neurofilaments
neuronal morpholgy
- sensory = pseudounipolar- somatomotor, autonomic, interneurons = multipolar
CNS supporting cells (neuroglia)
oligodendrocytes = produces myelin (fried egg)astrocytes = scaffolding in brain tissue (star)microglia = phagocytic cells (dark spots)ependymal = produce CSF in ventricles and spinal canal (next to a space)
PNS supporting cells
schwann cells = surround all axons; produce myelin for myelinated nervesneurilemma = thin layers of schwann cells
myelin histology
H&E = clear area surrounding axonOsmium = dark ring
neuronal histology
cross section:- fascicle = bundle of nerve fibers surrounded buy perineurium- endoneurium = loose connective tissue surrounding individual nerve fibers- epineurium = dense irregular connective tissue surrounding/between fascicleslongitudinal:- long nerve fibers- schwann cell nuclei (thin, long, wavy)
white and gray matter of CNS
grey = cell bodies and supporting cellswhite = myelinated nerve fibers
myelin sheath function
allow faster transmission of a nerve impulse
nerve impulse
propagation of axonal membrane depolarization toward the axon terminal as sodium channels open and allow influx
synapse
site of transmission of an impulse from a neuron to another neuron, muscle cell (neuromuscular junction), or gland cell
kinds of synpases
axodenderitic, axosomatic, axoaxonal; few or 1000s per neuron
ganglia
PNS neuron cell bodies- parasympathetic: located in organ being innervated- sympathetic: located in chain ganglia/dorsal root ganglia