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exam 4
ch 12,13,14
29
Anatomy
Undergraduate 2
12/06/2011

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Term
central nervous system (CNS)
Definition
brain and spinal cord enclosed in bony coverings

enclosed by cranium and vertebral column
Term
peripheral nervous system (PNS)
Definition
all the nervous system except the brain and spinal cord

composed of nerves and ganglia
nerve – a bundle of nerve fibers (axons) wrapped in fibrous connective tissue
ganglion – a knot-like swelling in a nerve where neuron cell bodies are concentrated
Term
somatic sensory division
Definition
carries signals from receptors in the skin, muscles, bones, and joints
Term
soma
Definition
the control center of the neuron
Term
anterograde transport
Definition
movement down the axon away from soma
Term
retrograde transport
Definition
movement up the axon toward the soma
Term
Six Types of Neuroglial Cells
Definition
four types occur only in CNS
oligodendrocytes,ependymal cells,microglia,astrocytes

two types occur only in PNS
Schwann cells,satellite cells
Term
oligodendrocytes
Definition
form myelin sheaths in CNS

each arm-like process wraps around a nerve fiber forming an insulating layer that speeds up signal conduction
Term
ependymal cells
Definition
lines internal cavities of the brain

cuboidal epithelium with cilia on apical surface

secretes and circulates cerebrospinal fluid (CSF)
-clear liquid that bathes the CNS
Term
microglia
Definition
small, wandering macrophages formed white blood cell called monocytes

thought to perform a complete checkup on the brain tissue several times a day

wander in search of cellular debris to phagocytize
Term
astrocytes
Definition
most abundant glial cell in CNS

cover entire brain surface and most nonsynaptic regions of the neurons in the gray matter of the CNS

diverse functions
Term
Schwann cells
Definition
envelope nerve fibers in PNS

wind repeatedly around a nerve fiber

produces a myelin sheath similar to the ones produced by oligodendrocytes in CNS

assist in the regeneration of damaged fibers
Term
satellite cells
Definition
surround the neurosomas in ganglia of the PNS

provide electrical insulation around the soma

regulate the chemical environment of the neurons
Term
tumors
Definition
masses of rapidly dividing cells
mature neurons have little or no capacity for mitosis and seldom form tumors
Term
brain tumors arise from
Definition
meninges (protective membranes of CNS)
Term
meninges
Definition
three connective tissue membranes that envelop the brain

lies between the nervous tissue and bone

as in spinal cord, they are the dura mater, arachnoid mater, and the pia mater

protect the brain and provide structural framework for its arteries and veins
Term
31 pairs of spinal nerves (mixed nerves)
Definition
8 cervical (C1 – C8) C1 between skull and atlas
-others exiting at intervertebral foramen
12 thoracic (T1 – T12)
5 lumbar (L1 – L5)
5 sacral (S1 – S5)
1 coccygeal (Co)
Term
denticulate ligaments
Definition
extend through the arachnoid to the dura
anchors spinal cord to limit side to side movement
Term
Aristotle
Definition
thought brain was ‘radiator’ to cool blood
Term
Cerebellum
Definition
occupies posterior cranial fossa

marked by gyri, sulci, and fissures

about 10% of brain volume

contains over 50% of brain neurons
Term
dura mater
Definition
-in cranial cavity - 2 layers
outer periosteal – equivalent to periosteum of cranial bones
inner meningeal – continues into vertebral canal and forms dural sac around spinal cord

-cranial dura mater is pressed closely against cranial bones
no epidural space
not attached to bone except: around foramen magnum, sella turcica, the crista galli, and sutures of the skull
layers separated by dural sinuses – collect blood circulating through brain

-folds inward to extend between parts of the brain
falx cerebri separates the two cerebral hemispheres
tentorium cerebelli separates cerebrum from cerebellum
falx cerebelli separates the right and left halves of cerebellum
Term
meningitis
Definition
inflammation of the meninges

serious disease of infancy & childhood

especially between 3 months and 2 years of age


signs include high fever, stiff neck, drowsiness, and intense headache and may progress to coma – death within hours of onset
Term
bacterial meningitis
Definition
cause swelling the brain, enlarging the ventricles, and hemorrhage


lumbar puncture (spinal tap) draws fluid from subarachnoid space between two lumbar vertebrae
Term
buoyancy (csf)
Definition
allows brain to attain considerable size without being impaired by its own weight

if it rested heavily on floor of cranium, the pressure would kill the nervous tissue
Term
protection (csf)
Definition
protects the brain from striking the cranium when the head is jolted

shaken child syndrome and concussions do occur from severe jolting
Term
chemical stability (csf)
Definition
flow of CSF rinses away metabolic wastes from nervous tissue and homeostatically regulates its chemical environment
Term
longitudinal fissure
Definition
deep groove that separates cerebral hemispheres
Term
nerves of peripheral nervous system are ensheathed in Schwann cells
Definition
forms neurilemma and often a myelin sheath around the axon

external to neurilemma, each fiber is surrounded by basal lamina and then a thin sleeve of loose connective tissue – endoneurium

fascicles – nerve fibers gathered in bundles

perineurium – wraps fascicles
composed of up to 20 layers of overlapping, squamous ,
epithelium-like cells

epineurium – bundles numerous fascicles that constitutes whole nerve
composed of dense irregular connective tissue
protects nerve from stretching and injury
Term
visceral sensory division
Definition
carries signals from the viscera of the thoracic and abdominal cavities

heart, lungs, stomach, and urinary bladder
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