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56 terms

Anat ch 13- The nervous system:neural tissue

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What does the nervous system include?
all the neural tissue in the body
The two divisions of nervous system?
CNS and PNS
CNS consists of
brain and spinal cord
cns is reponsible for
integrating, processing, and coordinating sensory input and motor output
PNS includes
all neural tissue outside of CNS
PNS provides
sensory information to the CNS and carries motor commands from the cns to the peripheral tissues and systems
PNS is divided into what two divisions?
afferent-carries sensory info to CNS
efferent-carries motor commands to muscles and glands
afferent division begins at?
receptors
somatic sensory receptors
monitor skeletal muscles, joints, and the skin
visceral sensory receptors
monitor other internal tissues such as smooth muscle, cardiac muscle and glands
somatic nervous system
controls skeletal muscle contractions
autonomic nervous system
regulates smooth muscle, cardiac muscle, and glandular activity
activities of the somatic nervous system may be....
voluntary and involuntary
autonomic nervous system...
involuntary, usually outside of our control
what two types of neural tissue are there?
Neurons(impulse conduction) and neuroglia(supporting cells, can divide unlike neurons, common source of tumors)
parasympathetic vs sympathetic?
para-just chillin
sympathetic-fight or flight
PNS nerves?
31 spinal nerves and 12 pairs of cranial nerves
general characteristics of neuroglial cells
smaller than neurons
more numerous than neurons
most found in brain and spinal cord
source of tumors
CNS neuroglial cells
Astrocytes
Microglia
Ependyma
Oligodenrocytes
astrocytes
controlling interstitial environment
maintaining the blood-brain barrier
performing repairs in damaged neural tissue
guiding neuron development
microglia
smallest of glial cells, work as phagocytic cells in the CNS engulfing cellular debris, waste products and pathogens
ependyma
produce spinal fluid
oligodenrocytes
produces myelin and wraps axons
PNS gial cells
schwann cells(neurolemmocytes)
satellite cells
satellite cells
regulate exchange of nutrients and waste products between the neuron cell body and the extracellular fluid
schwann cells
every peripheral axon whether unmyelinated or myelinated is coverd with Schwann cells; Supporting cells of the peripheral nervous system responsible for the formation of myelin.
axolemma
plasmalemma of an axon
neurilemma
thick outermost coil of myelin sheath- bulging of Scwann cell contains nucleus and cytoplasm
the two anatomical subdivisions of the nervous system?
central and peripheral nervous system
what two terms are used to refer to the supporting cells in neural tissue?
glial or neuroglial
specifically what cells help maintain the blood-brain barrier?
astrocytes help maintain the blood-brain barrier
what is the name of the membranous coating formed around axons by oligodendrocytes?
myelin is what oligodendrocytes produce
identify the cells in the peripheral nervous system that form a covering around axons
in the PNS, schwann cells form a myelin covering around axons
what does the cytoskeleton of the perikaryon contain?
neurofilaments and neurotubules
what is a bundle of neurofilaments?
neurofibrils
cytoplasm of an axon?
axoplasm
terminal bouton
synaptic knob
anaxonic neurons
small neurons; cannot distinguish axons from dendrites; only found in CNS; functions are poorly understood
bipolar neurons
One dendrite and one axon; Receive limited inputs (special sense organs), rare, axons are not myelenated
pseudounipolar neuron
located in the periphery of the pody, where it conveys sensory impulses; characterized by a single process that divides into two, and a cell body located in a sensory ganglia
multipolar neurons
have multiple dendrites and a single axon; most common type of neuron in CNS; all motor neurons that control skeletal muscles are this type
Sensory neurons
pseudounipolar neurons with their cell bodies located outside the CNS in peripheral sensory ganglia; form the afferent division of the PNS-deliver info to the CNS
Afferent Fibers
axons of sensory neurons
somatic sensory neurons
monitor effects of external environment
visceral sensory neurons
transmit info about internal conditions and the status of other organ systems
exteroreceptors
sensitive to stimuli arising outside body (touch, pressure, pain receptors)
proprioreceptors
Type of sensory receptor that monitors the body's position in space.
interoceptors
monitor digestive, respiratory, cardiovascular, urinary, and reproductive systems
efferent fibers
axons traveling away from the CNS
preganglionic fibers
axons extending from the CNS to a ganglion
postganglionic fibers
axons connecting the ganglion cells with the peripheral effectors
Wallerian Degeneration
Changes that occur in the axon distal to the site of axonal damage; the axon swells up and becomes irregular; eventually, the axon and the terminals are broken down into fragments that are phagocytosed by adjacent macrophages and Schwann cells.
excitability
ability of the plasmalemma to conduct electrical impulses
action potential
an electrical impulse developed after the threshhold level has been reached, the membrane permeability to sodium and potassium ions changes
neuroeffector junctions
site where synapses permit communication between neurons and other cells
Chemical(vescular) synapses
synapses which involved the release of a chemical neurotransmitter by the presynaptic neuron