7 Nervous System Flashcards
nervous system
the controlling and communicating system of the body
the controlling and communicating system of the body
the nervous system
the three overlapping functions of the nervous system
sensory input - monitor changes
integration - processes and interprets
motor output - effects, causes a response
structural classification of the nervous system consists of what two subdivisions?
central nervous system
peripheral nervous system
what does the central nervous system consist of?
the brain and the spinal cord
what part of the nervous system is the brain a part of?
the central nervous system
what part of the nervous system is the spinal cord a part of?
the central nervous system
what is the role of the brain and spinal cord in the nervous system?
acts as the integrating and command centers of the nervous system
acts as the integrating and command centers of the nervous system
brain and spinal cord
what is the role of the central nervous system?
interprets incoming sensory information and issues instructions based on past experiences and current conditions
interprets incoming sensory information and issues instructions based on past experiences and current conditions
the central nervous system
the part of the nervous system outside the central nervous system
peripheral nervous system
the peripheral nervous system
the part of the nervous system outside the CNS; consists mainly of nerves that extend from the brain and spinal cord which serve as communication lines to and from the entire body
consists mainly of nerves that extend from the brain and spinal cord which serve as communication lines to and from the entire body
the peripheral nervous system
spinal nerves
part of PNS; carry impulses to and from the spinal cord
part of PNS; carry impulses to and from the spinal cord
spinal nerves
cranial nerves
part of PNS; carry impulses to and from the brain
part of PNS; carry impulses to and from the brain
cranial nerves
link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands of muscles
the nerves of the PNS
the functional classification of the nervous system is only concerned with which part?
only with PNS structures
the two principal subdivisions of the Peripheral nervous system
sensory (afferent) division
motor (efferent) division
sensory (afferent) division of the PNS
consists of nerves that convey impulses TO the CNS from sensory receptors throughout the body; keeps the CNS constantly informed of events going on both inside and outside the body
consists of nerves that convey impulses TO the CNS from sensory receptors throughout the body
sensory (afferent) division of the PNS
keeps the CNS constantly informed of events going on both inside and outside the body
sensory (afferent) division of the PNS
motor (efferent) division of the PNS
consists of nerves that carry impulses FROM the CNS to effector organs, muscles and glands; carry impulses that bring about a motor response
consists of nerves that carry impulses FROM the CNS to effector organs, muscles and glands
motor (efferent) division of the PNS
carry impulses from the CNS that bring about a motor response
motor (efferent) division of the PNS
the two subdivisions of the motor division of the PNS
somatic (voluntary) nervous system
autonomic (involuntary) nervous system
another name for the somatic nervous system
voluntary nervous system
another name for the autonomic nervous system
involuntary nervous system
another name for the voluntary nervous system
somatic nervous system
another name for the involuntary nervous system
autonomic nervous system
somatic nervous system
allows us to consciously control our skeletal muscles; voluntary nervous system
allows us to consciously control our skeletal muscles
somatic nervous system
autonomic nervous system
regulates events which are automatic, such as glands and cardiac muscle; has two parts, sympathetic and parasympathetic
regulates events which are automatic, such as glands and cardiac muscle
autonomic nervous system
has two parts, sympathetic and parasympathetic
autonomic nervous system
what are the principal types of cells making up nervous tissue?
supporting cells (neuroglia, glia, glial cells) neurons (nerve cells)
other names of supporting cells in nervous tissue
neuroglia
glia
glial cells
another name for neuron cells in nervous tissue
nerve cells
the supporting cells in the CNS are collectively called this
neuroglia, glia, or glial cells
functions of the neuroglia
support, insulate and protect the delicate neurons; different types also have special functions
support, insulate and protect the delicate neurons
neuroglia
astrocytes
star-shaped cells that account for nearly half of the neural tissue; projections cling to neurons, bracing them and anchoring them to their nutrient supply lines, the blood capillaries; hold neurons apart
star-shaped cells that account for nearly half of the neural tissue
astrocytes
their projections cling to neurons, bracing them and anchoring them to their nutrient supply lines, the blood capillaries
astrocytes
glia which hold the neurons apart
astrocytes
microglia
glia which are phagocytes; monitor the health of nearby neurons; dispose of debris including dead brain cells and bacteria
glia
supporting cells of the CNS
glia which are phagocytes
microglia
monitor the health of nearby neurons; dispose of debris including dead brain cells and bacteria
microglia
ependymal cells
glial cells that line the central cavities of brain and spinal cord; the beating of their cilia helps to circulate the cerbralspinal fluid that fills that cavities and forms a protective cushion around the CNS
glial cells that line the central cavities of brain and spinal cord
ependymal cells
the beating of their cilia helps to circulate the cerbralspinal fluid that fills that cavities and forms a protective cushion around the CNS
ependymal cells
oligodendrocytes
glia that wrap their flat extensions (processes) tightly around the nerve fibers, producing fatty insulating covers called myelin sheaths
glia that wrap their flat extensions (processes) tightly around the nerve fibers
oligodendrocytes
glia that produce fatty insulating covers called myelin sheaths
oligodendrocytes
myelin sheaths
fatty insulating covers around nerve fibers, made up of oligodendrocytes (glia) in the CNS, and schwann cells in the PNS
fatty insulating covers around nerve fibers, made up of oligodendrocytes (glia)
myelin sheaths
compare glial cells and neurons
both similar structurally-both have cell extensions
glia unable to transmit nerve impulses
glia never lose ability to divide like neurons do
why are most brain tumors made up of glial cells and not neurons?
because glia never lose their ability to divide, neurons do
supporting cells in the PNS
schwann cells
satellite cells
schwann cells
form the myelin sheaths around neurons in the PNS
satellite cells
act as protective, cushioning cells in the PNS
form the myelin sheaths around neurons in the PNS
schwann cells
act as protective, cushioning cells in the PNS
satellite cells
neurons
nerve cells; highly specialized cells which transmit messages (nerve impulses) from one part of the body to another
nerve cells
neurons
highly specialized cells which transmit messages from one part of the body to another
neurons
messages transmitted by neurons
nerve impulses
nerve impulses
the messages transmitted by neurons
common features of a neuron
all have a cell body which contains the nucleus and is the metabolic center of the cell, and one or more slender processes extending from the cell body
cell body of a neuron
metabolic center; contains nucleus
process of a neuron (fibers)
vary in length from microscopic to 3 or 4 feet; longest in humans reach from lumbar region of spine to great toe; convey messages (electrical signals) either a dendrite or an axon
dendrites
neuron processes that convey incoming messages TOWARD the cell body; neurons may have hundreds of the branching dendrites
neuron processes that convey incoming messages TOWARD the cell body
dendrite
neurons may have hundreds of these branching processes
dendrites
axons
neuron processes that generate nerve impulses and conduct them AWAY from the cell body; each neuron only has one axon which arises from the region on the body called the axon hillock
neuron processes that generate nerve impulses and conduct them AWAY from the cell body
axons
each neuron only has one of these processes
axon
axon hillock
cone-like region of the cell body where the axon rises from
cone-like region of the cell body where the axon rises from
axon hillock
branches of an axon
occasionally there is a collateral branch along the length, but at the terminal ends of axons there are hundreds to thousands of axon terminals
axon terminals
thousands of branches at the terminal end of axons; contain hundreds of tiny membranous sacs containing chemicals called neurotransmitters
thousands of branches at the terminal end of axons
axon terminals
contain hundreds of tiny membranous sacs containing chemicals called neurotransmitters
axon terminals
neurotransmitters
chemicals contained in the axon terminals; released into the extracellular space when stimulation from nerve impulses reach the axon terminals
chemicals contained in the axon terminals
neurotransmitters
released into the extracellular space when stimulation from nerve impulses reach the axon terminals
neurotransmitters
synaptic cleft
tiny gap separating each axon terminal from the next neuron
tiny gap separating each axon terminal from the next neuron
synaptic cleft
synapse
the region of communication between neurons; the junction of an axon terminal, the synaptic cleft, and the next neuron
the region of communication between neurons
synapse
the junction of an axon terminal, the synaptic cleft, and the next neuron
synapse
neurofibrils
filaments abundant in a neuron cells body which are the cytoskeleton which holds the cell shape
filaments abundant in a neuron cells body which are the cytoskeleton which holds the cell shape
neurofibrils
myelin
whitish fatty material most long nerve fibers are covered with; has a waxy appearance; protects and insulates fibers and increases transmission rate of nerve impulses
whitish fatty material most long nerve fibers are covered with
myelin
protects and insulates fibers and increases transmission rate of nerve impulses
myelin
how do schwann cells orient themselves on the nerve fibers?
they wrap around the axon in a jelly roll fashion end to end, look like beads on a string, to create the myelin sheath
they wrap around the axon in a jelly roll fashion end to end, look like beads on a string, to create the myelin sheath
schwann cells
the gaps between the individual schwann cells making up the myelin sheath on the axon (the space between the beads on a string)
nodes of Ranvier
nodes of Ranvier
the gaps between the individual schwann cells making up the myelin sheath on the axon (the space between the beads on a string)
neurilemma
the area of the Schwann cell cytoplasm and its exposed membrane (the outermost shell as its wrapped around the axon)
the area of the Schwann cell cytoplasm and its exposed membrane (the outermost shell as its wrapped around the axon)
neurilemma
ganglia
clusters of neuron cell bodies outside the CNS (in the PNS)
clusters of neuron cell bodies outside the CNS (in the PNS)
ganglia
myelin sheath’s difference in CNS and PNS
CNS - formed by oligodendrocytes; each can coil around up to 60 different fibers; no neurilemma
PNS - formed by Schwann cells; takes many to make up one fiber’s sheath; if damaged the neurilemma can stay intact & helps fiber regeneration
nuclei (nervous system)
the clusters cell bodies are found in in the CNS
the clusters cell bodies are found in in the CNS
nuclei
tracts
bundles of nerve fibers running through the CNS
bundles of nerve fibers running through the CNS
tracts
nerves
bundles of nerve fibers running through the PNS
bundles of nerve fibers running through the PNS
nerves
difference between nerves and tracts
both are bundles of nerve fibers
CNS - tracts
PNS - nerves
what do the terms white matter and gray matter refer to?
myelinated versus unmyelinated regions of the CNS
myelinated and unmyelinated regions of the CNS
white matter and grey matter
white matter
dense collections of myelinated fibers (tracts) in the CNS
gray matter
unmyelinated fibers and cell bodies in the CNS
dense collections of myelinated fibers (tracts) in the CNS
white matter
unmyelinated fibers and cell bodies in the CNS
gray matter
multiple sclerosis
myelin sheaths around the fibers are destroyed; electrical current is short-circuited
disease where myelin sheaths around the fibers are destroyed; electrical current is short-circuited
multiple sclerosis
neurons carrying impulses from sensory receptors to the CNS
sensory (afferent) neurons
where are the cell bodies of sensory neurons found?
in a ganglion outside the CNS
purpose of sensory neurons
keep us informed about what is happening both inside and outside the body
neurons carrying impulses from the CNS to the visera, muscles, and glands
motor (efferent) neurons
where are the cells bodies of motor neurons found?
always in the CNS
types of neurons
sensory (afferent)
motor (efferent)
interneurons (association neurons)
interneurons (association neurons)
connect the motor and sensory neurons in neural pathways
connect the motor and sensory neurons in neural pathways
interneurons (association neurons)
where are the cell bodies of interneurons found?
always in the CNS
multipolar neuron
neuron with several processes extending from cell body; most common structural type; all motor and association neurons
bipolar neuron
neurons with two processes - an axon and a dendrite; rare in adults, only found in special sense organs (eyes, nose) where they act in sensory processing as receptor cells
unipolar neurons
have a single process emerging from the cell body
