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Anatomy & Physiology 34A
Chapter 11 – Nervous System Fundamentals
I.
Overview
A. Divisions & Functions of the Nervous System
B. Nervous Tissue
C. Nerves
D. Neuronal Organization of the Nervous System
II. Divisions & Functions of the Nervous System
A. The __________ System works closely with the __________ system to maintain
bodily ________________
1. The nervous system reacts rapidly via _______________, and has 3 major
functions:
a.
__________ __________ - sensory receptors within and near the
body’s surface respond to stimuli and send nerve impulses to the CNS
b.
________________ - the CNS receives, processes, and interprets the
sensory input, then decides what to do about it
c.
_________ _______ – the CNS sends nerve impulses to effector
organs (muscles or glands) in response to the sensory input
3. The __________ system reacts more slowly via ________
4. _______________ is the study of nervous system function and disorders.
B. ______________ of the Nervous System
1. Central Nervous System (____) - consists of ________ & _____________.
Most impulses that stimulate muscles to contract and glands to secrete
originate in the CNS.
2. Peripheral Nervous System (____) – outside the CNS; consists primarily of
cranial nerves and spinal nerves
a. __________ nerves – carry signals to & from the brain
b. ______ nerves – carry signals to & from the spinal cord
c. Cranial & spinal nerves are composed of sensory and motor neurons
1)
_________ (afferent) neurons, whose cell bodies are located near
the CNS, conduct nerve impulses from the ______ to the CNS.
2)
_________ (efferent) neurons, whose cell bodies originate in the
CNS, conduct impulses from the _____ to muscles & glands.
3. ______ Subdivisions include the somatic and autonomic nervous systems
a. ______________ (voluntary) Nervous System (SNS) - consists of
1) Input from ____________ neurons that conduct impulses from the
________, muscles, bones, and joints to the CNS
2) __________ neurons that conduct impulses from the CNS to
_________ _________ tissue.
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b.
_____________ (involuntary) Nervous System (ANS) - contains
1) Input from _____________ neurons from interoceptors in internal
__________ and blood vessels to the CNS
2) General ___________ neurons that convey impulses from the CNS to
_______ muscle, ________ muscle, and _________. The ANS is
further subdivided into:
a) _____________ NS – controls “flight or fight” functions
b) _______________ NS – controls “rest and digest” (vegetative)
functions
III. _______ ___________ and cells: neuroglia & neurons
A. ____________ (glia) - Small cells that make up the majority of cells in the CNS;
neuroglia support, nourish, and protect neurons. __________ brain tumors are
formed by rapidly dividing glial cells.
1. _______ Neuroglia
a. ___________ - star-shaped cells with many processes; most abundant
glial cell in the CNS; functions:
1) Form structural ____________ between capillaries and neurons of the
CNS
2) Take up & release ______ (e.g., K+) to control the neuronal
environment
3) Stimulate capillaries to form __________________, establishing the
blood-brain barrier
c. ______________ - small, phagocytic cells derived from monocytes;
_____________ pathogens within the CNS
d. _____________ cells – ciliated epithelial cells that line brain ventricles
and the spinal cord central canal; they produce and help circulate
cerebrospinal fluid (_____).
e. ___________________ - similar to astrocytes but with shorter & fewer
processes. Functions:
1) Guide ______________ of neurons in the CNS
2) Produce _______________ (lipid & protein) around CNS neuron
axons, which insulates axons, increasing speed of nerve impulse
conduction.
3) ___________ _____________ involves an autoimmune destruction of
this myelin sheath.
2. _____ Neuroglia
a. __________ _______- (neurolemmocytes) - flattened cells arranged in
series around axons or dendrites; produce the ________ sheath around
PNS neuron axons
1) _______________ is the outer nucleated cytoplasmic layer of a
Schwann cell; helps to regenerate damaged myelinated PNS neuron
________ or dendrites
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2) Nodes of ___________ (neurofibral nodes) are gaps between myelin
sheath segments on the neuron axon.
b. ________ cells (ganglionic gliocytes) - support neurons in _________
(collection of neuron cell bodies in PNS).
3. ___________ – the insulation on myelinated nerve fibers.
a. Composition – similar to plasma membranes: 20% __________ and 80%
__________ (phospholipids, glycolipids, cholesterol)
b. Development – formation begins in the ___th week of fetal development
and is complete in late _____________
c. Myelination in the CNS – _______________ processes wrap around a
nerve fiber
d. Myelination in the PNS – _________ cells wrap many times around a
nerve fiber in “jelly roll” fashion.
e. Unmyelinated nerve fibers in the PNS lack a _______ sheath, but
Schwann cells fold once around the fibers
f. Nerve impulse __________ depends on 2 factors
1) Nerve fiber _____________: thicker fibers transmit impulses more
______________ than thinner fibers
2) ___________ nerve fibers conduct impulses ______ (up to 120 m/sec)
than unmyelinated fibers (2 m/sec)
4. Schwann cells allow the ________________ of damaged PNS nerve fibers
a. The severed end of an ________ and its myelin sheath degenerate
b. ______________ remove the debris
c. A ______________ _______ is formed by the Schwann cell neurilemma
d. The tube guides the growing ______ back to its original destination
e. Skeletal muscle cells _____________ when their nerve fiber is severed, but
_____________ when the connection is reestablished
B. ___________ - nerve cells that conduct nerve impulses at up to ____ mph;
lengths range from 1 mm to longest cells in body (about 1 m). Neurons are long
lived, have a high metabolic rate, and do not divide. Neuron terms:
1. Nerve _________ - neuron dendrite or axon
2. __________ - bundle of nerve fibers in the PNS; most nerves include both
sensory and motor fibers.
3. ____________ - Group of nerve cell bodies in the PNS.
4. ______________ (nuclei) - mass of nerve cell bodies and dendrites inside
the CNS.
5. ___________ - Bundle of myelinated nerve fibers in the CNS. Tracts
interconnect brain regions as well as regions in the brain to the spinal cord.
6. ________ matter - contains nerve cell bodies, dendrites, and axon terminals
or bundles of __________________ axons and neuroglia; forms the Hshaped inner core of spinal cord and covers the cerebrum.
7. ________ matter - aggregation of _______________ neuron processes;
surrounds H-shaped inner core of spinal cord and found within the
cerebrum.
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C. Neuron Structure
1. Cell _________ (soma or perikaryon) - contains nucleus, cytoplasm,
lysosomes, mitochondria, golgi bodies as well as:
a. Lipofuscin - yellowish-brown ___________ remnants
b. Nissl bodies - neuronal rough __ for protein synthesis
c. ______________ - cytoskeletal intermediate filaments that give the
neuron its shape and transport materials
2. ______________ - treelike processes extending from cell body that
___________ impulses from receptors or other neurons and conduct the
impulses to the cell body.
3. ________ – single process extending from cell body that ______________
the nerve impulse from the neuron to another neuron, or to an ___________
(muscle or gland).
a. Axon ________ (trigger zone) - cone-shaped structure where axon joins
cell body
b. Axon __________ – infrequent branches off the axon
c. Axon ______________ - specialized processes at end of axon
collaterals and axons; may end with swollen bumps called
____________________, which contain synaptic vesicles containing
neurotransmitters, which influence other neuron, muscle, or gland
activities.
D. Axons transport materials both ways
1. _____________ transport is the movement of substances (e.g., proteins) from
the _______ down the axon
2. _____________ transport moves materials from the ____ terminals to the
soma for disposal or recycling
E. __________ & Nerve Classification - related to structure (number of cell body
processes) and function (sensory/afferent or motor/efferent). ____________classifications include
1. _______polar – usually have several ___________ and one _______;
includes most neurons found in brain & spinal cord; ________ neurons are
multipolar
2. ____polar - have ___ main dendrite and ___ axon; rare - found in
________, inner ear, and olfactory area of brain; have mostly
____________ functions.
3. ____polar (pseudounipolar) - has _____ process extending from cell body;
______ only. Dendrites located at distal tip of axon; monitors sensory
stimuli (touch or pain).
4. _____________ (association neurons) - found only in the _____; not purely
sensory or motor; conduct impulses to other neurons; 90% of all neurons in
body.
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5.
6.
Neuron & nerve classifications according to ___________ are:
a. __________ ____________ - afferent receptors in the _______, bones,
muscles, joints, eyes, & ears, deliver impulses (pain, temp., touch,
vibration, pressure, position, vision, hearing) ___ the CNS via ________
& some cranial nerves.
b. _____________________ - efferent neurons that relay impulses ______
the CNS via motor cranial & spinal nerves and cause the contraction of
_________ muscle.
c. ___________________ - autonomic afferent neurons that send impulses
relaying distention and chemical conditions from ________, blood
vessels, tongue, & nasal epithelia to ______ via cranial & spinal nerves.
d. _______________ - efferent neurons (autonomic motor fibers) that relay
impulses from the CNS via cranial & spinal nerves to smooth & cardiac
________ and _____
A _________ is a collection of neuron fibers held together by loose CT
outside the CNS; it consists of the following layers:
a. ______neurium CT sheath surrounds each individual nerve fiber
b. ______neurium CT surrounds a group of nerve fibers (_____________)
c. ______neurium CT surrounds the entire nerve and contains blood vessels
& adipose cells
d. Most nerves are composed of both motor & sensory fibers, thus are called
________ nerves
e. Some ________ nerves consist of only sensory or motor neurons
1) Sensory nerves serve the special _________ (taste, smell, sight,
hearing)
2) Motor nerves conduct impulses to _______, causing contraction, or
__________, causing secretion.