Download Chapter 12 - Nervous Tissue

Anatomy 32 Lecture
Chapter 12 - The Nervous System & Nervous Tissue
I.
Overview
A. Divisions & Functions of the Nervous System
B. Nervous Tissue
C. Nerves
D. Nerve Impulses
II. Divisions & Functions of the Nervous System
A. The __________ system works closely with the ___________ system to maintain bodily
homeostasis.
1. The nervous system reacts rapidly via ____________________, and has 3 major
functions:
a.
___________ input - 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.
___________ output – the CNS sends nerve impulses to effector organs
(muscles or glands) in response to the sensory input
1.
2.
The endocrine system reacts more slowly via ____________.
______________ is the study of nervous system function and disorders.
B. ________________ of the Nervous System
1. _____________ Nervous System (CNS) - consists of _______ &
________________. Most impulses that stimulate muscles to contract and glands to
secrete originate in the CNS.
2.
_______________ Nervous System (PNS) – outside the CNS; consists of cranial
nerves & spinal nerves
a.
b.
c.
____________ nerves – carry signals to & from the ______
__________ nerves – carry signals to & from the _____ cord
Cranial & spinal nerves are composed of ___________ and ___________ neurons
1)
Sensory (_________) neurons, whose cell bodies end in the CNS,
conduct nerve impulses from the _______ to the CNS.
2)
Motor (_________) 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) ________ neurons that conduct impulses from the ______ and sense receptors
to the CNS
2
2) ________ neurons that conduct impulses from the CNS to ____________
___________ tissue.
b.
__________ (involuntary) Nervous System (ANS) - contains sensory neurons
from visceral ______ and motor neurons that convey impulses from the CNS to
________ muscle, ______ muscle, and __________. ANS is further subdivided
into:
1) ____________ ANS – controls “flight or fight” functions
2) _____sympathetic ANS – controls “vegetative” functions
III. Nervous ____________: neuroglia & neurons
A. ___________ (glia) - Small cells that make up about 50% of 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; functions:
1) Form structural support between _____________ and _______ of the CNS
2) Take up & release ______ to control the neuronal environment
3) Establish the _______________ barrier
c.
_________ - small, phagocytic cells derived from monocytes; phagocytize
pathogens within the CNS
d.
__________ cells – ciliated columnar epithelial cells that line brain ventricles and
spinal cord central canal; they produce and help circulate cerebral spinal fluid
(CSF).
e.
2.
__________________ - most common glial cell, similar to astrocytes but with
shorter & fewer processes. Functions:
1) Guide development of _________ in the CNS
2) Produce ______________ (lipid & protein) around CNS neuron axons,
which insulates axon, increasing speed of nerve impulse conduction.
3) __________________ involves an autoimmune destruction of the myelin
sheath.
______ Neuroglia
a.
________ cells (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 regenerate damaged myelinated PNS neuron axon or dendrite.
2) _______ of ___________ (neurofibral nodes) are gaps between myelin
sheaths on the neuron axon.
b.
__________ cells (ganglionic gliocytes) - support neurons in ___________
(collection of neuron cell bodies in PNS).
3
B. _________ - nerve cells that conduct nerve impulses at up to 280 mph; lengths range
from 1 mm to longest cells in body (from brain to toes). Neurons are long lived, have a
high metabolic rate, and do not divide. Neuron ________:
1.
2.
Nerve __________ - neuron dendrite or axon
3.
4.
5.
____________ - Group of nerve cell bodies in the PNS.
6.
_____ matter - contains nerve cell bodies, dendrites, and axon terminals or bundles
of ______________ axons and neuroglia; forms H-shaped inner core of spinal cord
and covers cerebrum.
_________ - bundle of nerve fibers; most nerves include both sensory and motor
fibers.
Nucleus (________) - mass of nerve cell bodies and dendrites inside the CNS.
__________ - Bundle of myelinated nerve fibers in the CNS. Tracts interconnect
brain regions as well as regions in the brain to the spinal cord.
7.
_______ matter - aggregation of ____________ neuron processes; surrounds Hshaped inner core of spinal cord.
C. Neuron Structure
1. Cell ______ (soma or perikaryon) - contains nucleus, cytoplasm, lysosomes,
mitochondria, golgi bodies as well as:
a.
b.
c.
______________ - yellowish-brown lysosome remnants.
_________ bodies - neuronal rough ER
_______________ - cytoskeletal intermediate filaments that move materials
through the neuron.
2.
__________ - treelike processes extending from cell body that ___________
impulses from receptors or other neurons and conduct the impulses to the cell body.
3.
________ - process extending from cell body that _________ the nerve impulse
from the neuron to the dendrites or cell body of another neuron, or to an
____________ (muscle or gland).
a.
b.
Axon _________ - cone-shaped structure where axon joins cell body.
Axon __________ - specialized processes at end of axon collaterals and axons;
may end with swollen bumps called synaptic _____________, which contain
synaptic vesicles containing ________________, which influence other neuron,
muscle, or gland activities.
D. Neuron & Nerve Classification - related to _________ (number of cell body
processes) and ____________ (sensory/afferent or motor/efferent).
1.
_______polar – usually have _______ dendrites and one axon; includes most
neurons found in brain & spinal cord; have both ________ & ___________
functions.
2.
____polar - have one main __________ and one _______; rare - found in retina,
inner ear, and olfactory area of brain; have mostly ___________ functions.
4
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 CNS; not purely sensory or
motor; conduct impulses to other neurons; 90% of all neurons in body.
5.
Neuron & nerve classifications according to ____________:
6.
a.
________ ____________ afferent receptors in the _____, bones, muscles,
joints, eyes, & ears, deliver impulses (pain, temp., touch, vibration, pressure,
position, vision, hearing) to the CNS via spinal & some cranial nerves.
b.
__________ ________ - afferent neurons that send impulses relaying distention
and chemical conditions from ________, blood vessels, tongue, & nasal
epithelia to CNS via cranial & spinal nerves.
c.
________________ - efferent neurons relay impulses from the CNS via motor
cranial & spinal nerves and cause the contraction of _________ __________.
d.
______________ - efferent neurons (autonomic motor fibers) 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.
b.
c.
_______neurium CT sheath surrounds each individual nerve fiber
d.
Most nerves are composed of both motor & sensory fibers, thus are called
_________ nerves
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 glands,
causing secretion.
e.
_______neurium CT surrounds a group of nerve fibers (____________)
_____neurium CT surrounds the entire nerve and contains blood vessels &
adipose cells
IV. Transmission of Nerve Impulses
A. Nerve __________ - the exchange of sodium (___) and potassium (___) ions along the
length of a nerve fiber, resulting in a stimulus that activates another neuron or tissue (e.g.:
muscle or gland)
1.
A ___________ nerve fiber has more ____ ions outside than inside, and more ____
ions inside than outside, creating a difference in charge called the __________
_________ across the plasma membrane
2.
A strong stimulus received by the neuron opens Na+ ion channels in the membrane,
allowing an influx of ___ ions, resulting in _____________ that generates an action
potential, which continues the length of the axon
5
3.
After depolarization, ________________ occurs as ____ ions are transported out of
the neuron via K+ ion channels.
4.
The neuron’s resting potential is restored by the __________-_________ pump,
which pumps Na+ out and K+ into the neuron
B. ___________ - the junction between an _____ terminal and an ____________, such as
another neuron, muscle, or gland.
1.
The axon terminal contains many synaptic ___________ that contain
neuro______________, such as acetylcholine (ACh)
2.
When the action potential reaches the axon terminal, it stimulates the release of
neurotransmitter into the synaptic ________ between the axon and effector
3.
The neurotransmitter stimulates the _________, propagating the impulse and causing
a _________, such as muscle contraction or glandular secretion.