Transcript Anatomy of a Nerve Cell

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Vicki Hughes
CHAPTER 7: NERVOUS SYSTEM
Assignments:
OL CH 7 PT
Nerves (coloring)
We are doing chapter 7
before chapter 6.
Nervous system = master control and communication
Three functions:
1. Gathering Sensory input
2. Integration (interpretation
and decision-making about
the stimuli).
3. Effects a response – motor
output.
Organization of the Nervous System
CNS:
Central Nervous System
includes brain and spinal cord
PNS:
Peripheral Nervous System
includes all other nerves
Anatomy of a Neuron
Myelin Sheath
Node of Ranvier
Organization of the Nervous System
Afferent (Sensory) Division: conveys impulses TO the CNS
CNS
Efferent (Motor) Division: conveys impulses FROM the CNS
Subdivisions: Somatic/Voluntary and Autonomic/Involuntary
Supporting Cells of the CNS
Neuroglia (Glia ) = nerve “glue” cells
Astrocytes:
• 50% of nerve tissue
• protect neurons from harmful substances in blood
Supporting Cells of the CNS
Neuroglia (Glia ) = nerve “glue” cells
Oligodendrocytes:
• produces myelin (protective covering)
Supporting Cells of the CNS
Extensions from the
oligodendrocyte form
myelin sheaths for axons
within the central
nervous system.
Nervous Tissue
Supporting
Cells of the CNS
Ependymal cells on
the surface of the
choroid plexus secrete
cerebrospinal fluid.
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?
it=swf::500::500::/sites/dl/free/007
3520713/462745/07_q10.swf::Vie
w%20this%20animation%20befor
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ion
Supporting Cells of the CNS
Microglia found within
the central nervous
system are similar to
macrophages in that
they “eat” harmful
substances.
microglia
Supporting Cells of the CNS
Extensions from
the Schwann
cells form a
myelin sheath
called the
neurilemma
around each
axon within the
peripheral
nervous system.
Nervous Tissue
Supporting
Cells of the CNS
Neuron cell bodies within
ganglia are surrounded
by satellite cells that
nourish and protect the
underlying neuron cell
body.
Anatomy of a Nerve Cell
Dendrites conduct
impulses toward the
nerve cell body.
Axons conduct
impulses away
from the nerve cell
body.
Anatomy of a Nerve Cell
CNS clusters of nerve cells = nuclei
PNS clusters of nerve cells = ganglia
ganglion
nuclei
neuromedia.neurobio.ucla.edu
eftlab.org
Anatomy of a Nerve Cell
Tracts = bundles of nerves in CNS
Nerves = bundles of nerves in the PNS
Tract
Nerves
spiltmartini.com
Anatomy of a Nerve Cell
Types of Sensory
Receptors
1. Naked Nerve Endings =
pain & temperature
Anatomy of a Nerve Cell
Types of Sensory Receptors
2. Meissner’s corpuscles =
touch
kushtush.com
ttouchnorth.co.uk
Anatomy of a Nerve Cell
Types of Sensory Receptors
3. Pacinian corpuscle =
deep pressure
russiablog.org
responsiblemarketing.com
impactlab.net
Anatomy of a Nerve Cell
Types of Sensory Receptors
4. Proprioceptors =
muscular stretching
or tension
zimbio.com
webmd.com
Anatomy of a Nerve Cell
White matter = myelinated regions of the brain
Gray matter = unmyelinated regions of the brain
http://www.youtube.com/
watch?v=N2iJF2I94pg
Anatomy of a Nerve Cell
White matter and gray matter in MRI scans:
Comparing normal brain (left) with Huntington’s Diseased brain (right).
wordadaywonder.com
radlink.com.sg
The Nerve Impulse
Major functional properties:
1. Irritability
…ability to respond to
stimuli
I am irritable!
And…You are getting
on my very last nerve!
The Nerve Impulse
Conductivity …ability to conduct electrical currents
A. Resting membrane –
Na+ and K+ levels are equal
Na+
Na+
Na+
Na+ Na+ Na+
K+
K+
K+
K+
K+
K+
Nerve impulses are “all-or-nothing” events.
Conductivity
The Nerve Impulse
B. Depolarization starts –
Na+ moves into nerve cell.
Cell depolarizes (becomes too + inside)
Action Potential is generated.
Depolarization
Na+
Na+
Na+ Na+ Na+ Na+
K+
K+
K+
ACTION
POTENTIAL
K+
K+
K+
De = reversal
Conductivity
The Nerve Impulse
C. Action potential is propagated.
Depolarization
Na+
Na+
Na+ Na+ Na+
Na+
K+
K+
K+
K+
ACTION
POTENTIAL
K+
K+
Conductivity
The Nerve Impulse
Re = again
REpolarization
D. REpolarization.
K+Na+K+Na+K+Na+K+ Na+
K+
Na+K+Na+
Back
Too much
to+equal!
inside!
Nerve Impulse
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html
http://www.youtube.com/watch?v=90cj4NX87Yk
The Nerve Impulse
Saltatory conduction = fast, jumping motion that moves impulses
along the nodes of Ranvier
Stimulation of Muscles:
Ca+
Ca+
Ca+
Ca+
NA+
NA+
ACH
NA+
1. An action potential arrives at
a presynaptic terminal.
2. The Calcium ion channel
opens releasing calcium ions
into the presynaptic terminal.
3. Calcium ions cause the
synaptic vesicle to move to
the synaptic cleft.
4. The synaptic vesicle releases
ACH neurotransmitter into
the cleft.
5. ACH diffuses across the cleft
and and binds to ACH
receptors on the muscle fiber
membrane.
6. Sodium channels open and
release sodium into the
muscle.
7. The muscle membrane
depolarizes and a
postsynaptic action potential
results.
Reflexes
Auto = self
Reflex = rapid, predictable, involuntary response
Reflex Arc = neural pathway of a reflex
(goes only one way)
Autonomic reflexes
regulate smooth muscles
Reflexes
Soma = body
http://www.sumanasinc.com/webcontent/an
imations/content/reflexarcs2.html
Somatic reflexes
stimulate skeletal muscles
Brain Stem
About the size of a thumb in diameter and about 3 inches long.
Made up of medulla,
pons, and midbrain.
rainbowrehab.com
Brain Stem
Midbrain = small part that relays impulses and
controls reflexes for vision and hearing.
Brain Stem
Pons = bridge
Pons = rounded structure of mostly fiber tracts
involved in the control of breathing.
Brain Stem
Medula Oblongata = merges into spinal cord;
regulates vital internal activities including heart
rate, blood pressure, breathing, swallowing,
vomiting, etc.
Brain
Cerebellum = Outer gray
matter; inner white matter.
Provides timing for skeletal
muscle activity, controls
balance, and equilibrium.
Compared to “autopilot”
because it constantly checks
and adjusts.
Ataxia = Clumsy and
disorganized movements
as a result of damage to
the cerebellum.
http://www.youtube.com/watch?v=-s77voH8nRI
THE CNS
Pushing the Limits: BRAIN POWER
THE CNS
Quiz Tomorrow!
THE CNS
13.
12.
A.
B.
C.
D.
11.
10.
14.
9.
15.
8.
7.
16.
6.
17.
5.
18.
4.
19.
1.
2.
3.
Facial recognition
Body awareness
Primary motor
Primary
somatosensory
E. Speech
F. Smell
G. Hearing
H. Taste
I. Reading
J. Vision
K. Language
L. Cerebellum
M. Frontal lobe
N. Olfactory bulb
O. Spinal cord
P. Occipital lobe
Q. Parietal lobe
R. Temporal lobe
S. Central sulcus
Bonus: What anatomical place would this view represent?
X. transverse Y. midsaggitalZ. frontal
BRAIN FUN!
RIGHT BRAIN VS LEFT BRAIN
http://homeworktips.about.com/library/brainquiz/bl_leftrightbrain_quiz.htm
http://similarminds.com/brain.html
What are your results? Are you right or left brained?
What does it mean?
Protection of CNS
Meninges = three membranes covering the CNS structures (p 211)
Duramater = outermost layer
Dura = hard
Mater = mother
netterimages.com
schools-wikipedia.org
Arachnoid Mater = web-like middle layer
commons.wikimedia.org
Arachno = spider
Pia Mater = innermost layer following folds
commons.wikimedia.org
pia = gentle
Meningitis = inflammation of meninges
OCTOBER 23, 2013 5:30 PM EST
http://www.youtube.com/watch?v=omaAwMr_ric
Continually made from blood
plasma in choroid plexuses which
hang from the “roof” of the
brains ventricles.
Circulates continuously by being
produced and then drained back
into blood plasma to keep a
constant volume of about 150 ml.
Function: protection
Spinal Tap = sampling technique
to test CSF.
Hydrocephalus = “water on the
brain”
Cerebrospinal Fluid
(CSF) = fluid surrounding
the brain and spinal cord
BLOOD-BRAIN BARRIER
Keeps neurons separated from
blood-borne substances.
Made of LEAST PERMEABLE
capillaries in the body.
vandenberg.af.mil
Can’t keep out
fats, respiratory
gases, alcohol,
nicotine, or
anesthetics.
Brain Injuries
Traumatic Brain Injuries and Brain Dysfunctions
Head injuries are the leading cause of accidental death in the USA.
Concussion = slight injury, dizziness, brief loss of consciousness.
http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000034&ptid=17
Contusion = marked tissue
destruction, coma
Cerebral Edema = swelling
of the brain, death
Stroke = cerebrovascular accident (CVA) occurs when
circulation is cut off to the brain.
http://www.pennmedicine.org/encyclopedia/em_DisplayAnimatio
n.aspx?gcid=000123&ptid=17
Aphasia = result of damage to left cerebral hemisphere, affects
speech.
motor aphasia = affects Broca’s area and loss of speech
sensory aphasia = loss of understanding of language
TIA = transient ischemic attack (mini-stroke)
Alzheimer’s Disease
• mental deterioration
• progressive degenerative disease
• originally called “senile dementia”
• memory loss, irritability, moodiness,
confusion, possibly violent
• later stages include hallucinations
topnews.net.nz
articles.mercola.com
Alzheimer’s Disease 19:10 http://www.alzheimer.ca/english/disease/whatisit-video.htm
Alzheimer’s Disease
Teepa Snow
Parkinson’s Disease
Interactive tutorial
http://www.nlm.nih.gov/medlineplus/tutorial
s/parkinsonsdisease/htm/index.htm
Parkinson’s Disease Treatment
http://www.edheads.org/activities/brain_sti
mulation/
Sheep Brain Dissection Lab
http://www.youtube.com/watch?v=08iZVEa5H9Y&feature=related
Spinal Cord
About 17 inches (42 cm) long.
31 pairs of nerves arise from it.
Motor neurons
Sensory neurons
Association neurons
White matter of the spinal cord
Quadriplegic = damage high in cord
Paraplegic = damage low in cord
Oh man, my brain is fried!
Any Questions?
Sheep Brain Dissection
http://www.youtube.com/watch?v=vE3Yf_xy_
mE