Transcript I. Coverings of the Brain and Spinal Cord

Chapter 13: Central Nervous System
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/brain.gif
Parts & Functions of the Brain & Spinal Cord
Learning Goals
I. Coverings of the Brain and Spinal Cord
Identify and locate each layer of the meninges
Identify the important anatomical
characteristics of the dura mater and the
spaces between and around the meninges
II. Cerebrospinal Fluid (CSF)
Discuss the formation, circulation, and function of
the cerebrospinal fluid
Protection for the CNS
Meninges- 3 protective membranes
1- dura mater (outermost)- “tough mother”
2- arachnoid mater (CT-cobweb-like)
3- pia mater (innermost, transparent, contains
blood vessels, adheres to brain)- “gentle mother”
CSF absorbs and disperses excessive mechanical
forces
Coverings of the Brain
"The meninges PAD the brain."
Pia; Arachnoid; Dura.
Coverings of the Brain
Cranial
bones and
vertebraeouter
protection
Meningesinner
protection
Anatomy of Meninges
Dura Mater has
3 important inward
extensions
1- Falx cerebri: project
downward into the
longitudinal fissure
(between 2
hemispheres)
2- Falx cerebelli: sickleshaped extension that
separates the two
halves
3- Tentorium cerebelli:
separates the
cerebellum from the
cerebrum
Falx cerebri
Spaces between & around meninges
Epidural space- outside dura mater but
inside bony coverings of spinal cord- cushion
of fat and CT
Subdural space- “under dura” space
between the dura mater and arachnoid mater;
small amount of lubricating serous fluid
Subarachnoid space- under the arachnoid
and outside the pia mater- CSF
Want a hematoma to be out not in…or brain damage
can damage can result
Protection of Spinal Cord
Vertebral column (+ ligaments and muscles)allows for flex but guards against direct knocks and
blows
CSF- shock absorber
Epidural space- cushion of fat and CT (between
the periosteum and dura mater)
Nerve Tracts (Diagram)- Ascending and
Descending Tracts
Dorsal, Lateral and Ventral horns
Spaces around meninges
Cerebrospinal Fluid Flow
Clear liquid renewed 4-5 times a day
Proteins and glucose for E for brain cells
Protects and nourishes brain and cord
Produced by choroid plexuses =cluster of thinwalled capillaries (in lateral ventricles)
Cerebral arteries help circulate the fluid
Direction of flow- brain’s lateral ventricles 
3rd and 4th ventriclesup the back of brain
down spinal cordup front of brain
Cerebrospinal Fluid or CSF
Protection: the CSF protects the brain from damage by "buffering"
the brain, acts to cushion a blow to the head and lessen the
impact
Buoyancy: brain is immersed in fluid, the net weight of the brain is
reduced from about 1,400 g to about 50 g- pressure at the base
of the brain is reduced
Excretion of waste products: one-way flow from the CSF to the
blood takes potentially harmful metabolites, drugs and other
substances away from the brain
Endocrine medium for the brain: CSF serves to transport
hormones to other areas of the brain
Also provides a reservoir of circulating fluid that helps the CNS
monitor the body and contains nutrients.
“The total volume of CSF is 125-150 ml.
Total production of CSF is about 400-500 ml/day (about .36
ml/min).” ~20ml during this class.
# from your textbook: avg adult 140ml, ~23 ml in ventricles &
~117ml in subarachnoid space.
Fluid Spaces
• CSF is found in:
Midsagittal section of
brain
– subarachnoid space around
the brain and spinal cord,
– within the four ventricles of
the brain,
– central canal of the spinal
cord.
• Four ventricles:
– Two lateral (1st and 2nd)
– 3rd ventricle
Third ventricle
– 4th ventricle
http://faculty.washington.edu/
chudler/vent.html
Anterior horn of lateral ventricle
Interventricular foramen
Posterior horn of lateral ventricle
Cerebral aqueduct
Fourth ventricle
Inferior horn of lateral ventricle
Hydrocephalus
Hydrocephalus
Blockage of CSF circulation
Can be treated in infants with shunts to drain
CSF; flexible cranium gives to excess
pressure
Can cause ventricles to enlarge or
subarachnoid hemorrhage, which leads to
blood clots
In older children, can causes brain damage
or death
http://www.telegraph.co.uk/new
s/graphics/2005/04/28/wviet28
a.jpg
http://tier.cs.berkeley.edu/gallery/albums/ghana05/IMGP1551_001.jpg
http://neurosurgery.seattlechildrens.org/assets/images/hydrocephal
us-normal-non-normal-ct-scans_large.gif
http://uuhsc.utah.edu/healthinfo/images/ei_0433.gif
Choroid plexuses
• Networks of capillaries that project from the pia
mater into the lateral ventricles and into the
roofs of the 3rd and 4th ventricles
• Glial cell (ependymal) releases CSF
Meningitis
• Infection or inflammation
of the meninges
• Bacteria such as
Neisseria meningitidis,
Streptococcus
pneumoniae, or
Haemophilus influenzae;
viral and fungal
infections
• Fever and severe
headaches; neck stiffness
and pain
Symptoms of Meningitis
Quick Check
• Name the three membranous coverings of
the central nervous system in order,
beginning with the outermost layer.
Quick Check
• Name the three membranous coverings of
the central nervous system in order,
beginning with the outermost layer.
Dura mater
Arachnoid mater
Pia mater
Quick Check
• Trace the path of cerebrospinal fluid from
its formation by a choroid plexus to its
reabsorption into the blood.
Figure 13-5 Flow of cerebrospinal fluid in textbook
• The fluid produced
by filtration of
blood by the choroid
plexus of each
ventricle flows
inferiorly through
the lateral ventricles,
interventricular
foramen, third
ventricle, cerebral
aqueduct, fourth
ventricle, and
subarachnoid space
and to the blood
Lumbar puncture
• Withdrawal of
some of the
CSF from the
subarachnoid
space in the
lumbar region
of the spinal
cord
Learning Goals
II. The Spinal Cord
 Discuss the structure and function
of the spinal cord
 Identify the major ascending and
descending tracts of the spinal cord.
Give at least one primary function
of each
Spinal Cord Basics
• Bundle of nerve fibers (40-45 cm) long
• Base of brain to lumbosacral part of
column
• Flat cylinder only slightly wider than
pencil
• 31 spinal nerves branch from
• Resembles an “inside-out” brainbutterfly shaped gray matter inside (gray
matter =neuron cell bodies and
unmyelinated nerve fibers; white
matter= myelinated nerve fiber tracts)
Spinal Cord Terms
Central canal- CSF fills
this canal providing
nourishment and waste
collection
Anterior fissure- deep
groove along front of
spinal cord
Sensory nerve rootlets
(dorsal)
Sensory root ganglion
(dorsal)
Motor nerve rootlets
(ventral)
Spinal nerve
Nerve fiber tract
Structure of Spinal Cord
Nerve Tracts of Spinal Cord
• Ascending Tracts- bundles of nerve fibers
relay impulses about bodily sensations and
inner sensors like pain up the spinal cord to
the brain
• Descending Tracts- convey motor signals
from the brain to skeletal muscles of the
torso and limbs in order to bring about
voluntary movements
Nerve Tracts
• Figure 13-8 Major tracts of the spinal cord
in textbook and Table 13-1 and 13-2
Pain Control Areas
Place in pain
conduction
pathway where
impulses from
pain receptors
can be
inhibited
Substantia
gelatinosagate- skin
receptors
Quick Check
• What are spinal nerve roots? How does the
dorsal root differ from the ventral root?
Quick Check
• What are spinal nerve roots? How does the
dorsal root differ from the ventral root?
Spinal nerve roots =Two
bundles of nerve fibers that
project from each side of the
spinal cord
Dorsal (posterior) nerve rootcarry sensory info into the spinal
cord, unipolar, in small region of
gray matter in dorsal root
ganglion
Ventral (anterior) nerve rootcarry motor info out of the spinal
cord; multipolar, in gray matter
of the inner core of spinal cord
Quick Check
• Name the regions of the white and gray
matter seen in a horizontal section of the
spinal cord.
Gray Matter: H- shaped rod of gray matter is made up of anterior,
lateral and posterior gray columns; joined in middle by a band (= gray
commissure)- made up of cell bodies of interneurons and motor neurons
White matter: subdivided in each half into three white
columns (funiculi)- large bundles of axons divided into
spinal tracts
Quick Check
• Contrast ascending tracks and descending
tracts of the spinal cord. Can you give an
example of each.
Quick Check
• Contrast ascending tracks and descending tracts of the
spinal cord. Can you give an example of each.
Ascending- conduct sensory impulses up the cord to the
brain (lateral spinothalamic tracts, anterior spinothalamic
tracts, fasciculi gracilis and cuneatus tracts,
spinocerebellar tracts, spinotectal tracts
Descending- conduct motor impulses down the cord
from the brain (lateral corticospinal, anterior
corticospinal, reticulospinal, rubrospinal, tectospinal,
vestibulospinal tracts)
Learning Goals
IV: The Brain
List the major divisions of the brain
Identify the major divisions of the brainstem
and describe the functions of each
Describe the structure and function of the
cerebellum
Brain has 2 Hemispheres
Left & Right sides are separate
Corpus Callosum : major pathway
between hemispheres
Some functions are ‘lateralized’
Corpus Callosum
Right
Hemisphere
– language on left
– math, music on right
• Lateralization is never 100%
100 billion neurons and 900 billion
glia
1.4 kg (3 lbs)
Brain attains full size by about the
18th year, rapid growth first 9 years
Left
Hemisphere
The Brain
Neurons have been around since the first few months
of postnatal life.
Six main divisions of the brain:
1. Medulla oblongata (Myelencephalon)
2. Pons (Metencephalon)
Brainstem
3. Midbrain (Mesencephalon)
4. Cerebellum (Metencephalon)
5. Diencephalon
6. Cerebrum (Telencephalon)
Human brain
http://www.morphonix.com/software/education/s
cience/brain/game/specimens/wet_brain.html
Brain Structure Terms
•
•
•
•
•
Sulci = shallow grooves of cerebrum
Fissures = deep grooves of cerebrum
Gyrus = on surface of the brain, raised areas
Folia = delicate, roughly parallel gyri “leaves”
Vermis = central section of the left and right
cerebellar hemispheres
Vermis
Fissures, gyrus, sulcus…oh my!
Blood Supply to the Brain
• 2% of total body weight- yet 20% of blood
• 4-8 minutes of oxygen depravation brain
damage or death
• Blood supply from carotid arteries (side of
neck)
• Blood supply from two vertebral arteries
(along spinal cord)
Circle of Willis
• Ring of
communicating
arteries
• Encircle the base of
brain
• Pathways to supply
oxygenated blood
Midsagittal Sections
Brainstem
Inferior to Superior View
http://static.howstuffworks.com/gif/brain-brainstem.gif
http://www.mult-sclerosis.org/brainstem.gif
http://www.waiting.com/brainstem.html
Brainstem
Consists of the medulla oblongata, pons, and midbrain.
Location: at the juncture of the cerebellum and the spinal
column. The medulla oblongata lies right above the foramen
magnum of the occipital bone.
Functions:
– Alertness, Arousal, Breathing, Blood Pressure, Most of
the Cranial Nerves, Digestion, Heart Rate
– Other Autonomic Functions
– Relays Information Between the Peripheral Nerves and
Spinal Cord to the Upper Parts of the Brain
– Nonvital: vomiting, coughing, sneezing, hiccupping,
swallowing, pupillary reflexes.
Medulla Oblongata
Size: a few centimeters in length
Located inferior to the pons by the
horizontal groove.
• Functions:
– Involuntary reflexes, such as
swallowing, vomiting,
sneezing, coughing,
hiccupping, and regulation of
cardiovascular & respiratory
activity.
http://images.encarta.msn.com/xrefmedia/sharem
ed/targets/images/pho/t012/T012859C.jpg
Most vital part of the brain!!
– Medulla oblongata & Waterboy: not
possible.
Horizontal groove
• Origin of many cranial nerves.
http://www.injuryresources.com/MEDIA/Slide24.jpg
http://www.movieactors.com/90stars/
sandler-posters.htm
The Pons
Pons = bridge in Latin.
Location: superior to the
medulla oblongata and inferior
to the midbrain.
Function: connect cerebellum
to the rest of brain, and
modify urespiratory otput of
the medulla.
Origin of 4 cranial nerves.
http://upload.wikimedia.org/wikipedia/comm
ons/thumb/f/fb/Pons.jpg/200px-Pons.jpg
http://www.injuryresources.com/MEDIA/Slide25.jpg
Midbrain
• Location: superior
to the pons and
inferior to the
cerebrum. Most
superior portion of
the brainstem.
• Function:
processes some
auditory and visual
information,
pupillary reflexes
and eye movements
Midbrain
http://www.mhhe.com/socscience/intro/ibank/ibank/0012lll.jpg
http://web.lemoyne.edu/~hevern/psy285/photos/midbrain.jpg
Cerebellum
• Location: at the bottom rear of the
head, directly above the brainstem.
• Functions:
1. Works w/cerebral cortex
(especially visual cortex) to
produce skilled movements by
coordinating the actions of
groups of muscles.
2. Controls posture & movement.
3. Controls skeletal muscles to
maintain balance.
• Inputs: Receive inputs from much of
the cerebral cortex but mainly from
visual cortex and somatosensory
cortex.
• Outputs: To motorneurons,
thalamus and cortex.
•
http://www.neuroskills.com/images/cerebellum.jpg
Arbor vitae
http://en.wikipedia.org/wiki/Cerebellum
http://learntech.uwe.ac.uk/radiography/Gfx/nervous/sectionthrucerebellum.gif
Cerebellum
• Structure
**2nd largest part of brain
More neurons than all the
other parts of the nervous
system combined!
Gray mater in cortex; white
matter in interior (arbor
vitae = “tree of life”)
Cerebellum
coordinating function of
• impulses from the motor control areas of the
cerebrum travel down to skeletal muscle tissue
and to the cerebellum at the same time
• Cerebellum compares the intended movement
with the actual movement; then sends impulses to
both the cerebrum and the muscles, thus
coordinating and “smoothing” muscle activity
Quick Check
• Name the three major divisions of the
brainstem, and briefly describe the function
of each.
Quick Check
• Name the three major divisions of the
brainstem, and briefly describe the function
of each.
Medulla oblongata-vital and nonvital reflexes
Midbrain- pupillary reflexes and eye
movements
Pons-regulate respiration & other reflexes
regulated by 6th, 7th, 8th cranial nerves
Quick Check
• What are gyri or folia? What are sulci?
Quick Check
• What are gyri or folia? What are sulci?
Gyri- raised areas on cerebellum
Folia- “leaves”, delicate and parallel gyri
Sulci- furrow or groove
Quick Check
• How does the cerebellum work with the
cerebrum to coordinate muscle activity?
Quick Check
• How does the cerebellum work with the
cerebrum to coordinate muscle activity?
1- acts with cerebral cortex to produce skilled
movements by planning and coordinating
the activities of groups of muscles
2- helps control posture
3- controls skeletal muscles to maintain
balance
4- coordinates incoming sensory info and acts
to complement and assist cerebrum
Brain Evolution
• When did the paths get crossed? (Sensory
and Motor)
Learning Goals
Identify the structure and function of
the two major components of the
diencephalon
Describe the structure of the cerebrum
Diencephalon
Location:
Between the cerebral
hemispheres and above the
midbrain.
Structures:
– thalamus, hypothalamus,
pineal gland, the optic tracts,
optic chiasma, infundibulum,
posterior pituitary gland,
ventricle III, mammillary
bodies.
• Functions:
– Chewing, Directs Sense
Impulses Throughout Body ,
Equilibrium, Eye Movement,
Vision, Facial Sensation,
Hearing, Phonation,
Respiration, Salivation,
Swallowing, Smell, Taste
http://www.driesen.com/diencephalon.htm
•
http://biology.about.com/library/organs/brain/bldienceph.htm
Thalamus: Brain’s Relay Station
• Large, oval-shaped pile of
gray matter on each side of the
brain
• Relay station mainly-
sensory information
(except for olfactory
information) has to make a pit
stop at the thalamus in order
to be relayed appropriately.
• Filter out unnecessary
sensory information and
synchronize important sensory
information.
• Arousal, alerting
mechanism.
http://distance.stcc.edu/AandP/AP/AP1pages/nervssys/unit13/dienc
eph.htm
http://learntech.uwe.ac.uk/radiography/Gfx/nervous/diencephalon.
gif
Hypothalamus
Below ("hypo") the thalamus.
Helps us control all of our
autonomic (involuntary)
functions
For example- regulates our body
temperature,
hunger/satiety, hormonal
output, and our
sleep/wake cycle.
Connection between psyche and
soma.
Connection between nervous
and endocrine systems.
Pleasure center for eating,
drinking, sex.
http://medicalimages.allrefer.com/large/hypothalamus.jpg
Pineal Gland:
Biological Clock
• Aka-Pineal body = “Pine cone.”
• Located above the midbrain.
•
Produces hormone melatonin.
•
Thought to synchronize, or re-
set, the circadian rhythm to
the day/night cycle.
•
For example, when you travel to
New York, it is three hours later
there. You have to readjust your
circadian rhythm to match the
day/night cycle around you.
•
http://distance.stcc.edu/AandP/AP/AP1pages/nervssys/unit13/dienc
eph.htm
http://www.sirinet.net/~jgjohnso/modpinhypopit.jpg
The Anatomy of the Brain
The Anatomy of the Brain
Quick Check
• What are the two main components of the
diencephalon? Where are they located?
Quick Check
• What are the two main components of the
diencephalon? Where are they located?
Thalamus and hypothalamus
Diencephalon = “between brain”- located
between the cerebrum and the midbrain
(mesencephalon)
Quick Check
• Name three general functions of the
thalamus.
Quick Check
• Name four general functions of the thalamus.
1- relay station for pain, temperature and touch
sensation
2- role in emotions- makes association of
sensory impulse with feelings of pleasantness
and unpleasantness
3- role in arousal or alerting mechanism
4- role in complex reflex movements
Quick Check
• Name three general functions of the
hypothalamus.
Quick Check
• Name three general functions of the
hypothalamus.
1- functions as link between the mind
(psyche) and the soma (body)
2- links nervous system to endocrine system
3- pleasure centers or reward centers for
primary drives such as eating, drinking, and
sex
Quick Check
• What is the pineal gland’s primary
function?
Quick Check
• What is the pineal gland’s primary
function?
Important part of the body’s biological clock
mechanism (secreting melatonin)
Learning Goal(s)
Discuss the sensory,
motor, and
integrative functions of the
cerebral cortex
Compare and contrast somatic
sensory and somatic motor
pathways
Cerebrum
http://us.i1.yimg.com/us.yimg.com/i/edu/ref/ga/s/728.jpg
http://umanitoba.ca/faculties/medicine/units/anatomy/bmr/graphics/cortex.html
1. right cerebral cortex
2. longitudinal fissure
3. cerebellum
4. frontal lobe
5. central sulcus
6. parietal lobe
Cerebrum
• Cerebral cortex: 2-4 mm of gray matter on the
surface of cerebrum.
• Important dividing lines: longitudinal fissure,
central sulcus, lateral fissure, &
parietooccipital fissure.
• Largest and uppermost division of brain
• Cortex has 6 layers of millions of axons and
dendrites
• 4 lobes named for bones that lie over them
(front, parietal, temporal and occipital)
Occipital Lobe
• Input from Optic nerve
• Contains primary
visual cortex
Occipital
Lobe
– most is on surface inside
central fissure
• Outputs to parietal
and temporal lobes
Visual
Lobe
Temporal Lobe
 Contains primary auditory cortex
• Inputs are auditory, visual
patterns
–
–
–
–
speech recognition
face recognition
word recognition
memory formation
• Outputs to limbic System,
basal Ganglia, and
brainstem
Auditory
Cortex
Temporal
Lobe
Parietal Lobe
• Inputs from multiple senses
 contains primary
somatosensory cortex
 borders visual &
auditory cortex
Outputs to Frontal lobe
 hand-eye coordination
 eye movements
 attention
Somatosensory
Parietal
Cortex
Lobe
Frontal Lobe
• Contains primary motor
cortex
• No direct sensory input
• Important planning and
sequencing areas
Broca’s area for speech
• Prefrontal area for
working memory
Working
Memory
Motor
Cortex
Frontal Lobe Disorders
• Broca’s area
– productive aphasia
• Prefrontal area
– lose track of ongoing context
– fail to inhibit inappropriate responses
• Wisconsin Card Sorting Task
Wisconsin Card Sorting Task
• Row of 4 example cards
set out
• Patient is given a deck
of 64 different cards
• Told to place each card
under the one it best
matches
• Told correct or incorrect
after each card
• Must deduce what the
underlying rule is.
Correct!
http://www.youtube.com/watch?v=rIX5YTPtKCs
Corpus Callosum
• Major ( but not only)
pathway between sides
• Connects comparable
structures on each side
• Permits data received on
one side to be
processed in both
hemispheres
• Aids motor coordination
of left and right side
Medial surface of right hemisphere
Corpus Callosum
Corpus Callosum
• What happens when the corpus
callosum is cut?
• Sensory inputs are still crossed
• Motor outputs are still crossed
• Hemispheres can’t exchange data
The ‘Split Brain’ studies
• Surgery for epilepsy : cut
the corpus callosum
• Roger Sperry, 1960’s
• Special apparatus
– picture input to just one side of
brain
– screen blocks objects on table
from view
Verbal
left
hemisphere
Nonverbal
right
hemisphere
The ‘Split Brain’ studies
• Picture to right brain
“What
“Using
“What
yourdid
left
did hand,
see?”
Pick you
up
you
what
see?”
you saw.”
– can’t name the object
– left hand can identify by
touch
• Picture to left brain
– can name the object
– left hand cannot
identify by touch
??
I saw an
Verbal
Verbal
apple.
leftleft
hemisphere
hemisphere
Nonverbal
right
hemisphere
Functions of the Cerebral Cortex
• Cerebral localization: specific functions have a location
in the brain.
• Cerebral plasticity: if areas are damaged, other areas
compensate.
• Postcentral gyrus: general somatic sensory area; heat,
cold, and touch stimuli.
• Precentral gyrus: somatic motor area; impulses travel
down via the motor tracts and stimulate skeletal
muscles.
• Transverse gyrus of the temporal lobe: auditory
associate region.
• Occipital lobe: primary visual areas.
Quick Check
• Name the five lobes that make up each
cerebral hemisphere. Where is each
located?
Quick Check
• Name the five lobes that make up each cerebral
hemisphere. Where is each located?
Frontal, parietal, occipital, temporal lobes
Quick Check
• Name the basal nuclei, and describe where
they are located within the cerebrum.
Quick Check
• Name the basal nuclei, and describe where they
are located within the cerebrum.
3 types= projection tracts, association tracts and
commissural tracts
Projection tracts- extensions of the sensory and
motor tracts
Association tracts- extend from one convolution to
another in the same hemisphere
Commissural tracts- corpus callosum
Functions of the Cerebral Cortex
Functions of the Cerebral Cortex
Motor Functions of the Cortex
http://www.brainconnection.com/med/medart/l/motor-cortex.jpg
Contralateral Motor Control
• Movements
controlled by motor
area
• Right hemisphere
controls left side of
body
• Left hemisphere
controls right side
• Motor nerves cross
sides in spinal cord
Motor Cortex
Somatosensory Cortex
Motor Functions of the Cortex
• Frontal lobe.
• Voluntary movement is
not well understood.
• Primary somatic motor
area in precentral
gyrus. Mapped
according to the
specific areas of the
body it controls.
http://www.brainconnection.com/med/medart/l/motor-cortex.jpg
Sensory Functions of the Cortex
• General senses: touch,
pressure, temperature, body
position (proprioception) -primary somatic sensory area
in postcentral gyrus (parietal
lobe).
• Special senses: vision, hearing,
and other senses involving
complex sensory organs.
• Sensory inputs are processed
and relayed to other parts of
the brain.
• “Homunculus” of the brain
http://cti.itc.virginia.edu/~psyc220/kalat/JK237.fig8.8.principle_area.jpg
Sensory info
sent to opposite hemisphere
• Principle is Contralateral
Organization
• Sensory data crosses over in
pathways leading to the
cortex
• Visual Crossover
Left visual
field
Right visual
field
Optic
nerves
– left visual field to right hemisphere
– right field to left
• Other senses similar
Left Visual
Cortex
Corpus
Callosum
Right Visual
Cortex
Integrative Functions of the Brain
Consciousness and mental activities
– Reticular activating system (RAS): reticular formations
(in brainstem) receive incoming messages, relay them to
thalamus, which in turn relays them to other parts of the
cerebral cortex.
1. Arousal/alert system
2. Necessary for maintaining consciousness
•
Drugs, such as barbiturates, depress the RAS and induces
sleep (as opposed to the effects of amphetamines).
•
Slow-wave-sleep (SWS) and rapid eye movement (REM):
former is a dreamless sleep and latter is sleep associated with
dreaming.
•
Altered state of consciousness can be produced by anesthesia
and meditation. Disease and injury can cause a comatose
state.
Brain of a Genius
• http://faculty.washingt
on.edu/chudler/ein.ht
ml
• Einstein's brain: 1,230
g
• http://www.npr.org/te
mplates/story/story.ph
p?storyId=4602913
• http://www.echonyc.c
om/~steven/einstein.ht
ml
• http://www.cse.emory.
edu/sciencenet/misme
asure/genius/research0
5.html
Language
• Spoken and written words
• Broca’s area (motor speech area): on the frontal lobe
• Wernicke’s area (sensory speech area): on the
parietal lobe
• Left cerebral hemisphere contains these areas in about
90% of the population; in the rest, the right or both
hemispheres contain them.
• Aphasia: speech defect caused by lesions in the
speech areas.
– Damage to Broca’s area leads to a person being unable to
articulate words, but can make vocal sounds and understand
words heard and read.
Broca's & Wernicke's Areas
http://www.cerebromente.org.br/n02/historia/areabroca.gif
http://www.molbio.princeton.edu/courses/mb427/2000/projec
ts/0008/normbrainmain.html
Emotions
• Involves the limbic system, situated around the corpus callosum.
• Cingulate gyrus and hippocampus connect with thalamus, fornix, septal nucleus,
amygdaloid nucleus, and hypothalamus.
• Lets us feel emotions: anger, fear, pleasure, sorrow, grief, joy…
• “Considerable evidence exists that limbic activity without the modulating influence
of the other cortical areas may bring on the attacks of abnormal, uncontrollable rage
suffered periodically by some unfortunate individuals” (p. 396).
• Robots & human emotions: http://www.ai.mit.edu/projects/
sociable/facial-expression.html
Emotions
http://cti.itc.virginia.edu/~psyc220/kalat/JK362.fig12.4.limbic_system.jpg
http://www.lifesci.sussex.ac.uk/home/Martin_Yeomans
/Teaching/biofound/emotion2_files/image001.jpg
Memory
• Short-term memory and long-term memory:
– Short: few seconds to minutes. Can be made into long-term.
– Long-term: days to years.
• Repeated impulses produces synaptic change.
– Increase the number of presynaptic axon terminal or
increase the number of receptor proteins in the postsynaptic
neuron’s membrane.
• Limbic brain (“emotional brain”) plays a key role in memory
formation.
• Posttraumatic stress disorder (PTSD): repressed memories
• Inducible memories?: Dr. Wilder Penfield in the 1920s;
temporal lobe of epileptic patients
•
http://serendip.brynmawr.edu/biology/b103/f97/projects97/Warren.html
• Let's test your short-term memory!
http://faculty.washington.edu/chudler/chmemory.html
Cerebral Hemispheres
• Left: Usually serves
language function;
dominates hand
movements
• Right: perception of
auditory stimuli, such as
melodies, coughing,
crying, and laughing;
spatial relationships
• Both hemispheres
communicate with the
other via the corpus
callosum.
Electroencephalogram (EEG)
• Brain electrical potentials are
measured as brain waves.
• Four types of brain waves
based on frequency and
amplitude of waves: beta,
alpha, theta, and delta (fastest
to slowest)
• Waves vary in different regions
of the brain, in different states
of awareness, and in abnormal
brain conditions.
• Used to locate brain
dysfunction, identify altered
states of consciousness, and
establish death.
Use it or lose it
http://www.newhorizons.org/neuro/diamond_use.htm
Do we use only 10% of our brain?
• http://faculty.washington.edu/chudler/tenper.html
http://www.stanford.edu/group/hopes/basics/braintut/f_ab16limbic.gif
Quick Check
• Where is the primary somatic motor area of
the cerebral cortex? Where is the primary
somatic sensory area?
Quick Check
• Where is the primary somatic motor area of
the cerebral cortex? Where is the primary
somatic sensory area?
• Precentral gyrus, the most posterior gyrus
of the frontal lob, constitutes the primary
somatic motor area
• Primary area for general somatic senses =
postcentral gyrus
Quick Check
• What does the reticular activating system
have to do with alertness?
Quick Check
• What does the reticular activating system
have to do with alertness?
Centers in the brainstem that receive
impulses from the spinal cord and relay
them to the thalamus and from the
thalamus to all parts of the cerebral
cortex; essential for regulating levels of
consciousness
Quick Check
• What is the function of the limbic system?
Quick Check
• What is the function of the limbic system?
Quick Check
• What is the function of the limbic system?
Limbic = “border or fringe”- the emotional
brain; functions to make us experience
many kinds of emotions- anger, fear,
sexual feelings, pleasure, and sorrow, etc.
Quick Check
• Over how many afferent neurons does
somatic sensory information usually pass?
• Explain why stimuli on the left side of the
body are perceived by the right side of the
cerebral cortex.
Quick Check
• Over how many afferent neurons does somatic
sensory information usually pass?
3 pools of sensory neurons (primary, secondary and
tertiary)
• Explain why stimuli on the left side of the body
are perceived by the right side of the cerebral
cortex.
Sensory pathways in the cerebral cortex are crossed
pathways (each side of the brain registers
sensations from the opposite side of body); axon
of a secondary sensory neuron crosses at some
level in its ascent to the thalamus
Quick Check
• What is the “principle of final common
path” as it pertains to somatic motor
pathways?
• Distinguish between pyramidal and
extrapyramidal pathways.
Quick Check
• What is the “principle of final common path” as it
pertains to somatic motor pathways?
“only one final common path-namely, each single
motor neuron from the anterior gray horn of
the spinal cord- conducts impulses to a specific
motor unit within a skeletal muscle”
• Distinguish between pyramidal and
extrapyramidal pathways.
Pyramidal- fibers that come together in the
medulla to form the pyramids
Extrapyramidal-more complex, consist of all
motor tracts from the brain to the spinal cord
anterior horn motor neurons except the
corticospinal tracts
http://www.neurosurgery.ufl.edu/Images/Pit.gif
http://info.med.yale.edu/caim/cnerves/
http://faculty.washington.edu/chudler/cranial.html
The Brain
Disorders and Diseases:
A Look at Strokes, Alzheimer’s
Disease, and Mad Cow Disease
Strokes
•
• Every 45 seconds,
someone in America
has a stroke.
Blood flow to the brain tissue can be
hampered in two ways:
1.
The vessel clogs within (ischemic
stroke).
2.
The vessel ruptures, causing blood to
leak into the brain (hemorrhagic
stroke).
• About 700,000
Americans will have a
stroke this year.
•
• Stroke is our nation's
No. 3 killer and a
leading cause of
severe, long-term
disability
Ischemic stroke accounts for about 83%.
It results from an obstruction of a blood
vessel, typically a blood clot. These are
called a cerebral thrombus or cerebral
embolism.
•
Hemorrhagic stroke accounts for about
17% of stroke cases. It results from a
weakened vessel that ruptures and bleeds
into the surrounding brain. The blood
accumulates and compresses the
surrounding brain tissue.
•
Leads to death of brain cells.
• 80% of strokes are
preventable
Stroke Warning Signs
 Sudden numbness or weakness
of the face, arm or leg,
especially on one side of the
body
 Sudden confusion, trouble
speaking or understanding
 Sudden trouble seeing in one or
both eyes
 Sudden trouble walking,
dizziness, loss of balance or
coordination
 Sudden, severe headache with
no known cause
http://www.ahaf.org/hrtstrok/about/strokeEmbolismBorder.jpg
http://www.strokecenter.org/pat/ais.htm
Transient Ischemic Attacks:
“Warning Strokes”
• Transient ischemic attacks, also called TIAs, are
minor or warning strokes.
• TIAs have similar symptoms as ischemic strokes
and the typical stroke warning signs develop.
– However, the obstruction occurs for a short time and
tends to resolve itself.
• Even though the symptoms disappear after a short
time, TIAs are strong indicators of a possible
major stroke.
Stroke Diagnosis
 CT (Computed Tomography) scan or CAT scan is a key imaging test. It
uses radiation to create a picture of the brain. It's usually one of the first
tests given to patients suspected of stroke. CT test results give valuable
information about the cause of stroke and the location and extent of brain
injury.
 Blood flow tests show any problem that may cause changes in blood flow to
the brain. This test is often done using ultrasound or angiography.
Usually performed after CT scan.
 MRI (Magnetic Resonance Imaging) uses a large magnetic field to produce
an image of the brain. Like the CT scan, it shows the location and extent of
brain injury. The image produced by MRI is sharper and more detailed
than a CT scan, so it's often used to diagnose small, deep injuries.
 In an EEG, small metal discs (electrodes) are placed on a person's scalp to
pick up electrical impulses or brain waves.
 An Evoked Response test measures how the brain handles different sensory
information. Electrodes record electrical impulses related to hearing, body
sensation or vision.
http://www.ukb.de/de/klinikeninstitute/neuro/img/leistungsspektrum3-1.jpg
EEG
http://www.meddean.luc.edu/lumen/MedEd/Radi
o/curriculum/Neuroscience/MRI_sagittala.jpg
http://www.ne.jp/asahi/ueda/stroke/ag-ap1.jpg
Angiography
http://www.theuniversityhospital.com/s
troke/images/diagnosis/mri.jpg
http://www.faqs.org/health/images/uchr_09_img0995.jpg
CAT scan
MRIs
•
Treatment:
Ischemic
Quick treatment is vitally important.
• Ischemic stroke is treated by removing obstruction and restoring blood
flow to the brain.
• Acute Treatment
– Clot-busters, e.g., tPA (tissue plasminogen activator): must be
administered within a three-hour window from the onset of
symptoms to work best. Generally, only 3 to 5% of those who
suffer a stroke reach the hospital in time to be considered for this
treatment.
• Preventative Treatment
– Anticoagulants/Antiplatelets: Antiplatelet agents such as aspirin
and anticoagulants such as warfarin interfere with the blood's
ability to clot.
– Carotid Endarterectomy: A procedure in which blood vessel
blockage is surgically removed from the carotid artery.
Treatment: Hemorraghic
 Surgical Intervention: either place a metal clip at
the base of the aneurysm or remove the abnormal
vessels.
 Endovascular Procedures, e.g., "coils": less
invasive and involve the use of a catheter
introduced through a major artery in the leg or arm,
guided to the aneurysm where it deposits a
mechanical agent, such as a coil, to prevent
rupture.
Hemispheric Effects of Stroke
The effects of a stroke depend on a number of factors including the location
of the obstruction and how much brain tissue is affected. However, because
one side of the brain controls the opposite side of the body, a stroke
affecting one side will result in neurological complications on the side of
the body if affects:
• Right Brain
If the stroke occurs in the brain's
right side, the left side of the body
(and the right side of the face) will
be affected, which could produce
any or all of the following:
• Left Brain
If the stroke occurs in the left side
of the brain, the right side of the
body (and the left side of the face)
will be affected, producing some or
all of the following:
– Paralysis on the left side of the
body
– Paralysis on the right side of
the body
– Vision problems
– Speech/language problems
– Quick, inquisitive behavior
– Slow, cautious behavior
– Memory loss
– Memory loss
Risk Factors for Stroke: Uncontrollable
• Increasing age: people of all ages, including children, have strokes. But
the older you are, the greater your risk for stroke.
• Sex (gender): stroke is more common in men than in women. In most
age groups, more men than women will have a stroke in a given year.
However, women account for more than half of all stroke deaths.
Women who are pregnant have a higher stroke risk. So do women taking
birth control pills who also smoke or have high blood pressure or other
risk factors.
• Heredity and race: risk is greater if a parent, grandparent, sister or
brother has had a stroke. African Americans have a much higher risk of
death from a stroke than Caucasians do. This is partly because blacks
have higher risks of high blood pressure, diabetes and obesity.
• Prior stroke or heart attack: someone who has had a stroke is at much
higher risk of having another one. If you've had a heart attack, you're at
higher risk of having a stroke, too.
Risk Factors for Stroke: Controllable and Treatable
• High blood pressure: high blood pressure (140/90 mm Hg or higher) is
the most important risk factor for stroke.
• Tobacco use: cigarette smoking is a major, preventable risk factor for
stroke. The nicotine and carbon monoxide in tobacco smoke reduce the
amount of oxygen in your blood. They also damage the walls of blood
vessels, making clots more likely to form. Using some kinds of birth
control pills combined with smoking cigarettes greatly increases stroke
risk.
• Diabetes mellitus: having diabetes increases a person's risk of stroke.
Many people with diabetes also have high blood pressure, high blood
cholesterol and are overweight. This increases their risk even more.
• Carotid or other artery disease: carotid arteries in your neck supply
blood to your brain. A carotid artery narrowed by fatty deposits from
atherosclerosis (plaque buildups in artery walls) may become blocked by
a blood clot. Carotid artery disease is also called carotid artery stenosis.
Risk Factors for Stroke: Controllable and
Treatable (Cont.)
• Peripheral artery disease: increases the risk of carotid artery disease,
which raises their risk of stroke. Peripheral artery disease is the
narrowing of blood vessels carrying blood to leg and arm muscles. It's
caused by fatty buildups of plaque in artery walls.
• Atrial fibrillation: heart rhythm disorder raises the risk for stroke. The
heart's upper chambers quiver instead of beating effectively, which can
let the blood pool and clot. If a clot breaks off, enters the bloodstream
and lodges in an artery leading to the brain, a stroke results.
• Other heart disease: coronary heart disease or heart failure increases
the risk of stroke. Dilated cardiomyopathy (an enlarged heart), heart
valve disease and some types of congenital heart defects also raise the
risk of stroke.
• Transient ischemic attacks (TIAs): "warning strokes" that produce
stroke-like symptoms but no lasting damage. Recognizing and treating
TIAs can reduce your risk of a major stroke.
Risk Factors for Stroke: Controllable and
Treatable (Cont.)
• Certain blood disorders: a high red blood cell count thickens the blood and
makes clots more likely. Doctors may treat this problem by removing blood
cells or prescribing "blood thinners.”
• Sickle cell disease (also called sickle cell anemia): a genetic disorder that
mainly affects African Americans. "Sickled" red blood cells are less able to
carry oxygen to the body's tissues and organs. They also tend to stick to blood
vessel walls, which can block arteries to the brain and cause a stroke.
• High blood cholesterol: a high level of total cholesterol in the blood (240
mg/dL or higher) is a major risk factor for heart disease, which raises your risk
of stroke. Recent studies show that high levels of LDL ("bad") cholesterol
(greater than 100 mg/dL) and triglycerides (blood fats, 150 mg/dL or higher)
increase the risk of stroke in people with previous coronary heart disease,
ischemic stroke or transient ischemic attack (TIA). Low levels (less than 40
mg/dL) of HDL ("good") cholesterol also may raise stroke risk.
Prevention of Strokes
Stroke Prevention Guidelines:
1. Know your blood pressure.
2. Find out if you have atrial fibrillation.
3. If you smoke, stop.
4. If you drink alcohol, do so in moderation.
5. Find out if you have high cholesterol
6. If you are diabetic...
7. Exercise.
8. Enjoy a lower sodium (salt), lower fat diet.
9. Circulation (movement of the blood through the heart and blood
vessels) problems.
10.Know the Symptoms of Stroke.
• http://www.stroke.org/site/PageServer?pagename=PREVENT
Alzheimer's Disease
Dr. Alois Alzheimer,
a German doctor,
diagnosed
Alzheimer's disease
in 1906
http://nihseniorhealth.gov/alzheimersdiseas
e/defined/dralzheimer_crop_popup.html
Alzheimer’s Disease
•
4.5 millions Americans (2000)
•
Amyloid plaques (pronounced AM i loyd)
= clumps of protein fragments that
accumulate outside of cells.
Neurofibrillary tangles (pronounced NUR
o FI bri lair ee) =lumps of altered
proteins inside cells.
•
Beta-amyloid (BAY-tuh AM-uh-loyd) is
a small, sticky protein fragment that
tends to clump together in the brain. (its
accumulation may be the key factor that
damages brain cells in Alzheimer’s
disease.)
•
Risk factors: age and family history
•
A person with Alzheimer’s disease will
live an average of eight years and as
many as 20 years or more from the onset
of symptoms.6
•
Dementia: decline in thinking
skills. Common symptoms: gradual
loss of memory, problems with
reasoning or judgment,
disorientation, difficulty in
learning, loss of language skills,
and decline in the ability to
perform routine tasks.
•
Also possible: changes in
personalities and behavioral
problems, such as agitation,
anxiety, delusions, and
hallucinations.
Alzheimer’s Disease
How the Brain and Nerve Cells
Change During Alzheimer's Disease
Video:
http://nihsenio
rhealth.gov/al
zheimersdisea
se/defined/06.
html
http://www.ahaf.org/alzdis/about/Brain_Neurons_AD_Normal.htm
10 Warning Signs of Alzheimer’s
• 1. Memory loss. Earliest signs-forgetting recently learned information,
those with dementia will forget such things more often and not
remember them later.
• 2. Difficulty performing familiar tasks- find it hard to complete
everyday tasks that are so familiar we usually do not think about how to
do them, for example- not knowing the steps for preparing a meal,
using a household appliance, or participating in a lifelong hobby.
• 3. Problems with language- forgets simple words or substitutes unusual
words, making his or her speech or writing hard to understand. If a
person with Alzheimer’s is unable to find his or her toothbrush, for
example, the individual may ask for “that thing for my mouth.”
• 4. Disorientation to time and place. It’s normal to forget the day of the
week or where you’re going. But people with Alzheimer’s disease can
become lost on their own street, forget where they are and how they got
there, and not know how to get back home.
10 Warning Signs (Cont.)
• 5. Poor or decreased judgment -may dress without regard to the weather,
wearing several shirts or blouses on a warm day or very little clothing in cold
weather, often show poor judgment about money, giving away large amounts of
money to telemarketers or paying for home repairs or products they don’t need.
• 6. Problems with abstract thinking. Balancing a checkbook may be hard when
the task is more complicated than usual, could forget completely what the
numbers are and what needs to be done with them.
• 7. Misplacing things- may put things in unusual places: an iron in the freezer or a
wristwatch in the sugar bowl.
• 8. Changes in mood or behavior- can show rapid mood swings—from calm to
tears to anger—for no apparent reason.
• 9. Changes in personality- becoming extremely confused, suspicious, fearful, or
dependent on a family member.
• 10. Loss of initiative- may become very passive, sitting in front of the television
for hours, sleeping more than usual, or not wanting to do usual activities.
Stages of Alzheimer’s Disease
Stage 1: No cognitive impairment
• Unimpaired individuals experience no memory problems and
none are evident to a health care professional during a medical
interview.
Stage 2: Very mild cognitive decline
• Individuals at this stage feel as if they have memory lapses,
especially in forgetting familiar words or names or the
location of keys, eyeglasses, or other everyday objects. But
these problems are not evident during a medical examination
or apparent to friends, family, or coworkers.
Stages of Alzheimer’s Disease (Cont.)
Stage 3: Mild cognitive decline
• Friends, family, or coworkers begin to notice deficiencies. Problems with
memory or concentration may be measurable in clinical testing or
discernible during a detailed medical interview. Common difficulties
include:
– Word- or name-finding problems noticeable to family or close
associates.
– Decreased ability to remember names when introduced to new people.
– Performance issues in social or work settings noticeable to family,
friends, or coworkers.
– Reading a passage and retaining little material.
– Losing or misplacing a valuable object.
– Decline in ability to plan or organize.
Stages of Alzheimer’s Disease (Cont.)
Stage 4: Moderate cognitive decline (mild or early-stage Alzheimer's
disease)
• At this stage, a careful medical interview detects clear-cut
deficiencies in the following areas:
– Decreased knowledge of recent occasions or current events
– Impaired ability to perform challenging mental arithmetic-for
example, to count backward from 100 by 7s.
– Decreased capacity to perform complex tasks, such as marketing,
planning dinner for guests, or paying bills and managing finances.
– Reduced memory of personal history.
– The affected individual may seem subdued and withdrawn,
especially in socially or mentally challenging situations.
Stages of Alzheimer’s Disease (Cont.)
•
Stage 5: Moderately severe cognitive decline (moderate or mid-stage
Alzheimer's disease)
•
Major gaps in memory and deficits in cognitive function emerge. Some
assistance with day-to-day activities becomes essential. At this stage,
individuals may:
– Be unable during a medical interview to recall such important details as
their current address, their telephone number, or the name of the college or
high school from which they graduated.
– Become confused about where they are or about the date, day of the week,
or season
– Have trouble with less challenging mental arithmetic; for example,
counting backward from 40 by 4s or from 20 by 2s
– Need help choosing proper clothing for the season or the occasion
– Usually retain substantial knowledge about themselves and know their own
name and the names of their spouse or children
– Usually require no assistance with eating or using the toilet
Stages of Alzheimer’s Disease (Cont.)
Stage 6: Severe cognitive decline (moderately severe or mid-stage Alzheimer's disease)
•
Memory difficulties continue to worsen, significant personality changes may emerge, and affected
individuals need extensive help with customary daily activities. May…
– Lose most awareness of recent experiences and events as well as of their surroundings.
– Recollect their personal history imperfectly, although they generally recall their own name.
– Occasionally forget the name of their spouse or primary caregiver but generally can distinguish
familiar from unfamiliar faces.
– Need help getting dressed properly; without supervision, may make such errors as putting
pajamas over daytime clothes or shoes on wrong feet.
– Experience disruption of their normal sleep/waking cycle.
– Need help with handling details of toileting (flushing toilet, wiping, and disposing of tissue
properly).
– Have increasing episodes of urinary or fecal incontinence.
– Experience significant personality changes and behavioral symptoms, including suspiciousness
and delusions (for example, believing that their caregiver is an impostor); hallucinations (seeing
or hearing things that are not really there; or compulsive, repetitive behaviors such as handwringing or tissue shredding.
– Tend to wander and become lost.
Stages of Alzheimer’s Disease (Cont.)
Stage 7: Very severe cognitive decline (severe or late-stage
Alzheimer's disease)
• This is the final stage of the disease when individuals lose the
ability to respond to their environment, the ability to speak, and,
ultimately, the ability to control movement.
– Frequently individuals lose their capacity for recognizable
speech, although words or phrases may occasionally be
uttered.
– Individuals need help with eating and toileting and there is
general incontinence of urine.
– Individuals lose the ability to walk without assistance, then the
ability to sit without support, the ability to smile, and the
ability to hold their head up. Reflexes become abnormal and
muscles grow rigid. Swallowing is impaired.
Alzheimer’s Web Resources
• http://www.alz.org/
• http://www.alzheimers.org/
• http://www.ninds.nih.gov/health_and_medical/disorders/alzhe
imersdisease_doc.htm
• http://www.ahaf.org/alzdis/about/adabout.htm
• http://www.nlm.nih.gov/medlineplus/alzheimersdisease.html
http://www.crystalinks.com/alzheimersbrain.jpg
Mad Cow Disease
Mad Cow Disease
• Bovine spongiform encephalopathy (BSE)
• Identified as a fatal bovine CNS disease in UK in
1986.
• “Wasting away” disease.
• Affected animal exhibits poor coordination,
trouble walking, and weight loss.
• Countries where affected cattle were found: UK,
France, Switzerland, Canada, Spain, Germany,
Japan, Russia, and, as of December 22, 2003, in
the United States as well.
• As of May 2003, vCJD has affected 139 people
worldwide.
Cause of BSE
“The exact cause of BSE is not known but it is
generally accepted by the scientific community that
infectious forms of a type of protein, prions,
normally found in animals cause BSE. In cattle with
BSE, these abnormal prions initially occur in the
small intestines and tonsils, and are found in central
nervous tissues, such as the brain and spinal cord,
and other tissues of infected animals experiencing
later stages of the disease.”
http://www.cfsan.fda.gov/~comm/bsefaq.html
Related Brain Disease in Humans
“vCJD, like other transmissible encephalopathies, robs an
affected individual of mental faculties and muscle coordination,
eventually leading to coma and death. This category of illnesses is caused
by prions, proteins that are normal in their molecular makeup but
abnormal in their shape, like springs that have been bent out of
configuration. It is believed that vCJD results from contact with prions in
tissues of cattle with bovine spongiform encephalopathy (BSE), or “mad
cow disease,” which, in turn, distort normal proteins in human brain and
nerve cells. Only minuscule amounts of prion-tainted tissues are required
in order to transmit the disease.7 Prions concentrate in the brain and spinal
cord, but also have been found in blood and muscle tissue. Prions are very
difficult to destroy, even by the chemical or heat disinfectant methods
used in hospitals. Heating to 134 degrees Celsius (273 degrees Fahrenheit)
does not reduce their infectivity”.
http://pcrm.org/health/prevmed/madcow_facts.html
Safeguards
Against
BSE
Since 1989, the FDA and other federal agencies have had ongoing
regulatory measures in place to prevent BSE contamination of U.S.
food and food products since 1989. Following the identification in a
Washington state dairy herd of the BSE-positive cow imported from
Canada, the USDA has issued four new regulations containing
additional safeguards to further minimize risk for introduction of the
BSE agent into the U.S. food supply. These safeguards include:
– A ban on use of live, but non-ambulatory cattle from
entering the human food supply
– A ban on use of organs, from cattle older than 30 months,
in which infectious prions occur and the tonsils and small
intestine of cattle of all ages for human food
– Restrictions on techniques to mechanically remove meat
from bones, and
– Meat from tested animals will not be certified as USDAinspected until test results are final.
Mad Cow Disease Web Resources
• http://www.fda.gov/oc/opacom/hottopics/bs
e.html
• http://www.usda.gov
• http://www.cdc.gov/ncidod/diseases/cjd/cjd.
htm
• http://www.alz.org/alzheimers_disease_creu
tzfeldt_Jakob_disease.asp
How to Tell if Your Cow Has Mad
Cow Disease
• http://www.cybersalt.org/cleanlaugh/madco
w.htm
http://www.familydoctor.co.uk/htdocs/STROKE/STROKE_specimen.html
Risk Factors for Stroke: Controllable and
Treatable (Cont.)
• Physical inactivity and obesity: both can increase your risk
of high blood pressure, high blood cholesterol, diabetes,
heart disease and stroke. So go on a brisk walk, take the
stairs, and do whatever you can to make your life more
active. Try to get a total of at least 30 minutes of activity
on most or all days.
• Excessive alcohol: Drinking an average of more than one
alcoholic drink a day for women or more than two drinks a
day for men can raise blood pressure and may increase risk
for stroke.
• Some illegal drugs: Intravenous drug abuse carries a high
risk of stroke. Cocaine use has been linked to strokes and
heart attacks.