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Home , Central nervous system

Central 1-2 min interruption of blood flow may impair Brain & cells >4 min w/o ! permanent damage Brain

besides O2 must get continuous supply of glucose one of largest organs in body: very little in reserve men: 1,600 g (3.5 lbs) decrease in glucose: women: 1,450g (3.2 lbs) dizziness [size is proportional to body size not intelligence convulsions ! Neanderthals had larger than us!!] unconsciousness early thoughts on function of brain: The Brain is Subdivided Into: ancient Greeks weren’t particularly impressed with the brain where snot was generated cooling device for blood 1. Cerebral Hemispheres (60% of brain mass) divide only during prenatal development and a few months - “” part: thought, creativity, after birth communication

after that they increase in size, but not numbers 2. moods, memory, manages internal environment one of most metabolically active organs in body comprises only 2% of total body weight it yet

! gets 15% of blood 3. – coordinating movement and balance

!consumes 20% of our oxygen need at rest 4. Brain Stem – oldest and smallest region, basic bodily (more when mentally active) functions = vegetative functions

blood flow and O2 increase to active brain areas medulla Human & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 1 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 2

cardiac center Some General Terminology for CNS: rate and force of heartbeat vasomotor control center gray matter = thin ; mostly cell bodies controls diameter of blood vessels & controls the distribution of blood to specific organs controls -outer layer of brain = cortex -inner layer of spinal cord respiratory center -nuclei: small areas of gray matter deeper inside the regulates the rate and depth of brain especially affects this center in medulla ! resp failure (iron ) = thick insulation; mostly also contains many nonvital reflex centers (nuclei): -inner layers of brain: tracts = bundles of speech axons that interconnect various parts of the brain swallowing -outer layer of spinal cord coughing Brain Stem sneezing hiccuping 1. Medulla 2. Pons lowest portion of just above medulla continuous with the spinal cord bridge connecting spinal cord with brain and parts all ascending and descending tracts from spinal of brain with each other cord and brain = white matter contains 2 centers that help to regulate breathing most tracts cross over as they pass through the medulla ! pneumotaxic center ! apneustic center helps control several vital functions ! contains important autonomic reflex centers also contains nuclei that affect sleep and bladder control

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 3 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 4 Parkinsons Disease 3. Midbrain progressive loss of motor function begins in 50’s or 60’s can be hereditary in the form of 4 lobes above and behind pons due to degeneration of dopamine releasing neurons in = Corpora Quadrigemina substantia nigra (inhibitory neurons) leads to hyperactivity of basal nuclei and involuntary muscle contractions upper 2 lobes = Superior Colliculi results in shaking , facial muscles become rigid, range of motion decreases develops smaller steps, slow shuffling gait with forward bent control center for some visual : posture and a tendency to fall forward speech becomes slurred, handwriting illegible a. pupillary reflex b. reflex centers for coordinating eye movement with head and 4. (~Reticular Activation System) movement in response to visual stimuli diffuse system of interconnecting fibers extending through several areas of brain including brain lower two lobes = Inferior Colliculi stem

-comprises a large portion of entire brainstem control center for some auditory reflexes: -extends into spinal cord and diencephalon -interlacing of gray and white matter a. reflex centers for movements of head and trunk in response to Functions of RAS - both sensory and motor auditory stimuli to locate sound 1. Sleep and consciousness b. to loud noises maintains consciousness and awakens from also contains: sleep ! alarm clock barbiturates depress RAS, decrease alertness & substantia nigra ! suppresses unwanted produce sleep muscle contractions stimulate RAS producing wakefulness

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 5 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 6

general anesthetics may produce unconsciousness by and intermediate mass depressing RAS

falling asleep may be caused by specific mainly a sensory relay center that inhibit RAS ! “Rome of the Nervous System” 2. helps control muscle tone, balance or “gateway to ” and posture during body movements ! main relay station for sensory impulses 3. filters flood of sensory input that reach cerebral cortex from spinal (=habituation) cord, brain stem and cerebellum

highlights unusual signals; disregards rest eg. , touch, heat, cold, pain, some smell (99%) the only sensory signals that can reach the cortex without going through the thalamus are LSD interferes ! get flood of sensory stimuli for of smell

Diencephalon 3. Hypothalamus

1. Epithalamus part of the brain most involved in regulating internal environment includes roof of 3rd ventricle no blood brain barrier mainly forms floor and part of lateral walls of 3rd ventricle 2. Thalamus: a. link between “” and “body” 4/5ths of diencephalon controls and integrates activities of autonomic 1.2” long NS

forms lateral walls of 3rd ventricle means by which emotions express themselves by altering body functions

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 7 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 8 ! ?role in psychosomatic illnesses & output is geared mainly toward the experience and expression of b. relays reflexes related to smell emotions

c. manufactures and transports releasing eg. pain, anger, fear, pleasure that control the “Master Gland” continuous back & forth communication between limbic system and frontal lobes of ! anterior pituitary ! much of the richness of your emotional life e. regulates body temperature depends on these interactions has receptors that monitor blood temperature outward expression of these emotions requires participation of the hypothalamus f. regulates food and water intake all sensory impulses are shunted through the has receptors that monitor osmotic pressure limbic system ! center smell is directly wired to limbic system other receptors monitor some concentrations in blood produces a crude appreciation of some sensations; 4. Limbic System eg. pleasure, anger, pain

but can’t distinguish their location or intensity diencephalon is a main part of a diffuse group of structures called the Limbic System eg. contains pleasure center

includes thalamus, hypothalamus, , -rats pressing bar for stimulation of pleasure center midbrain, (cerebrum), mammalary body (relay -ignore sleep, food, water, sexual partners center from limbic system to thalamus), fornix (connects -continue until exhausted (50-100x’s/min) hippocampus to mammalary body of hypothalamus) -willing to cross electrified grid to seek reward [420 !amps vs 60-180 !amps for food] = the emotional brain in stimulates erotic feelings

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 9 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 10

smooths and coordinates complex sequences of and are concentrated in muscular activity needed for body movements limbic pathways 2. controls skeletal muscles to maintain balance

!is site of action of many addictive receives input from proprioceptors in muscles, tendons and joints and equilibrium receptors and eyes

Cerebellum ! compares intended movement with actual movement 2nd largest part of brain 3. and storing motor skills just below and posterior to cerebrum eg. playing musical instrument, riding a bike, typing, etc only other part of brain that is highly folded 4. recent research indicates that the cerebellum also has roles in , emotion and judging the passage of time consists of 2 hemispheres diseases of cerebellum produce outside eg. tremors speech problems white matter inside difficulty with equilibrium

= arbor vitae (tree of life) NOT paralysis

Functions of Cerebellum: Cerebral Hemispheres helps to coordinate voluntary muscles: largest portion of brain (~60% of brain mass)

but does not send impulses directly to muscles two hemispheres joined by tracts =

1. acts with cerebrum to coordinate different heavily convoluted: gyri and sulci groups of muscles

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 11 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 12 folding allows greater area of cortex in smaller space (area = 2 2,500 cm = area of 4.5 textbook pages or 1 keg of beer) neurons of cortex are arranged into a highly also has larger grooves (= fissures) that divide each organized, radial array of 6 cellular layers hemisphere into 4 main regions named after bones (=) they lie under: ! differ in composition 1. frontal functional properties 2. parietal sets of connections 3. occipital cortex has been systematically subdivided into 4. temporal >40 functionally distinct areas each hemisphere: cortex is responsible for our most “human” traits a. outer gray matter = cerebral cortex (2-4mm) conscious mind b. inner white matter = tracts abstract thought memory ! bundles of myelinated axons awareness c. nuclei = islands of gray matter in interior of A. on simplest functional level, the cerebral cortex brain contains: ! cell bodies and sometimes dendrites a. motor areas eg. basal nuclei (=) that control voluntary motor functions clusters of gray matter around thalamus (5) help direct movements overactivity due to lack of dopamine produces b. sensory areas Parkinson’s disease provide conscious awareness of sensations hemispheres connected by nerve tracts in corpus c. association areas callosum integrate wide variety of information from several different areas of brain Function of Cerebral Cortex:

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 13 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 14

each hemisphere is mainly concerned with sensory and motor functions of the opposite side of the 2. nonverbal communication: interprets more body subtle aspects of language - metaphor, allegory, ambiguity eg. left hemisphere controls right 3. also concerned with emotions, intuition B. Lateralization of Hemispheres 4. global holistic aspects of sensory processing on top of this basic functions is “lateralization”: eg. does reality checks of new information a specialization of some cortical functions into each hemisphere eg. holistic aspects of vision

a division of labor ! “reading” facial expressions

! each hemisphere takes on ! recognize complementary functions there appears to be a gender difference in brain Left Hemisphere: lateralization

1. does all the talking males process spatial tasks in right hemisphere by 6 yrs of age females spatial function is equally developed in both ! repository of language hemispheres until age of 13

! processes many aspects of language: ! damage to rt hemisphere in childhood impairs language devel in males more than females syntax, semantics, etc Hemispheric Dominance: ! also analytical skills, math, logic lateralization as described is true for 97% of all people

Right Hemisphere: for ~90% of these people ! traits characteristic of the left hemisphere are dominant 1. mainly concerned with visuospatial tasks more verbal, analytical Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 15 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 16 all are right handed Prefrontal: elaboration of thought for 7% of these people intelligence ! traits characteristic of right hemisphere are dominant visuospatial tasks personality these are left handed abstract ideas more likely to be males judgement planning for 3% of population functions are shared = bilateral (no “civilizing behaviors” dominance) damage: lateralization is reversed or reduced in bilateral folks often ambidextrous wide mood swings sometimes leads to confusion and dyslexia loss of attentiveness become oblivious to social constraints careless about personal appearances C. Lobes of the cerebrum prefrontal fissures divide each hemisphere into 4 regions, reduced each with a specific set of functions: but lost initiative had mood swings

1. frontal Frontal personality control of voluntary movement motor processing areas: 2. parietal touch, stretch a. Motor Cortex perception of somatic sensations directs conscious individual muscle 3. occipital contractions processing of vision

4. temporal large body zones ! homunculus processing of sound and speech awareness of equilibrium within each zone: neurons that control specific movements are scattered as combinations of muscles are arranged in useful ways 1. Frontal (& prefrontal) damage causes paralysis Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 17 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 18

3. Occipital Lobe c. Olfactory Cortex visual processing areas small area just above orbits perception of odors, smells a. Visual Cortex

2. Parietal Lobe image is 1st mapped here receives info from of eyes sensory processing areas analyzes image in terms of its elementary features a. Sensory Cortex orientation color receives information from skin sensors texture depth presence of movement when stimulated patient reports “feeling” in some part of body 4. Temporal Lobe

muscle, tendon and joint sensations, and touch a. Auditory Cortex & Association Area provides feedback to motor cortex interprets sounds: pitch, rhythm, loudness spatial discrimination b. Vestibular (equilibrium) Cortex motor and sensory cortex, like other areas are malleable

eg. learning Braille awareness of balance the area representing touch in the finger used in somatosensory cortex expands into areas previously devoted to neighboring fingers

c. Gustatory Cortex

conscious awareness of taste stimuli

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 19 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 20 Higher Brain Functions seems to be an innate process !world’s languages are all governed by the same Integration ! interaction of several areas or universal grammar processes occurring at the same time ! all infants are born with the ability to learn all most not hard wired, circuits constantly forming and human languages reforming however this ability diminishes with age these functions are much more complex than simple reflex arcs integrated with memory and consciousness

! often involve learning it can’t be all under conscious control since it happens so quickly just beginning to understand them and some of the programming involved also, cant be all reflex

Examples: Language involves up to 6 areas in cerebral cortex: Sleep/Wake Cycles Language and Speech 1. Broca’s speech area (frontal lobe) Consciousness = Self Awareness motor aspects of speech and language Emotions and Behavior active when speaking Memory and Learning or when moving tongue and hands muscular coordination for speech Abstract Thought Intelligence damage: aphasia slow and poorly articulated speech Language and Speech loose ability to speak fluently and grammatically and to express ideas in writing comprehension not affected language is closely associated with distinctly functions 2. Wernicke’s Area (temporal lobe) Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 21 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 22

comprehension of written and spoken word ! localized damage of specific region does not active in children while reading destroy consciousness but does alter it and in adults reading unfamiliar words speech integration impulses from visual and auditory assoc 2. is superimposed onto other types of neural connects to Broca’s area activity damage: aphasia rapid, fluid speech 3. is totally interconnected no information content– “word salad” no comprehension of spoken or written language Awareness Wernicke’s area is reduced in size in dyslexics one of the simplest forms of consciousness is 3. neurons in Left frontal and midfrontal cortex awareness (=perception): responsible for semantics of surroundings word associations of sensations symbolic processing of relationships to those stimuli

4. Left Frontal Cortex consciousness is often defined as “self” awareness essential for enunciating verbs what is self? or self identity 5. Left temporal cortex “whips out” nouns ! requires interactions of numerous specific 6. Occipital Lobe brain areas color concepts and associations one of most important that gives us information Consciousness about our surroundings and interactions with it is vision What exactly is consciousness? visual stimuli that reach brain are first mapped little is actually known but some generalizations: into visual cortex visual imprint of retinal image: 1. involves simultaneous activity of large areas of from there it goes to ~30 areas in cortex for higher cerebral cortex level processing Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 23 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 24 she could “see” the left side of the plate information from primary visual cortex is then in her right field of view -never occurred to her that she could just relayed through 2 pathways: turn left -left didn’t exist ! How Pathway to parietal lobe to discern spatial layout of outside world !also show “mirror confusion” try to reach through mirror for objects allows you to reach out for objects, know where you are ! also may have difficulty reading maps or ! What Pathway to temporal lobe to recognize and name individual objects finding their way around the house and respond to them appropriately with emotion is not blindness but indifference

(?the man who mistook his wife for a hat?) receives sensation, lacks correct eg Neglect patients perception of what they indicate

esp if Rt parietal lobe is damaged most, not all, such patients recover in a few weeks yet most benefit from exercising left arm is during this time when “left” doesn’t exist – why ? The right hemisphere has broad “sphere of interest” encompasses both left and right The left hemisphere “sphere of interest” is visual fields only the right side of the body and the world If right is damaged ! If left is damaged ! temporary neglect of left side of body right can compensate doesn’t pay attention to left side of space or anything in it visual awareness (perception) is not just the image imprinted on eg. draw 1/2 of a picture (left doesn’t exist) it’s a neural image formed in cortex eg. eat from only rt side of plate -one patient “knew something wasn’t right” that neural image is not a completely accurate -rolled wheelchair in huge circle (clockwise) till Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 25 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 26

representation of what is going on in the ck? dummy hand in front of 2’x2’ wall world have friend stroke identical location on dummy and your hand

brain can “fill in” (eg. blindspot) by Disorders: extrapolation eg. blind spot is filled in certain variations in levels of consciousness are eg. Necker cube eg. faces/vase normal: awake & alert relaxed & nonattentive sleep some have larger areas of “blindness” due to damage and fill in with hallucinations: altered states of consciousness also occur ! no reaffirming information to induced by injury or disease “squash” hallucinations no vocalizations, no spontaneous eye movements brainstem reflexes intact ! sometimes patient “knows” they are “trip” eg LSD hallucinating – but can’t get rid of meditation them eg yoga confusion eg. monkeys in lab alteration in perception of stimuli eg. cartoon characters disorientation to time first, then to place, eventually to person but, even your own body is a phantom shortened attention span lethargy, stupor, obtundation

your brain temporarily constructs it for your locked-in state convenience motor cease functioning; the body is completely paralyzed while the mind continues to function normally; patient may appear to be clinically dead it can be profoundly modified with simple tricks synesthesia eg. how deeply do denial patients believe they are not paralyzed all of our senses contribute to consciousness cold water in corrects delusions and denial about (not just vision) paralysis, etc Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 27 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 28 hallucinatory welding of senses: ! epileptic sometimes produce 2 or more sensations are comingled profound experiences

sensory impulses not sent to appropriate sensory temporal lobe is associated with: areas of cortex auditory hallucinations out of body experience eg. a musical note may taste like pickles eg. a guitar chord may be felt as a brushing sensation on ankle “religious” experiences eg. the taste of chicken may feel “round” ! feelings of absolute omnipotence eg. a boyfriends kiss was seen as “orange sherbert foam” ! feelings of omniscience eg. see brilliant blue after eating salty pretzel ! insights into “cosmic truths” eg. specific letters or number ! associated with specific colors eg. feel pain in colors sense of truth and enlightenment derive from limbic structures rather than “thinking” part of the brain

these are consistent over time for one Intelligence person what is anatomical/physiological basis for intelligence? but not necessarily the same for other synesthetes brain mass # neurons in brain?, in cerebrum? 1 person in 2000 is a synesthete; # synapses? but may be even more common 1 in 300 where is it centered? more common in women: 6 women to 1 male !is our intelligence part of our cortex? seems to run in families: genetic component may be the ability to juggle lots of possibilities Is there a consciousness “center” in the brain? working memory may play important role does consciousness arise from specialized brain circuits? What we know: ! brain lesions that produce the most profound disturbances in consciousness a. intelligence may have more to do with when and are due to “temporal lobe seizures” how the brain grows than with its overall size Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 29 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 30

*Jeremy can stand at the side of the railroad tracks and give you the cumulative total of the serial numbers on the boxcars !the brain regresses as it matures *George can tell you all the years in which your birthday fell on a Thursday

eg. 3-11 yr old has 2x’s energy/gm as 11-14 yr old * George can also tell you within a span of 40,000 years backward or foreward, the day of the week on which any date eg. the cerebral cortex thickens in childhood, peaks and you choose fell or will fall then thins again in adolescence *Leslie, upon Tchaikovskys Piano Concerto No 1 on the piano for the first time can play it back flawlessly and without hesitation !2x’s # synapses in certain areas of child’s brain vs adolescent brain *Ellen constructs complicated chords to accompany music of any type she hears on radio or TV. She can sing back the entire soundtrack of the musical Evita after one hearing while b. angular gyri in cerebral hemispheres is important transposing orchestra and chorus to the piano *Kenneth can give the population of every city and town in the US with a population over 5,000; the names, number of rooms eg. we know damage to angular in left and locations of 2,000 leading hotels in the US; the distance hemisphere can leave “intelligent” people unable to do simple from each city and town to the largest city in its state; and the subtraction (eg. 100-7) dates and essential facts of over 2,000 inventions *Jedediah can answer the question: “in a body whose three eg. we know damage to angular gyrus in right sides are 23,145,789 yards, 5,642,732 yards and 54, 965 yds, how many cubicle 1/8th ‘s of an inch exist” after 5 hours of hemisphere leads to disruption of artistic skills computation he has the correct 28 digit figure and asks “do you want it backwards or forewards” c. specific circuits are used for specific functions *David can be given the number of the bus and time of day, and tell you on what corner you are standing in milwaukee Savants are mentally retarded yet some can: most savants are not truly “creative” ! replay any music when heard once ! state exact time of day with no clock in sight rote, not interpretive ! exact counts of numerous objects eg “rainman” d. there is lots of redundancy and plasticity in the ! can tell you in span of 40,000 years, the day brain in terms of intelligence of the week any date you choose fell on John Lorber asks: “Is your brain really necessary?”

most of brains higher functions are mediated by cortex !we view the cerebrum as what makes us

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 31 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 32 human Spinal Cord

he studies hydrocephalic patients located in the of the ! extremely large cavities in brain, brain mass, including cerebral cortex is greatly reduced 17 – 18 inches long many hydrocephalics suffer intellectual and physical retardation extends from to lower border of 1st vertebrae but of ~60 whose brain scans showed water cavities filled 95% of subdivided into cervical, thoracic, lumbar, sacral regions ! ~ half had IQ’s > 100 (normal IQ=90-110) spinal cord terminates in a bundle of nerves eg. Hydrocephalic boy = honor student = cauda equina had <20% of normal cerebral cortex (his 1 mm (1/32”); normal = 4.5 cm (1.75”)) associated with cord in spinal canal are: normal IQ = 90-110; his = 126 adipose cushion CSF blood vessels

space between vertebrae and = epidural space

is occupied by blood vessels, adipose and loose

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Cross Section of Spinal Cord: Protection of CNS

Post. Median Post. Horn of gray matter both brain and spinal cord are heavily protected: Tracts 1. bone: skull and vertebral column Central Canal Lateral Horn of gray matter 2. adipose cushion around spinal cord Ant. Horn of gray matter 3. meninges: tough flexible covering Ant. Median Fissure 4. liquid cushion:

white matter: myelinated, divided into columns Meninges and tracts; “highways” composed of 3 layers: gray matter: unmyelinated, cell bodies & dendrites, synapses 1. dura mater

Nerve Tracts strong fibrous connective tissue

numerous tracts can be identified in the spinal cord outer layer in skull is of cranial bones spinal cord tracts serve as 2-way conduction paths between peripheral nerves and brain 2. arachnoid layer

each tract is composed of bundles of axons delicate cobwebby layer

ascending tracts & descending tracts subdural space = between dura mater and arachnoid membrane eg. spinothalamic tract all axons originate from cell bodies in spinal cord subarachnoid space = between arachnoid layer and pia and terminate in thalamus of brain mater all are sensory (ascending) 3.

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 35 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 36 transparent ! brain actually “floats” in CSF (~140 ml of CSF)

adheres to outer surface of brain and cord CSF provides buoyancy and protection to delicate brain tissues also produces chemical stability contains blood vessels CSF mainly in: 3 extensions of the meninges form partitions between various parts of the brain: a. brain ventricles and ducts

falx cerebri b. central canal of spinal cord largest partition between cerebral hemispheres c. in subarachnoid space of the meninges

falx cerebelli !space between arachnoid layer and pia mater separates cerebellar hemispheres not in sheep brain Ventricles tentorium cerebelli separates cerebrum from cerebellum ventricles are fluid filled cavities inside brain: meninges continues around spinal cord and extends 1st & 2nd in side cerebral hemispheres beyond the end of the spinal cord = !safer site for to get CSF 3rd small at base of brain = inflammation of arachnoid, pia and CSF inside diencephalon (thalamus) usually bacterial or viral; may lead to th Encephalitis = inflammation of brain tissue itself 4 diamond shaped expansion of central spinal canal in brainstem Cerebro Spinal Fluid beds in pia mater of meninges extend into the as further protection against damage the brain and 4 ventricles of the brain where they form spinal cord have a cushion of fluid around and choroid plexi within

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surrounded by (blood brain barrier) fluid moves to central canal of spinal cord each choroid secretes CSF into ventricles fluid moves out to subarachnoid space around produces ~500ml of CSF/day cord and brain ! only 100-160ml at a time in circulation reabsorbed from subarachnoid space into isolated by “Blood Brain Barrier” arachnoid granulations

are much less leaky than normal capillaries ! tight junctions if circulation is blocked by tumor or other means ! astrocytes help regulate flow into CSF during fetal development may cause hydrocephalus some substances easily, rapidly passed: glucose, O2, CO2, , caffein, nicotine, heroin, anesthetics ! fluid is still produced but can’t circulate and be reabsorbed others cross more slowly; creatinine, urea, most ions (Na+, K+, Cl-)

larger molecules cannot cross at all; proteins, antibodies

!difficulty getting drugs to brain tissue

!any trauma to head may damage BBB

Circulation of CSF

Choroid plexus in each ventricle

fluid moves from lateral ventricles through duct to 3rd ventricle

another duct moves fluid to 4th ventricle

Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 39 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 40 Aging Central Nervous System Disorders of the Central Nervous System reaches peak development ~30 : by age 75 average brain weighs slightly half its 30 yr often debilitating and excruciating headaches weight 10-12% of US !28M in US suffer; ~70% are women gyri are narrower sulci are wider 92 M workdays lost/yr; $11 B/yr (AAS 97) cortex is thinner 2 kinds: more space between brain and meninges Classic (with aura) some or all of symptoms: neurons show signs of slower metabolism, accumulate seeing zigzagging lines neurofibrillary tangles and lipofuscin pigment tingling or numbness in , arm, leg seeing blind spots and tunnel vision Common (without aura) less efficient signal conduction and transmission pain on one or both sides of head sometimes vomiting myelin sheath degenerates sensitivity to light, smell or noise throbbing, intense pain fewer synapses may be due to: a. fluctuations in levels of less NT produced, fewer receptor proteins imitrex increases serotonin levels to stop language skills and long term memory hold up better b. excessive levels of dopamine than motor coordination, intellectual function and c. may be a genetic component short term memory Tourette’s Syndrome recurrent involuntary muscle contractions = tics eg. eyeblinking, nose twitching, facial grimacing, head shaking, shoulder shrugging usually begins in childhood between ages of 2 – 15 worldwide, all races; males more than females may affect 1 in 2000, worldwide; US ~100,000 affected may be due to chemical abnormality in basal ganglia Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 41 Human Anatomy & Physiology: Nervous System -–Central Nervous System, Ziser, Lecture Notes, 2010.4 42

one type of tourette’s in inherited

Alzheimers Disease affect 11% in us over 65; 47% by 85 ~half of all nursing home admissions leading cause of death among elderly AD may begin before 50 with very mild, undiagnosed symptoms one of 1s t symptoms is memory loss, esp of recent events progresses with reduced attention span, disorientation, moody, confused, paranoid, combative or hallucinatory may lose ability to read, write, talk, walk, and eat death usually from pneumonia or other complications of confinement and immobility

Parkinsons Disease progressive loss of motor function begins in 50’s or 60’s can be hereditary due to degeneration of dopamine releasing neurons in substantia nigra (inhibitory neurons) leads to hyperactivity of basal nuclei and involuntary muscle contractions results in shaking hands, facial muscles become rigid, range of motion decreases develops smaller steps, slow shuffling gait with forward bent posture and a tendency to fall forward speech becomes slurred, handwriting illegible

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