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Physiology Exam #2 part 2: Central Nerv. System - Flashcards

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Class:BIOL 2150 - PRINCIPLES OF PHYSIOLOGY
Subject:Biology
University:The Richard Stockton College of New Jersey
Term:Fall 2012
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Central Nervous System: PROTECTION by... brain + spinal cord 

PROTECTED BY:
-bone (the skull)
-meninges coverings
-cerebral spinal fluid cushions around brain  "CSF"
-blood brain barrier "BBB" = tight capillaries don't let things to brain
Meninges -system of membranes that envelops the central nervous system
-3 layers:
                1) Dura mater - under skull, tough
                2) Arachnoid  - spider like filling right under dura mater
                3) Pia Mater - "gentle" thin layer right on top of brain
Cerebral Spinal Fluid -clear colorless bodily fluid produced in the choroid plexus of the brain

-about 4 times a day its exchanged/absorbed into venus sinus 
-flows in subarachnoid space 

- 4 ventricles

*** MAIN FUNCTION = shock absorber  
CSF Homeostasis with interstitial fluid - bout same Na+ content as serum 

- has less K+ (astrocytes help keep low) 

- less glucose (30%)

-greater chloride (Cl-)
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What can you do with Cerebral Spinal Fluid? stick needle into spinal cord and distract some to look for an infectious organisms

-if you take too much or go to far you can get head aches since the fluid cushions the brain.
Blood Brain Barrier
-no capillary pores - considered tight junctions so there's no space  
  between them. "capikkaries"

-very hard for drugs to get into the brain (some exceptions)

-hypothalamus is excluded (doesn't have BBB) 
Brain Nutrition - Brain's only food/nutrient = glucose

-brain can't go without oxygen very long

-brain is only aerobic 

-can't store glucose at all though
Stroke
- (cerebral vascular accident) 

- no glucose or 02 to brain 



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Pathology of CNS: Tetanus (INHIBITOR)

-GABA blocked 
Pathology of CNS: Strychnine (INHIBITOR)

-glycine - ISPS - blocked
Pathology of CNS:Parkinson's (INHIBITS)

-dopamine blocked

-which causes tremors 
Pathology of CNS: Caffeine - increases synaptic transmissions

- (adenine) - threshold = fast depolarization 
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Pathology of CNS: Aspirin -decreases pain by decreasing synaptic transmissions 
Pathology of CNS: Cocaine - blocks dopamine re-uptake 

-sort of a reverse of parkinson's 
Organization of the CNS -GRAY matter = cell bodies

-WHITE matter = myelin 

brain + spinal cord 
Organization of the CNS: Brain -14 billion neurons

- each neuron has about 50-100,000 inputs

- there are about 70+ neurotransmitters 

- every micro sec. (usec) = there's 100,000,000,000,000 possibilities 
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Brain: Cerebrum -most of the brain

-"cortex" is outer layer, made of mostly gray matter

- 2 hemispheres (left and right) joined by corpus callosum 

- 4 lobes

- Has basal ganglia

- hippocampus

-amygdala
Right Hemisphere of Cerebrum -conceptual 

-controls left hand
Left Hemisphere of Cerebrum -language 

-controls right hand
4 Lobes of Cerebrum 1) Frontal = speech

2) Parietal = sensory 

3) Occipital = vision 

4) Temporal = hearing
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Basal Ganglia of Cerebrum -motor control
hippocampus + amygdala of Cerebrum -controls memory 

-cell division (but not enough to replace nervous tissue) 
Brain: Diencephalon -located between cortex and brain stem 

-connects brain with rest of body

-3 parts:
              1) thalamus 
              2) hypothalamus 
              3) pineal gland
Thalamus -part of the diencephalon 

-located between the cerebral cortex and midbrain

-responsible for pain
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Hypothalamus -part of the diencephalon 

-contains a number of small nuclei with a variety of functions that helps the body maintain homeostasis (does everything)
Pineal Gland -part of the diencephalon 

-an endocrine gland 

-releases compound Melatonin which helps our sleep/wake cycle 
Midbrain Associated with
     - vision (eye movement)
      - hearing
      
Cerebellum and Pons -most of brain's neurons are located here

- integration of motor function = coordinates muscle movements
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Medulla Oblongata -the lower half of the brainstem 

- has involuntary control over : 
               -heart rate
               -breathing
               - blood pressure


Medulla Oblongata : Pyramids crossover between left and right side

go from brain to spinal cord
Reticular Activating System (RAS) -aka reticular formation

- scattered throughout the lower brain

-involved with awake and awareness

-keeps cerebrum alert

-where anesthesia hits 
Spinal cord - 31 pairs of spinal nerves (come out between vertebrae)

- gray matter on outside
- white matter on inside

-connects brain to PNS (called "spinal tracks" white matter)


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Spinal Cord: WHITE matter -ascending pathways/tracks = sensory

-descending pathways/tracks = motor (autonomic) 
Spinal Cord: GRAY matter -composed of interneurons -nerves of the body

-and motor neuron cell bodies
Spinal Cord: Monosynaptic REFLEXES -short circuit (by pass brain)

 = simplest

- stretch = hitting top of knee reflex

 - withdraw

Peripheral Nervous System -consists of the nerves and ganglia outside of the brain and spinal cord

-two parts:
                 1) Afferent = sensory 
                 2) Efferent = somatic and autonomic
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Afferent System = Sensory -afferent nerves convert stimuli to electrical signals (IPSP, EPSP input)

-high GPSP can start an action potential 

-CNS integrates info via: 
        -cerebral cortex
        -brain stem
        -interneurons 
Afferent System: RECEPTORS Two Genres:

1) Somatosensory receptors = skin/GI (free nerve endings)

2) specialized sense organs = receptor potential (IPSP & EPSP)
                                                  skin-pressure
RECEPTOR TYPE : "Chemo" Chemo = chemical 

-tongue
-smell
RECEPTOR TYPE : "Mechano" Mechano = pressure
                   vibration
                    sound
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RECEPTOR TYPE : "Thermo" Thermo= temperature

-skin
RECEPTOR TYPE : "photo" photo = light 

-eyes
RECEPTOR TYPE : "Nociceptor" nociceptor = noxious stimuli 

-(chem/mech/therm)

-when body is in danger 

EXAMPLE: being in 25* water-->loose heat--->hypothermia
Receptive Fields (afferent system) -area that receptors cover

-these areas overlap

-larger the field   =  the less sensitive 

-convergence 

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Signal Conversion ((afferent system)) 1st) transduction - stimulus to elect signal 

2nd) change in membrane potential (EPSP, IPSP)
            -potentials are graded
            -generator potential = neural
            -receptor potential = non neural (special sense)
Signal Conversion Examples stimulus --> somatosensory --> IPSP/EPSP ---> Action
                      (neural)            (generated potential)



stimulus -->specialized sense organ ---> IPSP/EPSP
                     (non-neural)                      (receptor potential)

***potentials are graded***
CODING (afferent system) -use coding to distinguish inputs

1) nature of sensation 

2) location - cerebral cortex

3) Intensity - must meet threshold 

4) duration: tonic or phasic
"Phasic" duration ((afferent system: CODING) adapts and stops firing signals
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"tonic" duration (afferent system: CODING) keeps sending signals
Hearing Coding THE EXCEPTION to coding norm.

-it measures time difference in each ear
Touch/Pressure (somatic senses) -common

-mostly skin 

- small, low vibrations

- free nerve endings

-speed: fast is myelinated . slow is non-myelinated
Touch/Pressure: "Compression" (somatic sensory) -Pacinian Corpuscle 

-large

-highly studied

-respond to high frequency vibrations

-mechanical gated ion channels
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Temperature (somatic sensory) -subcutis = free nerve endings

-cold = below 37 degrees C

- warm = 37-45 degrees C

-adapt only between 20-40 degrees C 
Nociceptors (somatic sensory) -a sensory receptor that responds/activated by potentially damaging stimuli by sending a nerve signal to CNS.

-pain/itch

-fast = small myelinated 
-slow =small unmyelinated 

-substance P = neurotransmitter 

-withdraw reflex

-suppressed by inhibitory pathways
-referred pain - poor localization 

Nociceptors: Deep Pain - metabolites mediate muscle 

- K+ in muscle 

-lack of blood

-decreased pH
Chemoreceptors (somatic sensory) receptors for smell and taste

smell - --> Olfaction 

taste - --> Gustation

-smell linked to memory and visual cortex

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Olfactory Epithelium -specialized epithelial tissue inside the nasal cavity that is involved in smell.

-non-neural neurons that divide

-how do they find receptors

- dog's sense of smell is 100,000 to 1,000,000,000x's better than humans
Olfactory Binding Protein - odor molecules present to epithelium receptors (400 different)--> population summation

-usually G protein gets activated 
-then second messenger opens ion channel to make AP

-nasal mucous 
Chemoreceptors to Cerebrum -no thalamus 

-about 10,000 odor codings
Vomeronasal organ -olfactory sense organ

-used to detect pheromones (rodents) 

-no odor 
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Gustation: Types of Taste Buds - Salt = Nat+

- Sweet = nutritious 

- Sour = H+

- Bitter = harmful 

- Umami (savory) = glutamate (MSG)
Gustation: Epithelial Cells -bind with substance / saliva 

-depolarize AP

-non neural 

-mostly G protein

-medulla ---> thalamus ---> cerebrum
-depends on smell, receptors, and strength
Pinna -the visible part of the ear that resides outside of the head 

-funnel for sound

-outer ear
Tympanic Membrane -the eardrum

-part of outer ear

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Malleus -hammer

-part of middle ear

-amplifies sound waves 

Incus - anvil

-middle ear

-amplify sound waves
Stapes -stirrup 

-middle ear

- amplifies sound waves
Cochlea -auditory portion of the inner ear

-spiral shaped cavity

-oval window/round window


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Endolymph - fluid contained on the inside of the cochlea (inner ear)

-cochlear duct
Perilymph -fluid contained on the outside of the cochlea (inner ear)

-vestibular duct

-tympanic duct


Organ of Corti -organ in the inner ear 

-contains auditory sensory cells aka "hair cells"
Ear Transduction 1) vibrations travel into oval window of cochlea 

2) fluid waves hit the perilymph fluid in the vestibular duct

3) organ of corti displaced by waves

4) hair cells bend (they detect the sound)

5) ion channels open and depolarization takes place

6) a neurotransmitter is then released

7) AP in sensory neuron 

8) hair cells bend back and causes ion channels to close
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flexion of ear ion channel open

AP 

return

ion channels close
Cochlear Processing: PITCH - vestibulocochlear nerve VIII controls

HIGH frequency near oval window

LOW frequency at distal end of cochlear 

Cochlear Processing: LOUDNESS
- vestibulocochlear nerve VIII controls

more rapid firing of neurons due to amplitude 

 --->thalamus --->cerebrum ---> location loudness pitch
Processing of Medulla -pyramids crossing over

-ipsilateral and contralateral 
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Processing of Midbrain -thalamus
Deafness: Conductive -outer / middle ear

-mechanical

-by gestacian tube
Deafness: Sensorineural -inner ear

-hair cells are the problem
Deafness: Central -between ear and brain

-strictly nerve damage 
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Semicircular canals -part of the inner ear/equilibrium 
-somatosensory - proprioception 

-part of Vestibular Apparatus 
-has 3 planes

-has "ampulla" to detect movement at the end of the canal

-made of endolymph hair cells/gel
Utricule - part of inner ear/equilibrium / Vestibular Apparatus 

- forward/back of head  (horizontal) effects

-has hair cells in gel called "otoliths"  
Saccule
- part of inner ear/equilibrium / Vestibular Apparatus 

- up/down of head effects

-has hair cells in gel called "otoliths"  

-THINK ELEVATOR
Transduction of Vestibular Apparatus - endolymph moves hair cells / otoliths 

- rotational acceleration of semicircular canals

- linear acceleration :
                                  - utricule = horizontal
                                  - saccule = vertical 
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Processing of Vestibular Apparatus - thru the vestibulocochlear nerve VIII 

- medulla 

-cerebrum (not as much thru here)
Cornea -transparent front part of the eye that covers the iris
Sclera - the white part of the eye 
Conjunctiva -lines the inside of the eyelids

- PINK

-covers the sclera
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Anterior Chamber of Eye - aqueous humor fluid in the chamber between the iris and cornea 

- CLEAR

- allows transmission of light
Iris - color of your eye 
Pupil -hole in center of the iris of the eye 
Posterior Chamber of Eye - vitreous humor behind the iris 

- like a gel ball 

-(marble part of cow eyeball i tried to cut through) 
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Retina -lining on the inner surface of the eye
Optic Nerve -comes out of the eye out the back 

-blind spot 
Electromagnetic Energy -visible spectrum we can see 400-750 nm

-in between ultra violet and infra red wavelengths 

LIGHT into eye -bends at cornea

-bends at lens

lens accommodates for focus 

- pupil controls amount of light

- retina receives images 
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Transduction of Eye (retina is backwards = the nerves are in the front and photoreceptors in the back)

- bipolar neurons pick up message 
-ganglion cells receive message and form optic nerve
-optic chiasma is where signals cross over
-travel to lateral geniculate nuclei and to thalamus
-then to visual cortex (occipital lobe)
Optic Chiasma - part of brain where the optic nerves cross
Rods - for night time 

- are 20x's the amount of rods than cones

- "rhodopsin" 
Cones - color

-red
-green
-blue
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Type of Photoreceptors in Retina 1) rods

2) cones

3) bipolar neurons

4) ganglion cells

5) optic nerve 
Lateral Geniculate Nuclei -  the primary relay center for visual information received from the retina 

-found inside the thalamus
Visual Cortex -part of the cerebral cortex

-responsible for processing visual information
Mechanism of Eye 1st) visual pigments (rhodopsin and cone pigments) bound to membrane 

2nd) light causes unbinding of rhodopsin 
        (opsin + retinol = called "bleaching")

3rd) G protein activated (cGMP reduced, Na+ channels close, 
        hyperpolarization occurs (K+ leaking out))

(this is a slow process, adaptation takes time)
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Mechanism of the Eye Resulting from = Total darkness After unbinding of opsin and retinol (bleaching):

-continuous depolarization occurs = signaling 

-graded potential

-Na+ / Ca ++  ---> in
Mechanism of the Eye Resulting from = Dim Light After unbinding of opsin and retinol (bleaching):

- the dim light inhibits depolarization

- not as much signaling occurs 

- starts to block Na+ / Ca++
Mechanism of the Eye Resulting from = Total Lightness After unbinding of opsin and retinol (bleaching):

- total light shuts off all neurotransmission

-no signals occur ---aka--> hyperpolarization  

- blocks K+


Fovea of Eye -focal spot on retina of eye

-neurons are pushed aside of fovea which allows photons to go right through, instead of having to go through two layers of neurons 

-most sensitive 

-lets us see fine details
        
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Coding of Signals : Convergence -photons ---> to bipolar ---> to ganglion 

-there are about 100 bipolar cells that converge into 1 ganglion 



Bipolar Ganglion: Inhibitory -center of vision field is inhibited 

-outside rim of field is excited 



(if light hits entire field = see nothing)
Bipolar Ganglion: Excitatory -bright light hits center of vision field and excites 

-outside of field is inhibited

(if light hits entire field = see nothing)
Coding of signals - Receptors (glutamate) -inhibits or excites bipolar cells
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binocular vision -both eyes are used together 

-left and right fields overlap
Efferent System -Somatic = voluntary muscles 

-Autonomic = involuntary 
                   = sympathetic(fight/fight) and parasympathetic (rest/digest)
Pre-post Ganglionic (autonomic) collections of neurons 
Autonomic Neurotransmitter at ganglion Acetylcholine (ACh) for all pre-post synapses 
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Axons of Autonomic - end in vesicles 

- those vesicles send out neurotransmitters which find receptors
Exceptions to Innervation (autonomic system) ONLY THE SYMPATHETIC DIVISION innervates:

-blood vessels 
-sweat glands
-adrenal glad
-kidneys
-fat
Neurotransmitter for Parasympathetic Division Cholinergic - acetylcholine (ACh)
Origin of Parasympathetic Division (the nerves) Cranial Nerves III, VII, IX, X

and sacral nerves
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Parasympathetic Division rest of digest

"slow system" 
Parasympathetic Division Ganglia -either right NEAR the organ

-or they are ON the organ

(this means it has long presynaptic/preganglionics)
Parasympathetic Division: Receptor = Nicotinic -reacts to nicotine

- are all pre-post ganglia 

-at neuro-muscular junctions
Parasympathetic Division: Receptor = Muscarinic  -all post. gang. organs

-on effector cells

-mechanism = G protein - 2nd messenger 
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Atropine -drug that blocks secretions 

-also prevents you from vomiting 

-doesn't effect muscle at all or ganglia

-is a muscarinic blocker in the Parasympathetic Division  
Physostigmine -a drug that blocks both receptors (nicotinic and muscarinic)

-but, more muscle blocking

(Parasympathetic Division)
Sympathetic Division: neurotransmitter Adrenergic (meaning that its dealing with a form of adrenaline) :

(Catecholamines (tyrosine))
1) Epinephrine (E)
2) Norepinephrine (NE)
Sympathetic Division Origin -Thoracic Spine 

and

-Lumbar Spine
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Sympathetic Division flight or fight system

-fast system = short preganglionics 
Sympathetic Division Ganglia -comes out right next to spinal cord = short presynaptics 

-called "Collateral Ganglia"
          -Celiac (stomach)
          -Superior Mesenteric 
          -Inferior Mesenteric 
Adrenal Medulla (Sympathetic Division) -acts like a ganglion 

-no post ganglionic fibers

- 20% NE
                         puts both of these into blood
- 80% E
Sympathetic Division Receptor: Alpha 1, 2 -most common Sympathetic Division receptor

-responds to (NE) norepinephrine 

-not very fast

-may inhibit or excite depending on receptor
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Sympathetic Division Receptor: Beta 1 -innervated by heart and kidney

-responds to NE and E

-not very fast

-may inhibit or excite depending on receptor
Sympathetic Division Receptor: Beta 2 - no innervation 

-mostly adrenal (arterioles and bronchioles)

-responds to E

-not very fast

-may inhibit or excite depending on receptor
Beta Blockers -are used for people with heart disease

- LOWER heart rate
Somatic Efferent Neurons -arise form motor neuron cell bodies in the ventral horns of gray matter within the spinal cord

-neuromuscular 

-for the most part voluntary 
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Motor Unit motor neuron + fibers 
Somatic Efferent: Neurotransmitter Acetylcholine (ACh)
Somatic Efferent: Receptor nicotinic 

(but these are different than the nicotinic receptors on ganglia)
Somatic Efferent Neurons: ONLY STIMULATORY AP leads to muscle twitch

-all or none 

(except you can get a weak signal sometimes)
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Somatic Efferent Neurons: Final Common Pathway -from motor neuron to muscle 
ALS "Amyotrophic Lateral Sclerosis"

-loose motor neurons

-lateral horn

-aka lou gehrigs disease 


Polio -virus that destroys motor neurons

-once they're done, they're done (can't grow em back)

-can contract disease in swimming pools 
Too much CSF -fluid pressure builds 

- hydrocephalus
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Too little CSF -could mess up by spinal tap

-get headaches
What substances can make it through the BBB? (these are the exceptions to the normal rule)
- glucose 

- O2/CO2

- alcohols

- lipids
HYPOglycemia
- low blood sugar
- 10-15 minutes before brain has problems
Hypoxia (to the brain) lack of oxygen 
- can go 5 minutes before problems occur
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Spinal Cord: Polysynaptic REFLEXES
= many circuits, 
 - crossed extensor for balance
 - contracts automatically (when you lift left leg, right leg tightens and contracts to balance out.
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 Central Nervous System: PROTECTION by...brain + spinal cord 

PROTECTED BY:
-bone (the skull)
-meninges coverings
-cerebral spinal fluid cushions around brain  "CSF"
-blood brain barrier "BBB" = tight capillaries don't let things to brain
 Meninges-system of membranes that envelops the central nervous system
-3 layers:
                1) Dura mater - under skull, tough
                2) Arachnoid  - spider like filling right under dura mater
                3) Pia Mater - "gentle" thin layer right on top of brain
 Cerebral Spinal Fluid-clear colorless bodily fluid produced in the choroid plexus of the brain

-about 4 times a day its exchanged/absorbed into venus sinus 
-flows in subarachnoid space 

- 4 ventricles

*** MAIN FUNCTION = shock absorber  
 CSF Homeostasis with interstitial fluid- bout same Na+ content as serum 

- has less K+ (astrocytes help keep low) 

- less glucose (30%)

-greater chloride (Cl-)
 What can you do with Cerebral Spinal Fluid?stick needle into spinal cord and distract some to look for an infectious organisms

-if you take too much or go to far you can get head aches since the fluid cushions the brain.
 Blood Brain Barrier
-no capillary pores - considered tight junctions so there's no space  
  between them. "capikkaries"

-very hard for drugs to get into the brain (some exceptions)

-hypothalamus is excluded (doesn't have BBB) 
 Brain Nutrition- Brain's only food/nutrient = glucose

-brain can't go without oxygen very long

-brain is only aerobic 

-can't store glucose at all though
 Stroke
- (cerebral vascular accident) 

- no glucose or 02 to brain 



 Pathology of CNS: Tetanus(INHIBITOR)

-GABA blocked 
 Pathology of CNS: Strychnine(INHIBITOR)

-glycine - ISPS - blocked
 Pathology of CNS:Parkinson's(INHIBITS)

-dopamine blocked

-which causes tremors 
 Pathology of CNS: Caffeine- increases synaptic transmissions

- (adenine) - threshold = fast depolarization 
 Pathology of CNS: Aspirin-decreases pain by decreasing synaptic transmissions 
 Pathology of CNS: Cocaine- blocks dopamine re-uptake 

-sort of a reverse of parkinson's 
 Organization of the CNS-GRAY matter = cell bodies

-WHITE matter = myelin 

brain + spinal cord 
 Organization of the CNS: Brain-14 billion neurons

- each neuron has about 50-100,000 inputs

- there are about 70+ neurotransmitters 

- every micro sec. (usec) = there's 100,000,000,000,000 possibilities 
 Brain: Cerebrum-most of the brain

-"cortex" is outer layer, made of mostly gray matter

- 2 hemispheres (left and right) joined by corpus callosum 

- 4 lobes

- Has basal ganglia

- hippocampus

-amygdala
 Right Hemisphere of Cerebrum-conceptual 

-controls left hand
 Left Hemisphere of Cerebrum-language 

-controls right hand
 4 Lobes of Cerebrum1) Frontal = speech

2) Parietal = sensory 

3) Occipital = vision 

4) Temporal = hearing
 Basal Ganglia of Cerebrum-motor control
 hippocampus + amygdala of Cerebrum-controls memory 

-cell division (but not enough to replace nervous tissue) 
 Brain: Diencephalon-located between cortex and brain stem 

-connects brain with rest of body

-3 parts:
              1) thalamus 
              2) hypothalamus 
              3) pineal gland
 Thalamus-part of the diencephalon 

-located between the cerebral cortex and midbrain

-responsible for pain
 Hypothalamus-part of the diencephalon 

-contains a number of small nuclei with a variety of functions that helps the body maintain homeostasis (does everything)
 Pineal Gland-part of the diencephalon 

-an endocrine gland 

-releases compound Melatonin which helps our sleep/wake cycle 
 MidbrainAssociated with
     - vision (eye movement)
      - hearing
      
 Cerebellum and Pons-most of brain's neurons are located here

- integration of motor function = coordinates muscle movements
 Medulla Oblongata-the lower half of the brainstem 

- has involuntary control over : 
               -heart rate
               -breathing
               - blood pressure


 Medulla Oblongata : Pyramidscrossover between left and right side

go from brain to spinal cord
 Reticular Activating System (RAS)-aka reticular formation

- scattered throughout the lower brain

-involved with awake and awareness

-keeps cerebrum alert

-where anesthesia hits 
 Spinal cord- 31 pairs of spinal nerves (come out between vertebrae)

- gray matter on outside
- white matter on inside

-connects brain to PNS (called "spinal tracks" white matter)


 Spinal Cord: WHITE matter-ascending pathways/tracks = sensory

-descending pathways/tracks = motor (autonomic) 
 Spinal Cord: GRAY matter-composed of interneurons -nerves of the body

-and motor neuron cell bodies
 Spinal Cord: Monosynaptic REFLEXES-short circuit (by pass brain)

 = simplest

- stretch = hitting top of knee reflex

 - withdraw

 Peripheral Nervous System-consists of the nerves and ganglia outside of the brain and spinal cord

-two parts:
                 1) Afferent = sensory 
                 2) Efferent = somatic and autonomic
 Afferent System = Sensory-afferent nerves convert stimuli to electrical signals (IPSP, EPSP input)

-high GPSP can start an action potential 

-CNS integrates info via: 
        -cerebral cortex
        -brain stem
        -interneurons 
 Afferent System: RECEPTORSTwo Genres:

1) Somatosensory receptors = skin/GI (free nerve endings)

2) specialized sense organs = receptor potential (IPSP & EPSP)
                                                  skin-pressure
 RECEPTOR TYPE : "Chemo"Chemo = chemical 

-tongue
-smell
 RECEPTOR TYPE : "Mechano"Mechano = pressure
                   vibration
                    sound
 RECEPTOR TYPE : "Thermo"Thermo= temperature

-skin
 RECEPTOR TYPE : "photo"photo = light 

-eyes
 RECEPTOR TYPE : "Nociceptor"nociceptor = noxious stimuli 

-(chem/mech/therm)

-when body is in danger 

EXAMPLE: being in 25* water-->loose heat--->hypothermia
 Receptive Fields (afferent system)-area that receptors cover

-these areas overlap

-larger the field   =  the less sensitive 

-convergence 

 Signal Conversion ((afferent system))1st) transduction - stimulus to elect signal 

2nd) change in membrane potential (EPSP, IPSP)
            -potentials are graded
            -generator potential = neural
            -receptor potential = non neural (special sense)
 Signal Conversion Examplesstimulus --> somatosensory --> IPSP/EPSP ---> Action
                      (neural)            (generated potential)



stimulus -->specialized sense organ ---> IPSP/EPSP
                     (non-neural)                      (receptor potential)

***potentials are graded***
 CODING (afferent system)-use coding to distinguish inputs

1) nature of sensation 

2) location - cerebral cortex

3) Intensity - must meet threshold 

4) duration: tonic or phasic
 "Phasic" duration ((afferent system: CODING)adapts and stops firing signals
 "tonic" duration (afferent system: CODING)keeps sending signals
 Hearing CodingTHE EXCEPTION to coding norm.

-it measures time difference in each ear
 Touch/Pressure (somatic senses)-common

-mostly skin 

- small, low vibrations

- free nerve endings

-speed: fast is myelinated . slow is non-myelinated
 Touch/Pressure: "Compression" (somatic sensory)-Pacinian Corpuscle 

-large

-highly studied

-respond to high frequency vibrations

-mechanical gated ion channels
 Temperature (somatic sensory)-subcutis = free nerve endings

-cold = below 37 degrees C

- warm = 37-45 degrees C

-adapt only between 20-40 degrees C 
 Nociceptors (somatic sensory)-a sensory receptor that responds/activated by potentially damaging stimuli by sending a nerve signal to CNS.

-pain/itch

-fast = small myelinated 
-slow =small unmyelinated 

-substance P = neurotransmitter 

-withdraw reflex

-suppressed by inhibitory pathways
-referred pain - poor localization 

 Nociceptors: Deep Pain- metabolites mediate muscle 

- K+ in muscle 

-lack of blood

-decreased pH
 Chemoreceptors (somatic sensory)receptors for smell and taste

smell - --> Olfaction 

taste - --> Gustation

-smell linked to memory and visual cortex

 Olfactory Epithelium-specialized epithelial tissue inside the nasal cavity that is involved in smell.

-non-neural neurons that divide

-how do they find receptors

- dog's sense of smell is 100,000 to 1,000,000,000x's better than humans
 Olfactory Binding Protein- odor molecules present to epithelium receptors (400 different)--> population summation

-usually G protein gets activated 
-then second messenger opens ion channel to make AP

-nasal mucous 
 Chemoreceptors to Cerebrum-no thalamus 

-about 10,000 odor codings
 Vomeronasal organ-olfactory sense organ

-used to detect pheromones (rodents) 

-no odor 
 Gustation: Types of Taste Buds- Salt = Nat+

- Sweet = nutritious 

- Sour = H+

- Bitter = harmful 

- Umami (savory) = glutamate (MSG)
 Gustation: Epithelial Cells-bind with substance / saliva 

-depolarize AP

-non neural 

-mostly G protein

-medulla ---> thalamus ---> cerebrum
-depends on smell, receptors, and strength
 Pinna-the visible part of the ear that resides outside of the head 

-funnel for sound

-outer ear
 Tympanic Membrane-the eardrum

-part of outer ear

 Malleus-hammer

-part of middle ear

-amplifies sound waves 

 Incus- anvil

-middle ear

-amplify sound waves
 Stapes-stirrup 

-middle ear

- amplifies sound waves
 Cochlea-auditory portion of the inner ear

-spiral shaped cavity

-oval window/round window


 Endolymph- fluid contained on the inside of the cochlea (inner ear)

-cochlear duct
 Perilymph-fluid contained on the outside of the cochlea (inner ear)

-vestibular duct

-tympanic duct


 Organ of Corti-organ in the inner ear 

-contains auditory sensory cells aka "hair cells"
 Ear Transduction1) vibrations travel into oval window of cochlea 

2) fluid waves hit the perilymph fluid in the vestibular duct

3) organ of corti displaced by waves

4) hair cells bend (they detect the sound)

5) ion channels open and depolarization takes place

6) a neurotransmitter is then released

7) AP in sensory neuron 

8) hair cells bend back and causes ion channels to close
 flexion of earion channel open

AP 

return

ion channels close
 Cochlear Processing: PITCH- vestibulocochlear nerve VIII controls

HIGH frequency near oval window

LOW frequency at distal end of cochlear 

 Cochlear Processing: LOUDNESS
- vestibulocochlear nerve VIII controls

more rapid firing of neurons due to amplitude 

 --->thalamus --->cerebrum ---> location loudness pitch
 Processing of Medulla-pyramids crossing over

-ipsilateral and contralateral 
 Processing of Midbrain-thalamus
 Deafness: Conductive-outer / middle ear

-mechanical

-by gestacian tube
 Deafness: Sensorineural-inner ear

-hair cells are the problem
 Deafness: Central-between ear and brain

-strictly nerve damage 
 Semicircular canals-part of the inner ear/equilibrium 
-somatosensory - proprioception 

-part of Vestibular Apparatus 
-has 3 planes

-has "ampulla" to detect movement at the end of the canal

-made of endolymph hair cells/gel
 Utricule- part of inner ear/equilibrium / Vestibular Apparatus 

- forward/back of head  (horizontal) effects

-has hair cells in gel called "otoliths"  
 Saccule
- part of inner ear/equilibrium / Vestibular Apparatus 

- up/down of head effects

-has hair cells in gel called "otoliths"  

-THINK ELEVATOR
 Transduction of Vestibular Apparatus- endolymph moves hair cells / otoliths 

- rotational acceleration of semicircular canals

- linear acceleration :
                                  - utricule = horizontal
                                  - saccule = vertical 
 Processing of Vestibular Apparatus- thru the vestibulocochlear nerve VIII 

- medulla 

-cerebrum (not as much thru here)
 Cornea-transparent front part of the eye that covers the iris
 Sclera- the white part of the eye 
 Conjunctiva-lines the inside of the eyelids

- PINK

-covers the sclera
 Anterior Chamber of Eye- aqueous humor fluid in the chamber between the iris and cornea 

- CLEAR

- allows transmission of light
 Iris- color of your eye 
 Pupil-hole in center of the iris of the eye 
 Posterior Chamber of Eye- vitreous humor behind the iris 

- like a gel ball 

-(marble part of cow eyeball i tried to cut through) 
 Retina-lining on the inner surface of the eye
 Optic Nerve-comes out of the eye out the back 

-blind spot 
 Electromagnetic Energy-visible spectrum we can see 400-750 nm

-in between ultra violet and infra red wavelengths 

 LIGHT into eye-bends at cornea

-bends at lens

lens accommodates for focus 

- pupil controls amount of light

- retina receives images 
 Transduction of Eye(retina is backwards = the nerves are in the front and photoreceptors in the back)

- bipolar neurons pick up message 
-ganglion cells receive message and form optic nerve
-optic chiasma is where signals cross over
-travel to lateral geniculate nuclei and to thalamus
-then to visual cortex (occipital lobe)
 Optic Chiasma- part of brain where the optic nerves cross
 Rods- for night time 

- are 20x's the amount of rods than cones

- "rhodopsin" 
 Cones- color

-red
-green
-blue
 Type of Photoreceptors in Retina1) rods

2) cones

3) bipolar neurons

4) ganglion cells

5) optic nerve 
 Lateral Geniculate Nuclei-  the primary relay center for visual information received from the retina 

-found inside the thalamus
 Visual Cortex-part of the cerebral cortex

-responsible for processing visual information
 Mechanism of Eye1st) visual pigments (rhodopsin and cone pigments) bound to membrane 

2nd) light causes unbinding of rhodopsin 
        (opsin + retinol = called "bleaching")

3rd) G protein activated (cGMP reduced, Na+ channels close, 
        hyperpolarization occurs (K+ leaking out))

(this is a slow process, adaptation takes time)
 Mechanism of the Eye Resulting from = Total darknessAfter unbinding of opsin and retinol (bleaching):

-continuous depolarization occurs = signaling 

-graded potential

-Na+ / Ca ++  ---> in
 Mechanism of the Eye Resulting from = Dim LightAfter unbinding of opsin and retinol (bleaching):

- the dim light inhibits depolarization

- not as much signaling occurs 

- starts to block Na+ / Ca++
 Mechanism of the Eye Resulting from = Total LightnessAfter unbinding of opsin and retinol (bleaching):

- total light shuts off all neurotransmission

-no signals occur ---aka--> hyperpolarization  

- blocks K+


 Fovea of Eye-focal spot on retina of eye

-neurons are pushed aside of fovea which allows photons to go right through, instead of having to go through two layers of neurons 

-most sensitive 

-lets us see fine details
        
 Coding of Signals : Convergence-photons ---> to bipolar ---> to ganglion 

-there are about 100 bipolar cells that converge into 1 ganglion 



 Bipolar Ganglion: Inhibitory-center of vision field is inhibited 

-outside rim of field is excited 



(if light hits entire field = see nothing)
 Bipolar Ganglion: Excitatory-bright light hits center of vision field and excites 

-outside of field is inhibited

(if light hits entire field = see nothing)
 Coding of signals - Receptors (glutamate)-inhibits or excites bipolar cells
 binocular vision-both eyes are used together 

-left and right fields overlap
 Efferent System-Somatic = voluntary muscles 

-Autonomic = involuntary 
                   = sympathetic(fight/fight) and parasympathetic (rest/digest)
 Pre-post Ganglionic (autonomic)collections of neurons 
 Autonomic Neurotransmitter at ganglionAcetylcholine (ACh) for all pre-post synapses 
 Axons of Autonomic- end in vesicles 

- those vesicles send out neurotransmitters which find receptors
 Exceptions to Innervation (autonomic system)ONLY THE SYMPATHETIC DIVISION innervates:

-blood vessels 
-sweat glands
-adrenal glad
-kidneys
-fat
 Neurotransmitter for Parasympathetic DivisionCholinergic - acetylcholine (ACh)
 Origin of Parasympathetic Division (the nerves)Cranial Nerves III, VII, IX, X

and sacral nerves
 Parasympathetic Divisionrest of digest

"slow system" 
 Parasympathetic Division Ganglia-either right NEAR the organ

-or they are ON the organ

(this means it has long presynaptic/preganglionics)
 Parasympathetic Division: Receptor = Nicotinic-reacts to nicotine

- are all pre-post ganglia 

-at neuro-muscular junctions
 Parasympathetic Division: Receptor = Muscarinic -all post. gang. organs

-on effector cells

-mechanism = G protein - 2nd messenger 
 Atropine-drug that blocks secretions 

-also prevents you from vomiting 

-doesn't effect muscle at all or ganglia

-is a muscarinic blocker in the Parasympathetic Division  
 Physostigmine-a drug that blocks both receptors (nicotinic and muscarinic)

-but, more muscle blocking

(Parasympathetic Division)
 Sympathetic Division: neurotransmitterAdrenergic (meaning that its dealing with a form of adrenaline) :

(Catecholamines (tyrosine))
1) Epinephrine (E)
2) Norepinephrine (NE)
 Sympathetic Division Origin-Thoracic Spine 

and

-Lumbar Spine
 Sympathetic Divisionflight or fight system

-fast system = short preganglionics 
 Sympathetic Division Ganglia-comes out right next to spinal cord = short presynaptics 

-called "Collateral Ganglia"
          -Celiac (stomach)
          -Superior Mesenteric 
          -Inferior Mesenteric 
 Adrenal Medulla (Sympathetic Division)-acts like a ganglion 

-no post ganglionic fibers

- 20% NE
                         puts both of these into blood
- 80% E
 Sympathetic Division Receptor: Alpha 1, 2-most common Sympathetic Division receptor

-responds to (NE) norepinephrine 

-not very fast

-may inhibit or excite depending on receptor
 Sympathetic Division Receptor: Beta 1-innervated by heart and kidney

-responds to NE and E

-not very fast

-may inhibit or excite depending on receptor
 Sympathetic Division Receptor: Beta 2- no innervation 

-mostly adrenal (arterioles and bronchioles)

-responds to E

-not very fast

-may inhibit or excite depending on receptor
 Beta Blockers-are used for people with heart disease

- LOWER heart rate
 Somatic Efferent Neurons-arise form motor neuron cell bodies in the ventral horns of gray matter within the spinal cord

-neuromuscular 

-for the most part voluntary 
 Motor Unitmotor neuron + fibers 
 Somatic Efferent: NeurotransmitterAcetylcholine (ACh)
 Somatic Efferent: Receptornicotinic 

(but these are different than the nicotinic receptors on ganglia)
 Somatic Efferent Neurons: ONLY STIMULATORYAP leads to muscle twitch

-all or none 

(except you can get a weak signal sometimes)
 Somatic Efferent Neurons: Final Common Pathway-from motor neuron to muscle 
 ALS"Amyotrophic Lateral Sclerosis"

-loose motor neurons

-lateral horn

-aka lou gehrigs disease 


 Polio-virus that destroys motor neurons

-once they're done, they're done (can't grow em back)

-can contract disease in swimming pools 
 Too much CSF-fluid pressure builds 

- hydrocephalus
 Too little CSF-could mess up by spinal tap

-get headaches
 What substances can make it through the BBB? (these are the exceptions to the normal rule)
- glucose 

- O2/CO2

- alcohols

- lipids
 HYPOglycemia
- low blood sugar
- 10-15 minutes before brain has problems
 Hypoxia (to the brain)lack of oxygen 
- can go 5 minutes before problems occur
 Spinal Cord: Polysynaptic REFLEXES
= many circuits, 
 - crossed extensor for balance
 - contracts automatically (when you lift left leg, right leg tightens and contracts to balance out.
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