NEUROLOGY

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NEUROLOGY

• The study of the Nervous System

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3 Broad functions of Nervous System

• 1. sensory input
• 2. integration
• 3. motor output

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1. Sensory Input

• Monitor changes in Bodys internal and external
  environment

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2. Integration

• Processes and interprets sensory input

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3. Motor Output

• Responding to interpretations by active muscles
  or glands

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ORGANIZATION OF Nervous System

• I. Central Nervous System (CNS)
• II. Peripheral Nervous System (PNS)

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I. Central Nervous System (CNS)

• The Brain and spinal cord (control center)
• Functions as the processing, interpreting and
  responding center.

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Peripheral Nervous System (PNS)

• Remainder of nervous center. The communication
  link between CNS and the muscles and glands

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Peripheral Nervous System (PNS)

• Subdivided into
• A. Afferent (sensory) System
• B. Efferent (Motor )System

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Afferent (sensory) System

• Input System
• Carries information toward CNS

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Efferent (Motor ) System

• Output system
• Carries information from CNS to organs (muscles,
  glands etc..)

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Efferent (Motor )System

• Subdivided into
• 1. Somatic Nervous System
• 2. Autonomic Nervous System

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Somatic Nervous System

• Carries impulses to skeletal muscles (voluntary)

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Autonomic Nervous System

• Carries information to the viscera ( organs,
  cardiac muscle, glands)
• (Involuntary)

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Autonomic Nervous System

• Subdivided into
• A) Sympathetic system
• B) Parasympathetic system

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Sympathetic system

• Increases organs activity in response to some
  stress
• Fight or Flight response
• Dilates pupils, brachial tubes, increases heart
  and respiratory rates

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Parasympathetic system

• Inhibits an organs activity or returns it to
  normal
• Ex Loss of control of bladder or bowel functions

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CNS
PNS
Aff.
Eff.
Som.
Auto.
Symp
Parasymp
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HISTOLOGY

• A CELLULAR LOOK AT THE NERVOUS SYSTEM

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NEURON A nerve cell

• Consists of
• Perikaryon cell body
• Nucleus
• Axons long cell extensions, carry info away from
  cell body
• Dendrites short cell extensions, carry info
  toward cell body

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NEURON
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NEURON
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NEUROGLIA ( GLIAL) CELLS

• Support or protective cells,
• do not carry impulses
• They insulate, nourish and protect neurons

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NEUROGLIAL CELL Examples
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Astrocytes

• Star shaped cells, nourish neurons by connecting
  them to blood vessels.

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Schwann cells

• Insulate axon/dendrites in PNS
• Space between Schwann cells are called Nodes of
  Ravier
• 8 in diagram

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Schwann cells
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Schwann cells
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NOTICE THE WORD NEURILEMMA FROM THE PREVIOUS SLIDE

• In Nerve cells the cell membrane is called the
  neurilemma.
• The cytoplasm is called the neuroplasm.
• And the nerve cell is called the neuron.

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Oligodendrocytes

• Cells wrapped around CNS neurons forming
  insulation ( myelin sheath)

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Types of Neurons

• BY FUNCTION
• 1. SENSORY ( afferent) Neuron conduct impulses
  from receptors to CNS
• 2. Associated ( Interneuron) Neuron conducts
  impulses between sensory and motor neurons
• 3. Motor ( efferent) Neurons conducts impulsess
  from CNS to muscle and glands

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Types of Neurons

• BY STRUCTURE
• Multipolar Neurons have 1 axon and many
  dendrites
• Bipolar Neurons have 1 axon and 1 dendrite
• Unipolar Neurons have extensions which branch
  into an axon and a dendrite

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Structure of a nerve

• Nerve a cordlike grouping of parallel nerve
  cells enclosed by C.T. wrapping
• Endoneurium encloses individual cells (neurons)
• Perineurium encloses bundles of neurons ( bundle
  fascicle)
• Epineurium surrounds bundles of fascicles

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Structure of a nerve
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Neuron regeneration (repair)

• At about 6 months of age, neurons lose the
  ability to divideso if destroyed they cannot be
  replaced.
• However, if the perikaron is intact and thee
  axons and dendrites are myelinated they can
  regenerate (PNS only)
• The repair will be imperfect ( axonal ends are
  not mylinated and axon may stop short or in wrong
  place)

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Nerve Impulses ( action potential)

• Is electrical in nature
• Steps
• The resting membrane potential occurs in a
  neuron when it is not firing an impulse ( cell
  pos on outside and neg on inside this is due to a
  higher concentration of sodium ions)

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Nerve Impulses ( action potential)

1. The action potential causes the release of a
   neurotransmitter ( chemical signal) ex
   acetylcholine
2. The neurotransmitter diffuses across the
   synapses ( area between 2 neurons)
3. The neurotransmitter excites the next cells
   located on the other side of the synapses

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Nerve Impulses ( action potential)

1. Sodium begins to diffuse into the postsynaptic
   cell starting the development of its action
   potential
2. Neurotransmitter is broken down and transported
   away from the synapses.
3. The process starts over

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Cranial and Spinal Nerves

• Part of the P.N.S
• Nerve a bundle of axons and dendrites outside
  CNS
• Tract A bundle of axons and dendrites inside CNS
• Ganglion a collection of celol bodies and
  dendrites outside CNS

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Spinal nerves

• 31 pairs that emerge from spinal cord ( they each
  enter the spinal cord by 2 attachment points
  called roots)
• Dorsal (posterior) root Contains sensory nerve
  fibers onlyso impulse is carried from receptor
  to the spinal cord.
• Ventral (anterior) root contains motor neurons
  onlyimpulses are conducted out to effector

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Spinal nerves

• So spinal nerve is a mixture of both sensory and
  motor neurons
• Grouped as followed
• Cervical 8 pr
• Thoracic 12 par
• Lumbar 5pr
• Sacral 5 pr
• Coccygeal 1 pr

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Cervical Nerves (12)

• Number/ Name sensory/motor
• Olfactory (on) s (some)
• Optic (old) s (say)
• Occularmotor (olympus) m (marry)
• Trochlear (towering) m (money)
• Trigeminal (top) both (b) (but)
• Abduscen (a) m (my)
  

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Cervical Nerves (12)

• Number/ Name sensory/motor
• Facial (fin) b (brother)
  
• Auditory (and) s (says)
• Glosopharyngeal (germ) b (bad)
• Vegus (viewed) b (business)
• Spinal accessory (some) m (marry)
• Hypoglosseal (hop) m (money)

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NEROLOGICAL DISORDERS
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NEURON-INTRANUCLEAR INCLUSION BODY E.G. HERPES
SIMPLEX
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RABIES
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PARKINSONS
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Parkinson's disease

• a disorder that affects nerve cells, or neurons,
  in a part of the brain that controls muscle
  movement.
• In Parkinson's, neurons that make a chemical
  called dopamine die or do not work properly.
  Dopamine normally sends signals that help
  coordinate your movements.
• No one knows what damages these cells.

• Symptoms of Parkinson's disease may include
• Trembling of hands, arms, legs, jaw and face
• Stiffness of the arms, legs and trunk
• Slowness of movement
• Poor balance and coordination

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NEURON-LAFORA BODY MYOCLONIC EPILEPSY
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NEUROFIBRILLARY TANGLE-ALZHEIMER'S DISEASE
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TANGLE-ALZHEIMER'S DISEASE

• Neurofibrillian tangles are abnormal collections
  of twisted threads found inside nerve cells.
• The main component of the tangels is one form of 
  the protein tau. The tau protein has a ability to
  bind and stabilize the cells internal skeleton
  called microtubule. In neuron cells that are
  healthy microtubules form structures like train
  tracks,
•   In cells affected by AD the train track
  structures collapses, tau is changed chemically
  and can no longer hold the pieces together.. The
  collapse of the transport system first may result
  in malfunctions in communication between nerve
  cells and later lead to neuron death.

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GROSS HEMORRHAGE IS A MASS OF BLOOD DISSECTING
INTO TISSUE
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MULTIPLE SCLEROSIS -GROSS
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NEURONAL STORAGE DISEASE e.g.TAY SACHS-MICRO

• hereditary metabolic disorder that causes
  progressive mental and neurologic deterioration
  and results in death in early childhood. The
  disease is inherited as an autosomal recessive
  trait and occurs most commonly among people of
  eastern European

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TAY SACHS

• The disease occurs when harmful quantities of a
  fatty acid derivative accumulate in the nerve
  cells of the brain
• SYMPTOMS include speech and swallowing
  difficulties, unsteadiness of gait, spasticity,
  cognitive decline, and psychiatric illness,
  particularly schizophrenic-like psychosis.
  Patients with LOTS frequently become full-time
  wheelchair users in adulthood, but many live full
  adult lives

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MENINGITIS-MICRO SHOWING POLYS
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JAKOB-CREUZFELDT DISEASE
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The Brain

• weighs 1300 - 1400 g
• made up of about 100 billion neurons
• the most complex living structure on the
  universe Society for Neuroscience
• makes us who we are

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The Brain

• 4 principal parts
• Brain stem composed of medulla, pons, and mid
  bread ( corpora quadrigemina)
• Diencephalon thalamus and hypothalamus
• Cerebrum 7/8 of total weight of brain
• Cerebellum inferior to cerebrum and posterior

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Protection of brain Meninges( 3 coverings of
brain)

1. Dura mater tough outer layer
2. Arachnoid delicate net like middle layer
3. Pia mater delicate innermost layer

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Brain structure
Cerebrum
cerebellum
hypothalamus
Pituitary gland
brain functions
medulla
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Brain parts

1. Medulla oblongata most inferior portion of
   brain, contains respiratory, cardiac and
   vasomotor (blood pressure) centers
2. Pons relay system for medulla, cerebellum and
   cerebrum
3. Cerebellum responsible for motor coordination,
   controls body equilibrium , posture and muscle
   tone

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Brain parts

• Midbrain relay center, includes corpora
  quadrigemina. Controls reflex motion of eyes,
  head in response to vision and reflex movements
  in response to auditory
• Thalamus relays sensory input except for
  olfactory to cerebrum and interprets some basic
  sensory data like heat, pressure and pain

Brain parts
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Brain parts

1. Hypothalamus contains centers for thirst,
   hunger, body temperature and water balance.
   Controls feelings of aggression and rage,
   controls pituitary gland and thus releases of
   hormones.
2. Cerebrum 7/8 brain in most people the left
   hemisphere is dominant and specialized for
   language and mathematical skills, where the right
   side is more concerned with visual and spatial
   skills and creative endeavors

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Lobes of brain and their functions

1. Frontal, somatic motor, speech, premotor, seat
   of intelligence and abstract reasoning
2. Brocas area speech ( part of frontal lobe)
3. Temporal hearing, smell and memory, language
   /speech comprehension
4. Parietal muscle movement, touch and taste,
   primary sensory cortex
5. Occiptial visual areas

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Parts of the cerebrum
memory game
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sheeps brain
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Spinal Cord part of CNS

• Is 17 inches long,
• sits inside the vertebral canal of vertebra
• Contains white matter and gray mater
• Has all three meninges

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Senses notes

• Sensation a state of awareness (
  conscious/unconscious) of the external/internal
  environment
• Perception the conscious awaremess and
  interpretation of a sensation
• Receptors convert a stimulus into an impulse

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4 prerequisites for a sensation

1. Stimulus must be received
2. Stimulus must be converted into a nerve impulse
   by a receptor
3. Conduction of impulse to CNS
4. Translocation of impulse to sensation

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Some examples of receptor types

• Thermoreceptors respond to changes in temp. ex
  skin
• Photoreceptors respond to light energy ex retina
  of eye
• Chemoreceptors detect changes in chemicals
  including taste and smell

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Olfactory (smell) Sense

• these receptors are found in the nasal epithelium
  
• To be sensed a substance must be all gaseous and
  water soluble ( to dissolve in mucus)
• Humans can react to as many as 50 chemicals in
  the air to give the spectrum of odors we know

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Gustatory (taste) sensation

• Receptors are located in taste buds on tongue and
  scattered on the palate and that There are 4
  primary taste sensations sweet, sour, bitter,
  salty
• It is estimated that about 80 of taste is due to
  smell.

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Super tasters

• With scientists suggesting that 1 in 4 persons
  has extra taste buds
• Supertasters, as those with extra taste buds are
  known, do not only derive more pleasure out of
  food.
• Having extra taste buds is associated with
  obesity and colon polyps.
• Despite the link between extra taste buds and
  potential health problems, there is some good
  news for supertasters- they have a higher than
  average likelihood of becoming wine tasters or
  professional chefs.

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"tongue map"

• One of the most dubious "facts" about taste--and
  one that is commonly reproduced in textbooks--is
  the oft-cited but misleading "tongue map" showing
  large regional differences in sensitivity across
  the human tongue. These maps indicate that
  sweetness is detected by taste buds on the tip of
  the tongue, sourness on the sides, bitterness at
  the back and saltiness along the edges.

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"tongue map"

• Taste researchers have known for many years that
  these tongue maps are wrong.
• The maps arose early in the 20th century as a
  result of a misinterpretation of research
  reported in the late 1800s, and they have been
  almost impossible to purge from the literature.

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Vision

1. Accessory structures of eye
2. Eyebrow/lash
3. Eyelids
4. Conjunctiva it lines the eyelid. When the
   vessels in the conjunctiva are dilated, you have
   blood shot eyes
5. Lacrimal apparatus manufactures tears
6. Extrinsic eye muscles move eyes

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Parts of eye Parts of eye

1. Sclera tough, white covering of eye
2. Cornea transparent covering of eye
3. Choroid pigmented layer, provides nutrients to
   posterior surface of retina
4. Ciliary body secretes aqueous humor and contains
   ciliary muscles which change the shape of the
   lens for focusing
5. Iris smooth muscle controls amount of light
   entering eyegives eye its color

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Parts of eye

1. Retina found in posterior 2/3 of eye contains
   the light sensitive receptors called rods (
   detect diff in light intensity) cones ( detect
   color) The rods and cones are most concentrated
   in the fovea centralis.. Optic disk no rods and
   cones blind spot and is where optic nerve
   enters eye and becomes retina
2. Lens separates the anterior cavity and posterior
   cavity, made completely of protein

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Vision

• Light passes through cornea to aqueous humor to
  lens to vitreous body to retina.
• Each of these structures has the ability to
  refract or bend light
• By convergence the light rays are collected and
  concentrated.
• The image which lands on the retina is upside
  down and backwards ..our mind (cerebrum returns
  it to normal)

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Ear

• 3 subdivisions
• External ear pinna , external auditory meatus,
  tympanic membrane
• Middle ear ossicles, oval and round window and
  eustachian tube
• Internal ear osseous labyrinth ( a series of
  tubes in temporal bone made up of the cochlea,
  vestibule and semicircular canals)

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Hearing

• Sound passes through the ear in the following
  order
• Auricles, external auditory meatus, tympanum,
  malleus, incus, stages, oval window, vestibular
  canal, round window
• As these structures vibrate, they amplify the
  vibrations causing sound to become louder

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