Nervous System

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School House RockNervous system
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Nervous System
Read Ch 7 Review pg 248 S/A 6, 9, 12, 14
Clinic 2, 5, 10 Read Ch 8 Review pg 277 S/A
5, 9, 14, 21 Clinic 2, 3, 7
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Divisions of the Nervous System

• Central Nervous System
• Command center of the NS
• Integrates all impulses
• Consists of brain and spinal cord
• Enclosed in bonenerves arent very sturdy!

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Divisions of the Nervous System

• Peripheral Nervous System
• Consists of all nerves coming from CNS
• Cranial nerves (12 pair)
• Spinal nerves (31 pair)

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• http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
  spindle.gif

• Nerves are amitotic (will not replicate) because
  they have no centrioles.

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Cranial Nerves
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Spinal Nerves
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Nerve Anatomy
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Functions of Nerve parts

• Cell BodyMetabolic Center
• Dendritebranched projections conveying messages
  TOWARD the cell body
• Axonsingle, elongated projection conveying
  messages AWAY from the cell body

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Functions of Nerve parts

• Myelinwhitish, fatty material that protects and
  insulates nerve fibers. Myelin increases
  transmission rates. Impulse speed 400ft/sec!
• Synapsetiny gap separating each axon from the
  next neuron.
• Nodes of Ranvierindentations between each
  myelinated section of axon

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Functions of Nerve parts

• Neurotransmitterschemicals that must be present
  to transmit impulses to next neuron

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Types of Neurons

• Sensory (Afferent) neuronsconveys impulses to
  CNS from rest of body
• Motor (Efferent) neuronsconveys impulses from
  CNS to muscles and glands

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Types of Neurons

• Interneurons (Association neurons)connect
  sensory and motor neuronsonly found in CNS.

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Spinal Cord

• 17 18 long travels from occipital bone to 1st
  or 2nd lumbar vertebrae
• thickness of thumb
• Primary reflex center
• Carries impulses to and from the brain via a
  2-way conduction system (ascending and descending
  tracts)
• Spinal nerves are named by vertebrae type and
  number

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Spinal Cordfunctions

• Connect PNS and CNS
• Control reflexes

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Reflex Arc

• Involuntary response in which the brain ISNT
  involved

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Reflex arcs cont

• Two-neuron arc
• Egs knee jerk, blinking, AB reflex
• Pathway

Sensory Neuron
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Reflex arcs cont

• Three neuron arc
• Egs hot object, getting a cut
• Pathway

Sensory neuron
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Brain

• Size 2 fists together
• Mass 3
• Texture Oatmeal
• No sensory neurons
• 100 billion neurons made prior to birth, will
  undergo mitosis until 15 18 years of age.

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Cerebrum

• Function Responsible for thinking, reasoning,
  all willed movements.
• Other info Largest, uppermost part

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Functions of cerebral lobes

• Frontal Intelligence, reasoning, use of
  skeletal muscles
• Occipital Visual

• Parietal Speech, reading, pain, cold, touch,
  taste
• Temporal Smell, hearing, memory

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Diencephalon

• Located between midbrain and cerebrum
• Composed of Thalamus and Hypothalamus

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Thalamus

• Function Relays info to Cerebrum, associates
  sensations with emotions
• Other info Dumbbell shaped section of grey
  matter, key part of alerting mechanism

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Hypothalamus

• Function Controls Autonomic Nervous System,
  (temp, metabolism, H2O balance)
• Other info Crucial in maintaining sleep cycles,
  appetite, pleasure, fear, sexual arousal, anger
  and pain.

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Pons

• Function Controls breathing, facial expressions
• Other info Consists of white matter with
  scattered bits of grey.

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Medulla Oblongata

• Function Regulates involuntary responses
  (heartrate, BP, swallowing, breathing)
• Other info Enlarged upward extension of spinal
  cord, consists of both grey and white matter

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Cerebellum

• Function Coordinates skeletal muscles, balance,
  and posture
• Other info 2nd largest part of brain

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Meninge Layers

• Dura Mater (outer)
• Function Tough attachment to skull
• Pia Mater (inner)
• Function Exchange point
• Arachnoid Mater (middle)
• Function Take nutrients and O2 to brain and
  carry waste products away.

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Meninge Layers

• Other info These areas are fluid filled
  membranes surrounding the brain and spinal cord.
  The cerebrospinal fluid fills in the space
  between the pia and arachnoid maters.

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Peripheral Nervous System

• Somatic Division Voluntary control
• Pathway

Peripheral Nervous System
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Peripheral Nervous System

• Autonomic Division NO voluntary control
• Responsible for most vital functions
• Heartrate, breathing, temp reg, etc.
• Pathway

Brain
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Autonomic Division cont

• Divided into Sympathetic and Parasympathetic
  Nerves
• Sympatheticfunctions as emergency system (fight
  or flight)
• Parasympatheticcounteracts the sympathetic
  responsible for normal, everyday lives.
  (resting, digesting, etc)

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Parasympathetic vs Sympathetic
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Parasympathetic vs Sympathetic
Organ Sympathetic Parasympathetic
Heart Stimulates Represses
Digestive Tract Slows Speeds up
Blood Vessels Mostly constricts Mostly dilates
Bladder Relaxes Constricts
Bronchi Dilates Constricts
Iris of eye Dilates pupil Constricts pupil
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Senses--Vision

• Ciliary body and musclechanges the shape of the
  lens to allow focusing

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Senses--Vision

• Iriscontrols the amount of light entering eye.

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Senses--Vision

• Aqueous HumorWatery fluid that gives the front
  of the eye its shape.

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SensesVision

• LensDirects images to retina held in place by
  ligaments.

• Perfectly transparent in youth, will become less
  flexible and opaque in older adulthood hazy
  vision cataracts

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Senses--Vision

• Cornearefracts light into eye

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Senses--Vision

• Vitreous humorgel-like fluid giving the back of
  the eye its shape.

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Senses--Vision

• Optic nerveTakes image to brain blind spot
  exists where the optic nerve meets the retina.

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Senses--Vision

• ScleraProtective covering forms white of eye
  and transparent cornea

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Senses--Vison

• Choroid coatrich supply of blood and decides
  iris color
• RetinaPicks up image, made up of photoreceptors
  (rods and cones)

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Senses--Vision

• General info/terms to know
• Emmetropia
• Hyperopia
• Photopupillary reflex
• Cataract
• Myopia

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Senses--Vision

• General info/terms cont
• Astigmatism
• Glaucoma
• Strabismus

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SensesTaste

• 10,000 taste budsmost on tongue, some on cheeks
  and soft palate
• Taste buds do
• not regenerate!

• Other factors affect taste aroma, temperature,
  texture

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Senses--Smell

• Thousands of smell receptors occupy a space the
  size of a postage stamp at the top of the nasal
  cavity.
• As chemicals dissolve in mucus in area of smell
  receptors, the impulses are transferred to the
  olfactory nerve.
• The olfactory nerve tires of a continuous odor in
  lt 5 minutes
• Half of the people over 80 cant smell at all.

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SensesHearing

• Outer ear
• Pinna
• Auditory canal
• Tympanic membrane

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Senses--Hearing

• Middle ear
• Malleus
• Incus
• Stapes

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Senses--Hearing

• Inner ear
• Semicircular canal
• Cochlea
• Eustachian tube
• Auditory nerve