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Anatomical Model

Anatomy & Physiology: Week Three

Chapter Ten: Nervous System

Divisions of the Nervous System

  • Central nervous system (CNS): includes the brain and spinal cord.
  • Peripheral nervous system (PNS): all nerves going to and away from the brain and cord.
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Functions of the Nervous System

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Cells of the Nervous system

Neuroglia or glial
  • Most abundant type
  • Support, protect, insulate, nourish, and generally care for neurons.
Neurons
  • Nerve cells
  • Do the communicating for the nervous system.
  • Long shape makes them delicate.

The Parts of a Neuron

  • Cell body
  • Dendrites
  • Axon: tail-like extension of the neuron
  • Myelin sheath
  • Nodes of Ranvier
  • Neurilemma
  • Axon Terminal
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             Click to review the                    parts of a neuron

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Types of Neurons

Sensory (afferent) neurons
  • Carry information from the periphery toward the CNS.
  • Carries information to the brain and spinal cord
Motor (efferent) neurons
  • Carry information from the CNS toward periphery.
  • Carries information away from the brain and spinal cord
Interneurons
  • Found only in CNS; connect sensory and motor nerves.

White Matter vs Gray Matter

White matter
  • Made up of myelinated axons
Gray matter
  • Made up of: unmyelinated axons, cell bodies, interneurons, synapses
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The Nerve Impulse: What It Is

  • Electrical Signals convey information along a neuron.
  • Also called action potential
  • Move along sensory or motor neurons

Parts of a Synapse

  • Receptors
  • Neurotransmitters
  • Inactivators
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Click to watch a
    video about
       synapses

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Four Major Areas of the Brain

  • Cerebrum: largest part of the brain
  • Diencephalon
  • Brain Stem
  • Cerebellum: posterior part of the brain, coordinates and maintains balance
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Cerebrum: Gray on the Outside, White on the Inside

Cerebral cortex
  • Made up of gray matter
  • Outermost portion of the cerebrum
White matter
  • Makes up the bulk of the cerebrum
  • Located right below the cerebral cortex

Markings of the Cerebrum

  • Gyrus (convolutions)
  • Fissures (sulci)
        Central
        Lateral
        Longitudinal
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             Click to review the                         parts of the                                  cerebrum

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Diencephalon
  • Thalamus
  • Hypothalamus
Brain Stem
  • Midbrain: Reflex center
Pons
Medulla Oblongata
  • Vital center
  • Emetic center
Cerebellum
  • Located at the base of the skull
  • Mediates reflexes
  • Coordinates motor activity
  • Evaluates sensory input
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             Click to review the                     parts of the brain
            and their Functions

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Protecting the Central Nervous System

  • Bone
  • Meninges: dura mater (thick, outermost layer), arachnoid layer, pia mater (delicate inner layer)
  • Cerebrospinal fluid: Circulates throughout the brain and spinal cord, formed in the ventricles by choroid plexus.
  • Blood-brain barrier: made of special cells (astrocytes), prevents toxins from entering CNS from blood.
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Chapter 13: Sensory System

Sensory System

  • Sensory system allows us to experience the world
  • External information: like the sound of a dog barking
  • Internal information: like a sudden change in blood pressure

Cells that Detect Stimuli

Receptor: Specialized area of a sensory neuron that detects a specific stimulus
  • Chemoreceptors: receptors of different chemicals
  • Pain receptors (nociceptors)
  • Thermoreceptors: receptors for cold and heat
  • Mechanoreceptors: pressure and touch receptors
  • Photoreceptors: receptors for light

Four Components of Sensation

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Five General Senses

  • Pain
  • Touch
  • Temperature
  • Pressure
  • Temperature
  • Proprioception
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Sites of Referred Pain

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  • Compare heart's location with possible sites of pain during a heart attack
  • Gallbladder attack present with shoulder pain

Five Special Senses

  • Smell - olfaction
  • Taste - gustation
  • Sight - vision
  • Hearing
  • Balance

Olfactory Sense: Smell

  • Chemoreceptors in nasal tissue
  • Nerve impulses travel on CN I to the temporal lobe for interpretation
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Gustatory Sense: Taste

  • Taste receptors are chemoreceptors
  • Nerve impulses move along three cranial nerves to parietal and temporal lobes
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Sense of Sight: The Eye

Visual Accessory Organs
  • Eyebrows
  • Eyelids
  • Conjunctiva
  • Eyelashes
  • Lacrimal apparatus
  • Extrinsic eye muscles
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Parts of the Eye

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             Click to review the                       parts of the eye

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Retinal Photoreceptors

Rods
  • Located on periphery
  • Responsible for black and white  or night vision
Cones
  • Located on the central part of the posterior eye
  • Responsible for color vision

    pdf diagram of
the eye for labeling

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Video of how
vision works

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Errors of Refraction

Myopia
  • Near-sighted
  • Focal point in front of the retina
Hyperopia
  • Far-sighted
  • Focal point behind the retina
Astigmatism
  • Result of irregularly curved cornea
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Vision Loss

Any defect along the pathway from the cornea to the brain can interfere with vision.
  • Scarred cornea
  • Cloudy lens
  • Errors of refraction

Sense of Hearing: Ear Structure

  • External: to the tympanic membrane
  • Middle: from the tympanic membrane to the oval window
  • Inner: behind the oval window
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    pdf diagram of
the ear for labeling

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             Click to review the                       parts of the ear

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Video of how
the ear works

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 Click for a week three review game

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