LAST LAB

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LAST LAB!!!

• Lab Practical NEXT WEEK!!!
• Whoo hoo- youre almost done!
• Objectives for this week
• Learn the differences between general sensation
  and the special senses.
• Learn the anatomy of the eye, its regions and
  their functions.
• Learn the anatomy of the ear, its regions and
  functions.
• Understand how we use the special senses to
  perceive the environment.

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Sensory receptors changing environmental
stimuli into afferent nerve impulses

• What are the five types of sensory receptors
  based on the type of stimulus they respond to?
• Mechanoreceptors respond to deformation by a
  force (touch, vibration, pressure, etc.)
• Thermoreceptors Temperature changes
• Photoreceptors respond to light
• Chemoreceptors respond to chemicals in solution
  (smell, taste, blood chemistry)
• Nociceptors pain receptors (all others can be
  pain receptors too)

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Sensory receptors changing environmental
stimuli into afferent nerve impulses

• What are the three types of sensory receptors
  based on location?
• Exteroceptors simple cutaneous and special
  senses- respond to external stimuli
• Interoceptors internal visceral stimuli
• Proprioceptors like interoceptors, but only in
  muscles and their associated connective tissue.
• What type of sensory receptors are general
  sensory receptors?
• All three!!! (Check out page 492 in your text)

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General Sensation

• Cutaneous receptors
• Non-encapsulated
• Free dendritic endings
• Merkel discs
• Root hair plexes
• Encapsulated
• Meissners corpuscles - Krauses End Bulbs
• Pacinian corpuscles
• Ruffinis corpuscles
• Muscle spindles and Golgi tendon organs

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Activities pages 357-359

• Activities 1,2 and 3
• Two Point Discrimination Test and Tactile
  Localization
• Density of receptors is not the same in all areas
  of the body.
• Why not?

• Activity 5
• Adaptation of sensory receptors
• Why is there a difference in the rate of
  adaptation across sensory receptor types?
• Which ones are slow?
• Which ones are fast?

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Special Senses Vision
General Anatomy
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Eye Anatomy - Internal and External

• External
• Eyelids (palpebrae)
• Conjunctiva (mucous membrane)
• Glands and ducts

• Internal
• 3 Tunics!
• Fibrous Cornea and Sclera
• Vascular Choroid, Ciliary body, Iris, and pupil
• Sensory Retina (pigmented and neural layers)

Where are the extrinsic eye muscles? Where are
the intrinsic eye muscles?
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Intrinsic eye muscles include the ciliary
muscles, which act to change the shape of the lens
Page 569 text
Intrinsic eyes muscles also include the circular
and radial iris muscles, which are smooth muscle,
and are controlled by the ANS. Which causes the
pupils to dilate? Which causes the pupils to
constrict? Which division of the ANS controls
each of the above actions?
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Extrinsic Eye muscles
Tarsal ducts and Lacrimal gland
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How does light travel through the eye?
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Pathway of excitation
Action potential generated at ganglion cell layer.
Pathway of light
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Visual Field
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Activities pages 364-375

• Activity 1 External Anatomy
• Activity 2 Internal Anatomy
• Activity 3 Histology of the Retina
  remember to tell them about Figure 24.4
• Activity 4- Understanding the visual field and
  effects of damage.
• Dissection of Sheeps Eye
• Activities 5, 6, 7, and 8 Visual tests and
  experiments

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Special Senses Hearing and Equilibrium
How do we hear? Sound waves vibrate the eardrum,
which in turn pushes a tiny linkage of bones that
press the fluid in the inner ear against
membranes that cause shearing forces on tiny hair
cell receptors that stimulate neurons to generate
an action potential which travels to the brain
via CN 8.
How do we keep our balance? Receptors in the
vestibule, and in the the semi-circular canals
monitor static and dynamic equilibrium
respectively.
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Anatomy of the Ear

• There are three major areas Outer, Middle and
  Inner Ear
• All are involved in the process of turning a
  sound wave into an electrical impulse via a
  fluid.
• When we get to the inner ear, things get a little
  complicated.
• Osseous and Membranous Labyrinths one is inside
  the other.

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Osseous vs. Membranous

• Cochlea (Scalae vestibuli and tympani)
• Vestibule
• Semicircular Canals

• Cochlear Duct (Scala media)
• Utricle and Saccule with their maculae.
• Semicircular ducts with enlarged Ampullae at the
  end and the crista ampullaris.

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Cochlear HistologyWhat is Osseous and what is
Membranous labyrinth?
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Activities pages 383-392

• Activity 1 Identify ear structures
• Activity 3 Histology of the Cochlea
• Activity 4 Only the Weber test to understand
  differences between types of hearing loss.
• Activity 7 Tilt A Whirl ! Need a volunteer!
  Demonstration of Nystagmus. Role of vision in
  Maintaining Equilibrium

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Use models, Sheep Eyes, cadaver and each other!!!

• Work in small groups on your activities
• Chapter 23 1,2,3, and 5
• Chapter 24 1-8
• Chapter 25 1,3,4, and 7