Lab 9: Special Senses

Lab 9 Part II Instructions - Special Senses

Objectives

• Explain the relationship between gustation and olfaction.

• List the major structures of the eye.

• Categorize the structures of the eye into tunics and explain their function.

• Differentiate between functions of the 3 regions of the ear.

• Label the internal and external structures of the ear.

Introduction

• Observation exercise:

  • Look at an image of a black vase:

  • Initial perception focused on the vase.

  • Shifting focus reveals the white area surrounding it.

  • This phenomenon exemplifies the collaboration between the brain and eyes to interpret environmental information.

• Overview of sense organs that assist in environmental perception:

  • Sensory modalities include:

  • Olfaction (smell)

  • Gustation (taste)

  • Vision

  • Hearing

  • Equilibrium

Gustation and Olfaction

• Description: The sensory systems for gustation (taste) and olfaction (smell) are closely linked.

• Influence of smell on taste:

  • Strong association between olfactory input and gustatory perception.

  • Example: The experience of food tasting bland during a cold due to impaired olfactory function.

• Focus: Analysis of the organs and receptors implicated in taste and smell.

The Tongue

• Function:

  • Integral for speech and digestion.

• Structure:

  • Surface covered with papillae (bumps).

  • Taste buds located beneath the papillae.

• Taste perception:

  • Taste buds contain receptors that differentiate various chemicals which the brain interprets as distinct tastes.

The Nose

• Function:

  • Cleans, warms, and humidifies inhaled air, facilitating the sense of smell.

• Process:

  • Volatile molecules enter through olfactory foramina in the skull.

  • Perception of smell mediated by olfactory neurons.

  • Brain interprets chemical signals as odors, which can vary from pleasant to malodorous.

Taste Sensation

• Process of taste:

  • Molecules ingested dissolve in saliva, covering the taste pore, enhancing flavor (explanation for dry food tasting bland until chewed).

  • There are approximately 4000 taste receptors (taste buds) located on the tongue's papillae.

Activities

Virtual Dissection

• Organs of Smell: Navigate to A&P Revealed -> Module "7. Nervous" to view nasal structures linked to olfaction.

• Organs of Taste: Navigate to A&P Revealed -> Module "7. Nervous" to examine structures associated with gustation.

Listing Taste Sensations

• 
  

• Create a table relating taste sensations to their corresponding substances and examples:
  

  Taste Sensation	Substance Stimulating the Sensation	Example
  Bitter
  Experiment on Relationship between Olfaction & Gustation

  • Experiment design:

    • Use different flavored chips or similarly textured items (e.g., life savers, star bursts).

    • Procedure:

    1. One individual closes their eyes and holds their nose while tasting a chip.

    2. Record perceived flavor with nose plugged.

    3. Repeat with nose uncovered and re-record.

  • Objective: Examine how olfactory input influences taste perception.

  Vision

  • Core Concept: Eyes perceive limited wavelengths of the visible spectrum; various wavelengths (like microwaves or ultraviolet light) are not detected.

  • Introduction to the eye's structure:

    • Components categorized into 3 layers or tunics.

  Tunics of the Eye

  A. Fibrous Tunic:

  • Characteristics: Tough, protective layer.

    • Components:

    • Sclera

    • Scleral venous sinus

    • Cornea

  B. Vascular Tunic:

  • Characteristics: Vascular layer providing nutrient and waste exchange.

    • Components:

    • Choroid

    • Ciliary body

    • Iris/pupil

  C. Nervous Tunic:

  • Location: Inner layer of the eye.

    • Function: Contains all receptors for vision.

    • Components:

    • Retina:

      • Contains cones (responsible for visual acuity)

      • Rods (function in low light)

      • Optic disc: Contains no photo-receptors, serves as a blind spot where the optic nerve exits.

  Activities

  Identifying Eye Structures

  1. Circle structures belonging to each tunic in the provided figure.

  2. Label each structure.

  3. Practice until all parts can be identified.

  Video Resource

  • Watch the “Vision” video in A&P Revealed for a comprehensive overview of visual processing.

  Eye Dissection

  • Instructions to dissect the eye in A&P Revealed, focusing on viewing and labeling relevant structures.

  Eye Function Tests

  • Conduct various vision tests found in the Blackboard folder to explore components of visual perception:

  Specific Tests:

  1. Astigmatism Test:

     • Tests for defects in lens/cornea refraction.

     • Visual each eye separately; record findings based on blurriness of lines.

  2. Color Blindness:

     • Use Ishihara plates to identify deficiencies in color photoreceptors (red, blue, green).

     • Record any missing color patterns.

  3. Depth Perception:

     • Comparative exercise using one eye versus two to demonstrate depth perception capabilities.

  4. Visual Illusions:

     • Interaction with illusions to demonstrate discrepancies between perception and reality. Examples include the Magic Cube, Muller-Lyer Illusion, and size illusions where objects appear different based on visual context.

  The Ear: Hearing & Equilibrium

  • Functional roles:

    • Hearing (auditory perception).

    • Two types of equilibrium:

    • Static equilibrium: Maintained when sitting or standing.

    • Dynamic equilibrium: Engaged during motion.

  • Structural Overview: The ear divided into three distinct regions.

  Regions of the Ear

  1. External Ear

  • Function: Air conduction.

    • Structures included:

    • Auricle

    • Auditory canal

    • Tympanic membrane

  2. Middle Ear

  • Function: Bone conduction associated with hearing.

    • Structures included:

    • Malleus (hammer)

    • Incus (anvil)

    • Stapes (stirrup)

  3. Inner Ear

  • Functions: Hearing and equilibrium through fluid conduction.

    • Structures included:

    • Cochlea (contains receptors for hearing, including the organ of Corti)

    • Semicircular canals (receptors for dynamic equilibrium)

    • Vestibule (receptors for static equilibrium)

  Activities

  Video Resource

  • Watch the “Hearing” video in A&P Revealed for insights into auditory mechanisms.

  Multiple Ear Function Tests

  1. Locating Sound:

     • Procedure to determine how humans identify the direction of sound; testing conducted with eyes closed and various tuning fork placements.

  2. Bone Transmission of Sound:

     • Experiment involving the hearing of a tuning fork placed between teeth while blocked ears.

  3. Ear Anatomy & Physiology:

     • Complete an anatomy exercise labeling ear structures and their functions.

  4. Field Sobriety Test:

     • Assessing balance and proprioception under varying conditions (eyes open/closed).

  5. Static Equilibrium Test:

     • Measuring time maintaining balance on one foot with varied sensory input.

  6. Proprioception Test:

     • Assessing coordination with eyes open and closed.

  Conclusion

  • Review the interconnectedness of the sensory modalities discussed.

  • Reflect on the relationships and dependencies between these sensory systems in producing a comprehensive experience of perception.