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Chapter 10. Somatic and Special Senses. Sensory Receptors = detect environmental changes and trigger impulses that travel to central nervous system for interpretation 2 major categories of sensory receptors: 1. somatic senses = touch, pressure, temperature and pain

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chapter 10

Chapter 10

Somatic and Special Senses

slide2

Sensory Receptors = detect environmental changes and trigger impulses that travel to central nervous system for interpretation

  • 2 major categories of sensory receptors:
      • 1. somatic senses = touch, pressure, temperature and pain
      • 2. special senses = smell, taste, hearing, equilibrium and vision
10.1
slide3

5 Types of Receptors:

1. Chemoreceptors = changes in chemical concentration

2. Pain Receptors = detect tissue damage

3. Thermoreceptors = temperature differences

4. Mechanoreceptors = pressure or movement differences

5. Photoreceptors = light energy

10.2
slide4

Special Senses

      • Smell------------Olfactory Organs
      • Taste--------------Taste Buds
      • Hearing----------Ears
      • Equilibrium----Ears
      • Sight--------------Eyes
10.4
10 5 smell

Olfactory Receptors = chemoreceptor s (chemicals dissolved in liquids stimulate them)

  • Olfactory Organs contain olfactory receptors
  • Olfactory Receptors Cells = neurons surrounded by cells and cilia(protrude into nasal cavity); before sense of smell, odorant molecules must dissolve in watery fluid (around cilia)
  • Located in upper nasal cavity
10.5 - SMELL
10 5 smell2

Did you know? Humans have about 12 million olfactory receptor cells. Bloodhounds have about 4 billion such cells!

  • 1. Olfactory receptors stimulated (Synapse with olfactory bulb)
  • 2. Olfactory bulb analyze impulse
  • 3. Olfactory cortex (temporal lobe-brain)
  • 4. Sense of Smell
10.5 - SMELL
10 6 taste

Taste Buds = special organs of taste

  • Approximately 10,000 located primarily on the surface of tongue within papillae.
  • Approximately 1,000 are scattered in the roof of the mouth and walls of the throat.
10.6 - TASTE
10 6 taste1

Each taste bud has about 50 – 150 taste cells that are replaced every 3 days.

  • Before a chemical can be tasted, it must be dissolved in watery fluid (saliva) surrounding the taste buds.
  • 4 primary taste sensations: sweet, sour, salty, bitter.
10.6 - TASTE
10 6 taste2

Did you know? Cats have only about 473 taste buds and dogs have about 1,700…..that is why they are satisfied with a less varied diet than humans.

  • Taste receptors stimulated
  • Impulses analyzed; sent to gustatory cortex (parietal lobe)
  • Sense of taste
10.6 - TASTE
10 7 hearing1

External Ear:

Auricle (pinna) = funnel structure that collects sound

External Acoustic Meatus (canal) = transports sound

10.7 - HEARING
10 7 hearing2

Middle Ear:

Tympanic Cavity= air filled space of temporal bone

Auditory Ossicles = 3 small bones within the middle ear/tympanic cavity: malleus, incus, stapes

10.7 - HEARING
10 7 hearing3

Auditory/Eustachian Tube

= Connects the middle ear to the throat

  • Maintains equal air pressure on both sides of tympanic cavity
10.7 - HEARING
10 7 hearing4

SOUND TRANSMISSION

  • Tympanic membrane vibrates malleus, vibrates incus, vibrates stapes
  • Stapes vibrates oval window fluid (inner ear) & receptors stimulated
10.7 HEARING
10 7 hearing5

Inner Ear:

Labyrinth= system of communicating chambers and tubes

2 parts to labyrinth:

    • Osseous Labyrinth - outside
    • Perilymph = fluid between Osseous & Membranous
    • Membranous Labyrinth - inside
    • Endolymph = fluid in membranous
10.7 - HEARING
10 7 hearing6

Inner Ear:

Cochlea= houses organ of hearing (organ of Corti)

Organ of Corti: contains hair cells (receptors on the basilar membrane) that extend into the cochlear duct

10.7 - HEARING
10 8 equilibrium

2 Parts:

Static Equilibrium=maintain head position when still

Dynamic Equilibrium = maintain balance when moving

10.8 - EQUILIBRIUM
10 8 equilibrium1

STATIC:

    • organs of static equilibrium located in vestibule (bone chamber between semi circular canals and cochlea)
    • Membranous labyrinth inside vestibule has 2 chambers (utricle and saccule)
    • Within chambers is structure called macula that contain numerous hairs acting as sensory receptors.
    • Otoliths = grains of calcium carbonate w/in mass of gelatinous material
10.8 - EQUILIBRIUM
10 8 equilibrium2

DYNAMIC:

    • organs of dynamic equilibrium are 3 semicircular canals
    • Semicircular canal functions = 1. detect head motion 2. balance head and body during sudden movement
    • Crista Ampullarisorgans of dynamic equilibrium that contain sensory hair cells
    • Like hairs of maculae, these extend upward into dome-shaped gelatinous mass, cupula
10.8 - EQUILIBRIUM
10 9 sight

Accessory Organs

  • Eyelids
  • Lacrimal apparatus – tears lubricate & cleanse eye; contains enzyme (lysozyme) that acts as an antibacterial agent
  • Extrinsic muscles – six muscles attached to the sclera (white part) that move the eye in all directions
10.9 - SIGHT
10 9 sight1

Eye Structure (3 layers)

  • Outer (fibrous) layer
  • Middle (vascular) layer
  • Inner (nervous) layer
  • Spaces are filled with fluid that support and help maintain shape.
10.9 - SIGHT
10 9 sight2

Outer (fibrous) layer

    • Cornea transparent; helps focus entering light
    • Sclera white; protects the eye and point of attachment for 6 extrinsic muscles
        • Optic nerve and blood vessels pierce the posterior (back)
10.9 - SIGHT
10 9 sight3

Middle (vascular) layer

    • Choroid coat dark coloration; provides nourishment; keeps inside of eye dark
    • Ciliary body ring of ciliary muscles; holds eye in place; allows lens to change focus;
    • Iris colored portion; between cornea and lens; controls amount of light that enters;
      • Anterior Chamber = cornea & iris
      • Posterior Chamber = iris & lens
      • Aqueous Humor = fluid that fills space and helps nourish
10.9 - SIGHT
10 9 sight4

Inner (nervous) layer

    • Retina contain visual receptor cells (photoreceptors)
    • When a person sees something, the object is giving off light or light waves are reflected from it. Light waves enter eye and retina focuses it by bending the light waves (refraction).
10.9 - SIGHT
10 9 sight5

Inner (nervous) layer

    • 2 types of visual receptors: Rods & Cones
      • Rods = light sensitivity
      • Cones = color
10.9 - SIGHT
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