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Key Sense Overview
Need to know sense organs
1. Skin → touch
o Structures
o Pathway of impulse to brain
2. Nose → smell
o Structures
o Pathway of impulse to brain
3. Tongue → taste
o Structures
o Pathway of impulse to brain
The Skin- Cross section
Hair
Epidermis
Blood vessels
Sensory Receptor
Dermis
Hypodermis
Fat cells
Nerve
The Tongue – Cross Section
Papillae
Taste bud
The Nose – Cross Section
Pathway of Impulse to brain
1. Sensory receptors pick up stimuli
• Skin: Sensory receptors for pain, pressure, touch, and temperature
• Tongue: Taste buds
• Nose: Cilia
2. Sensory receptor transform stimuli into nerve impulse
3. Sensory nerve send nerve impulse to brain
• Skin : Sensory nerve
• Tongue: Sensory nerve
• Nose: Olfactory nerve
Need to know sense organs
4. Ear → balance and sound
o Structure of a sound wave
o Wave terminology
o Structures for balance and sound
o Pathway of impulse to brain
5. Eye → sight
o Lens
o Light movement in plane mirror
o Structures for sight
o Pathway of impulse to brain
o Key vision problems
Wave Terminology (Image is transverse wave)
Wavelength
Amplitude
Wave Terminology
Crest: Highest point of wave
Trough: Lowest point of wave
Wavelength: Distance between two crests (one cycle)
Amplitude: Half the height of the wave
Frequency: Number of cycles per unit time
• Higher the frequency, more energy in the wave, higher pitch the
sound is
The Ear – Cross section (Structures needed in balance)
The Ear – Cross section (Structures needed in hearing)
Types of lenses
Concave / Diverging
• Spreads light rays outwards
Convex / Converging
• Brings light rays inwards
Reflection- Image made in plane mirror
Image has same dimensions
Image is horizontally inverted
Object
Image
The Eye – Cross Section
Pathway of Impulse to brain
1. Sensory receptors pick up stimuli
• Balance: Cilia in semi-circular canals
• Hearing: Cilia in cochlea
• Vision: Retina (cones and rod cells)
2. Sensory receptor transform stimuli into nerve impulse
3. Sensory nerve send nerve impulse to brain
• Balance: Vestibular nerve
• Hearing: Auditory nerve
• Vision: Optic nerve
The Eye – Vision Problems: Myopia
(Nearsightedness)
Problem
Solution
• Distance images are blurry
• Image forms before the retina
• Concave/Diverging lenses
needed to bring image back
towards retina
The Eye – Vision Problems: Hyperopia
(Farsightedness)
Problem
• Close images are blurry
• Image forms after the retina
Solution
• Convex/Converging lenses
needed to bring image forward
towards retina
The Eye – Vision Problems: Astigmatism
Problem
• Lens doesn’t bend properly
• Images are not focused properly
Solution
• Specialized lens to focus image
properly