Somatic and Special Senses
I. Aids to Understanding Words
Example: Choroid Coat – Middle, vascular layer of the eye.
Example: Cochlea – Coiled tube in the inner ear.
Example: Iris – Colored, muscular part of the eye.
Example: Labyrinth – Complex system of connecting chambers and tubes of the inner ear.
Example: Lacrimal Gland – Tear gland.
Example: Macula Lutea – Yellowish spot on the retina.
Olfact: To smell.
Example: Olfactory – Pertaining to sense of smell.
Example: Sclera – Tough, outer protective layer of the eye.
Example: Tympanic Membrane – Eardrum.
Example: Vitreous Humor: Clear, jellylike substance within the eye.
What is the function of sensory receptors?
Sensory receptors detect environmental changes and trigger impulses that travel on sensory pathways into the central nervous system.
10.2 Receptors, Sensations, and Perceptions
A. List five groups of sensory receptors.
Chemoreceptors, pain receptors, thermoreceptors, mechanoreceptors, and photoreceptors. Chemoreceptors are stimulated by changes in concentration of certain chemicals. Pain receptors are stimulated by pain receptors. Thermoreceptors stimulated by changes in temperature. Mechanoreceptors stimulated by changes in pressure/movement. Photoreceptors are caused by light.
B. The process that allows an individual to located the region of stimulation is called projection.
C. The process that makes a receptor ignore a continuous stimulus unless the strength of that stimulus is increased is sensory adaptation.
D. What is a sensation?
Sensations happen when sensory receptors reach threshold and the action potential causes the brain to become aware of the stimulus.
10.3 General Senses
Free Nerve Ending
Meissner’s (Tactile) Corpuscles
Pacinian (Lamellated) Corpuscles
Free Nerve Endings (Pain Receptors)
10.4 Special Senses
List the special senses:
Smell – Olfactory organs.
Taste – Taste buds.
Hearing – Ears
Equilibrium – Ears
Sight – Eyes
10.5 Sense of Smell
The sense of smell supplements the sense of taste.
10.6 Sense of Taste
A. Describe the structure of taste receptors.
Taste buds have 50 to 150 modified epithelial cells which work as receptor cells. Taste buds are included epithelial supporting cells. Structure is spherical. Has opening with the taste pores. Taste hairs are sensitive parts.
B. How does saliva contribute to the perception of taste?
Particular chemicals must be dissolved in fluids around the taste buds in order to be tasted. Saliva is the fluid provided. Saliva makes tasting possible.
D1. List five primary taste sensations.
1. Sweet (table sugar)
2. Sour (lemon)
3. Salty (table salt)
4. Bitter (caffeine)
5. Umami (certain amino acids/chemical relatives)
D2. What areas of the tongue are associated with each taste?
Tip of the tongue is most sensitive to sweet stimuli.
Margin of the tongue is sensitive to sour.
Back of the tongue can detect bitterness.
Saltiness can be sensed throughout the tongue.