Exam 4 Review: Chapter 15: General and Taste and Smell
somatic senses - The perceptions associated with stimulation of exteroreceptors to changes in the external physical environment and routed to the somatosensory cortex for interpretation; the set of five "skin" senses/modalities (pressure, touch, vibration, cold, warmth), two proprioceptive senses/modalities (sense of position, sense of force), and five "kinesthetic" (sense of body movements) senses/modalities (angle of joints, activities and tone of muscles, head movements, skin position relative to a touched surface, movements of the person within the environment (visual kinesthesis)); all are detected by mechanoreceptors except for cold and warmth which are detected by thermoreceptors. (Pain may be included but pain reception may be from both somatic and visceral sources.)special senses - Modalities of sensation which require complex specialized receptor organs for detection; in humans there are five (or six): sight, hearing, smell, taste, and equilibrium, both static and dynamic. [The so-called "five senses" are sight, hearing, smell, taste and touch. However, touch is not a special sense.]
transduction - The conversion of the energy of a stimulus (electrical, mechanical, chemical, radiant, etc.) into another from of energy; in the nervous system, the energy of the stimulus is converted by a receptor into a nerve impulse = action potential for transmission to the central nervous system (CNS).
chemoreceptors - Sensory nerve
cells or sense organs which respond to chemical stimuli; including
exteroreceptors for smell and taste and enteroreceptors sensitive to
concentration changes of a variety of molecules in the blood or other body
fluids.
circumvallate papillae - The third most numerous (about a dozen) and the largest of the papillae of the tongue; rounded "mushroom-shaped" eminences distributed in a “V”-shaped pattern at the junction of the anterior two-thirds and the posterior one-third of the tongue; one of the locations for taste buds containing chemoreceptors for taste sensations.
gustatory cells - The specialized chemoreceptor cells found in taste buds which contain hair-like processes extending to openings in the bud (taste pore) to taste substances; there are five primary tastes: sour, salt, sweet, bitter and umami ("beef").
olfactory epithelium - The olfactory epithelium of each of the two nasal passages in humans is a 2.5 square centimeter patch containing about 50 million sensory olfactory receptor cells; the reception of the odorant and the beginning of sensory signal transduction occurs in the olfactory cilia, which are hair-like extensions of the receptor neurons (10-20 cilia per neuron); it is the sensory tissue served by the olfactory nerve, Cranial Nerve I.
olfactory cilia - The hair-like extensions of the sensory
olfactory receptor neurons (10-20 cilia per neuron) which sample the odorant
chemicals from the air which become dissolved in the water of the nasal
secretions.
olfactory bulbs - The location of the cell bodies of the second order neurons (second in the transmission pathway) which receive nerve impulses carrying olfactory sensory information; they are located on the inferior surface of the frontal lobes of the cerebrum, directly above the cribiform plate of the ethmoid bone.
olfactory tracts
- The pathway for transmitting olfactory sensory information along the Olfactory
nerves (cranial nerve I) to the primary olfactory cortex of the frontal lobes of
the cerebrum without first passing through the thalamus; this bypass is unique
to olfaction, and is thought to reflect the early development of the olfactory
system in the evolution of vertebrates; odor information is widely distributed
among other brain areas for conscious recognition of odors.
Try these links for more information about TASTE and SMELL.
Worms Know Bad Food When They Smell It
Identify and describe:
1. the location and specific sites, including cellular components, for reception and transduction for the sensations of:
(a) smell: chemoreceptors (~1000 different types of odorant binding proteins) located on the olfactory cilia of the olfactory receptor cells located within region of olfactory epithelium within the mucosa of the superior surface of the nasal cavity.
(b) taste:
chemoreceptors (5 different types) located on the gustatory hairs of the gustatory
receptor cells located within taste buds in lingual papillae in the mucosa of the tongue and
the mucosa of the oral
cavity.
List and
describe:
1. the sequence of components
and physiological events in transduction of taste.
| 1. chemical substance (molecule to be tasted) becomes
dissolved in the mucous secretions of the oral cavity. 2. molecule diffuses through a taste pore into a taste bud. 3. molecule binds with a specific taste chemoreceptor (5 different types) on the gustatory hairs of the gustatory receptor cell. 4. depending on type of molecule and specific taste chemoreceptor, their interaction opens (or closes) gated ion channels on the gustatory receptor cell membrane. 5. the resulting ion flow (or inhibition of flow) alters the membrane resting potential. 6. an action potential = nerve impulse is generated which is transmitted to the CNS. |
2. the sequence of components and physiological events in transduction of smell.
| 1. chemical substance, "odorant," (molecule to be smelled) becomes
dissolved in the mucous secretions of the nasal cavity. 2. molecule diffuses through the mucus to reach the olfactory epithelium. 3. molecule binds with a specific smell chemoreceptor, odorant binding protein, 4. depending on type of "odorant" 5. the resulting sodium 6. if the olfactory |