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Questions and Answers
Which taste is primarily conferred by monosodium glutamate (MSG)?
Where are the sensory cells located that are responsible for detecting different tastes?
Which part of the tongue is maximally sensitive to sour taste?
How do salty substances stimulate receptors on the tongue?
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What happens when bitter substances bind to a receptor on the receptor cell membrane?
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Which type of substances give rise to the umami sensation?
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What type of channels do the molecules that bind to membrane proteins in specific receptor types open?
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Where is the primary sensory region of the cerebral cortex that receives gustatory information?
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How many types of olfactory receptors do we have?
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Where are the olfactory receptors located?
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How do we actively smell something?
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How do odors reach the olfactory receptors from food in the mouth?
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What are nociceptors?
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Which of the following substances is NOT mentioned as being released from damaged tissues?
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What is the role of prostaglandins in pain perception?
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How does the drug aspirin relieve pain?
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What type of nerve fibers are responsible for the sharp, initial pain in response to injury?
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Where are the cell bodies of the afferent neurons that carry pain information located?
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What is the primary function of the olfactory receptors?
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What is the role of the amygdala in the olfactory system?
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What is the purpose of the vomeronasal organ?
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What is the role of the cribriform plate in the olfactory system?
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What is the primary function of the olfactory bulbs?
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What is the role of the temporal lobes in the olfactory system?
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What type of sensory receptors are Pacinian corpuscles?
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Which statement about Merkel's disks and Ruffini endings is true?
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Which of the following is NOT an exteroceptive sense?
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Which type of skin has more touch receptors located closer together?
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What distinguishes exteroceptive senses from interoceptive senses?
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Which of the following statements about touch receptors is true?
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Study Notes
Taste
- The five basic tastes are: sweet, sour, salty, bitter, and umami (conferred by monosodium glutamate, MSG)
- Taste receptors are located throughout the mouth, primarily on the tongue, in papillae, which contain several taste buds
- Each taste bud contains several receptor cells
- Papillae on different parts of the tongue carry taste buds sensitive to different tastes:
- Front of the tongue: sweet
- Next region back: salt
- Sides behind this: sour
- Central, back part: bitter
- Receptors are stimulated when chemical substances dissolve in saliva and come into contact with gustatory receptors
- Different tastes stimulate receptors in different ways:
- Salty: metallic ions (e.g., sodium) enter sodium channels, depolarizing the cell
- Sour: hydrogen ions (H+) close potassium channels, producing depolarization
- Bitter: bind to receptor on receptor cell membrane, closing potassium channels, depolarizing the membrane
- Sweet: bind to receptor, opening calcium channels, depolarizing the membrane
- Umami: bind to membrane proteins, opening calcium (or nonspecific ion) channels, depolarizing the receptor membrane
Olfaction
- The sense of smell is mediated by olfactory receptors in the olfactory epithelium, located in two patches of tissue at the top of the nasal cavity
- There are about 1,000 types of olfactory receptors
- Odors are detected when airborne molecules reach the olfactory epithelium, either through the nose or from the back of the mouth
- Sniffing carries more air to the olfactory epithelium, allowing for active smelling
- Odors are also released by food in the mouth and travel to the receptors from the back of the mouth
- The olfactory system is involved in emotional control and memory, which is why odors are powerful evokers of emotion
Pain
- Pain receptors are free nerve endings (nociceptors) distributed throughout the skin, muscles, joints, and internal organs
- Nociceptors respond to stimulation that damages tissues, including:
- Mechanical injury (e.g., cutting, crushing)
- Chemical damage (e.g., corrosive substances)
- Extremes of temperature (burning or freezing)
- Pain information is carried to the brain by two types of neurons: A fibers (sharp, initial pain) and C fibers (dull, longer-lasting pain)
Somatosensory System (Senses of Touch)
- The skin senses are exteroceptive, giving us information about changes at the surface of the body
- There are several types of specialized receptors in the skin, including:
- Pacinian corpuscles (respond to vibration, but not constant pressure)
- Merkel's disks and Ruffini endings (respond to stimulation with sustained firing, sensitive to pressure or slow changes in pressure)
- Glabrous skin (e.g., palms of the hands) contains more receptors, closer together, reflecting our use of hands and fingers to actively manipulate the environment
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Description
Learn about the somatosensory system and the senses of touch, which provide information about changes at the surface of the body through various types of skin stimulation.
