1 (15) Special Senses Flashcards
In general, how do all sensory receptors work?
neurons are stimulated, info is sent to brain, cerebral cortex integrates info, forms perception
What is the difference between sensation and perception?
sensation - awareness of the stimuli
perception - interpreting the stimuli
How do we form perceptions?
neurons are stimulated, info is sent to brain, cerebral cortex integrates info, forms perception
What is the largest sense organ of the body?
skin
What do we mean by a threshold? Do receptors respond to only one stimulus?
- with enough stimulation the nerve fires
* receptors can respond to multiple stimuli
What are exteroceptive senses?
respond to stimuli arising outside the body
What are interoceptive senses?
respond to stimuli arising in internal viscera and blood vessels
What are proprioceptive senses?
respond to stretch in skeletal muscles, tendons, joints, ligaments, and CT coverings of bones and muscles (informs brain of one’s movement)
What do we mean when we speak of simple receptors?
- modified dendritic endings of sensory neurons
* found throughout body and monitor most types of general sensory info
Is the cerebral cortex the only place where information is processed?
no
How is information processed?
3 levels:
1) receptor level (sensory receptors)
2) circuit level (processing in ascending pathways)
3) perceptual level (processing in cortical sensory areas)
What is meant by a graded potential or receptor potential?
- graded potential: a ligand opens a ligand-gated channel in the dendrites, allowing ions to enter (or exit) the cell
- receptor (generator) potential: a type of graded potential, is the transmembrane potential difference produced by activation of a sensory receptor
What is transduction?
the conversion of a sensory stimulus from one form to another
What are generator potentials?
stationary depolarization of a receptor that occurs in response to a stimulus and is graded according to its intensity and that results in an action potential when the appropriate threshold is reached
What is sensory adaptation?
reduction in sensitivity to a stimulus after constant exposure to it
What is the difference between phasic and tonic receptors?
phasic - fast adapting (mainly to report changes)
tonic - sustained response w/ little or no adaptation
How is information processed at the perceptual level? What is frequency encoding?
information is processed in cerebral cortex // means by which the central nervous system, limited by the all-or-none properties of nerve impulse conduction, is able to convey information about varying intensity of signals
What sense organs help us feel touch and pressure? What are their receptor cells?
skin // mechanoreceptors
How do we sense different temperatures?
thermoreceptors in skin
What are the receptors for pain? What stimuli can cause pain?
nociceptors detect damage from mechanical, electrical, thermal, or chemical energy
What is substance P?
neurotransmitter involved in the synaptic transmission of pain and other nerve impulses
Do pain receptors adapt? Why is this good?
pain receptors adapt little, if at all (if adapted, protection from pain would be lost and would become useless)
What is the difference between pain threshold and pain tolerance?
all people have the same threshold (perceived pain at the same stimulus intensity), not all people have the same tolerance (how well you handle pain)
What can change a person’s pain tolerance?
age, chronic pain, cultural/psychological factors
What sensations do we get from our viscera?
pain receptors (nociceptors) are the only receptors in the viscera that produce sensations
What is referred pain?
pain that feel like it is coming from somewhere else in the body
What is phantom pain?
pain that comes from a limb that has been amputated
What are the two types of pain fibers and how do they differ?
acute pain fibers: thin, myelinated, conducts up to 30m/s, sharp/localized pain, seldom continues after stimulus stops
chronic pain fibers: thin, unmyelinated, conducts up to 2m/s, dull/aching/widespread pain, may continue after stimulus stops
Hope do ascending and descending fingers modulate pain or cause analgesia?
ascending: block pain transmission in spinal cord
descending: release norepinephrine or serotonin, which suppress pain or activate enkephalin releasing neurons
Hope does aspirin function in pain relief?
inhibits the synthesis of prostaglandins
What do muscle spindles sense? What reflexes do they cause?
sense of stretching of the muscle and cause contraction to maintain position
What do Golgi tendon organs sense? What reflexes do they cause?
sense of change in muscle tension and inhibits relaxation and prevents damage to the tendon
What do nociceptors detect?
respond to damage from mechanical, electrical, thermal, or chemical energy
What do thermoreceptors detect?
respond to changes in temperature
What do mechanorecptors detect?
respond to mechanical forces (fluid movement or pressure)
What do photoreceptors detect?
respond to light
What do chemoreceptors detect?
respond to chemical concentration of various substances
What do osmoreceptors detect?
respond to concentration of chemicals (osmotic pressure)
Which one of the types of receptors functions in the sense of taste?
chemoreceptors (same as smell)
Which one of the types of receptors functions in the sense of smell?
chemoreceptors (same as taste)
Which one of the types of receptors functions in the sense of hearing and equilibrium?
mechanoreceptors
Which one of the types of receptors functions in the sense of vision?
photoreceptors
The senses of smell and taste have nerve fibers that run through the limbic system. What effect does this have?
taste is 80% smell
Of the four types of body tissues, which type of cells form the receptors for the sense of smell? Where are these receptors located?
(bipolar neurons) olfactory epithelium is found in the superior nasal concha and nasal septum
Describe the olfactory mucosa.
located in upper region of nasal cavity, mucus protects the olfactory epithelium and allows odors to dissolve so that can be detected, contains sensory fibers (trigeminal nerve) which play a role in initiation of reflexes like sneezing
What role does the mucus play in the sense of smell? Where does it come from?
chemicals are dissolved in mucus to stimulate the receptor, epithelial supporting cells produce the mucus
How do we recognize thousands of different odors?
a combination of primary scents allow us to recognize thousands of different odors
Are olfactory receptors replaced during a person’s lifetime? Why is this unusual? How long do these receptors live?
receptors last 30-60 days (they are replaced), unusual bc they are neurons and neurons are not usually replaced
What happens to our sense of smell as we get older?
due to a gradual loss of receptors, sense of smell declines bc receptors are replaced more slowly as we age
What bony structure do the olfactory fibers pass through on their way to the olfactory bulb?
cribriform plate
How quickly does the sense of smell adapt?
olfactory cells adapt very rapidly