Sense System Flashcards
Characteristics of Sense organs
- Projection
- After-image
- Adaptation
- Local sign
- Contrast
- Intensity
projecting sensation to source of stimulation
Projection
sensation persists in consciousness after cessation of stimulation
After-image
continuous stimulus- one gets used to it or ignores it
Adaptation
ability to recognize point of application of stimulus
Local sign
sensation is affected by events which preceded or accompany it
Contrast
dependent on number of receptors stimulated and rate of transmission
Intensity
*Produce the somatic senses
*Widely distributed
receptors
General Senses
*Produce the special senses
*Grouped in localized areas
Special senses
Receptor is any structure specialized to detect a stimulus (simple nerve ending or sense organ)
Sensory receptors
receptors are free nerve endings; respond to a variety of stimuli as mechanical stretching, extremes in temperature to produce pain
Pain and temperature
respond to stimuli that ‘deform’ or change their shape and placement and that move hair
Touch and Pressure receptors
receptor for heavy touch, pressure, joint movements & skin stretching
Ruffini corpuscles
receptors for light touch & texture
Meissner corpuscles
tactile corpuscles in mucous membranes
Krause end bulb
receptor for deep pressure, stretch, tickle, itch & vibration
Lamellated (pacinian) corpuscles
Types of organic sensations
- Hunger
- Thirst
- projected to stomach
- associated with rhythmic contractions and weakness, trembling, nausea, headache
- NS is hyper-excitable
Hunger
- projected to pharynx
- due to low water levels
- extreme thirst leads to mental anguish
Thirst
Three groups of stimuli in visceral sensations
- Dilation/distension
- Spasm/strong contraction
- Chemical irritation
occurs because of the common nerve pathways leading from skin and internal organs.
Referred pain
- is misinterpreted pain
– Visceral impulse and cutaneous impulse share the same neurons to brain
– Results in confusion
Referred pain
Example of Referred pain
Angina pectoris
Pneumonia
spasm of smooth muscle in coronary arteries of heart
Angine pectoris
pain in abdomen
Pneumonia
The special senses
Taste-Gustation
Smell-Olfaction
Vision
Hearing
Balance
The Chemical Sense
Taste
specific receptor cells for taste and smells
Chemoreceptors
is the sensation of taste resulting from the action of chemicals on the taste buds
Gustation
(no taste buds)
* most abundant
Filiform
at tips & sides of tongue
Fungiform
- at rear of tongue
- contains 1/2 of taste buds
Circumvallate
