general senses Flashcards
magnitude of response decreases over time in response to continuous stimulus
adaptation of sensory receptors
remaining aware of sensation over time and interpreting what that sensation means in larger context
perception of sensory receptors
microscopic receptors widely distributed in the skin, mucosa, connective tissues, muscles, tendons, joints and viscera
general senses
localized receptors for smell, taste, vision, hearing/equilibrium
special senses
Selectivity: a given receptor responds vigorously to one particular kind of stimulus in its _______.
receptive field
converts energy in stimulus into a graded potential
transduction of the stimulus
graded potential reaches threshold and triggers propagation toward CNS
generation of nerve impulses
regions of CNS and post central gyrus receive and integrate impulses
integration of sensory input
3 classifications of receptors:
- location
- stimulus
- structure
3 groups of receptors can be identified by their location:
- exteroceptors
- visceroceptors
- proprioceptors
receptors located on or very ear the body surface
- respond most frequently to stimuli that arise external to the body itself
- sometimes called cutaneous receptors
exteroceptors
________ detect pressure, touch, pain, and temperature
exteroceptors
receptors located internally, primarily in blood vessels and viscera
- provide info regarding internal environment: usually not consciously perceived
Activated by: pressure, stretching, and chemical changes
visceroceptors/interoceptors
_____ are involved in mediating sensations such as hunger, thirst, BP, full bladder
visceroeptors/interoceptors
special type of visceroceptor; less numerous and more specialized than other visceroceptors
- located in skeletal muscle, joint capsules, and tendons
proprioceptors
_______ provide information regarding body movement, orientation in space, muscle stretch
proprioceptors
2 types of proprioceptors:
- tonic
- phasic
proprioceptor that provides information while the body is at rest.
tonic
proprioceptor that provides information during movement. Rapidly adapting and triggered only when there is a change in position
phasic
receptors are classified into 6 categories based on the types of stimuli that activate them:
- Mechanoreceptors
- chemoreceptors
- thermoreceptors
- nociceptors
- photoreceptors
- osmoreceptors
______receptors:
- detect mechanical stimuli that deform, or change position of the receptor
Ie. pressure to skin, blood vessels, anything that results in stretch or pressure in muscle, tendon, or lung tissue
mechanoreceptor
_____receptors:
- detect chemicals in the mouth, nose, and body fluids
- activated by either the amount or the changing concentration of certain chemicals
Ie. sense of taste, smell, homeostasis
chemoreceptors
_____receptors:
-activated by changes in temperature
thermoreceptors
_____receptors:
- activated by intense stimuli that could result in tissue damage
- chemical, intense light, sound, pressure, heat
- sensation produced is pain
nociceptors
_____receptors:
- found only in the eyes
- detect light that strikes the retina
photoreceptors
_____receptors:
- concentrated in the hypothalamus
- sense levels of osmotic pressure in body fluids
- activated by changes in concentration of electrolytes in extracellular fluids
- stimulate the hypothalamic thirst center
osmoreceptors
general sensory receptors may be classified anatomically as either of the following (2):
- free nerve endings
- encapsulated nerve endings
structure:
- bare denrites
- the simplest, most common, and most widely distributed sensory receptors
- include both exteroceptors and interoceptors
free nerve endings
structure:
- have some type of connective tissue capsule that surrounds the terminal end or denritic end
- usually mechanoreceptors
activated by mechanical or deforming stimulus
encapsulated nerve endings
Major types of ________:
- tactile/meissners corpuscle
- lamellar/pacinan corpuscle
- bulbous/ruffini cells
- bulboid/krause corpuscle
encapsulated nerve endings
nociceptors are ____ nerve endings
free
nociceptors:
- concentrated in the skin, mucous membranes, and other superficial areas
- sharp, intense, localized fast/somatic pain
- “fast pain” travels over myelinated fibers
- associated with superficial injury or trauma
pain-A Delta Fibers
nociceptors:
- originates in deeper/visceral regions (thoracic and abdominal regions)
- intense or less severe, but persistent, dull aching pain
- develops more slowly over time
- “slow pain” travels over unmyelinated fibers
pain-C fibers
________ mediate sense of heat and cold; called thermoreceptors
free nerve endings
____ receptors are located in dermis. Activated in temperature range of 77-114 degrees F. >118 = burning
Warm
____ receptors are located in deepest layer of epidermis. Activated in temperature range of 50 - 104 degrees F. <50 = dramatic decrease in firing rate but activates nociceptors (freezing pain_
cold
the 5 types of touch sensation:
- skin movement
- itch
- tickle
- light touch
- deep touch
sense of touch has both _____ and _____ endings
free and encapsulated
root hair plexuses with free nerve endings. Activated with very slight movement on or in the skin. Bends or deforms a hair follicle or shaft
touch-skin movement
touch:
- free nerve endings
- activated by chemical irritaiton
- inflammatory chemicals (bradykinin, or histamine)
touch-itch
touch:
- free nerve endings
- activated by touch from an outside source
- involves both thalamus and cerebellum before reaching the cerebral cortex
touch-tickle
touch:
- mediated by a variation of a free nerve ending
- tactile or merkel disk
- transmits compression of the outer layer of skin to the tactile disk neuron (mechanoreceptor)
- detects discriminative touch and surface form and contours
light/discriminative
touch:
- encapsulated nerve endings
- tactile/meissner corpuscles
- enmeshed in connective tissue
- located close to the dermal papillae in hairless skin areas like fingertips, lips, nipples and genitals
- mediate light touch, textual sensations and low frequency vibration
deep touch
there are # variants of Meissner corpuscles
3
anatomical variant of meissner corpuscles:
- more numerous in mucous membranes
Bulboid/krause corpuscle
anatomical variant of meissner corpuscles:
- crude, heavy and persistent touch
bulbous/ruffini corpuscle
anatomical variant of meissner corpuscles:
- deep pressure, high frequency vibration, and stretch
lamellar/pacini corpuscle
sense:
tells us level of contraction and stretch in each of our skeletal muscles
- muscle spindles
- golgi tendon receptors
sense of proprioception
discrete grouping of 5-10 modified muscle fibers called intrafusal fibers surrounded by sensoru nerve fibers
encaspulated nerve endings, stretch receptors: muscle spindles
respond to muscle twitch:
- stretch reflex
- subconscious postural adjustments
muscle spindles
stretch receptors:
- located at the junction between muscle tissue and tendon
- stimulated by excessive stretch of a tendon
- protects muscle from tearing
golgi tendon organ
