General senses Flashcards
Sensory receptors
- adaptation: magnitude of response decreases over time in response to continuous stimulus
- perception: remaining aware of sensation over time and interpreting what that sensation means in larger context
General senses
Microscopic receptors widely distributed in the skin, mucosa, connective tissues, mm, tendons, joints, and viscera
- somatic and visceral senses
Special senses
Localized receptors for
- smell
- taste
- vision
- hearing/equilibrium
Stimulation of the sensory receptor
Selectivity: a given receptor responds vigorously to one particular kind of stimulus (weakly or not at all to other stimuli) in its receptive field
Transduction of the stimulus
Converts energy in stimulus into graded potential
Generation of nerve impulses
Graded potential reaches threshold and triggers propagation toward CNS
Integration of sensory input
Regions of CNS and post central gyrus receive and integrate impulses
Classification of receptors
- Location
- exteroceptors - visceroceptors (interceptors) - proprioceptors - Stimulus
- mechanoreceptors - chemoreceptors - thermoreceptors - nociceptors - photoreceptors - osmoreceptors - Structure
- free nerve endings - encapsulated nerve endings
Exteroceptors
- located on or very near the body surface
- respond most frequently to stimuli that arise external to the body itself
- sometimes called cutaneous receptors (detect pressure, touch, pain, and temperature)
Visceroeptors (interoceptors)
Located internally
- primarily in blood vessels and viscera
- provide info regarding internal environment (usually not consciously perceived, if stimuli is strong may be perceived as pain or pressure)
- activated by pressure, stretching, and chemical changes
- involved in mediating sensations such as hunger, thirst, BP, full bladder
Proprioceptors
- Special type of visceroceptor
- less numerous and more specialized than other visceroceptors - Located in skeletal mm, joint capsules, and tendons
- Provide information regarding
- body movement
- orientation in space
- mm stretch
Two types:
- Tonic: provides information while the body is at rest, non-adapting
- Phasic: provides information during movement. Rapidly adapting and triggered only when there is a change in position
Mechanoreceptors
- detect mechanical stimuli that deform or change position of the receptor
- ex: pressure to skin, blood vessels, that results in stretch or pressure in mm, tendon, or lung tissue
Chemoreceptors
- detect chemicals in the mouth, nose, and body fluids
- activated by either the amount or the changing concentration of certain chemicals
- ex: sense of taste, smell, pH homeostasis
Thermoreceptors
Activated by changes in temperature
Nociceptors
- activated by intense stimulu that could result in tissue damage
- chemical
- intense light
- sound
- pressure
- heat - The sensation produced is pain