A & P 2 - Class 2 - Sensation & Perception Flashcards
Explain what changes in the environment means.
The entire nervous system is basically the body’s way of detecting and responding to “changes in the environment” both internal and external. A good starting point is therefore “changes in the environment”. Change in the environment=STIMULUS.
Define sensation
Subconscious or conscious registration of a stimulus in the central nervous system (CNS).
Define perception.
Conscious awareness of a sensation.
List the steps in the “Process of Sensation”.
Stimulus, sensory receptors, sensory neurons, action potentials.
Sensory receptors detect what?
Internal and external stimuli and they vary in how quickly they adapt to changes in the environment.
Sensory neurons do what?
Generate nerve impulses (action potentials).
Action potentials do what?
Travel along a sensory neuron and stimulate neurons in the CNS.
Perception occurs when?
If the CNS is stimulated at the conscious level - the “highest” outermost part of the brain (cerebral cortex).
Define adaption.
Many receptors become less sensitive to a stimulus that is continuously present.
Explain about tactile and smell receptors.
They are rapidly adapting receptors. Sensitive to CHANGE rather that continuous output.
Explain about nociceptors and proprioceptors.
They are slowly adapting receptors. Continue to trigger nerve impulses as long as the stimulus persists.
What is “phantom limb” sensation?
People with an amputated limb may still experience sensations as if the limb were still there.
What are two explanations for what causes “phantom limb”?
Impulses from sensory neurons in the stump enter the CNS: the brain projects the sensation (and perception) back to the nonexistent limb creating the felt sensory perception of a limborNeurons in the brain that generate the felt sense continue to be active, with or without input from the stump.
What is perception?
Stimuli that are perceived in the higher brain centers are projected back to the receptor by the brain.
Sensory receptors can be classified into what three categories?
By location, by cellular characteristics, and by stimulus.
Explain receptor/neuron specialization.
Each receptor responds to a particular type of stimulus. Each neuron conducts an impulse that has a particular function.
What are the three types of receptors that are found by location?
Exteroceptors, proprioceptors, interoceptors.
Explain exteroceptors.
They are cutaneous receptors located on or very near the surface (skin and superficial fascia) and usually respond to external stimuli.
Explain propriocepters.
Located in skeletal muscle, joint capsules, tendons, and fascia. Monitor stretch and tension - mechanical tugs on our tissues. Provide info about our physical orientation and movement.
Explain interoceptors.
Also called visceroceptors or enteroceptors that are located internally, often within viscera (organs). They respond to internal stimuli.
What two types of receptors are classified by cellular characteristics (physical structure)?
Simple and complex receptors.
What are the two types of nerve endings found in simple receptors?
Free nerve endings and encapsulated nerve endings.
Free nerve endings dendrites do what?
Dendrites respond directly to stimulus. Examples include nociceptors (pain receptors).
Encapsulated nerve endings dendrites are wrapped in what?
Dendrites wrapped in a connective tissue coating. Examples include various types of mechanorecptors and corpuscles.
Explain complex receptors (cellular receptors).
Entires cells that detect stimuli and initiate sensory impulses. Associated with special senses (sight, smell, taste, hearing, and balance).
List the classification of sensory receptors by stimulus.
Mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, and chemoreceptors.
Mechanoreceptors do what?
Respond to chemical deformation of tissue (pressure, etc.)
Thermoreceptors do what?
Respond to temperature.
Nociceptors do what?
Respond to pain (actual or near damage to tissue).
Photoreceptors do what?
Respond to visible light.
Chemoreceptors do what?
Respond to chemicals (smell, taste or internal).
What are the types of sensations?
General, visceral, somatic, cutaneous, and special.
What are general senses?
Sensed body-wide, simple receptors, include touch, pressure, vibration, pain, temperature, and proprioception.
Visceral sense do what?
They provide information about conditions within internal organs.
Somatic senses do what?
Include the cutaneous sensations PLUS proprioceptions - arise from the skin, muscles, joints, and fascia.
Cutaneous senses do what?
Arise from the skin AND subq tissue.
What are the three subcategories of the cutaneous senses?
Tactile-require contact.Thermal-temperature related (skin and deeper).Pain-from the surface to the deep fascia.
Name the five special senses.
Smell, taste, vision, hearing, and balance.
