chapter 16 senses Flashcards
Transduction
-the conversion of one form of energy to another
-Converts stimulus energy (light, smell, heat, touch, sound, etc.) into nerve signals
Sensation
-sensory receptor detects stimulus, creates small local electrical change (the receptor potential)
Perception
-conscious experience and interpretation of a stimulus
(Not all sensations lead to perception—many signals are filtered out before reaching cortex)
Modality
-type of stimulus or the perception it produces
-Examples: vision, hearing, taste
Sensory adaptation
-if a stimulus is prolonged, firing of the neuron gets slower over time and we become less aware of it
Phasic receptors
-adapt quickly; burst of signals when stimulus starts, then reduce/stop signaling even if stimulus continues
-Examples: smell, hair movement, cutaneous pressure
Tonic receptors
-adapt slowly; action potentials continue more steadily while stimulus is present
-Examples: body position, muscle tension, joint motion
Thermoreceptors
respond to heat and cold
Photoreceptors
the eyes, respond to light
Nociceptors
-respond to tissue injury, situations threatening damage
-Activation produces sensation of pain
Chemoreceptors
-respond to chemicals
- examples: Odors, tastes, body fluid composition
Mechanoreceptors
-respond to physical deformation
- example: Vibration, touch, pressure, stretch, tension, Includes organs of hearing and balance
Exteroceptors
-sense stimuli external to body
- example: receptors for vision, hearing, taste, smell, and cutaneous sensations such as touch, heat, cold, and pain
Interoceptors
-detect internal stimuli
- EX: Stomach, intestines, bladder
-Stretch, pressure, visceral pain (Internal organ pain), nausea
Proprioceptors
-sense body position and movements
-location: In muscles, tendons, and joint capsules
Unencapsulated nerve endings
dendrites with no connective tissue wrapping
Merkel discs
-flattened nerve endings that terminate at tactile cells in basal layer of epidermis
-Detect light touch, texture, edges, shapes
Meissner corpuscles
-2 or 3 nerve fibers within fluid-filled capsule of flattened Schwann cells
-Sense light touch and texture
Krause end bulbs
sensory nerve fiber surrounded by connective tissue sheath
Nociceptive pain
stems from tissue injury; occurs when nociceptors are activated
Neuropathic pain
stems from injuries to nerves, spinal cord, meninges, brain
Ruffini corpuscles
-Detect heavy touch, pressure, stretching of skin, deformation of fingertips, and joint movements
Pacinian corpuscles
-Detect deep pressure and vibration
-Found in periosteum of bone, joint capsules, some viscera, and deep in the dermis (especially on hands, feet, breasts, and genitals)
Visceral pain—
-arises from internal organs
-Diffuse, dull, and hard to locate
-nausea
