Somatic Senses
sensory adaption
ability of the brain to ignore unimportant stimuli
endorphins
creates pain-suppressing actions (like morphine) found in the pituitary gland and hypothalamus
sensory receptors
detect environmental changes and trigger nerve impulses that lead to CNS for processing, etc.
sensation
feeling that occurs when the brain interprets sensory impulses
cold receptors
free nerve endings that respond to temps between 10 C and 20 C (lower causes pain)
warm receptors
free nerve endings that respond to temps between 25 C and 45 C (higher causes pain)
enkephalins
inhibiting substance that can suppress acute and chronic pain impulses (bind to same receptors as morphine)
nervous tissue of the brain
lacks pain receptors
free nerve endings
nerves/receptors associated with sensations of touch and pressure; common in epithelial tissues
Pacinian corpuscles
nerves/receptors common in deeper subcutaneous tissues, muscle tendons, and joint ligaments; respond to heavy pressure/deep pressure; large structures of CT
Meissner's corpuscles
nerves/receptors found in the hair-less regions; can detect 'light touch'; small, oval masses of CT within CT sheaths
projection
occurs when the brain (cerebral cortex) causes the feeling to come from the stimulated receptors
stomach
pain from this may be referred to the area inferior to the sterna region
small intestine
pain from this may be referred to the area superior to the umbilical region
heart
pain from this may be referred to the left shoulder or upper limb
referred pain
pain that may feel as if it is coming from another location
visceral pain
pain within the body cavity
peripheral adaption
receptors becoming unresponsive
central adaption
receptors inhibited along the CNS pathway leading to sensory regions of the cerebral cortex
touch and pressure receptors
receptors that include free nerve endings, Meissner's corpuscles, and Pacinian corpuscles
acute pain fibers
relatively thin myelinated nerve fibers; conduct impulses rapidly; sharp pain from a restricted area (does not normally continue after cessation of stimulation) - often sensed from the skin
somatic senses
senses of touch, pressure, temperature, and pain
special senses
senses that include complex specialized organs(smell, taste, hearing, equilibrium, and vision)
photoreceptors
stimulated by changes in light energy
mechanoreceptors
stimulated by changes in movement (or pressure)
thermoreceptors
stimulated by changes in temperature
chemoreceptors
stimulated by chemical concentration changes
pain receptors
stimulated by tissue damage
seratonin
stimulates other neurons to release enkaphalins
chronic pain fibers
thin unmyelinated nerve fibers; conduct impulses slowly; dull (aching) pain that is difficult to pinpoint (often continues after cessation of stimulation)- may be felt from deeper tissues