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