3A: Somatosensory Disorders Flashcards
Cutaneous senses
perception of touch and pain from stimulation of the skin
Proprioception
ability to sense position of the body and limbs
Kinesthesis
ability to sense movement of body and limbs
Skin
the largest organ in the body both in surface and in weight. The skin provides protection, regulation of body temperature and water loss, and sensation.
Epidermis
the outermost, protective layer of the skin, composed mostly of dead cells
Basement membrane
immediately below the epidermis is the basement membrane, a specialized structure that lies between the epidermis and dermis. It includes various protein structures liking the basal layer of keratinocytes (skin cells) to the basement membrane and the basement membrane to the underlying dermis. Once skin cancer cells cross this boundary, they can begin to spread through the body through the vascular system of the dermis.
Dermis
the middle layer of skin below the epidermis that forms the true skin, containing blood capillaries, nerve endings, sweat glands, hair follicles, and other structures.
Subcutaneous tissue
the deepest layer of the skin, made up of vessels, fat, and connective tissue.
Hairy skin
most of our skin has hair. The primary somatosensory receptor in hairy skin is the follicle receptor, which is a mechanoreceptor triggered by distortion of the hair shaft.
Glabrous skin
hairless skin (ex. palms, soles, lips, labia, penis); contains more specialized types of mechanoreceptors
Mechanoreceptor
a sensory receptor that responds to mechanical pressure or distortion via mechanotransduction: movement of the cell membrane physically pulls open/pushes closed ion channels in the membrane, leading to changes in cell signaling.
Slowly adapting fibers (SA)
fire continuously as long as pressure is applied to provide detailed/high acuity tactile info; found in Merkel’s disks (upper dermis) and Ruffini cylinders (lower dermis)
Rapidly adapting fibers (RA)
fire at onset and offset of stimulation to provide info about the start of a sensation; found in Meissner’s corpuscles (upper dermis) and Pacinian corpuscles (lower dermis)
Acute nociceptive pain
-Part of a rapid warning relay instructing the motor neurons of the central nervous system to minimize detected physical harm. It is mediated by nociceptors, on A-δ and C fibers.
-these nociceptors are free nerve endings that terminate just below the skin, in tendons, joints, and in body organs. They serve to detect cutaneous pain, somatic pain and visceral pain.
-nociceptors are specialized for heat, chemicals, severe pressure, and cold. Hot and cold sensations are carried via thermoreceptors.
-threshold of eliciting receptor response must be balance to warn of damage but not be affect by normal activity.
Chronic inflammatory pain
-inflammatory nociceptive pain is associated with tissue damage and the resulting inflammatory process
-it is adaptive in that it elicits physiologic responses that promote healing