Term | Answer |
Mechanoreceptors | stimulus = mechanical force, mechanism = deforms cell membrane (cutaneous touch/pressure receptors) |
Chemoreceptors | stimulus = dissolved chemicals, mechanism = affects ionic permeability (smell, taste, osmoreceptors) |
Photoreceptors | stimulus = light, mechanism = photochemical reaction (rods and cones) |
Nociereceptors | stimulus = tissue damage, mechanism = chemical release (cutaneuous pain receptors) |
Unencapsulated free dendritic nerve endings | almost all body tissues; most in epithelial and connective tissue for pain, temp, pressure |
Encapsulated dendritic nerve endings | sensory nerve endings enclosed within connective tissue capsule, mechanoreceptors |
Meissener's corpuslces | sensitive to light pressure and discriminiative touch, found in dermal papillae of hairless skin (fingertips, palms) |
Krause's end bulbs | like Meissen's found in connective tissue of mucosae near body orfrices (mouth, eyes) |
Pacinian corpuscles | fast adapating mechanorecptors respond to deep pressure/stretch, found in subcutaneous tissue skin; tendons; ligaments |
Ruffini's corpuscles | slow adapting,deep presure/stretch, found in dermis, hypodermis, joint capsule helps cerebellum adjust for balance |
Muscle spindle fibers | respond to sudden changes in length (communicates with spinal cord) |
Golgi tendon organs | respond to changes in tension, causes muscle to relax after contraction |
joint kinesthetic receptors | monitor stretch in articular capsule enclosing joints, includes ruffini's, pacinian, and free dendritic endings |
Endoneurium | thin connectie tissue layer over each axon |
Perineurium | denser connective tissue bundles nerves into fasciles |
Epineurium | outer conective tissue, encloses all fasiciculi bundles to form nerve |
Mixed nerves | most nerves are mixed both afferent and efferent nerves |
PNS nerve classification | somatic afferent/efferent, visceral afferent/efferent, and cranial/spinal |
Spinal nerves | 31 pairs, all mixed (ventral and dorsal roots) |
Cervical spinal nerves | C1-C8 (C8 emerges inferior to vertebrae C7) |
Thoracic spinal nerves | 12 from T1-T12 |
Lumbar spinal nerves | 5 from L1-L5 |
Sacral | 5 from S1-S5 |
Cocygeal | 1 pair |
Spinal nerve proper | ventral root (motor) and dorsal root (sensory) fuse |
ventral ramus | on anterior portion, motor and sensory needs of muscles on extremities/thoracic and abdominal walls found in intercostal groove of rib |
dorsal ramus | posterior side, smaller; serves skin and musculature of posterio rbody trunk |
meningeal branch | re-enters spinal cord to innervate the meninges and blood vessels |
Dermatome | area of body served by one common sensory nerve (test this first) |
Myotome | group of muscles served by one common motor nerve (test this second) |
Spinal Reflexes | involuntary somatic reflexes like the knee jerk. Reflexes by spinal cord, remain even with cortical brain damage but not if cord is transected |
Stretch/Deep tendon reflexes | Muscle spindle fibers cause contraction in response to rapid increase in length |
Flexor reflex | Ispilateral (same side of body), withdraw body part from perceived or real threat |
Crossed extensor reflex | withdrawl on threatened side and extend on opposite (contralateral) side |