Chapter 13

·       Receptors:

o   Mechano- respond to touch, pressure, vibration, stretch, and itch

o   Thermo- sensitive to changes in temp

o   Photo- respond to light energy (retina)

o   Chemo- respond to chemicals (smell, taste, changes in blood chemistry)

o   Noci- sensitive to pain-causing stimuli

o   Extero-

-respond to stimuli arising outside the body

-receptors in the skin for touch, pressure, pain, and temp

-most special sense organs

o   Intero-

-respond to stimuli arising inside the body

-(visceroreceptors)

o   Proprio-

-stretch receptors in muscles, tendons, ligaments, joints, and connective tissues

o   Kinesthetic

·       Nerve structure:

o   Epineurium, perineurium, endoneurium: connective tissue coverings

-endoneurium: around an axon

-perineurium: around a group of axons (fascicle)

-epineurium: around groups of fascicles and blood vessels

·       Spinal Nerves

o   Ventral- motor //efferent; fibers innervate skeletal muscles

o   Dorsal- sensory //afferent; impulses from peripheral receptors

-8 cervical (C1-C8), 12 thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), 1 Coccygeal (C0)

·       Reflexes:

o   Intrinsic

-rapid, involuntary, predictable motor response to a stimulus

o   Acquired

-result from practice or repetition

-ex) driving skills

·       Components of a reflex arc:

o   Receptor, sensory neuron, integration center, motor neuron, effector

1.     Receptor: site of stimulus action

2.     Sensory neuron: transmits afferent impulses to the CNS

3.     Integration center: either monosynaptic or polysynaptic region within the CNS

4.     Motor neuron: conducts efferent impulses from the integration center to an effector organ

5.     Effector: muscle fiber or gland cell that responds to the efferent impulses by contracting or secreting