Reflexes

reflex

comparatively simple automatic response to a stimulus

reflex arc steps

receptor
sensory relay
integration
motor command relay
effector

monosynaptic reflexes

faster and integrated into the spinal cord

monosynaptic reflex example

knee jerk

polysynaptic reflex

at least one interneuron involved

somatic reflex

voluntary involving skeletal muscle

autonomic reflex

reflex that involves smooth muscles, glands, or visceral organs

acquired reflexes

reflexes that are learned through experience

exteroceptors

general sensory receptors that monitor external conditions like heat, cold, pain, pressure

interoceptors

sensory receptors that monitor internal conditions

chemoreceptors

monitor blood pH

visceral stretch receptors

monitors distension of visceral organs

proprioceptors

monitor postural info

free nerve endings

dendrites terminate in epidermic/dermis junction and surrounding tissue; detect pain

merkel cells

associated with free nerve endings; detect light touch

meissner's corpuscles

more superficial encapsulated receptors; detect light touch

pacinian corpuscles

deeper encapsulated receptors; detect forceful pressure

proprioception

sense of body movement and position

muscle spindle

monitor muscle position to ensure muscles don't overstretch

intramural fibers

located in extramural skeletal muscle fibers

alpha-motor neurons

innervate contractile region of extramural fibers

gamma-motor neurons

innervate contractile region of intramural fiber

willful muscle contraction

brain-> gamma-motor neurons to contract the intramural fibers, relieving compression of spindle

receptor transducing function

convert stimuli to action potentials

adaptation

desensitization to constant stimuli

sensitive receptor field

smaller, more dense receptor field