Lesson 11 Flashcards
reflex arc
mediated by neural paths (connections of neurons) to yield rapid involuntary muscle response to stimuli
two main groups of reflexes
- autonomic
- somatic
autonomic reflexes
mediated through autonomic nervous system; smooth muscles in digestion, glands in sweating
somatic reflexes
involve sensory stimulation that causes skeletal muscle to react; withdraw reflex from pain
components of a reflex arc (5)
- receptor
- sensory neuron
- integration sensor
- motor neuron
- effector
spinal reflexes
initiated and completed at the spinal cord level without the involvement of higher brain centers (somatic)
knee-jerk reflex
utilizes a two neuron, monosynaptic reflex arc
flexor reflex
utilizes sensory and motor neurons connected by interneurons, polysynaptic reflex arc
spinal reflex: stretch reflex (2)
- maintains posture/balance and locomotion
- tendon stretch causes agonist muscle contraction and antagonistic relaxation
spinal reflex: crossed extensor reflex
flexion of one limb followed by extension of the opposite limb
spinal reflex: superficial cord reflex (2)
- results from pain and temperature changes
- ex. plantar reflex, Babinski’s sign
patellar (jerk) reflex (4)
- tapping the patellar ligament excites muscles
- afferent impulse travels to spinal cord where info is relayed to motor/interneurons
3a. motor neuron send activating impulse to quadriceps, extending the knee
3b. interneurons make inhibitory synpases with ventral horn that prevent antagonist muscle contraction
cranial nerve reflex: corneal reflex (2)
- a function of cranial nerve V (trigeminal)
- touching of the cornea causes blinking
cranial nerve reflex: gag reflex (2)
- a function of cranial nerves IX (glossopharyngeal) and X (vagus)
- touching of uvula causes gag
pupillary reflexes
reflex caused by light stimulation of cranial nerve II (optic) causing iris constriction by cranial nerve III (oculomotor)
pupillary light reflex
pupil constricts due to light stimulus
consensual reflex
light stimulation of one eye causes constriction in contralateral (opposite) eye
ciliospinal refelx
stimulation of the back of the neck causes ipsilateral pupil dilation (same side)
salivary reflex
food order detection causes salivation
exteroceptors
react to external stimuli
interoceptor/visceroreceptors
react to internal stimuli
proprioceptor
detects body/limb position
hair follicle receptor (3)
- free/naked nerve ending
- non-encapsulated
- detects light touch
free nerve endings detect (2)
pain and temperature
encapsulated nerve endings: tactile Meissner’s corpuscle
detects light touch and light pressure
encapsulated nerve endings: bulbous Ruffini’s corpuscle
detects deep pressure and stretching
encapsulated nerve endings: lamellar Pacinian corpsucle
detects deep pressure and high frequency vibrations
four qualities of cutaneous sensation
- touch
- heat
- cold
- pain
are cutaneous sensations distributed evenly throughout the body?
no, it’s distributed non-uniformly; distribution is based on importance of the area and need for the receptors
two-point threshold
smallest distance two points of contact can be perceived; use a vernier caliper for this activity
tactile localization
determining which point on skin has been stimulated
adaptation
sensory receptor discharge from stimulus slows causing the perception of stimulus to decrease
referred pain
perception of pain from one area of the body when another area is actually receiving the noxious stimulus
