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Physio lab

Reflex

Specific sensory stimuli evoke characteristics motor responses very rapidly because few synapses are involved.

Specific simple reflex

occurs at a specific spinal chord segment and involves particular nerves

What determines the speed of motor response?

The number of synapses to be crossed between the afferent flow of impulses and the activation of efferent nerves

Patellar Reflex

(knee-jerk reflex) the simplest reflex requires only one synapse between sensory and motor neurons.

Patellar Reflex (procedure and tests for)

procedure:knee extension
tests:Femoral nerve

Achilles Reflex

procedure:plantar flexion should happen
tests:Tibial nerve

Biceps Tendon Reflex

procedure:elbow flexion
tests:musculocutaneous nerve

Triceps tendon

Procedure: extension of the elbow
tests: radial nerve

cutaneous reflex, the plantar reflex and Babinski's sign

Procedure: planter flexion and toe flexion

If you are unable to elicit a response from your patient you can have them try several things. What are they

1) Have them grip their hands together and try to pull apart
2) Have them count backwards from 100 by
7's out loud
3) Have them clench their teeth together really hard
4) Have them say the alphabet backwards out loud

4 cutaneous sensations

warmth, cold, touch, pain
(also pressure, itch and tickle)

5 receptors

1) free nerve endings
2) Merkel's Discs
3) Ruffini Corpuscles
4) Meissner's Corpuscles
5) Pacinian Corpuscles

Free nerve endings

sensation: light, touch, cold, hot, pain
Location: around hair follicles

Merkel's discs

sensation: sustained touch, pressure
Location: stratum Basale

Ruffini Corpuscles

sensation: sustained pressure
location: deep in dermis, hypodermis

Meissner's corpuscles

sensation: changes in texture, slow vibrations
location: papillary dermis

Pacinian corpuscles

sensation: deep pressure, fast vibrations
location: deep in dermis

where is touch receptor density dense?

hands, lips, and face

How is the density of touch receptors tested?

By using the test-point threshold test.
A calipers w/2 points is applied w/equal pressure to the skin. Subject is asked if 2 distinct points can be felt. The caliper points are moved closer together and the subject retested until only 1 point can be felt

sensory adaptation

ability of our sensory receptors to respond strongly to acute changes and then stop responding when these stimuli become constant

what is susceptible to sensory adaptation

temperature and smell

what sensation rarely adapts at all

pain

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