Reflex Physiology Flashcards
Reflexes are rapid, predictable, involuntary motor responses to stimuli that function over pathways called ______.
reflex arcs
Reflexes can be categorized into two large groups:
1.
2.
-Somatic reflexes
-Autonomic (or visceral) reflexes
______ include all those reflexes that involve stimulation of skeletal muscles by the nervous system
Somatic reflex
(Ex: rapid withdrawal of a hand from a hot object)
_______ are mediated through the autonomic nervous system. These reflexes activate smooth muscles, cardiac muscles, and the glands of the body, and they regulate body functions such as digestion, elimination, blood pressure, salivation, and sweating.
Autonomic (or visceral) reflexes
Reflexes that are mediated through spinal nerves without involving the higher brain centers are…
spinal reflexes
Reflexes mediated by cranial nerves are termed…
cranial reflexes
All reflex arcs have 5 essential components…
1.
2.
3.
4.
5.
- Receptor
- Sensory Neuron
- Integration Center
- Motor Neuron
- Effector
______ is the site of stimulus action
receptor
The ____ transmits afferent impulses to the CNS.
sensory neuron
The ______ consists of one or more neurons in the CNS
integration center
The ______ conducts efferent impulses from the integration center to an effector organ.
Motor neuron
The ______, muscle fibers or glands, responds to the efferent impulses.
Effector
What is the clinical significance of reflex testing?
It is an important diagnostic tool for assessing the condition of the nervous system. Unusual or absent reflexes may indicate degeneration or pathology of portions of the nervous system. If the spinal cord is damaged, the reflex tests can help pinpoint the area (level) of spinal cord injury. Motor nerves above the injured area may be unaffected, whereas those at or below the lesion site may be unable to participate in normal reflex activity.
What are the primary structural/anatomical differences between a somatic versus a visceral reflex arc?
The muscle is the effector in somatic. Viscera is the effector in autonomic.
Some people suffer from a condition known as congenital insensitivity to pain, in which they cannot detect painful stimuli at all, yet all their motor skills are normal. Which portion of the somatic reflex arc might be defective in people with this condition?
The integration center or the sensory receptor.
(both are before motor neurons)
There is a related condition known as congenital indifference to pain, in which people can detect painful stimuli, but they do not react properly to the stimulus. Essentially, these people do not feel pain as very painful. People with this condition have normal motor function. Which portion of the somatic reflex arc might be defective in people with this condition?
The integration center
When your small intestine begins to fill with food, a signal is sent to the brainstem that initiates contraction of the smooth muscle in the abdominal wall and the movement of the food through the intestines. Is this an example of a somatic or visceral reflex arc?
Visceral reflex arc
_______ are somatic reflexes important in maintaining posture, balance, and locomotion.
Stretch reflexes
Stretch reflexes are initiated by tapping a _____, which stretches and stimulates the muscle spindles.
tendon
The inhibition of those interneurons and the antagonist muscles is called _______.
reciprocal inhibition
Stretch reflexes tend to be hypoactive or absent in cases or _______ or _______.
peripheral nerve damage or ventral horn disease
The _______ is a technique to enhance sluggish stretch reflexes.
Jendrassik Maneuver
(Clench teeth, interlock hands, look at ceiling, and when given a verbal cue, pull hands apart without letting go)
The patellar reflex (knee-jerk) assesses the _____ level of the spinal cord.
L3-L4
What muscles contract during the patellar reflex?
Quadriceps
