Nerve Reflexes Flashcards
Pathways of reflex arc
(River sometimes invade mountain environments)
Receptor
Sensory neuron
Interneuron
Motor neuron
Effector
An often-used model of nerve pathways is the ___.
reflex arc
A ___ are is a way of visualizing the direction of transmission of nerve, signals (action potentials).
reflex arc
Synthesizing the component parts of the reflex arc, we see that a ____ at the receptor results in a reaction by an effector.
stimulus
TRUE or FALSE
In addition, less than one sensory neuron may converge on a single association neuron, or multiple motor neurons may diverge from a single association neuron.
False, more than one sensory neuron
Autonomic reflexes typically involve ___ efferent neurons, whereas somatomotor reflexes involve only ___ efferent neuron.
two, one
Afferent and efferent neurons generally form bundles of parallel fibers called ___ (in the peripheral nervous system [PNS]) or ____ (in the CNS)
nerves, tracts
a classic example of stretch reflex in which the stimulus is stretching of the quadriceps femoris muscles; done when the patellar ligament is tapped.
Function: Measures the posture maintenance and coordination of muscle activity if absent or greatly exaggerated, it may indicate that neurons within the brain or spinal cord is damaged
The patellar reflex, or knee-jerk reflex
(exaggerated response) results from damaged or diseased motor areas in the central nervous system
hyperreflexia
(inhibited response) results from degeneration of nerve pathways, voluntary motor control, and other factors
hyporeflexia
The ___ is a spinal reflex that involves nerves C5 and C6. Have the subject sit with the elbow flexed at approximately 90 degrees and palm facing downward. Put your thumb on the biceps (brachii) tendon at the inside angle of the elbow and press gently. Tap your thumb with a reflex mallet. Flexion of the elbow is the normal response.
biceps reflex
The __ is a spinal reflex that involves nerves C6 and C7. Have the subject lie on a table, with an arm across the abdomen. Supporting the subject’s arm with the elbow flexed at a 90 degree angle, sharply tap the posterior surface of the upper arm just proximal to the olecranon
The lower arm should extend as the triceps brachii muscle reflexively contracts.
triceps reflex
(ankle-jerk reflex) is a spinal reflex that involves nerves S1 and S2, and results in plantar flexion of the foot. Have the subject kneel on a chair, facing away from you, with the toes pointing toward the floor. Tap the middle of the Achilles (calcaneal) tendon with a reflex mallet.
The Achilles reflex
are those that result from the stimulation of cutaneous (skin) receptors.
Cutaneous reflexes
involves cutaneous receptors rather than deep receptors in muscles or tendons. Position the subject’s bare foot with the lateral surface resting on a table or chair.
Demonstrate this reflex by firmly sweeping the handle of the mallet along the lateral region of the sole
In a normal adult, the toes flex. In a Babinski response, the toes extend and move apart. The ___ is normal in infants (up to 18 months) in whom the nerves have not fully myelinated, but the response is abnormal in adults.
The plantar reflex, Babinski response
Begin the ___ demonstration by having the subject lie supine on a clean, flat surface. Expose the skin of the abdomen. Use the handle of the reflex mallet to sweep gently along the anterior, lateral aspect of the skin. Move in a superior-to-inferior direction.
Abdominal reflex
involve cranial nerves and autonomic reflex centers.
• 1 In a dimly lit area, demonstrate the ___, which are centered in the brainstem. Have the subject stare straight ahead, with a hand held vertically between the eyes.
Shine a penlight in the subject’s left eye (from 5 to 7 cm away). Normally, the light receptors in the eye receive the bright light and trigger a reflexive response by the muscles in the iris.
pupillary reflexes
The ___ is an automatic response to a stimulus that does not receive or need
conscious thought as it occurs through a reflex arc.
reflex
Reflex ___ act on an impulse
before that impulse reaches the brain
arcs
involuntary reactions in response to a stimulus applied to the periphery & transmitted to CNS; allow a person to react to stimuli more quickly; no conscious thought is required.
Reflexes
The neuronal pathway by which a reflex occurs; basic functional unit of nervous system; smallest, simplest pathway capable of receiving a stimulus & yielding a response.
Reflex Arc
pick up the stimulus; stimulated by a change in its environment.
Receptor
Afferent; send stimulus to interneurons in spinal cord
Sensory Neuron
Located in CNS and connect to motor neurons; process stimulus to some reflexes
Interneurons
efferent; send response to effector
Motor Neuron
Muscles or glands innervated by a motor nerve. It responds in some way to nerve signals, perhaps by contracting or secreting a chemical.
Effector Organ
NEURONAL PATHWAYS
Converging
Diverging
two or more neurons synapse with the same postsynaptic neuron; allows transmitted information in more than one neuronal pathway to converge into a single pathway
Converging Pathway
Axon from one neuron divides & synapses with more than one other postsynaptic neuron; allows transmitted information in one neuronal pathway to diverge into two or more pathways
Diverging Pathway
this allows the integration of multiple subthreshold local potentials from the
signals in neuronal pathways which can bring the membrane potential to
threshold & trigger action potential.
SUMMATION
the process of combining electrical impulses to create a response, such as an action potential
Summation
Occurs when the local potentials originate from different locations on the postsynaptic neuron (ex: from converging pathways)
Spatial Summation
Occurs when local action potentials overlap in time; from a single input that fires rapidly, which allows the local potentials to overlap briefly
Temporal Summation
contains pain receptors as its sensory
receptors; if stimulated, reflex occurs
Function: Remove a limb or another body part from a painful stimulus
Withdrawal Reflex / Flexor Reflex
