Lecture 9 9/5/23 Flashcards
What are the components of a reflex arc?
-sensory receptor
-sensory neuron
-synapse (can be multiple)
-motor neuron
-target organ/muscle
Where does the sensory neuron enter the spinal cord?
dorsal root
Where does the motor neuron exit the spinal cord?
ventral root
What is the role of the sensory receptor?
translate stimulus into action potential
What is the role of the sensory neuron?
carry action potential from sensory receptor to CNS
What does the number of synapses in the CNS depend on?
the number of neurons involved
What is the role of the motor neuron?
carry action potential from CNS to effector organ
What is the role of the effector organ/muscle?
undergo muscle contraction
Why is the patellar reflex important?
it helps an animal to maintain a normal gait
How is the patellar reflex tested?
-a hammer is used to hit the patellar tendon and stretch the muscle
-a “kick” signifies the reflex is present
Why is the withdrawal reflex important?
it signifies an animal’s ability to feel pain and withdraw limb from uncomfortable situations
How is the withdrawal reflex tested?
-toe is pinched on the skin
-flexing leg indicates presence of reflex
Which nerve acts in the patellar reflex?
femoral nerve
Which nerve acts in the withdrawal reflex?
sciatic nerve
Why is the pupillary light reflex important?
it allows for an animal to constrict the pupil and protect its eyes in conditions of bright light
How is the pupillary light reflex tested?
-a light is shown in the animal’s eyes
-pupil should constrict if reflex is normal
Which nerves are involved in the pupillary light reflex?
-ocular (sensory)
-ocular motor (motor)
How do segmental and intersegmental reflexes differ?
-segmental reflexes are local and involve only a small section of the CNS
-intersegmental involves larger sections of the CNS
Which type of reflex makes it harder to identify problems and why?
-intersegmental
-more difficult to narrow down where a lesion may be located due to greater CNS involvement
-requires more reflex tests
What is proprioceptive positioning?
test to determine an animal’s awareness of where their feet are
How is proprioceptive positioning tested?
-animal is supported under trunk
-foot is flipped under so dorsal side is weight bearing
-want animal to quickly correct their foot
What aspects of the nervous system are involved in proprioceptive positioning?
-peripheral nervous system
-spinal cord
-brainstem
-forebrain
What is ataxia?
abnormal gait (swaying/staggering) due to a loss of proprioception
