Physiol Lab Quiz 2: Labs 3&4 Flashcards
What is somatic reflex?
- Fast
- Effector - skeletal muscles
What is visceral reflex?
- Slower than somatic
- Effector - smooth m., cardiac m., and glands
What is monosynaptic reflex?
- only have “ONE synapse” between the afferent and motor neuron
— Total of two neurons; No interneuron needed
What is polysynaptic reflex?
- have more than one synapse
- have at least three neurons (afferent/sensory neuron, at least one interneuron, and an efferent/motor neuron)
What is innate reflex?
- reflexes that we have naturally/born with
What is learned reflex?
- reflexes we learned
What is withdrawal reflex?
- reflex that withdraws away from a painful stimulus
- an example of polysynaptic neuron, contains at least one interneuron
What is crossed extensor reflex?
- builds upon the withdrawal reflex and has the contralateral side involved by having the opposing muscles contract or relax to help keep balance
Name the brain structure referred to as the primary motor cortex
Precentral gyrus
Determine the number of neurons usually involved in a stretch reflex
TWO neurons (afferent and efferent neuron)
- aka monosynaptic
Determine the function & if it is considered phasic or tonic for the following receptors: free nerve ending
Free nerve endings - phasic
* detect warm temperature by warm receptors
AND
* detect cold temperature by cold receptors
Determine the function & if it is considered phasic or tonic for the following receptors: nociceptor
Nociceptors - tonic
* detect nociception/pain
Determine the function & if it is considered phasic or tonic for the following receptors: hair receptor
Hair receptors - phasic
* detect hair movement
Determine the function & if it is considered phasic or tonic for the following receptors: tactile disc/Merkel disc
Tactile disc/Merkel disc - tonic
* for light touch
Determine the function & if it is considered phasic or tonic for the following receptors: bulbous corpuscle/Ruffini corpuscle
Bulbous/Ruffini corpuscle - tonic
* for pressure, stretch and joint movement
Determine the function & if it is considered phasic or tonic for the following receptors: Tactile corpuscle/Meissner’s corpuscle
Tactile corpuscle/Meissner’s corpuscle - tonic
* for light touch
Determine the function & if it is considered phasic or tonic for the following receptors: lamellar corpuscle/Pacinian corpuscle
Lamellar corpuscle/Pacinian corpuscle - phasic
* for deep pressure, tickle, vibration
Define sensory adaptation
how the sensory neuron adapts to prolonged stimulus
- not exclusive for general senses
Distinguish phasic vs. tonic receptors
— Phasic receptors: fast adapting so with prolonged stimuli, there is a quick burst of action potential but decreases soon after
— Tonic receptors: adapt slowly and so generates signals more uniformly
Name the location where the information on general senses gets relayed to after reaching the thalamus
Postcentral gyrus/ Primary somatosensory cortex
Name the brain structure referred to as the primary somatosensory cortex
Postcentral gyrus
What are the 3 properties of a reflex?
Fast, involuntary, and stereotypical
What are the components of a reflex arc? Draw an example.
- Stimulus
- Sensor/ receptor
- Afferent/sensory neuron
- Integrating center
- Efferent/motor neuron
- Effector
- Response
The reflex arc is an example of which type of feedback loop? Why?
Negative feedback loop; response is opposite from the stimulus
What are the different types of muscle fibers and how are they different?
- Intrafusal fibers:
* Contains muscle spindles (detects length of muscles and proprioception)
* Sends signals to the CNS through afferent/sensory neurons, whenever length of muscle changes
* Still able to contract by gamma motor neurons - Extrafusal fibers
* For contraction
* Innervated by efferent/motor neurons = alpha motor neurons
What type of motor neurons innervates each of these different muscle fibers?
Intrafusal fiber - innervated by gamma motor neurons
Extrafusal fiber - innervated by alpha motor neurons
What are muscle spindles and where are they found?
Muscles spindles: sensors that detect the length of the muscles and helps us with proprioception (body position awareness)
— Location: found within skeletal muscle
What is reciprocal inhibition? Give an example of this.
Reciprocal inhibition/reciprocal innervation: occurs along with the reflex, which inhibits the antagonistic muscles, causing the response to be more exaggerated
— EX: Patellar reflex
* When the afferent neuron sends signals to the spinal cord that the quadriceps are being stretched, one place it will synapse is at the motor neuron going to the quadriceps, making this a monosynaptic reflex.
* Another location the afferent neuron synapses on is an interneuron. This interneuron is depolarized and sends an inhibitory post-synaptic potential (IPSP) to a separate motor neuron that will innervate the hamstrings, which are the antagonistic muscles of the quadriceps.
— By inhibiting this motor neuron, it causes relaxation of the hamstrings, which will allow the quadriceps to contract without the hamstrings opposing them, allowing the kick to be more exaggerated than when the hamstrings are contracted.
What does ipsilateral mean? Give an example.
When the neuron, stimuli and response, occur on the same side of the body
— EX: Right hand and right leg
What does decussation mean?
Decussation: Cross over the midline
What does contralateral mean? Give an example.
Contralateral: When a stimulus occurs on one side of the body, but the brain on the opposing side from the stimulus picks up that sensory information
— EX: withdrawal reflex and crossed extensor reflex
* If one were to step on a sharp object with their right foot, they would react by lifting the right foot but also balance on their left leg. This occurs because sensory information is sent to the CNS, where the sensory neurons and interneurons will synapse and the interneuron will then cross over to contralateral interneurons, which will then cause the left leg to balance.
How are ascending tracts different from descending tracts?
Ascending tracts: Carry sensory information UP the white matter of the spinal cord to the brain
Descending tracts: Motor signals from the brain going DOWN the spinal cord
Where in the brain are most sensory information sent prior to reaching their respective cortex?
Thalamus
Which part of the brain is for general senses? Which part of the brain makes sense of general senses?
- Thalamus - for general senses
- Postcentral gyrus / primary somatosensory cortex - makes sense of general senses
Which part of the brain plans voluntary movements? Which part of the cerebral cortex helps carries out these voluntary movements?
- Premotor cortex/motor association area (frontal lobe of the brain) - plans voluntary movement
- Primary motor cortex/precentral gyrus - carry out these voluntary movements by sending signals down the spinal cord until it synapses with an alpha motor neuron.
What do the stretch reflexes test for?
Purpose: test if the nerves that innervate the muscles and the spinal cord where the synapse occurs are functioning properly
Determine the nerve(s) tested, muscle(s) contracted, muscle relaxed, and the patient’s response for the following reflex: Patellar reflex
Patellar Reflex
Nerve(s) tested - Femoral nerve
Muscle(s) tested - Quadriceps
Muscle(s) relaxed - Hamstrings
Patient’s response - Knee extends
Determine the nerve(s) tested, muscle(s) contracted, muscle relaxed, and the patient’s response for the following reflex: Biceps reflex
Biceps reflex
Nerve(s) tested - Musculocutaneous nerve
Muscle(s) tested - Biceps brachii
Muscle(s) relaxed - Tricep
Patient’s response - Flexion of the forearm
Determine the nerve(s) tested, muscle(s) contracted, muscle relaxed, and the patient’s response for the following reflex: Triceps reflex
Triceps Reflex
Nerve(s) tested - Radial nerve
Muscle(s) tested - triceps brachii
Muscle(s) relaxed - Bicep
Patient’s response - Extension of the forearm
Determine the nerve(s) tested, muscle(s) contracted, muscle relaxed, and the patient’s response for the following reflex: Ankle jerk reflex
Ankle Jerk reflex
Nerve(s) tested - Sciatic and tibial nerves
Muscle(s) tested - Calf muscles (gastrocnemius and soleus)
Muscle(s) relaxed - Tibialis anterior
Patient’s response - Plantar flexion
What is the difference between a positive and negative Babinski sign?
Positive Babinski sign - the flaring of the toes and extension of the hallux
Negative Babinski sign - the toes curling and slight plantar flexion
What is considered a normal response for an infant vs. an adult regarding the Babinski sign? Why is there a difference?
- Normal response for infant - Positive Babinski sign (flaring of toes and extension of hallux)
- Normal response for adults - Negative Babinksi sign (toes curling and slight plantar flexion)
- The difference occurs when infants begin to learn how to walk, descending tracts will start to develop to cause plantar flexion instead to help keep our balance, due to inhibition by descending tracts as we mature.
What is considered abnormal for an adult regarding the Babinski sign? Why might this occur?
- Abnormal response for adults - Positive Babinksi sign
- If the adult has CNS damage, whether along the spinal cord or the brain, the inhibition by the descending tracts will no longer function properly, causing the positive sign of the Babinski reflex, since the plantar reflex is a spinal reflex.
Explain why the room temperature water bath felt different after placing your hands at different temperatures?
— Since thermoreceptors are phasic receptors, they will first give a burst of action potential for their particular temperature.
— After time, they will quickly ADAPT to the temperature by sending FEWER action potentials to the CNS. The warm receptors of the skin will decrease the number of action potentials it generates.
— When we change that temperature, they are LESS sensitive to the temperature that they are adapted to, so it feels more like the opposing temperature. When the hand from the warm water is placed in room temperature water, it will feel cold because the warm receptors is still sending fewer action potentials to the CNS, while on the contrary the cold receptors will be sending more frequent action potentials to the CNS, giving us the perception of coldness, even though the water is not actually colder than room temperature.