Exam 2 Flashcards
Name the five general senses
Seeing, hearing, smelling, tasting, touching
What is the feedforward control system?
Type of control system that anticipates and compensates for disturbances affecting the system
What is the feedback control system?
A control mechanism that uses information from measurements to manipulate a variable to achieve the desired result
What is the Theory of Feedback Control?
When sensory signals detect deviation from the desired state during movement, feedback control comes into play.
What are the six steps to optimal feedback control?
- Brain sends out command, 2. Movement, 3. Detect error (sensory feedback), 4. compared to original ‘out’ signal, 5. Make changes in position, velocity, or force, and 6. Repat task with improved performance
Sensory information from the trunk and limbs is relayed through where?
the spinal cord
From the spinal cord, where does sensory information go to?
the brain or back to muscle
Specifically, what part of the spinal cord receives sensory information?
the dorsal horns of the spinal cord
Specifically, what part of the spinal cord outputs motor information?
the ventral horn of the spinal cord
What are the parts of the Short-Latency Reflex (SLR)?
Limb (muscle), spinal cord, and the limb (muscle)
What are the parts of the Long-Latency Reflex (LLR)?
Limb (muscle), spinal cord, brain, spinal cord, and limb (muscle)
What makes a reflex complex?
It is voluntary and decision-based, it occurs 50-100 ms after event, and persistently mutable
What makes a reflex simple?
It is faster, 20-50 ms after event, and somewhat mutable
What does decussation in the spinal cord mean?
It signifies crossing over. Most tracts decussate in the spinal cord just before they synapse with lower motor neurons.
What sensations travel through the medial lemniscal tract?
Fine touch and proprioception
What sensations travel through the anterolateral tract?
Coarse touch, pain, and temperature
What sensation travels through the gracile nucleus?
touch and proprioception for the lower body
What sensation travels through the cuneate nucleus?
touch and proprioception for the upper body
Sensory information is relayed through the _______ to the _____________ cortex.
thalamus, somatosensory
What are the four maps in the somatosensory cortex?
area 1- texture, area 2- size and shape, area 3a- proprioceptive, and area 3b- touch
Why do the index finger and face occupy such large portions of the sensory map?
they have a higher sensitivity due to denser concentration of sensory receptors
What is a dorsal root ganglion neuron?
these neurons play a crucial role in transmitting sensory impulses from the peripheral nervous system to the central nervous system
How many different muscle nerves are there?
four
Describe muscle nerve type Ia
large receptor: primary spindle endings, sensitive to: muscle length and rate of change of length
Describe muscle nerve type Ib
large receptor: golgi tendon organs, sensitive to: muscle tension
Describe muscle nerve type II secondary spindle endings
medium receptor, sensitive to muscle length with little rate sensitivity
Describe muscle nerve type II nonspindle endings
medium receptor, sensitive to deep pressure
Describe muscle nerve type III
small receptor: free nerve endings, sensitive to: pain, chemical stimuli, and temperature
Describe muscle nerve type IV
small UNMYELINATED receptor: free nerve endings, sensitive to: pain, chemical stimuli, and temperature
What are the largest sensory afferent in the body?
Ia afferents
Group Ia and II afferent carry information from where?
Muscle spindles
Muscle spindles detect what?
Changes in muscle length (stretch reflexes)
How does muscle spindles lie with extrafusal muscle fibers?
In-parallel
What fibers detect dynamic changes in length?
Dynamic nuclear bag fibers (Ia)
What fibers detect sustained stretch?
Static nuclear bag fiber (Ia, II), and nuclear chain fiber (Ia, II)
What kind of connection do Ia and II afferents make in the spinal cord?
monosynaptic
Describe a monosynaptic connection and give an example of an afferent receptor that uses it
The sensory neuron directly synapses directly onto the motor neuron in the spinal cord. Ia and II afferents use it.
How does an alpha motor neuron differ from a gamma motor neuron?
Alpha motor neurons innervate skeletal muscles as the largest neurons in the CNS. Gamma motor neurons innervate spindle organs of the muscle.
Define proprioception
Status of the body internally, or where various parts are in space and in relation to one another
What is joint position sense?
The ability of a person to perceive a presented joint angle, and then after the limb is moved, actively or passively move the joint to reproduce the same angle
What is a lidocaine nerve block?
By blocking certain nerves, Ia afferents shut off therefore blocking proprioception
How does ischemia affect joint position sense?
Ischemia, mechanically compresses the nerve, shutting off the Ia afferents
How does tendon vibration affect joint position sense?
Vibration of the tendon overexcites- overestimating the position of the limb i
How does muscle fatigue affect joint position sense?
As the muscle gets more tired, the muscle spindles get more fatigued. Proprioception decreases as you fatigue.
What is the stretch reflex? How does it work?
The stretch reflex occurs as an unexpected muscle stretch weighs upon the muscle. The muscle is able to stretch to the desired length via contraction. This helps prevent injuries!
Explain the hold-relax stretching technique
Maximally activate a muscle then relax and stretch. Reflex occurs up to 15 seconds following a contraction.
Explain the agonist contract technique. How does it work?
Maximally activate a muscle and then stretch the opposing (antagonist) muscle. It works through reciprocal inhibition- AKA extending the extensors and inhibiting the flexors.
Where has the stretch reflex been shown to be greatly reduced?
in ballet dancer
When can plasticity in the stretch reflex be negative?
Following stroke
Describe Ib afferents
Larger and fast conducting. Carry information from Golgi Tendon Organs
GTOs do what?
detect changes in muscle tension
How can GTOs prevent injuries in muscles?
They inhibit the same muscle that is generating force
What afferent does NOT make a direct connection onto the motor neurons in the spinal cord?
Ib afferents
What way do GTOs lie with extrafusal muscle fibers?
in-series
Where do Ib afferent synapse onto first following a muscular response?
an inhibitory interneuron
What type of synapse reflex do Ib afferents possess?
polysynaptic reflex
Name three ways skin is sensitive
Touch, stretch, and hair movement
Describe meissnner’s corpsucles
Detect stroking and fluttering (light touch), fast-adapting, and specific
Describe merkel disc receptors
Detect pressure and texture (coarse touch), slow-adapting, and specific
Describe Pacinian corpuscles
Detect vibration, slow-adapting, and diffuse
Describe Ruffini endings
Detect skin stretch, fast-adapting, and diffuse
What are free nerve endings sensitive to?
pain, chemical stimuli, and temperature
Why is the shape of the curve different in firing rates of afferent sensitive to hot and cold?
The pain threshold for heat is much higher due to immediate tissue damage
Group III and IV afferents are sensitive to what?
hot, cold, pain, chemical irritation, and mechanical pain
III and Iv muscle nerves correspond to which cutaneous nerves
A-alpha and C-fiber
Describe the difference between first and second pain
First pain is short, intense, and sharp. Second pain is dull, aching, and longer-lasting.
Explain the stretch reflex. Draw it!
Exciting the same muscle, uses Ia afferent, excitatory synapse
Explain how GTOs work- what reflex is it? Draw it!
Inhibiting the same muscle, uses Ib afferents, inhibitory synapse
Explain how recurrent inhibition works. Draw it!
Inhibiting the same muscle, uses the Renshaw cell to inhibit motor neuron, uses both an excitatory and inhibitory synapse
Explain how cutaneous input works. Draw it!
Uses III/IV afferents, uses an excitatory and inhibitory synapse, from a cutaneous sitmulus
Explain how reciprocal inhibition works. Draw it!
Excites the agonist, inhibits the antagonist, uses both excitatory and inhibitory synapses
Explain what the crossed-extension reflex is. Draw it out!
Exciting the flexor of one leg, exciting the extensor of the other leg, uses excitatory synapses
What is a CPG?
A Central Pattern Generator- a network of neurons capable of generating rhythmic patterns of motor activity
What is the vestibular sense?
A system that uses receptors to detect body position is in space and where you are going
Where are the vestibular receptors located?
The inner ear
How does the vestibular system work?
Gel like fluid in the inner ears moves past hair cells to detect them, movement of the bundle of inner ear hair cells determines whether cells are depolarized or hyperpolarized
How many total vestibular receptors do you have in your body?
10 (five in each ear)
What do the utricle and saccule detect?
Linear accelerations (up/down, and left/right)
What do the 3 semicircular canals detect?
Angular accelerations (rotations)
Describe the Vestibular-ocular Reflex. Give an example!
Keeps the eye stable when your head moves. Looking at billboards from the passenger side of a moving vehicle.
Figure skaters habituated to stimuli through what?
Galvanic stimulation
What is nystagmus? How does it differ from saccades?
Nystagmus is voluntary or involuntary eye movement. Saccades specifically takes the eyes away from the visual target. Saccades is rapid while nystagmus is steady.
What is vertigo? What causes it?
Inadvertently experiencing or perceiving motion. Can be caused by colds, influenza, physical trauma, epilepsy, MS, and drinking.
What systems does the visual system affect?
sleep wake cycles, head tilt and motion, perceptual system, motor learning/control, behavioral learning, and cognitive learning
Dr. Riley describes the visual system like a what?
A computer!
What covers the eye?
The cornea
What controls the amount of light let in?
Iris
What parts of the eye act like a camera shutter?
Cornea and iris
You step outside to bright light. What photoreceptors are working to help you visualize the world around you?
Cones
How many more rods do we have than cones?
Twenty times as many. 120 million compared to 6 million
Rods work best in what kind of light?
Dim light.
After light is detected by the rods/cones, where does it go next to be processed?
Bipolar and horizontal cells
Information passed from horizontal and bipolar cells in the eyes goes to what cells?
Ganglion
The ganglion cells functions to pass information from stimuli to what region?
The Lateral Geniculate Nucleus via the Optic nerves
100 million receptors is condensed to less than 1 million receptors by the time the information leaves where in the eye?
ganglion cells
Why is having both monocular and binocular vision important?
Monocular vision allows us to focus one eye, while binocular allows us to focus both eyes. These work together to create depth perception and peripheral vision of our visual field.
After leaving the LGN, receptors travel to where in the visual cortex?
Simple and complex cells
Why is it important for babies to be exposed to bright light after birth?
To help develop the visual pathway in the brain. Without this exposure, monocular deprivation can occur.
What is stabismus?
One eye is able to focus on a visual field while the eye turns inwards, outwards, up, or down.
Describe monocular deprivation. What happened in the newborn kitten experiment?
Covering the one eye of a newborn kitten removed virtually all connections to the visual cortex from that eye.
By cutting the lateral muscle in the eye of baby kittens, what happened?
Bilateral function of the eye was removed. This eliminates any binocular cells in the visual cortex.
What is hemispatial neglect?
With hemispatial neglect, the person will virtually ignore that whole side of their world. Awareness of any sensory information on the side of the damaged body is diminished. Leads to difficulty in balance and performing activities of daily living.
