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There are two types of pain, name them and describe the difference between the two including what afferent signals transmit the information. Also what sensory receptor is responsible for pain and what are those receptors a specific version of?
Fast pain and slow pain.
Fast pain is felt within .1 seconds of it occuring, this type of pain is sharp, mechanical or thermal stimuli. Aδ fibers, therefore slow transmission (6-30 m/s)
Slow pain is felt within 1 or more seconds and can increase slowly over seconds or minutes. burning, aching, nauseating, ususally caused by chemical stimuli but could be anything. Transmitted by AC fibers so superrr slow (.5-2 m/s)
Nocioceptors and they are a specific type of free nerve ending
Which pathway is for pain and temperature sensory neurons? Where do they enter and where do they go/what happens to them after they enter the spinal cord? Where do these signals decussate and how do they travel up the spinal cord?
The anterolateral pathway is for pain and temperature sensory neurons. They enter the spinal cord via the dorsal root and then immediately synapse in the dorsal horn. Some terminate there whereas others decussate immediately and go up the spinothalamic pathways. The ones that do go up the pathways terminate in one of two locations either the reticular nuclei of the brainstem (slow pain) or the ventrobasal complex of thalamus (fast pain).
You step on a lego with your right foot, before you consciously registering the pain, you quickly withdraw that foot and shoft all of your weight to your left leg. Draw the neural circuit for this.
Should include the nocioceptor receiving the input, then travelling up the afferent pathway to the spinal cord where the sensory neuron is recievied in the DRG and enters via the dorsal root. Shoud synapse immediately in dorsal horn (grey matter) then on the right side still the sensory neuron should excite the interneuron that synapses on and activates an alpha motor neuron which casues the flexor muscle to contract and another sensory neuron inhibits the extensors on this side so there is no oppositon. At the same time, and interneuron is crossing to the other side of the spinal cord and excites an extensor muscle for the left leg and inhibits a flexor muscle.
The second order neuron (immediately after the first synapse) crosses over to the left side of the spianl cord and travels up the spinthalamic tract where it then reaches the thalamus, synapses again and finally goes to the somatosensory cortex.
What is the most important neuroanatomical element in the nervous system involved in motor control?
Motor Neuron
Muscle contraction is driven by two kinds of pyramidal neurons - name them and describe them.
Dynamic neurons (lesser proportion) - excite at a high rate for a short duration at the onset of contraction to initiate rapid development of force.
Static neurons (higher proportion) - fire at a slower, more continuous rate to maintain the force of the contraction.
Stretch reflex
neural circuit needs
Stetch in forearm muscle muscle spindle
DRG cell body enters spinal cord via dorsal root
sensory neuron directly synapses on alpha motor neuron, that muscle contracts
Sensory neuron synapses on an inhibatory interneuron -- inhibits antagonist muscle
If the right dorsal column is damaged, which side loses vibration sense?
The right side
A stretch reflex is ___synaptic and a golgi tendon reflex is __synaptic. Walk through the basics of each relfex circuit.
A stretch reflex is monosynaptic.
A muslce is stretched suddenly, the primary ending of the muscle spindle is activated, at the same time: it is synapse with Aα motor neuron to contract the muscle, synapses with synergistic muscles to aid contraction and synapses with antagonist muscles to relax them and encourage further contraction.
A golgi tendon reflex is bisynaptic. A muscle contracts and the shortened extra fusal fibers are activate the golgi tendon organ, at the same time: it synapses on Aα neurons to inhibit their firing and synapses on synergistic muscles to relax them as well. Synapses on excitatory interneurons - antagonistic muscles to contract
What is the very important difference between autonomic motor neurons and somatic motor neurons? Draw it for us? For the autonomic neuron - draw two, one for the sympathetic system and one for the parasympathetic system.
The important difference is that there is a gaglion in the middle of the pathway for the autonomic one. There should be a labeled CNS then a pre-ganglion fiber connection to the autonomic ganaglion that holds the autonomic motor neuron. Then that has a post ganglion fiber coming out and connecting to the affected tissue. The parasympathetic ganglion should be very close to the affected tissue.
If you damage the white matter in the spinal cord describe where in the cross section you've done damage and the impact it will have. Do the saem for grey matter.
White matter - outside of butterfly. Will harm the pathways beneath the injury for sensation and motor.
Grey matter - inside the butterfly. Will only cause damage locally.
Where do motor neurons reside? What are the two types of motor neurons? What are their differences?
They reside in the ventral root. There are alpha and gamma motor neurons. Alpha neurons is faster and causes contraction when told to contract. Gamma neurons are slower and are responsible for tightening the spindle inside the arm to control monitor stretch and control precision.
There are two corticospinal tracts. Name and describe them adn what they are responsible for.
Lateral corticospianl tract - 75% of all cotricospinal fibers, axons descend in lateral areas of spinal cord, provides fine control, asscoiated with distal and flexor muscles
Ventral corticospinal tract - 25% of all corticospinal fibers, axons descend in medial and ventral areas of the spinal cord, participates in whole body actions like posture, associated with axial and extensor muscles
What is the fucntion of the cerebellum and how is its composition different from other brain structures?
To evaluate the difference between intention and action. Maintains movements and coordination during movements.
10% of the brain, but >50% of the neurons
~40% more axons enter than leave
Describe the difference between visceral pain and referred pain. What kind of pain is a headache?
Referred - pain felt in a part of the body that is fairly remote to the tissue causing the pain.
Headaches are a referred pain type.
There are like 600 billion functions of the brainstem name 3.
- control of respiration
- control of the cardiovascular system
- partial control of urinary function
- partial control of the gastrointestinal function
- control of many stereotyped movements of the body
- control of equilibrium
- control of eye movements
If the left spinothalamic tract is damaged, which side loses pain?
The right side
You have two types of thermal receptors, name them and what fibers trasmit the information for each?
Cold receptors - special Aδ myelinated nerve endings located immediately beneath the skin
Warmth receptors - free nerve endings of unmyelinated C fibers immediately under the skin
you have 10x more cold "spots" than warm spots fun fact (goose bumps!)
What kind of cell did we learn about that can be de/hyper polarized based on direction? Draw this cell and the direction for both de and hyper polariztion and the corresponding firing rate with each polarization.
going to the right - depolarization - increased impulse frequency, (excitation)
going to the left - hyperpolarization - decreased impulse frequency (inhibition)
Sympathetic - fight or flight - responds to sudden changes in the internal/external environment - pathways convey outputs to the ganglia alongside the spinal cord
Parasympathetic - rest and digest - maintains digestive system, homeostasis - peripheral pathway arise from brainstem and sacral spinal cord
Enteric - almost fully independent of the CNS - controls gastrointestinal tract, pancreas, and gallbladder.
We talked about a back up pathway for limb control. Name it and give a brief description?
What are the two synaptic transmitter substances we learned about? There is one for the parasympathetic and one for the sympathetic system.
Parasympathetic - Acetylcholine
Sympathetic - Norepinephrine
What is the corticospinal tract? What is it's pathway (general-ish)?
The corticospinal tract is the main pathway to transmit signals from the motor cortex to the muscles.
30% signals from the motor cortex, 30% for premotor cortex, 40% from the somatosensory cortex
1. leaves the motor/whatever cortex
2. passes through the posterior limb of the internal capsule
3. downward through the brainstem
4. splitting of fibers at the lower medulla oblongata
5. termination (mostly on interneurons)
I'm thinking of two sensory receptor locations for the muscle: one that can tell the length and rate of change and one that can tell the tension and rate of change. Which two reflexes are determined by these two locations and what do these reflexes cause in the muscle?
Muscle spindle can tell the length. Muscle spindles sense a muscle stretch and causes a stretch reflex which causes that same muscle to contract.
Golgio tendon organs tell the tension. Golgi tendon organs sense too much tension and cause a golgi tension reflec and causes the same muscle to relax.
How is the primary motor cortex organized? There are layers, how many and what is the function of the layers?
Hint: we didn't talk about layer 1, layers 2-4 are the same, 5 is important, and 6 is also kinda important.
The primary motor cortex is organized in vertical columns. There are 6 layers to each column. Layers 2-4 are the input layers. Layers 5 and 6 are the output layers.
Corticospinal tract: layer 5 (pyramidal)
Intercerebral cortex tracts: layer 6
In the last game we named the parts of the spine and how many vertebrae each part had! Now name each part of the spine and how many pairs of spinal nerves it has!
Cervical - 8
Thoracic - 12
Lumbar - 5
Sacral - 5
Coccyx - 1