PNB 2XB3 Midterm 2 Review Questions And Answers Rated A+ New Update Assured Satisfaction
12 views 0 purchase
Course
PNB 2XB3
Institution
PNB 2XB3
Benefits of Adaption in touch sensations - ️️1) Helps us to ignore constant,
innocuous stimuli, reducing distraction
2) Helps to avoid saturation of neuronal firing rates, allowing us to detect changes in
stimulus intensity over a larger ranger of intensities.
Merkel Cells and Mechanotransd...
PNB 2XB3 Midterm 2 Review
Benefits of Adaption in touch sensations - ✔️✔️1) Helps us to ignore constant,
innocuous stimuli, reducing distraction
2) Helps to avoid saturation of neuronal firing rates, allowing us to detect changes in
stimulus intensity over a larger ranger of intensities.
Merkel Cells and Mechanotransduction - ✔️✔️When skin is presed:
1) Mechanically-gated ion channels in the A beta membrane open, letting in ions (Na)
2) This causes the first ("dynamic phase") action potential
3) Mechanically-gated ion channels in the Merkel cell membrane also open, letting in
ions (Na)
4) This depolarizes the Merkel cell and results in the opening of voltage gated Ca
channels
5) As a result, a neurotransmitter (norepinephrine) is released onto the A beta axon
terminal, which contains transmitter receptors
6) This causes the second ("static") action potentials
Dorsal Column Medial Lemniscus Pathway - ✔️✔️Pathway that responds to light touch
A delta axons go up lumbar and cervical spinal cord, then the dorsal column nuclei, then
medial lemniscus in the caudal medulla (base of brain).
From there to pons, midbrain, thalamus and eventually parietal cortex using
thalamocortical axons.
Decussates at caudal medulla.
A beta Fibers - ✔️✔️Large sensory fibers involved in rapidly transmitting sensation.
Responds to touch
(around 50 m/s)
A delta Fibers - ✔️✔️Slower fiber that responds to sharp pain ( around 10m/s)
C fibers - ✔️✔️Slow fiber that is associated with dull pain (around 1m/2s)
Spinothalamic Tract - ✔️✔️Pathway that responds to painful touch. (A delta and C
axons)
Travels in ventral matter of the spinal cord. Decussates immediately.
Brown-Sequard Syndrome - ✔️✔️Damage to half of the spinal cord.
, Results in loss of touch on the ipsilateral side, and on the contralateral side, no pain
sensations.
Upper body still has normal sensation.
Meissner Receptors - ✔️✔️Small receptive field size
Responds best to low frequency vibration (2 to 50Hz)
Located near surface (around 1mm deep into the skin)
Merkel Receptors - ✔️✔️Small receptive field size.
Responds best to static indentation (pressure
Located near surface (around 1mm deep into the skin)
Ruffini Receptors - ✔️✔️Large receptive field size
Responds best to skin stretch
Located deeper in skin
Pacinian Receptors - ✔️✔️Large receptive field size
Responds best to high frequency vibrations
(greater than 50Hz)
What does the sensation of vibrations help us do? - ✔️✔️Allows us to perceive the
texture of materials, the "slippage" between the skin and grasped object and the small
vibrations of tools.
EX Detecting change in amplitude when you're running you fingers across an etched
design.
4 Sections of the spinal cord - ✔️✔️1. Cervical
2. Thoracic
3. Lumbar
4. Sacral
Stimulus Response Spike Train - ✔️✔️Merkel and Ruffini cells have an onset response
(dynamic phase) and an ongoing response (static phase)
Meissner and Pacinian cells respond to the first part of the stimulus
2 different ways to get an action potential along the A beta axon - ✔️✔️1) Deforming
the A beta axon
2) Deforming the Merkel cell
Both the A beta axon and the Merkel cell have voltage gated channels. Responds
mainly to the ongoing part of the stimulus (ongoing indentation)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller PatrickKaylian. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
