Nerve Physiology Flashcards
At rest, is potential positive or negative intracellular vs extracellular?
Intracellular = negative Extracellular = positive
At rest what does the sodium potassium ATP pump do
Pumps out three sodium ions while pumping in 2 potassium ions
And rest what is the difference in sodium and potassium concentration intracellularly versus extracellularly
More sodium outside and more potassium inside
Effect of decreased temperature on velocity, amplitude and latency
Decreased velocity, increased latency, increased amplitude for focal cooling and decreased amplitude for generalized cooling
What does a decrease in temperature do to sodium channel gates?
Delays opening and closing of gates.
Orthodromic versus antidromic
Orthodromic is in the direction of physiologic conduction and antidromic is opposite direction of physiologic conduction
Orthodromic of motor and sensory fibers
Motor is away from spinal cord and sensory is toward spinal cord
Antidromic of motor and sensory fibers
Motor is toward spinal cord and sensory is away from spinal
MEPPs vs EPP vs MUAP
Miniature endplate potentials (MEPP) = spontaneous release of quanta at rest
Endplate potential (EPP) = multiple MEPP summate to make EPP
Motor Unit Action Potential (MUAP) = When EPP is high enough, it generates a MUAP
What is the safety factor?
EPP’s amplitude is much larger than needed to create an action potential which allows time for Ach storage compartments to replenish
Safety factor depends on what 2 factors
Quantal content and quantal response
What is the quantal content
of Ach quanta release with each nerve depolarization
What is quantal response
Ability of Ach receptors to respond to Ach
What 2 main proteins make up skeletal muscle fibers
Actin and myosin
Basic unit of a muscle myofibril
Sarcomere
Z-lines
Length of sarcomere
H zone
Actin to actin length
I zone
Myosin to myosin
A band
Length of myosin filament
What happens to sarcomere length, Z lines, H zone, A band, I band during contraction?
Sarcomere length - decreases as Z lines move closer to each other.
H zone - gets smaller as actin filaments get closer.
A band - Stays the same because myosin length doesn’t change during contraction.
I band - gets smaller as myosin filaments get closer
What is the only section of the sarcomere that does not change in size with contraction
A band
Action potentials penetrate through the muscle through the _________
T-tubules
Calcium binds to what to cause muscle contraction
Troponin-tropomyosin complex
What is exposed when calcium binds to muscle filaments
Actin active sites
What allows muscle relaxation
ATP pumps that pump calcium out
