Phys Exam 1 Memory/Terms Flashcards
Depolarization
Decrease in membrane potential
Voltage difference between inside & outside of membrane is less
Hyperpolarization
Increase in membrane potential
More difference in voltage across membrane
Membrane Potential (Vm)
Difference in voltage across membrane
Resting membrane potential (Vr)
Voltage across membrane when cell is inactive
Capacitance
Membrane’s ability to store charge
Conductance (g)
ease of flow
Current (I)
Change in ion conductance
Equilibrium Potential of K+
-90 mV
Equilibrium Potential of Na+
+60 mV
Equilibrium Potential of Ca2+
+120 mV
Equilibrium Potential of Cl-
-70 mV
Ohms Law
V=IxR
Voltage = Current x Resistance
Contractility
Cardiac muscle’s ability to change force of contraction w/o changing muscle length
Occurs by change in Ca regulation
Activates sympathetic nervous system for increase of NE release
Gs (type of G protein-coupled receptor)
increase AMP | inhibit MLCK | stimulate SERCA
=relaxation
Gi (type of G protein-coupled receptor)
decrease cAMP | promote MLCK | inhibit SERCA |
=contraction
Gq (type of G protein-coupled receptor)
produce IP3 / DAG | Ca2+ release from SR | activates PKC
=contraction
Contraction Mechanism for Smooth Muscle
Ca2+ in | Calmodulin binds to Ca2+ | MLCK activated | phosphorylation of MLC | cross bridge formation | myosin flexibility =contraction
Relaxation Mechanism in Smooth Muscle
Ca2+ out of cell | decrease MLCK | dephosphorylate MLC | decrease myosin flexibility
= relaxation
Dystrophin & Role in Muscular Dystrophy
Binds sarcomere to outside of cell
Mutation = damage/wasting overtime with stretch (MD)
Order of Motor Unit Recruitment
Type I (slow/deep) –> Type II (fast/superficial)
Twitch
Muscle contraction from single action potential
Summation
combination of EPSPs & IPSPs which can form an Action Potential
Type I Motor Unit
Slow oxidative | Low myosin ATPase | Low SERCA | Lots mitochondria | Energy-conservative | Deeper | More excitable
“fine” motor control | fatigue-resistant | small neurons
Type IIA Motor Unit
Fast-oxidative | quick shortening | high myosin ATPase | medium SERCA | lots mitochondria