Term
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Definition
| specialized, high density of nicotinic ACh receptors |
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Term
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Definition
non-selective, activated by ACh binding
allows Na+ and Ca2+ in, and K+ out
results in depolarization when activated
has 2 ACh binding sidtes |
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Term
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Definition
| blocks neuronal and muscle Na+ channels |
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Term
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Definition
| blocks muscle ACh receptor channels |
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Term
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Definition
stimulates muscle AChR channels
agonist toxin |
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Term
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Definition
| inhits activating of acetylcholinesterase, therby stimulates AChR by prolonging period of ACh present in synaptic cleft |
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Term
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Definition
auto-immune diseases
attacks AChR
Tx: agonist to ACh recpeotrs or Acetylcholinesterase |
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Term
| skeletal muscle E-C coupling |
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Definition
depolarization of transverse tubules cause "calcium sparks" at triads, then CICR from SR
mechanical coupling of L-type channels and Ca-sensing-Ca-release channels
Ca frees up binding spot on actin leading to contraction |
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Term
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Definition
low contraction speed
postural/endurance muscles
low force generated
high resistance to fatigue |
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Term
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Definition
fast contraction speed
medium endurance
medium force generated
moderate resistance to fatigue |
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Term
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Definition
fast contraction speed
rapid, powerful movement
high force generated
low resistance to fatigue |
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Term
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Definition
maximal force generated upon stimulation of muscle
due to optimal overlap of actin and myosin filaments
also optimal length for maximum contraction velocity (might be different?) |
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Term
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Definition
| maximum recruitment of skeletal fibers due to temporal summation of stimulus using more fibers |
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Term
cross-bridge cycling
(skeletal) |
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Definition
ATP binds to myosin, myosin detaches from actin
myosin hydrolyes ATP -> ADP +Pi, head moves to cocked position
myosin binds to actin (in high Ca2+) Pi is released from myosin -> power stroke of myosin head
ADP is released, new ATP binds |
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Term
| types of smooth muscle excitation |
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Definition
spike (rare)
plateau (visceral)
slow waves (visceral, automaticity)
graded (vascular smooth muscle, long duration possible) |
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Term
| channels for smooth muscle |
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Definition
K+ channels = repolarization, calcium senstivie
Cl- = help with depolarization, sense calcium
Ca2+ L-type = depolarization, EC coupling |
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Term
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Definition
expressed in smooth muscle cells
agonist binds to GPCR
G-proteins activates PLC
PLc makes IP3 and DAG
IP3 opens Ca-release channels on SR
contraction results form increased [Ca2+] |
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Term
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Definition
tonically inhibits SERCA
always bound to SERCA, inhibited by PKA that phosphorylates it (increases Ca time in cell, increases contraction) |
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Term
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Definition
inhibit myosin ATPase in smooth muscles
inhibits contraction |
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Term
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Definition
activates calmodulin kinase and MLCK
promotes contraction in presence of Ca2+
binding sites for 4 Ca2+ |
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Term
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Definition
phosphorylates calponin, inhibiting it
thus promotes contraction |
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Term
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Definition
force maintained at lower MLCK phosphorylation
due to decreased rate at which myosin and actin detach
lower rate of cross-bridge cycling = less E consuming for prolonged muscle contraction |
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Term
| Ca2+ sensitization (smooth muscle) |
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Definition
inhibition of MLCP (i.e. by Rho kinase)
increase excitability of muscle
contraction can result with very little increase in Ca2+ |
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Term
| Ca2+ desensitization (smooth muscle) |
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Definition
activation of MLCP
decreased excitability of muscle
relaxation with no decrease in Ca2+ |
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Term
| cross-bridge cycle (cardiac muscle) |
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Definition
| membrane depolarization --> L-type Ca2+ open --> calcium sparks --> activates Ca-releasing channels on SR --> activates troponin C --> contraction |
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Term
| phases of cardiac AP + channels |
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Definition
Phase 0: fast Na channels (inward Na)
Phase 1: rapid inactivation of fast Na channels, transient outward K+
Phase 2: L-type (slow activation) Ca2+
Phase 3: delayed K channel activated (K+ efflux) |
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Term
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Definition
calcium blockade drugs
block VG-Ca channels on SR
decrease duration of AP slightly
decrease contractile force |
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Term
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Definition
rare inherited heart condition (or drug-induced)
causes delayed repolarization of heart
mutations in sodium, potassium and/or calcium channels can be the cause |
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Term
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Definition
VG-sodium-channel in heart
inhibited by TTX and local anesthetics |
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Term
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Definition
L-type calcium channel in heart
increased activation by depolarization of If, causes further depolarization
inhibited by nifedipine and verapamil |
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Term
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Definition
lots of different types in heart
constitutive current
inhibited by Ba2, Cs+, and TEA |
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Term
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Definition
packemaker current, HCN channel in heart (K+ and Na+ channel)
inhibited by Cs+
activated by hyperpolarization, thereby staring spontaneous depolarization in SA node |
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Term
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Definition
dec. If, inc. Ik -> dec. HR
inc. GIRK, more (-) maximum diastolic potential, more time need to depolarize -> dec. HR
dec. I(Ca), takes longer to depolarize b/c threshold is more (+) -> dec. HR |
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Term
SA node
(function, currents, epi and ACh effects) |
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Definition
pacemaker
I(Ca), I(K), If
Epi: increase conduction velocity, increase rate
ACh: decrease conduction velocity, decrease rate |
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Term
Atrial muscle
(function, currents, epi and ACh effects) |
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Definition
expel blood from atria
I(Na), I(Ca), I(K)
Epi: increase contraction strength
ACh: none |
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Term
AV node
(function, currents, epi and ACh effects) |
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Definition
secondary pacemaker
I(Ca), I(K), If
Epi: increase conduction velocity, increase rate
ACh: decrease conduction velocity, decrease rate |
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Term
Pukinje fiber
(function, currents, epi and ACh effects) |
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Definition
rapid conduction of AP, tertiary pacemaker
I(Na), I(Ca), I(K), If
Epi: increase rate
ACh: decrease rate |
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Term
Ventricular muscle
(function, currents, epi and ACh effects) |
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Definition
expel blood from ventricles
I(Na), I(Ca), I(K)
Epi: increase contractility
ACh: none |
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Term
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Definition
(+) on L arm, (-) on R arm
Axis = 0* from horizontal
characterized by small P wave, R amp 5.5, flat ST and positive T wave
Q and S are small or absent |
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Term
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Definition
(-) on R arm, (+) on L leg
axis = 60* CW from horizontal
characterized by larger P wave, QRS of 9, flat ST and positive T |
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Term
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Definition
(-) on L arm, (+) on L leg
axis = 120* CW from horizontal
characterized by small P wave, QRS 5, flat ST and positive T
S dip is deeper |
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Term
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Definition
(-) on heart, (+) on L leg
axis = 90* CW from horizontal
clear P wave, R spike 8, flat ST
small or no Q, larger T wave, S dips deep |
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Term
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Definition
(-) on heart, (+) R arm
axis = -150* CW (150 CCW from horizontal)
opposite deflection, but same amp as Lead II
large P wave, QRS 9, flat ST, negative T |
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Term
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Definition
(-) on heart, (+) L arm
axis = -30* CW (30* CCW from horizontal) |
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Term
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Definition
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Term
| anterior precordial leads |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
0-90*
Lead I and Lead aVF are positive |
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Term
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Definition
0-(-90*)
Lead I is positive, Lead aVF is negative |
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Term
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Definition
(90-180*)
Lead I is negative, Lead aVF is positive |
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Term
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Definition
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Term
acute myocardial infarction
(EKG, artery, tx) |
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Definition
ST segment elevated
due to predominance of depolarized epicardial myocytes
epicardial cell artery occlusion
Tx: stent |
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Term
acute ischemia
(EKG, artery, tx) |
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Definition
ST segment depression
due to subendocardial microvascular artery constriction
Tx: rest, vasodilators |
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