Week 5 Flashcards
Normal BPM
60 - 100 Beats / min
Cardiac output (L)
5 - 6L / Min (10,000 / day)
How many heart contractions a day?
100,000
Mean arterial pressure
90 - 95 mmHg
What conducts faster AV or SA node?
SA node
What is an intrinsic pacemaker frequency? (IPF)
Frequency if we remove all external effects
(hormones, autonomic inn.)
IPF of SA node
100 / min
IPF of Cardiomyocytes
No
No spontaneous excitation, they need AP from nodes
IPF of AV node & Bundle of His
40 - 60 / min
IPF of Bundle branches & Purkinje fibers
20 - 40 / min
Funny Current (If) Channel & Ions & Function
HCN4 (HCN1) V.G Channel
Na+
Pacemaker potential
(Gradual depol.) < -50 mV
What blocks the Funny Current (If)
Ivabradine
Ca T Current Channel & Ions & Function
T type VDCC
Ca2+ & Na+
Initial depol. -55 mV
What blocks the Ca, T Current?
Verapamil
Ca L Current Channel & Ions & Function
L type VDCC
Ca2+
Depol. -25 mV
K Current Channel & Ions & Function
Several Voltage Gated Types
K+
Repol.
K, ACh Current Channel & Ions & Function
GIRK 1 / GIRK 4 Channels
K+
Hyperpol.
Minimum diastolic potential of SA node
-65 mV
What is the Na+ influx from funny current called
Prepotential
(Gradual depol. towards threshold)
Chronotropic effect of Sympathetic
Positive chronotropic effect
(Increased heart rate)
Chronotropic effect of Parasympathetic
Negative chronotropic effect
(Decreased heart rate)
Which vagus nerve goes to SA & AV nodes
SA = Right Vagus
AV = Left Vagus
Does the Vagus n. innervate both atria and ventricles?
No, only the atria.
Ventricles not inn. by Vagus in Humans
Sympathetic system signal and receptor in Heart
Norepinephrine
B1 Receptor
(inc. CAMP)
Parasympathetic system signal and receptor in Heart
Acetylcholine
M2 muscarinic receptor
(dec. CAMP)
What blocks the Parasympathetic system?
Atropine
What blocks the Sympathetic system?
Propranolol
What activates the HCN channel?
Hyperpolarization (S4 sensor)
CAMP direct binding
What happens if the pacemaker activity of the SA node fails?
Other cells containing HCN channels take over the excitatory activity
What does Lidocaine inhibit?
V.G Na+ Channel
Where does most Ca2+ signaling to myocytes come from?
Ca2+ from E.C comes into cell, which allows for main Ca2+ signal from I.C stores in SR to be released
What inhibits L type VDCC?
Nifedipine (DHP)
Diltiazem
Importance of K+ channels in Heart
Provides a protective mechanism in case of Hypoxia by reducing O2 consumption
What part of conduction system of Heart has fastest conduction?
Purkinje Fibers
What causes delay bw Atrial and Ventricular contraction?
The slower conduction in the AV node
Systole duration
0.27s
Diastole duration
0.53s
EDV of Ventricle
140 ml
(end diastolic volume)
ESV of Ventricle
60 ml
(end systolic volume)
First heart sound
AV valve closing
Second heart sound
Aortic valve closing
Pressure in Aorta
(Stystolic & Diastolic)
Systolic= 120 mmHg
Diastolic= 80 mmHg
Stroke Volume (SV)
EDV - ESV
Ejection fraction Calculation & Normal range
EF = SV / EDV
0.5 < SV < 0.75
How long is Skeletal muscle AP
2 - 4 ms
How long is Cardiac muscle AP
200 ms
What terminates Ca signal in Skeletal Muscle?
SERCA uptake to SR store
What terminates Ca in Cardiac Muscle?
SERCA (phospholamban) - 70%
3Na+/Ca2+ Exchanger - 28%
(PMCA - 2%)
What are Cardiac Glycosides used for? Helps by?
Heart weakness
Causes a positive inotropic effect by inhibiting Na/K ATPase
What is Positive Inotropic effect?
The increase of force of contraction
How do Cardiac Glycosides work?
1) Inhibits NA/K ATPase
2) Na buildup in cell
3) Slow down of Ca/Na pump
4) Higher I.C Ca
5) More Ca release at AP, so stronger signal, Stronger contraction
What is muscle fiber Triad made up of?
1 Transverse Tubule
2 Terminal Cisternae of Longitudinal Tubules
What is Troponin Complex made up of?
TnT (tropomyosin)
TnC (Ca2+)
TnI (inhibition
Electromechanical Delay
Delay bw electrical signal (A.P) and muscle contraction
30 - 100 ms
Skeletal Muscle Fiber types
Type1 = Slow Oxidative (Red)
Type2-a = Fast Oxidative (Red)
Type2-b = Fast Glycolytic (White)
What links contracting elements to Extracellular Matrix
Dystrophin-glycoprotein complex
Pressure in atria/ventricle during atrial contraction
From 4 to 8 mmHg