CV Part 1 Flashcards
What type of blood and where does the vena cava empty?
Mixed venous blood
Right atrium
Sequential blood flow (13)
RA → tricuspid valve → RV → pulmonic semilunar valve → pulmonary arteries → lungs → pulmonary veins → LA → mitral valve → LV →aortic semilunar valve →aortic arch → aorta
How does the heart function as 2 pumps?
Pulmonary circulation
Systemic circulation
Diastole
Ventricular relaxation
Low intraventricular pressure
Systole
Ventricular contraction
High intraventricular pressure
What is the myocardium?
Cardiac muscle
What is the preferred energy in a healthy heart?
Free Fatty Acids
Heart has an extensive vascular network made of
Coronary arteries and veins
Majority of cardiac mass is (5)
Endothelium VSM Fibroblasts ECM Interstitium
What is the myocardium comprised of?
Myocytes
How are cardiac muscle cells and fibers joined?
Gap junctions
What do gap junctions allow?
High degree of electrical conductivity
Free diffusion of very small molecules
What kind of metabolism do cardiac myocytes use to produce ATP?
Oxidative phosphorylation
What are cardiac myocytes rich in?
Mitochondria (serves as intracellular Ca sinks)
Like skeletal muscle, what do cardiomyocytes contain? (3)
CK-MB (cardiac specific creatine kinase)
TnI
TnT
What are possible diagnostic markers for an MI?
TnI
TnT
CK-MB
2 ways cardiac muscle is different from skeletal muscle
Slight stretch causes release of intracellular Ca
Develop more tension from stretch
What makes up the majority of myocardial mass?
Ventricles
What happens during the beginning of diastole?
Aortic valve closed
Mitral valve ready to open
LV fibers have no load
What happens during early diastole?
Mitral valve opens, filling the LV
Why does the mitral valve open during early diastole?
Combination of increasing LA filling pressure and the low LV pressure
(Think gradients)
What happens during the late stage of diastole?
Atria contract due to SA nodal firing
Atrial kick
Atria contribute 20% to ventricular filling
What is preload caused by?
Blood induced filling that causes stretch
Filling causes
Preload on LV muscle fibers
Law of Laplace
T = P x R
Wall tension = pressure x radius
What happens if there’s a greater wall tension?
Think Law of Laplace
More filling
Upregulate O2 demand
What happens during an isovolumetric contraction?
Mitral and aortic valves are closed
LV pressure soars
What is afterload in the heart?
Aortic pressure
What happens when preload > afterload?
Aortic semilunar valve opens
LV ejects blood
What 2 things happen in phase 1?
Diastolic filling
Generation of preload
What happens in phase 2?
Isovolumetric contraction (systole)
What happens in phase 3?
Systolic ejection
What happens in phase 4?
Isovolumetric relaxation
What does the end systolic pressure-volume (ESPVR) plot represent?
Max. Ventricular pressure developed at a given inotropic state
What happens if we increase the EDV in an ESPVR plot? (3)
Inc. preload
Inc. systolic intraventricular pressure
Inc. ESV (a little)
What happens if we increase afterload in an ESPVR plot? (2)
Inc. systolic intraventricular pressure
Inc. ESV
What happens to the EsVPR plot given positive inotropy?
Inc. max. Systolic pressure
Dec. ESV
What are inotropic compounds?
Alter the force of cardiac muscle contractility
What is the goal of positive inotropic compounds?
Increase cardiac pumping efficiency
What do positive inotropic compounds increase? (4)
Ventricular contractile force
EDV
Contraction velocity
May or may not change time interval btwn excitation episodes
What is contraction of cardiac muscle dependent on? (2)
APs (induced by Na influx)
Inc. sarcoplasmic [Ca]
What does hypocalcemia due to the QT interval?
Lengthens
What does hypercalcemia due to the QT interval?
Shortens
What does Digoxin do?
Blocks Na/K ATPase → inc. intracellular Na → NCX can’t function → intracellular Ca inc. → contraction enhanced
What type of effect does digoxin have on the heart?
Positive inotropic effect
Digoxin acts as a vagomimetic agent, meaning that it (2)
Slows SA and AV nodal conduction
Sensitized baroreceptors
You can raise cardiomyocyte [Ca] by
Activating B1 and B2 adrenoceptors (norepi-dependent)
Lusitropy
Increased rate of relaxation due to mobilization of Gi protein-dependent signaling
Increased PKA signaling leads to: (3)
Activation of type L channels
Phosphorylation of phospholamban
Phosphorylation of Troponin I
ACh interrupts ______ which _______
Activation of L channels
Slows cardiac muscle contractility
Type L channels are dependent on (3)
Na induced AP
Catecholamines
ACh
Where is the SA node located?
Within RA
Where is the AV node located?
Between right and left atria and the ventricles
SA nodal activity controls
AV nodal activity
AV nodal activity initiates
Ventricular depolarization
