Cardiovascular- Anatomy and Physiology Flashcards
What artery supplies the right ventricle?
right (acute) marginal artery
What artery supplies the SA and AV node?
the right coronary a. (note that RCA infarct can cause complete heart block)
What are the main branches of the left main coronary a.?
- left circumflex coronary a. (LCX)
- left anterior descending a. (LAD)
What does the LCX supply?
the lateral and posterior walls of the left ventricle and the anterolateral papillary muscles
What does the LAD supply?
the anterior 2/3rds of the interventricular septum, anterolateral papillary muscle, and the anterior surface of the left ventricle
The majority (85%) of people are ‘right-heart dominant’. What does this mean?
the PDA (posterior descending a.) arises from the RCA
What does left-heart dominant mean?
the PDA arises from the LCX (co-dominant= arises from the LCX and the RCA)
Coronary artery occlusion most commonly occurs where?
LAD
When does coronary artery blood flow peak?
early diastole
Enlargement of what part of the heart is associated with dysphagia due to compression of the esophagus or hoarseness due to compression of the left recurrent laryngeal nerve?
the most posterior part, the left atrium
What is the eqn for CO?
HR X SV or via the Fick principle:
CO= rate of O2 consumption/ (arterial O2 content- venous O2 content)
What is the eqn for mean arterial pressure?
CO x TPR, or
MAP= 2/3 diastolic pressure + 1/3 systolic pressure
What is pulse pressure?
What is the eqn for SV?
end diastolic volume - end systolic volume
How does SV and HR change during exercise?
during the early stages of exercise, both HR and SV increase, and eventually SV plateaus
What are some things associated with increased pulse pressure?
- hyperthyroidism
- aortic regurg
- aortic stiffening
- obstructive sleep apnea
- exercise (transient)
Isolated increased systolic pressure in the elderly suggests what?
aortic stiffening
What are some things associated with decreased pulse pressure?
- aortic stenosis
- cardiogenic shock
- cardiac tamponade
- heart failure
What are the three variables that affect stroke volume?
- contractility
- preload and afterload
What things increase contractility?
- catecholamines (increase the activity of SR Ca2+ pumps)
- increased intracellular Ca2+
- decreased extracellular Na+ (via decreased activity of the Na/Ca2+ pump)
- Digitalis
How does digitalis increase contractility?
by blocking Na/K pumps leading to increased intracellular Na+, decreasing Na/Ca exchanger activity, and thus leading to elevated levels of Ca2+
What are some things that decrease contractility?
- B1-blockade (decreased cAMP)
- acidosis
- acidosis
- hypoxia/hypercapnia
- non-dihydropyridine CCBs
What are some things that increase myocardial oxygen demand?
What is the eqn for cardiac wall tension (aka thickness)?
WT= (pressure*radius)/(2*wall thickness)
Venodilators such as nitroglycerin ______ preload
decrease
How does the left ventricle compensate to increased afterload?
by thickening to decrease wall tension
Vasodilators such as hydralazine ______ afterload
decrease
How do ACEIs and ARBs affect pre- and afterload?
they decrease both
What is the eqn for equation fraction?
SV/EDV= (EDV- ESV)/EDV
Normal EF = 55+%
How is EF affected by systolic HF? diastolic HF?
systolic HF: decreased
diastolic HF: normal
What is inotropy?
An inotrope is an agent that alters the force or energy (aka contractility) of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents (e.g. digoxin) increase the strength of muscular contraction.
Contractility is proportional to what?
the end-diastolic length of cardiac muscle fibers (aka preload)
How does organ removal affect TPR and CO?
it increases TPR and decreases CO
_______ account for most of TPR
Arterioles
What is the period of heart contraction with the highest O2 consumption?
isovolumetric contraction
What is S1?
mitral and tricuspid valve closure. Loudest at the mitral area
When does S1 occur?
at the start of isovolumetric contraction
What is S2?
closure of the aortic and pulmonary valves
When does S2 occur?
at the end of systolic ejection when the aortic pressure generated becomes higher than that of the left ventricle
Where is S2 best heard?
left upper sternal border
When is S3 heard (pathologic)?
in early diastole during the rapid ventricular filling phase
What things cause an S3?
associated with increased filling pressure (e.g. mitral regurg, HF) and more common in dilated ventricles (but normal in children and pregnant women)
When is S4 heard (pathologic)?
in late diastole (aka atrial kick)