Physio Organization of the Cardiovascular System Flashcards
Lecture 16
Left heart
Left atrium/ventricle + mitral valve
Involved in systemic circulation
Right heart
Right atrium/ventricle + tricuspid valve
Involved in pulmonary circulation
Systemic Circulation
L ventricle –> aortic valve –> aorta –> aortic arteries –> arteries –> arterioles –> capillaries –> venules –> veins –> superior vena cava/inferior vena cava –> R atrium
Pulmonary Circulation
R ventricle –> pulmonic valve –> pulmonary artery –> lungs –> pulmonary veins –> L atrium
What drives blood flow?
differences in pressure and resistance; bulk flow
How do nutrients/O2 get from capillaries to the cells?
diffusion; capillaries are main site of transport of things between bloodstream/interstitial fluid
Systemic circulation is…
high pressure system
Pulmonary circulation is…
low pressure system
The rate at which blood is pumped from either ventricle is …
Interdependent (mutually dependent)
Cardiac output
rate which blood is pumped from either ventricle
Venous return
rate blood is returned to the atria from the body (through the superior/inferior vena cava)
Normal cardiac output
5 liters/minute
Cardiac index
cardiac output/square meter of body surface area
Normal cardiac index
3 L/min/m^2
Result of left and right heart being in series
cardiac output of left heart= cardiac output of right heart
Frank Starling’s Law of Heart
stretch of ventricle during diastole is proportional to the stroke work achieved in systole
Failure of left ventricle to empty properly results in:
decreased blood flow to systemic organs, dammed up blood in the left atrium, pulmonary veins/arteries
What determines blood flow to individual organs?
controlled independently based on the activity of the organs
Brain O2 consumption vs cardiac output distribution
18%; 14%
Kidneys O2 consumption vs cardiac output distribution
6%; 22%
Liver/gut O2 consumption vs cardiac output distribution
30%; 21%
Skin O2 consumption vs cardiac output distribution
2%; 6%
Left and right heart are in…
in series
Blood flow to organ systems is in…
in parallel
Arterial system to organs is in parallel, which means (3 points):
- blood flow into one organ system is not dependent on another organ system upstream
- adjustments can be made to one system without affecting blood flow to another organ system
- all systems receive identical blood (arterial blood)
What precedes mechanical contraction?
Electrical excitation
EKG
records electrical activity of heart
What does EKG capture?
Extracellular signals produced by the conduction of the action potential through cardiac myocytes.
P wave
depolarization of R/L atria
PR interval
conduction of action potential from SA node to AV node
QRS complex
R/L ventricular depolarization
ST segment
isoelectric segment; marks the plateau of ventricular action potential and the rapid ejection phase
T wave
ventricular repolarization
QT interval
duration of ventricular depolarization + ventricular repolarization
