Cardiovascular Hemodynamics Flashcards
The heart is between the lungs, in the:
Behind the:
mediastinum
sternum
The apex of the heart lies:
diaphragm pointing to the left
Pericardium
Outermost layer, protects the heart. Made of 2 layers fibrous and serous pericardium
Between 2 layers there is fluid to prevent friction/injury
Epicardium
visceral surface of the pericardium
Myocardium
Middle Layer. Thick muscular tissue. Responsible for major pumping action. Contains contractile fibers
Endocardium
Thin layer of the endothelium and connective tissue. Lines the valves and chambers
4 Layers of the Heart (outer to inner)
- Pericardium
- Epicardium
- Myocardium
4, Endocardium
Direction of Blood Flow through the heart with valves and chambers
- inferior and superior vena cava
- right atrium
- tricuspid atrium
- right ventricle
- pulmonic valve
- pulmonic artery
- lungs
- pulmonic veins
- left atrium
- mitral valve
- left ventricle
- aortic valve
- aorta
- systemic circulation
Function of the valves
Maintain forward flow of blood
Open and close with pressure & volume changes in the heart chambers
Function of coronary arteries
Supply and drain blood to the heart muscle (anterior and posterior surfaces) itself
When does coronary artery flow occur?
Diastole
3 Major Coronary Arteries
- right coronary artery
- Left coronary artery dissects into
a) left anterior descending
b) left circumflex
What does the RCA perfuse?
Perfuses right side of heart and inferior LV
What does the LAD perfuse?
left ventricle and left septum
What does the left circumflex perfuse?
Posterior surface and SA nose
Hemodynamics
the physical study of flowing blood and of all the solid structures (such as arteries) through which it flows
essentially the pressures and flows in circulatory sustem
Hemodynamic monitoring studies the relationship between what 4 variables?
- Heart rate
- Blood flow
- Oxygen delivery
- Tissue perfusion
2 components of successful delivery of oxygenated blood to tissues:
- Electrical impulse to stimulate a contraction
- Effective enough contraction to deliver appropriate cardiac output
Cardiac Output
The amount of blood the heart pumps each minute
CO = HR x SV
The delivery of oxygenated blood to tissues
Normal CO in adult
3-6L/min
3 Factors Effecting SV
preload + contractility + afterload
Stroke Volume
Amount of blood ejected from the heart (LV) with each pump
Normal stroke volume
60-70ml
Preload
Filling
Pressure/stretch in the myocardial fibers (ventricle muscle wall) at the end of diastole
Preload is the end ________ volume
Diastolic
When is preload increased>
Hypervolemia
Valve Regurgitation
Heart Failure
Contractility
Force/strength of the myocardial contraction
Effected by size of muscle
Afterload
The pressure against which the ventricles pump to eject blood
Afterload is t amount of resistance to the ejection of blood from the ventricle; amount of pressure that the heart needs to pump against when _________ during ________
contracting
systole
Pressure = _____ x ______
flow
resistance
Afterload is increased in:
hypertension and vasoconstriction
Increasing afterload increases:
Cardiac workload
Ejection Fraction
the amount of blood expelled with each contraction (50-80%)
Frank Sterling Law
The more the heart is filled during diastole (within limits – if overstretched, there will be decreased contractility; similar to rubber band), the more forcefully it contracts.
What 2 systems regulate CO?
- Autonomic Nervous System
- RAAS
2 Receptors that monitor CO
- baroreceptors
- chemoreceptors
What do baroreceptors monitor?
Blood pressure/pressures changes/stretch
Location of baroreceptors
carotid sinus & aortic arch
When baroreceptors detect pressure changes/decreased CO, what occurs?
ANS compensation
Increased HR
What do chemoreceptors monitor?
Chemical changes
2 types (peripheral and central)
Location of peripheral chemoreceptors and what they sense
carotid sinus & aortic arch
PO2 and pH changes causing ANS compensation
Location of central chemoreceptors and what they sense
brain
paCO2 and pH causing ANS compensaion
Goal of ANS and RAAS for CO regulation
Maintain CO through compensatory mechanisms (increase HR)
Neurotransmitter with sympathetic system
epinephrine and norepinephrine
Neurotransmitter with parasympathetic system
acetylcholine
Receptors with sympathetic system
alpha and beta adrenergic
Receptors with parasympathetic system
cholinergic
1. nicotinic (skeletal)
2. muscarinic (smooth)
Chronotropic effect of sympathetic stimulation
Increased HR
Chronotropic effect of parasympathetic stimulation
Decreased HR