Intro to Perfusion & EKGs Flashcards
(44 cards)
What is perfusion ?
the flow of blood through arteries and capillaries, delivering nutrients and oxygen to cells and removing cellular waste products
What is cardiac output ?
total amount of blood pumped from the ventricles in 1 min
- HR X SV (stroke volume)
- 4-8 L per min is normal in adults
- a faster HR doesn’t mean better CO
What is stroke volume ?
amount of blood ejected from heart after 1 beat
What is cardiac reserve ?
amount of blood left in the ventricles after each beat
What is preload ?
amount of blood in the ventricles at the end of diastole
- VOLUME
What increases preload ?
- hypervolemia
- regurgitation of valves
- HF (Rt side)
What is afterload ?
resistance the left ventricle must overcome to circulate blood
- BLOOD PRESSURE
- increased afterload leads to increased cardiac workload
What increases afterload ?
- hypertension
- vasoconstriction
What are the 2 main vessels in coronary blood flow ?
- Right Coronary Artery (RCA)
- Left Coronary Artery
- Left anterior descending (LAD)
- Circumflex
What is central perfusion ?
a coordinated effect of electrical and mechanical factors move blood through the heart
- cardiac cells must be oxygenated and perfused just as the peripheral cells do
What is peripheral perfusion ?
volume of blood that flows through target tissues
- different organs require different volumes of blood to function
- central perfusion affects peripheral
- peripheral perfusion can be impaired by itself
What is cardiac conduction in the heart ?
specialized nerve cells which can create and transport electrical impulse
- impulse triggers ventricular contraction
What is the pathway for cardiac conduction ?
- SA node (Rt atrium)
- AV node
- bundle of His
- Purkinje fibers
What are the properties of cardiac cells ?
- automaticity
- excitability
- conductivity
- contractility
What does automaticity mean ?
the ability of a cell to depolarize (contract) itself
What does excitability mean ?
the ease with which cardiac cells undergo a series of events characterized by sequential depolarization (contracting) and repolarization (relaxation)
What does conductivity mean ?
the property of conducting an electric current
What system controls the SA node ?
autonomic nervous system
How does the parasympathetic nervous system affect the heart ?
- decreases rate of SA node
- slows impulse conduction of AV node
- vagal nerve stimulation will decrease the HR
How does the sympathetic nervous system affect the heart ?
- flight or fight will increase the HR
- increases rate of SA node
- increases impulse conduction of AV node
- increases cardiac contractility
How do baroreceptors affect HR ?
react to the volume status
What is cardiac index ?
gives better insight into the hearts ability
- divides BSA (body surface area) with CO
What does intrinsic rate mean ?
the rate at which the heart beats when all cardiac neural and hormonal inputs are removed (no interference from the CNS)
- each node has a different intrinsic rate
What is the intrinsic rate for the SA node, AV node, and His-Purkinje System ?
- SA: 60-100
- AV: 40-60
- His-Purkinje: 20-40
