Cardiac review Flashcards
Anatomy of the heart
atriums, ventricles, valves, coronaries
R and L atrium and ventricles
Tricuspid valve, pulmonic valve, mitral valve, aortic valve
Right coronary artery: Posterior descending artery and Right marginal artery (80%)
Left coronary artery: LAD, L circumflex
Right atrium anatomy:
where is blood coming from: systemic veins
what are the two protective valves
right atrium
systemic veins: superior vena cava and inferior vena cava
protective valves: Eustachian valve: protects the IVC and Thesibian valve: protects the coronary sinus
Right ventricle
what valve protect the pulmonary artery
Right ventricle
infundibulum (Conus arteriosus)
Left Atrium Anatomy
what type of reservior is it
size and position compared to R.A.
where does it receive blood from
left atrium
reservior of oxygenated blood
Size: larger than R.A.
sits superior and posterior to other chambers
receives blood from pulmonary veins
left ventricle
where does it receive blood from
compesition of LV
left ventricle
receives blood from LA
upper 1/3 is smooth muscle
lower 2/3 is muscular
discuss the sizing of the AV valves and when they become sympomatic
tricuspid: 7cm | < 1.5cm
Pulmonic: 4cm | <1/3 size
Mitral: 4 - 6cm | <1/3 size
Aortic: 1 - 3cm | <1/3 size
how many leaflets does the aortic and pulmonic valve have
what is the sinus of valsalva
aoritc and pulmonic have 3 leaflets
sinus of valsalva: area of enlargement for leaflets of aorta to not occlude coronary sinus
where does coronary sinus flow start
at the sinus of valsalva
which leads look at the left coronary artery
which leads look at the right coronary artery
left coronary artery: V-V5
right coronoary artery II, III, aVf
what is the percentage of coronary dominance in people
50% are right coronary dominant
20% are left coronary dominant
30% are mixed between right and left
Coronary physiology
how much blood flow to the coronaries per min
how is flow determined
when does flow go to the LCA, RCA
when is myocardial oxygen consuption the highest
5% or 250ml/min
flow is determined by diastolic pressure - LVEDP
LCA is fed during diastole. RCA is fed during systole
myocardial oxygenation is highest when mixed venous sat is lowest at 30%
tell me about coronary autogulation
changes are dependent on what
greatest dilation occurs where
LCA vs RCA
autoregulation occurs between 50-120mmhg
changes are dependent on pressure
greatest dialtion occurs at the small vessels
LCA>RCA in autoregulation
what is the pathway of the conduction system
SA node, internodal tracts, AV node, bundle of his, purkinje fibers
SA node
what type of cells are located here (2)
SA node
P cells- pacemaker cells
transitional or intermediate cells - conduct impuleses within and away from the node
what are the pathways of internodal tracts (3)
anterior = buckmanns bundle
middle = Wenkebach
posterior = Thorels tract
how does the AV node compare to the SA node
smaller cells
resting membrane is lower at -60 vs -50
Rate is 50 bpm
fewer Gap junctions
more resistant to action potentials
where does the purkinje system spread?
- spreads under the endocardium 2. throughout the papillary muscles
Action potential of the heart
At rest, what is the action potential dependent and permiable to ?
at rest, heart is most dependent and permeable to potassium
Discuss the 5 phases of the actional potential to the heart
phase 0- depolarization, fast Na channels
phase 1 : repolarization - Na channels close and permiable to Cl-
phase 2: plateau phase: slow Ca channels open
phase 3: termination of repolarization: efflux of K
phase 4: diastolic phase: Na+ and K+ channels
ventricle fires at what mV conductance
-90 mv
when is absolute and relative refactory periods
absolute: phase 0 - middle phase III
relative: middle phase III to phase IV
discuss the sympathetic pathway of the cardiac conduction system
what occurs at the synaptic nerves
- cervical caudal fibers and stellate ganglion
- right dorsal median and lateral cardaic nerves
- merge in LCA
- branch into LAD and LCx
Ach released and interacts with postsynaptic nicotinic receptors which stimulate B1 receptors
parasympathetic fibers of the heart
what is the pathway
what happens the receptor
- arises from medulla at (dorsal vagal nucleus) and (nucleus ambiguious)
- RLN to TVN
- R and L cardiac nerves and left lateral cardiac nerves
postsynaptic interaction stimulate nictonic receptors and then muscarnic receptors
where are vagal receptors and sympathetic receptors in the heart
vagal receptors: all over. in R and L atrium. R and L ventricles. but most present in the RA
sympathetic fibers: all throughout the heart. RA contains 75% of B1 and Ventricles contain 85% of B1
