Cardiac Anatomy Flashcards
where does the heart lay inside the thoracic cavity & where does most of the heart lie?
Within mediastinum ► Medial cavity, b/w lungs
▪ Rests on diaphragm
▪ Approx. 2/3 lies to the left
of the midsternal line
where is the base of the heart located and what is its main function?
upper portion of the mediastinum at the R & L 2nd ICS
-attachment of large vessels
where is the apex located and what is it used to auscultate?
around ribs 5-6 on the left side
-point of maximal impulse (PMI)
AKA apical impulse
what is the purpose of the pericardium & what layers does it consist of?
double layered covering of the heart that encloses the heart & proximal large blood vessels 1. fibrous layer 2. serous pericardium > parietal > epicardium > pericardial cavity
what is the purpose of the fibrous layer of the pericardium?
- loosely fit layer of the pericardium (outside of heart) that anchors the heart to surrounding organs -> diaphragm, posterior sternum, large blood vessels
- fibrous layer prevents overfilling of the heart
what layers make up the serous pericardium and what separates it from the fibrous pericardium?
- parietal layer which attaches to ->
- epicardium (visceral layer)
*separated from the fibrous pericardium by the pericardial cavity which contains serous flud
what is pericarditis & how does it affect the heart?
inflammation of the pericardium which causes rubbing when the heart contracts (pleural rub)
-results in too much fluid in pericardial cavity that ultimately inhibits filling
what does calcification in the pericardial cavity cause in the heart & what can it indicate ?
stiffness
-diastolic CHF
what layers make up the heart wall?
- epicardium
- exterior surface that protects the heart - myocardium
- majority of heart muscle - endocardium
- simple squamous epithelial tissue that lines blood vessels
which layer of the heart wall consists of fibrous connective tissue & what is it responsible for?
myocardium
-contraction of the heart: pulls the fibrous muscle tissues together for the heart to pump
what is cardiac muscle made of & where is it thickest?
Connected to fibrous skeleton
► Striated collagen and elastin fibers
► Gives cardiac cells something to
pull or exert force against
► Thicker around valves, where great
vessels attached
what cellular structure helps the heart muscle contract in a coordinated way?
intercalated discs within the striated fibers which contain: ► Gap junctions – ions pass cell to cell ► Desmosomes – prevent cells separating during contraction
what cells are involved in producing myocardial contraction? what regulates this within the cardiac tissue?
actin & myosin
-calcium-mediated interaction
Troponin I & T
when myocardial injury occurs, what is released into the bloodstream?
Troponin I & T
why is Troponin I & T more specific than CK-MB?
Troponin is specific to cardiac tissue only
-CK-MB involved skeletal muscle breakdown
which part of the heart is affected by an anterior wall MI?
mostly the right atrium
-some of the right ventricle
which part of the heart is affected by an inferior wall MI?
right atrium & right ventricle
> RCA occlusion
what does the anterior (sternocostal) surface of the heart consist of?
MAINLY Right atrium -> right border
& Right ventricle
-separated by the vertical atrioventricular groove
what does the inferior (diaphragmatic) surface of the heart consist of?
R & L ventricles separated by posterior interventricular groove
-part of inferior surface of R atrium & inferior vena cava
what does the posterior surface of the heart consist of?
base of the heart which is mainly the left atrium
-where the 4 pulmonary veins are seen
when looking at the lateral surface of the heart, what does it mainly consist of?
left ventricle
what part of the heart does systemic circulation return blood to?
inferior vena cava
what is the ductus arteriosis & at what stage of life is it present? what does it form when it is fully developed?
patent connection from the aorta to the pulmonary trunk
-> becomes the ligamentum arteriosum
in what state of life is the foramen ovale present and where is it located in the heart?
fetus
-between right atrium & left atrium
> due to fetus not requiring blood flow to the lungs (HbF from mother)
what happens when the foramen ovale does not close & why is it problematic?
patent foramen ovale (PFO)
-can cause stroke but this is rare
what system does the left ventricle empty into?
peripheral circulatory
system
what system does the right ventricle empty into?
pulmonary system
- right ventricle pumps directly to the lungs
which ventricle is thicker and what does it provide?
left ventricle -> more musculature
-> more vector & impulses
which circuit contains more CO2 & what is its main function?
pulmonary circuit
► Carries carbon dioxide rich blood to the gas exchange surfaces of lungs
► Returns oxygen rich blood
back to the heart
which circuit contains more O2 & what is its main function?
systemic circuit ► Transports oxygen rich blood back to body’s cells ► Transports carbon dioxide rich blood back to the heart
what are valves made of & what is their purpose? what are they attached to in the heart?
thin leaflets made of tough/flexible endothelium-covered tissue
makes blood flow forward
-Attached to fibrous
skeleton of heart
what valves are open during diastole?
tricuspid valve
mitral valve
what valves are open during systole?
semilunar:
- pulmonary valve
- aortic valves
what are the AV valves & what is theri function?
Tricuspid & Mitral Valves
▪ Prevent backflow of
blood from ventricles to atria during systole
what happens when there is high intraventricucar pressure?
AV valves are closed
what anchors the valves to the fibrous skeleton of the heart & what keeps the valves closed?
papillary muscles
-chordae tendonae
what happens if the papillary muscles are ruptured?
there will be tricuspid valve or mitral valve regurgitation
what valves are closed during diastole?
pulmonic valve
aortic valve
if a murmur is heard during diastole, what valves are affected & what can this indicate?
tricuspid & mitral valves
- tricuspid stenosis
- mitral stenosis
what are the semilunar valves & how many cusps do they have?
pulmonary & aortic valves
-3 cusps
what is the primary function of the semilunar valves?
pulmonary & aortic valves prevent backflow of blood from the pulmonary trunk & aorta into R & L ventricles
when are the semilunar valves closed?
ventricular diastole
what force causes the semilunar valves to shut?
high pressures in the pulmonary trunk & aorta at the end of systole
which part of the electrical conduction system is the slowest? -> 20-40 bpm
ventricular focci
which part of the electrical conduction system depolarizes the fastest & why? -> 60-100 bpm
SA node
-pacemaker of the heart that is consistently firing
True or false: the auto-rhythmic cardiac cells are contractile.
false
what structures make up the electrical conduction system of the heart?
► Sinoatrial node ► Atrioventricular node ► Atrioventricular bundle ► R & L bundle branches ► Purkinje fibers
if a pt has cardiomegaly, what might be present on the EKG?
LVH or RVH due to larger muscles interrupting the electrical pathway
which part of the electrical conduction system initiates atrial systole?
sinoatrial node (SA node)
the ____ nerve is responsible for 75% of parasympathetic nervous system innervation of the heart
vagus
what part of the electrical conduction system correlates with the P waves on EKGs?
Bachman’s Bundle
what pathway does bachman’s bundle transmit signals to?
Tracts from SA node extending to L atrium
what part of the electrical conduction system transmit impulses through R atrium to AV node?
internodal tracts
anxiety, surprise, caffeine, and cocaine are examples of _____ factors that affect the SA node
extrinsic
where is the SA node located in the heart?
Located superior posterolateral wall of right atrium (just inferior to entrance of SVC)
what part of the electrical conduction system delays signals & allows ventricles to fill during diastole?
AV node
where is the AV node located in the heart?
Located inferior portion of interatrial septum (above tricuspid valve)
True or false: if the SA node cannot function properly, the ventricular focci will take over first.
False -AV node will assume pace-making duties if normal pace-making fails. ► Inherent rate range is 40-60bpm
the ___ is the only connection between the atria & ventricles in the intraventricular septum that splits into the right and left bundle branches
bundle of His
aka A-V bundle
if there are PVCs present on an EKG, what part of the electrical conduction system is responsible for this?
ventricular focci
the bundle of His transmits signals from the ____ to the ventricles by splitting into the left & right bundle branches.
AV node
what structures make up the intrinsic conduction system and what does this correlate to on an EKG?
-right bundle branch
-left bundle branch
► L anterior fasciculus
► L posterior fasciculus
*QRS complex = ventricular deolarization
the ___ is responsible for rapid
conduction through ventricles
intrinsic conduction system
the _____ are able to pace at 20-40/min & extend deep into the papillary muscles -> ventricular walls
Purkinje fibers
what do the Purkinje fibers branch off of?
left & right bundle branches
____ repolarization is when sodium & potassium are normalizing. this represents the ___ on EKG
T wave
when an EKG is isoelectric, there are flat waves & no _____ of the heart
contraction
this electrolyte is ionotropic and makes the heart beat harder
calcium
____ makes it harder for the heart to depolarize. what is given to treat this?
hyperkalemia
-calcium given
what occurs on a cellular level to the ventricular myocytes when there is rapid repolarization?
► Calcium channels close ► Potassium flows rapidly out of cell
during the plateau phase, the ___ continues to flow into the cell while the ____ begins to flow out of the cell
- calcium
- potassium
when there is a peak of action potential for the ventricular myocyte, there is an inactivation of _____ channels
sodium
during the resting phase, the _____ becomes impermeable to sodium
cell membrane of ventricular myocytes
when the sympathetic nervous system stimulates the heart to beat faster, the ___ appears shorter on EKG
PR interval
