Cardio Flashcards
Major borders and surfaces of the heart
Right border = RA
Left border = LA and LV
Inferior border = RV and some LV
RV forms most of the anterior surface of the heart
What do the two appendages look like?
Right atrial appendage is like snoopy’s nose, left is longer and skinnier like south america
Relative position of pulmonary artery and aorta
Pulmonary artery is anterior to aorta, to left shoulder,
Ascending aorta is posterior to PA, to right shoulder
Angle between the two is 60-90 degrees
Right coronary artery (where does it come from, where does it lie, what does it give rise to)
Right coronary artery arises from right sinus of Valsalva (aortic sinus)
Courses between RA and RV in atrioventricular groove
Gives rise to RA branch, acute marginal (feed RV) and usually the posterior interventricular artery
Left coronary artery (where does it come from, and what does it divide into
Left coronary artery arises from left sinus of Valsalva
Has a short segment (left main) then divides into circumflex and left anterior descending artery
Circumflex (where, and what does it give rise to)
In left atrioventricular groove
Gives rise to obtuse marginal branches that feed lateral LV wall
Left anterior descending artery (what does it do and where does it arise from)
Feeds septum and LV free wall
Gives rise to diagonals and septal branches
Where do the majority of the cardiac veins drain to? Where is it?
The coronary sinus (great cardiac vein) in posterior AV groove
Right atrium
Smooth and trabeculated walls separated by crista terminalis
Superior and inferior vena cava drain into smooth walled portion of RA
Fossa Ovalis is formed from downward migration of septum secundum and upward migration of septum primum
Associated with tricuspid valve
Upper chamber
2 mm thick
Conducts blood from systemic to RV
Coronary sinus empties here
Epicardium rich in ganglia
Myocytes smaller than ventricles
Electron dense granules store atrial naturietic peptide
What two things does the LA not have that the RA does?
No crista terminals or pectinate muscles
Right ventricle
L shaped (croissant) Thin walled Highly trabeculated Pumps through pulmonary valve At apex of heart Anterior most structure Inflow portion, apex, outflow portion (infundibulum or conus) Myocardium 5 mm thick Membranous septum contains conduction system Low pressure (25-30mmHg)
Left Ventricle
Cone shaped (donut) Thick walled No trabeculations Pumps through aortic valve high pressure Inflow/septal/outflow portions 15 mm thick Conducts blood from LV to aorta
What 5 things do the AV valves depend on for proper function?
Hinge lines Valve tissue Chordae Papillary muscles Ventricular wall function
Semilunar valves
Aortic and pulmonary
3 leaflets
Suspended from the pulmonary trunk and aortic root
Scalloped (commissures/hinge lines)
Competency dependent on attachments and elastic/collagenous nature of the leaftet tissue as well as the dimensions of the root and trunk
No chordae!
Relative amounts and cell numbers of endothelial cells and cardiomyocytes
Myocytes: 25% of total cell number, 90% of cell volume
Endothelial cells: 75% cell number, negligible volume
What is the pericardium? What is it made of?
Fibrous sac surrounding the heart Reflections from great vessels and veins Serous component over surface of heart Fibrous joins serous at reflections. Collagen rich, inelastic!
Beck’s triad
Hypotension, muffled heart sounds, distended jugular veins
Signs associated with acute cardiac tamponade.
50cc of straw coloured fluid is normal, but sudden increase to 250cc causes tamponade
Pericarditis
Really thick pericardium, calcifies and restricts the heart even without fluid
Fibrous skeleton
Base of the heart, dense collagenous tissue with elastin
Makes up AV valve rings and aortic annulus, extends to pulmonary trunk via conal ligament – point of attachment for valve leaflets and myocardium
Separates the atrial and ventricular chambers, separates the right and left ventricles (membranous septum)
AV conduction bundle embedded
Provides rigidity to prevent dilation of valves
Why is electrical isolation important between atria and ventricles?
Electrical isolation is important so that the atria and ventricles keep separated
Muscle cells have gap junctions that can share action potentials but they stop at the fibrous skeleton
So the entire heart doesn’t contract at once
Bundle of His is the only electrical connection between A/V
Epicardium
Analogue of vascular adventitia
Serous pericardium
Contains coronary arteries and veins, fat, nerves, fibroblasts and macrophages
Myocardium
Analogue of vascular media
Contractile myocytes
Also collagen, blood vessels, and elastin
Bundles of cardiac muscle separated by fibrous bands
Endocardium
Analogue of vascular intima Endothelial cells and connective tissue Continuous with intima of vessels Anticoagulant surface Has 3 major components
3 major components of the endocardium
Endothelium (single layer of squamous endothelial cells held together by tight junctions, also has gap junctions for communication)
Continuous basal lamina
Subendocardium (layer of loose connective tissue – binds the endocardium to myocardium)
5 components of cardiac myocytes
Cell membrane (sarcolemma and T tubules) responsible for impulse conduction – form gap junctions between adjacent cells, intercalated disks join adjacent myocytes both mechanically and ionically, myocardium is a functional syncytium (electrically unified)
Sarcoplasmic reticulum: Ca2+ reservoir, release of Ca into cytosol as a result of action potential causes contraction
Contractile elements: action, myosin, troponin, and tropomyosin – contraction is the net effect of sliding actin and myosin toward to center of the sarcomere – increased stretch results in longer pull (Starling’s)
Mitochondria: energy generation through aerobic metabolism, heart muscle almost exclusively aerobic, mitochondria make up 23% of myocyte volume (2% in skeletal)
Nucleus: very large
Ventricular cardiac muscle
Forms complex layers of cells wound helically around the ventricular cavity
Atrial cardiac muscle
Muscles in outer myocardium form a helical pattern around the chambers (like ventricles) Atrial cells are smaller Less T tubules More gap junctions Conduct impulses faster Contract more rhythmically Have many granules