Cardiology: Block 1 Flashcards
In humans, the formation of a linear heart tube from the primary cardiac crescent occurs between days _ and _ of gestation
21 - 23
Looping of the heart tube and trabecular formation of the ventricle occur at day _ of gestation
26
At __ weeks, the embryonic interventricular communication closes, followed by thickening and remodeling of the ventricular walls in the first trimester
6
By the end of week __, heart development is essentially finished, although the heart continues to enlarge throughout gestation
7
What happens during Phase 0 of myocardial contraction?
Depolarization
Na channels open, + Na flow into membrane causing depolarization
Na depolarizes SA Node
What happens during Phase 1 of myocardial contraction?
Brief repolarization
Peak positive point as Na influx slows and stops
K leaks out
Slow voltage Ca channel opens allowing influx and transition to Phase 2
What happens during Phase 2 of myocardial contraction?
Plateau phase
Influx of Ca balances w/ efflux of K
Ca influx initiates troponin and myosin causing contraction and marks the beginning of a contraction
What happens during Phase 3 of myocardial contraction?
Repolarization
Voltage gated K open and allows efflux from cell causing rapid repolarization and includes completion of contraction and relaxation
What happens during Phase 4 of myocardial contraction?
Resting Potential
K is equal intra/extracellularly and allows for resting potential and is ready to receive action potential
Ca inflow/K outflow occurs during Phases _ -_
These phases represent what event?
1-3
Myocardial contraction= QRS complex
What process returns the myocardium to a resting state?
NKAtp
Sodium Potassium Adenosine Triphosphatase
What four processes can cause/lead to myocardial atrophy?
Bed rest
VAD
CA
Weightlessness
What two processes can cause/lead to physiological hypertrophy?
Exercise
Pregnancy
What three processes can cause/lead to physiological hypertrophy?
HTN
MI
Neurhumoral activation
What happens when persistent stress is present on a pathologic hypertrophied heart?
Heart failure
Ventricular arrhythmia
What are the layers of the pericardium?
Fibrous layer
Parietal / Serous- forms sac
Pericardial cavity
Epicardium / Visceral
How much pericardial fluid is contained within the pericardium and where does it come from?
10-20cc formed by the serous layer
What happens if there is too much pericardial fluid?
Pericardial effusion then inflammation
What direction does the heart sit in the chest?
Rotated Left
Tilted forward
R ventricle- most forward
L atrium- furthest posterior
What borders the heart?
Anterior= sternum and L side of costal cartilage 3-5 Post= descending aorta, esophagus, trachea and posterior lungs Lateral= lungs Superior= ascending aorta and superior vena cava
What is a normal PMI diameter?
1 - 2.5cm
What is Erb’s Point best used for hearing?
Aortic/Pulmonic origin
HCM
Aortic insufficiency
What does it mean if a cardiac pulsation is visible lateral to left MCL?
What does a sustained apex impulse mean?
Cardiac enlargement
LVH
On a lateral x-ray, what forms the anterior border?
What primarily forms the posterior border?
Superior- pulmonary trunk
Inferior- right ventricle
Left ventricle, inferior vena cava