Heart Quiz Flashcards
Trabeculae carneae location and function
located along the lateral wall of the right ventricle
same function as papillary muscles, prevents tricuspid and bicuspid valves from inverting by pulling on chordae tendinae during contraction
Trabeculae septomarginalis location and function
Thin string crossing right ventricle
AKA moderator band
Contracts the Anterior papillary muscle (APM) to prevent the tricuspid regurgitation (back flow of blood to RA) through tension of the chordae tendineae.
Trabeculae septomarginalis carries part of the right branch of av-bundle from the septum to anterior papillary muscles
Papillary muscles location and function
Connected to chordae tendinae linked to tri/bicuspid valves and anchored on the muscular wall of the ventricles
These muscles provide stability for the chordae, but they cannot actively open and close the AV valves. The valves move passively when flowing blood pushes on them.
Valves of the heart
Atrioventricular Tricuspid: between right atrium and right ventricle - relaxed and open due to blood passing through during atrial contraction
Atrioventricular Bicuspid (mitral): between left atrium and left ventricle - relaxed and open due to blood passing through during atrial contraction
Pulmonary semilunar valve: between right ventricle and pulmonary trunk - 3 leaflets snap shut when blood attempts to back flow
- no connective tissues
Aortic semilunar valve: between left ventricle and aorta - 3 leaflets snap shut when blood attempts to back flow
- no connective tissues
Describe the coronary blood circulation
Right and left coronary arteries fill during diastole (when ventricles relax) from blood through aorta
LV –> aortic semilunar valve –> aorta –> right aortic sinus –> right coronary artery –> blood to RA + RV –> great coronary vein –> coronary sinus –> RA
LV –> aortic semilunar valve –> aorta –> left aortic sinus –> left coronary artery –> circumflex (coronary groove) to posterior surface of heart + paraconal (paraconal interventricular groove) towards apex of heart –> great coronary vein –> coronary sinus –> RA
Auricular surface vs atrial surface of the heart
Auricular surface shows the auricles or ears of the right and left atria
- pulmonary trunk facing away
Atrial surface shows the great coronary vein, pulmonary trunk and inferior vena cava (towards viewer)
Auricles are pectinate muscles
Heart coverings (connective tissues)
Pericardium = fluid filled sac providing
protection against friction
Epicardium = outer layer of heart wall
(visceral layer)
Myocardium = muscle tissue of heart
Endocardium = inner layer of heart wall
Systemic circulation
Deox blood from Superior & Inferior Vena Cava > to Right Atrium > right atrioventricular valve (tricuspid)
> to right ventricle > pulmonary semilunar valve > to pulmonary trunk > to left & right pulmonary arteries
> CO2-O2 exchange > oxygenated blood in pulmonary veins > to Left Atrium > left atrioventricular valve
(bicuspid) > to left ventricle > aortic semilunar valve > to Aorta (to whole body)
Pacemaker cells
Sinoatrial (SA) node: SA node or Pacemaker includes hundreds of cells (autorythmic) located in right atrial wall near superior vena cava (upper right laterial atrium wall)
Atrioventricular (AV) node: special cardiac tissue
located in right atrium along the lower part of interatrial septum
Atrioventricular bundle (bundle of His) + Purkinje fibers: special cardiac fibers originating in AV node, extend down septum, become PF at lateral walls of ventricles and papillary muscles.
Innervation of the heart
Heart is innervated/regulated by ANS - BUT only to increase or decrease heart rate
The sympathetic fibers arise from segments T2-
T4 of the spinal cord and are distributed through
the middle cervical and cervico-thoracic (or
stellate) ganglia and the first four ganglia of the
thoracic sympathetic chain.
The vagus [cranial nerve X] provides the
parasympathetic tonic control to the heart. If parasymp input decreases, HR increases to max intrinsic rate, beyond that, sympathetic influence takes over
ECG what it is and what it measures
Electrocardiogram: graphic record of the
heart’s electrical activity or conduction
impulse - this generates electrical currents in the heart, spread to tissue & to surface of the body
It is not a record of the heart’s contractions
but the electrical events that PRECEDE them.
Events represented by the ECG
A: The heart wall is completely relaxed, with no change in electrical activity, so the ECG
remains constant.
B: P wave occurs when the AV node and atrial walls depolarize.
C: Atrial walls are completely depolarized, and thus no change is recorded in the ECG.
D: The QRS complex occurs as the atria repolarize and the ventricular walls depolarize.
E: The atrial walls are now completely repolarized, the ventricular walls are now completely depolarized, and thus no change is seen in the ECG.
F: The T wave appears on the ECG when the ventricular walls repolarize.
G: Once the ventricles are completely repolarized, we are back at the baseline of the ECG— essentially back where we began in A.
- Note that depolarization triggers contraction in the affected muscle tissue. Thus cardiac muscle contraction occurs after depolarization begins.
What is the QRS complex?
What are the P and T waves?
Q is a downward deflection immediately preceding the ventricular contraction
R is contraction of left ventricle
S is the downward deflection immediately after the ventricular contraction
P wave is contraction of heart atria
T wave is relaxation of ventricles
Atrial diastole and systole on ECG
Ventricular diastole and systole on ECG
Atrial diastole = R to peak of P wave
Atrial systole = from peak P wave to R
Ventricular diastole = end of T wave to R
Ventricular systole = R to end of T wave
Isovolumetric Contraction:
Isovolumetric relaxation:
Isovolumetric Contraction: is a short period of time when the ventricular blood volume remains the same because all 4 valves (the AV and SL valves) are closed due to blood pressure created in the chambers during the beginning of ventricles systole (isovolumic). This phase marks the beginning of systole.
Isovolumetric relaxation: When the ventricular pressures drop below the diastolic aortic and pulmonary pressures, the aortic and pulmonary valves close producing the second heart sound. This marks the beginning of diastole.
