Cardiovascular System Notes

What are the four chambers of the heart?

Right atrium, left atrium, right ventricle, left ventricle

Which valves separate atria from ventricles?

Tricuspid (RA→RV) and Bicuspid/Mitral (LA→LV)

Which valves are semilunar?

Pulmonary valve (RV→pulmonary trunk) and Aortic valve (LV→aorta)

Trace blood flow through the heart starting at the right atrium.

RA → Tricuspid → RV → Pulmonary valve → Pulmonary arteries → Lungs → Pulmonary veins → LA → Mitral → LV → Aortic valve → Aorta → Body → SVC/IVC → RA

What are the two layers of the pericardium?

Fibrous pericardium (outer), Serous pericardium (inner)

What are the two parts of the serous pericardium?

Parietal layer (lines fibrous), Visceral layer/epicardium (covers heart surface)

Name the outer, middle, and inner layers of the heart wall.

Epicardium (outer), Myocardium (middle), Endocardium (inner)

When do AV valves open?

During ventricular diastole (filling)

When do semilunar valves open?

During ventricular systole (ejection)

Which valves close to produce the first heart sound (“lub”)?

AV valves

Which valves close to produce the second heart sound (“dup”)?

Semilunar valves

What is the pacemaker of the heart?

SA node

Order of conduction from SA node?

SA node → Internodal pathways → AV node → Bundle of His → Right & Left bundle branches → Purkinje fibers

Relative speeds of conduction?

SA node slow → AV node slower → Bundle branches faster → Purkinje fibers fastest

What is a heart block?

Impaired conduction of impulses from atria to ventricles

Name the three types of heart block.

1st-degree (prolonged PR), 2nd-degree (some dropped QRS), 3rd-degree (complete AV block)

Causes of abnormal heart rhythms?

Electrolyte imbalance, ischemia, drugs, myocardial damage

What does the P wave represent?

Atrial depolarization → atrial contraction

What does the QRS complex represent?

Ventricular depolarization → ventricular contraction

What does the T wave represent?

Ventricular repolarization

When do atria contract?

Just after the P wave

When do ventricles contract?

During/after the QRS complex

What is coronary circulation?

Blood supply to the heart itself

What is pulmonary circulation?

Blood flow to/from the lungs

What is systemic circulation?

Blood flow to/from the rest of the body

Stages of the cardiac cycle?

1. Atrial systole → 2. Isovolumetric contraction → 3. Ventricular ejection → 4. Isovolumetric relaxation → 5. Ventricular filling

CO = ?

CO = HR × Stroke Volume

Factors that determine stroke volume?

Preload, Contractility, Afterload

Sympathetic effect on HR?

Increases HR (extrinsic)

Parasympathetic effect on HR?

Decreases HR (extrinsic)

Chemicals that affect HR?

Epinephrine ↑, Norepinephrine ↑, Thyroid hormone ↑, Calcium ↑, Potassium ↑/↓, Sodium ↑/↓

Gender and age effects on HR?

Females > males; infants > adults > elderly

Arrhythmia

Irregular heart rhythm

Ischemia

Reduced blood flow

Fibrillation vs Flutter

Fibrillation: rapid uncoordinated contractions; Flutter: rapid coordinated contractions

Myocardial infarction / Heart attack

Death of heart tissue due to blocked blood supply

Frank-Starling law

More stretch (preload) → stronger contraction

Tachycardia / Bradycardia

Tachycardia: fast HR; Bradycardia: slow HR

Pulmonary vs Peripheral edema in heart failure

Pulmonary = left heart failure; Peripheral = right heart failure