Cardiovascular System

Structure of the Cardiovascular System

Heart Anatomy

• Location: Located in the mediastinum, between the lungs, behind the sternum.

• Chambers:

  • Right Atrium (RA): Receives deoxygenated blood from the body.

  • Right Ventricle (RV): Pumps blood to the lungs via the pulmonary artery.

  • Left Atrium (LA): Receives oxygenated blood from the lungs.

  • Left Ventricle (LV): Pumps oxygenated blood to the body via the aorta.

Heart Valves

Ensure one-way blood flow:

• Atrioventricular (AV) Valves:

  • Tricuspid Valve (RA → RV)

  • Mitral (Bicuspid) Valve (LA → LV)

• Semilunar Valves:

  • Pulmonary Valve (RV → Pulmonary artery)

  • Aortic Valve (LV → Aorta)

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Blood Vessels

• Arteries: Carry oxygenated blood away from the heart (except the pulmonary artery).

• Veins: Return deoxygenated blood to the heart (except the pulmonary veins).

• Capillaries: Microscopic vessels where gas and nutrient exchange occurs.

Coronary Circulation

• Coronary Arteries: Supply oxygenated blood to the heart muscle.

• Coronary Veins: Remove deoxygenated blood from the heart.

Physiology of the Cardiovascular System

Cardiac Cycle

Consists of systole (contraction) and diastole (relaxation) phases:

• Diastole: Heart relaxes, AV valves open, ventricles fill with blood.

• Systole: Ventricles contract, semilunar valves open, blood is ejected to the lungs and body.

Heart Sounds (Auscultation)

• S1 ("Lub"): Closure of AV valves (beginning of systole).

• S2 ("Dub"): Closure of semilunar valves (end of systole).

• S3 (abnormal in adults): May indicate heart failure.

• S4: Suggests stiff ventricles (e.g., hypertension, ischemic heart disease).

Cardiac Output (CO)

• The volume of blood pumped per minute.

• CO = Stroke Volume (SV) × Heart Rate (HR)

• Normal: 4-8 L/min

Blood Pressure (BP)

• Force exerted by circulating blood on vessel walls.

• Normal BP: ~120/80 mmHg.

• Regulated by: Autonomic nervous system, hormones (e.g., renin-angiotensin system), blood volume.

Pulse

• Represents heartbeats per minute.

• Normal Resting Heart Rate (RHR): 60-100 bpm.

Physical Assessment of the Cardiovascular System

Auscultation Landmarks

• Aortic Valve → 2nd right intercostal space (ICS), right sternal border.

• Pulmonic Valve → 2nd left ICS, left sternal border.

• Erb’s Point → 3rd left ICS, left sternal border (best place to hear S2).

• Tricuspid Valve → 4th left ICS, left sternal border.

• Mitral Valve (Apical Pulse) → 5th ICS, midclavicular line.

patient’s pulse

• 0 = pulse not palpable or absent

• +1 = weak, thready

• +2 = normal

• +3 = slight increase

• +4 = bounding

Differentiating Normal & Abnormal Findings

Analyzing Findings from Interviews, General Survey & Physical Exam

• Interview Findings:

  • Chief complaints: chest pain, palpitations, dizziness, swelling (edema).

  • History of hypertension, diabetes, smoking, alcohol use, family history of heart disease.

• General Survey:

  • Skin tone (cyanosis, pallor), breathing effort, edema, overall health status.

• Physical Exam Analysis:

  • Chest pain + ST-segment elevation on ECG → Myocardial infarction (heart attack).

  • Bradycardia + Syncope → Heart block.

  • Tachycardia + Hypotension + Cold skin → Shock.

  • JVD + Pitting Edema + Crackles in lungs → Congestive Heart Failure.

  • Weak pulses + Delayed capillary refill → Poor circulation, dehydration, shock.