2.2 Cardiovascular & Respiratory Systems
Key Takeaways
- The heart has four chambers: right atrium (receives deoxygenated blood), right ventricle (pumps to lungs), left atrium (receives oxygenated blood), left ventricle (pumps to body)
- Cardiac conduction pathway: SA node → AV node → Bundle of His → bundle branches → Purkinje fibers
- Normal adult vital signs: HR 60-100 bpm, BP <120/80 mmHg, RR 12-20/min, O2 sat 95-100%
- The respiratory system exchanges O2 and CO2 at the alveolar-capillary membrane in the lungs through diffusion
- Blood flow: right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → body
- Arteries carry blood AWAY from the heart (oxygenated, except pulmonary arteries); veins carry blood TO the heart (deoxygenated, except pulmonary veins)
Last updated: March 2026
Cardiovascular & Respiratory Systems
The cardiovascular and respiratory systems work together to deliver oxygen to every cell and remove carbon dioxide waste. These systems are heavily tested on the CCMA exam, particularly in relation to vital signs, EKG testing, and clinical assessment.
Cardiovascular System
Heart Anatomy:
- 4 chambers: Right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV)
- 4 valves: Tricuspid (RA→RV), pulmonary (RV→pulmonary artery), mitral/bicuspid (LA→LV), aortic (LV→aorta)
- 3 layers: Epicardium (outer), myocardium (muscle), endocardium (inner lining)
- Pericardium: Protective sac surrounding the heart
Blood Flow Through the Heart:
- Deoxygenated blood enters the right atrium via the superior and inferior vena cava
- Blood flows through the tricuspid valve into the right ventricle
- Right ventricle pumps blood through the pulmonary valve into the pulmonary arteries
- Blood travels to the lungs for gas exchange (CO2 released, O2 absorbed)
- Oxygenated blood returns via pulmonary veins to the left atrium
- Blood flows through the mitral (bicuspid) valve into the left ventricle
- Left ventricle pumps blood through the aortic valve into the aorta
- Oxygenated blood is distributed throughout the body
Cardiac Conduction System (Electrical Pathway):
- SA node (sinoatrial node) — "Natural pacemaker," fires 60-100 times/min
- AV node (atrioventricular node) — Delays impulse briefly to allow atrial contraction
- Bundle of His — Conducts impulse from atria to ventricles
- Right and left bundle branches — Divide to supply each ventricle
- Purkinje fibers — Distribute impulse throughout ventricular muscle, causing contraction
Blood Vessels:
| Vessel Type | Function | Wall Thickness | Direction |
|---|---|---|---|
| Arteries | Carry blood away from heart | Thick, muscular, elastic | Away from heart |
| Arterioles | Small arteries; regulate blood pressure | Medium | Away from heart |
| Capillaries | Gas/nutrient exchange with tissues | One cell thick | Connect arterioles to venules |
| Venules | Small veins; collect blood from capillaries | Thin | Toward heart |
| Veins | Return blood to heart; contain valves | Thinner than arteries | Toward heart |
Key Cardiovascular Terms:
- Systole — Contraction phase of the heart (ventricles pumping)
- Diastole — Relaxation phase of the heart (ventricles filling)
- Cardiac output — Amount of blood pumped per minute (~5 L/min at rest)
- Blood pressure — Force of blood against arterial walls (systolic/diastolic)
- Tachycardia — Heart rate > 100 bpm
- Bradycardia — Heart rate < 60 bpm
- Hypertension — Blood pressure ≥ 130/80 mmHg (per AHA guidelines)
- Hypotension — Blood pressure < 90/60 mmHg
Respiratory System
Structures of the Respiratory System:
| Structure | Location | Function |
|---|---|---|
| Nose/nasal cavity | Upper airway | Warms, moistens, filters inhaled air |
| Pharynx (throat) | Upper airway | Passageway for air and food |
| Larynx (voice box) | Upper airway | Sound production, protects airway (epiglottis) |
| Trachea (windpipe) | Lower airway | Conducts air to bronchi; supported by C-shaped cartilage rings |
| Bronchi | Lower airway | Two main branches (right and left) that enter each lung |
| Bronchioles | Lower airway | Smaller branches that lead to alveoli |
| Alveoli | Lower airway | Tiny air sacs where gas exchange occurs (300 million in lungs) |
| Diaphragm | Below lungs | Primary muscle of respiration; contracts during inhalation |
Gas Exchange (Respiration):
- External respiration — Gas exchange between alveoli and blood in pulmonary capillaries
- O2 moves from alveoli → blood (diffusion)
- CO2 moves from blood → alveoli (diffusion)
- Internal respiration — Gas exchange between blood and body tissues
- O2 moves from blood → cells
- CO2 moves from cells → blood
Normal Respiratory Values:
| Parameter | Normal Adult Value |
|---|---|
| Respiratory rate | 12-20 breaths/minute |
| Tidal volume | ~500 mL per breath |
| SpO2 (pulse oximetry) | 95-100% |
Key Respiratory Terms:
- Dyspnea — Difficulty breathing
- Apnea — Absence of breathing
- Tachypnea — Rapid breathing (>20/min in adults)
- Bradypnea — Slow breathing (<12/min in adults)
- Hypoxia — Insufficient oxygen reaching tissues
- Hypoxemia — Low oxygen in the blood
- Hypercapnia — Elevated CO2 in the blood
- Cyanosis — Bluish discoloration from low oxygen
- Orthopnea — Difficulty breathing when lying flat
Common Respiratory Conditions:
- Asthma — Chronic inflammation with bronchospasm; triggers include allergens, exercise, cold air
- COPD — Chronic obstructive pulmonary disease (emphysema + chronic bronchitis); often caused by smoking
- Pneumonia — Infection of lung tissue (bacterial, viral, fungal)
- Tuberculosis (TB) — Bacterial infection (Mycobacterium tuberculosis); airborne transmission
- Pulmonary embolism — Blood clot in pulmonary artery; medical emergency
Test Your Knowledge
What is the correct sequence of cardiac conduction from the natural pacemaker to the ventricles?
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Test Your Knowledge
Where in the respiratory system does gas exchange (O2 and CO2) primarily occur?
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Test Your Knowledge
Pulmonary arteries are unique because they carry:
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