Cardiovascular and Peripheral Vascular System
Summary – Cardiovascular and Peripheral Vascular System
- The heart resides within the pericardial sac and is in the mediastinal space within the thoracic cavity.
- The heart’s walls comprise an outer epicardium, a thick myocardium, and an inner lining layer of the endocardium.
- The heart’s internal conduction system establishes the heart rate and transmits this information to the myocardium. The normal path of transmission for the conductive cells is the sinoatrial (SA) node, internodal pathways, atrioventricular (AV) node, atrioventricular (AV) bundle of His, bundle branches, and Purkinje fibres.
- The contractile cells (cardiac myocytes) contract and propel blood. Contractile cells have an action potential with an extended plateau phase that results in an extended refractory period to allow complete contraction for the heart to pump blood effectively.
- The cardiac cycle comprises a complete relaxation and contraction of the atria and ventricles and lasts approximately 0.8 seconds.
- Many factors affect heart rate and stroke volume, and together, they contribute to cardiac function. HR is determined and regulated by autonomic stimulation and hormones.
- Common conditions encountered within the cardiovascular and peripheral vascular systems include myocardial infarction, congestive heart failure, hypertension, and atrial and ventricular arrhythmias such as atrial fibrillation and heart blocks.
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- The symptoms patients present with can be broad and may include shortness of breath, chest pain, cough, fatigue, heart rate change (slow, fast, irregular), skin colour and temperature changes, lower leg edema, bulging or discoloured veins in the legs, and ulcerations of the lower limbs.