Cardiovascular System & Heart Anatomy

• The cardiovascular system is vital for delivering oxygen, nutrients, hormones, and immune cells throughout the body
• It aids in the removal of metabolic waste products
• It plays a critical role in maintaining body temperature, pH balance, and fluid balance

Anatomy of the Heart

• The human heart is a muscular organ located in the chest, responsible for pumping blood throughout the body
• It is composed of four chambers: the right atrium, right ventricle, left atrium, and left ventricle
• The atria receive blood returning to the heart, while the ventricles pump blood out of the heart
• Valves within the heart ensure unidirectional blood flow
• The tricuspid valve is located between the right atrium and right ventricle
• The mitral valve is located between the left atrium and left ventricle
• The pulmonary valve is located between the right ventricle and the pulmonary artery
• The aortic valve is located between the left ventricle and the aorta
• The heart's wall consists of three layers: the epicardium, myocardium, and endocardium
• The epicardium is the outer layer
• The myocardium is the thick, muscular middle layer responsible for the heart's pumping action
• The endocardium is the smooth, inner layer lining the heart chambers
• The heart has a specialized conduction system that generates and distributes electrical impulses, controlling the heart rate and rhythm
• The sinoatrial (SA) node, located in the right atrium, is the heart's natural pacemaker
• The atrioventricular (AV) node delays the electrical signal, allowing the atria to contract before the ventricles
• The His-Purkinje system rapidly spreads the electrical impulse throughout the ventricles, causing them to contract in a coordinated manner
• The heart receives its own blood supply through the coronary arteries, which originate from the aorta
• The right and left coronary arteries branch off to supply blood to the heart muscle
• Blockage of these arteries can lead to myocardial ischemia or infarction

Blood Circulation Process

• Blood circulation is the continuous movement of blood through the heart and blood vessels, delivering oxygen and nutrients to the body's tissues and removing waste products
• The two main circuits of blood circulation are systemic circulation and pulmonary circulation
• Systemic circulation carries oxygenated blood from the left ventricle to the body's tissues and returns deoxygenated blood to the right atrium
• Oxygenated blood leaves the left ventricle through the aorta, the body's largest artery
• The aorta branches into smaller arteries, which deliver blood to organs and tissues
• In the capillaries, oxygen and nutrients are exchanged for carbon dioxide and waste products
• Deoxygenated blood returns to the heart through veins, eventually flowing into the superior and inferior vena cava, which empty into the right atrium
• Pulmonary circulation carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium
• Deoxygenated blood leaves the right ventricle through the pulmonary artery
• The pulmonary artery branches into the right and left pulmonary arteries, which carry blood to the lungs
• In the lungs, carbon dioxide is exchanged for oxygen in the alveoli
• Oxygenated blood returns to the heart through the pulmonary veins, which empty into the left atrium
• The cardiac cycle is the sequence of events that occur during one complete heartbeat
• It consists of two main phases: diastole and systole
• Diastole is the relaxation phase, during which the heart chambers fill with blood
• Systole is the contraction phase, during which the heart chambers pump blood out
• Blood pressure is the force exerted by circulating blood on the walls of blood vessels
• It is typically measured as systolic pressure (the pressure during ventricular contraction) over diastolic pressure (the pressure during ventricular relaxation)
• Normal blood pressure is around 120/80 mmHg

Cardiovascular Diseases

• Cardiovascular diseases (CVDs) are a group of disorders affecting the heart and blood vessels
• Coronary artery disease (CAD) is the most common type of CVD, characterized by the buildup of plaque in the coronary arteries, leading to reduced blood flow to the heart muscle
• Angina pectoris is chest pain or discomfort caused by reduced blood flow to the heart muscle
• Myocardial infarction (heart attack) occurs when blood flow to a part of the heart muscle is completely blocked, causing damage or death to the tissue
• Heart failure is a condition in which the heart is unable to pump enough blood to meet the body's needs
• Arrhythmias are irregular heartbeats caused by problems with the heart's electrical conduction system
• Atrial fibrillation is a common arrhythmia characterized by rapid and irregular beating of the atria
• Stroke occurs when blood flow to the brain is interrupted, causing brain cells to die
• Ischemic stroke is caused by a blocked artery, while hemorrhagic stroke is caused by a ruptured blood vessel
• Peripheral artery disease (PAD) is a condition in which the arteries that supply blood to the limbs are narrowed, leading to reduced blood flow
• Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg
• Pulmonary embolism (PE) occurs when a blood clot travels to the lungs and blocks a pulmonary artery
• Congenital heart defects are structural abnormalities of the heart that are present at birth
• Valve disorders involve problems with the heart valves, which can lead to reduced blood flow or backflow of blood

Risk Factors for Heart Disease

• Modifiable risk factors are those that can be changed through lifestyle modifications or medical treatment
• High blood pressure (hypertension) increases the risk of heart disease, stroke, and kidney disease
• High cholesterol levels, particularly LDL cholesterol, contribute to the buildup of plaque in the arteries
• Smoking damages blood vessels, increases blood pressure, and reduces the amount of oxygen in the blood
• Diabetes increases the risk of heart disease, stroke, and other complications
• Obesity is associated with high blood pressure, high cholesterol, and diabetes, all of which increase the risk of heart disease
• Physical inactivity increases the risk of heart disease, obesity, and other health problems
• Unhealthy diet, high in saturated and trans fats, cholesterol, sodium, and added sugars, increases the risk of heart disease
• Excessive alcohol consumption can raise blood pressure and contribute to heart failure
• Stress can contribute to high blood pressure and other risk factors for heart disease
• Non-modifiable risk factors are those that cannot be changed
• Age: the risk of heart disease increases with age
• Sex: men are generally at higher risk of heart disease than women until women reach menopause
• Family history: having a family history of heart disease increases the risk
• Race: certain racial and ethnic groups, such as African Americans, are at higher risk of heart disease

Diagnostic Methods

• Electrocardiogram (ECG or EKG) records the electrical activity of the heart, helping to detect arrhythmias, ischemia, and other heart conditions
• Echocardiogram uses sound waves to create images of the heart, allowing doctors to assess the heart's structure and function
• Stress test monitors the heart's performance during exercise, helping to detect ischemia and arrhythmias
• Cardiac catheterization involves inserting a thin, flexible tube into a blood vessel to visualize the heart chambers and coronary arteries
• Angiography is a type of cardiac catheterization that involves injecting dye into the coronary arteries to visualize blockages or narrowings
• Blood tests can measure cholesterol levels, blood sugar levels, and other markers of heart health
• Chest X-ray can reveal the size and shape of the heart and detect fluid buildup in the lungs
• Cardiac MRI uses magnetic fields and radio waves to create detailed images of the heart
• Cardiac CT scan uses X-rays to create detailed images of the heart and coronary arteries
• Holter monitor is a portable ECG device that records the heart's electrical activity continuously for 24-48 hours, helping to detect intermittent arrhythmias
• Event monitor is a portable ECG device that records the heart's electrical activity only when the patient experiences symptoms