Cardiovascular System: Heart, Blood Vessels, and Blood

• The cardiovascular system, also known as the circulatory system, is vital for supplying oxygen and nutrients to tissues and removing carbon dioxide and waste

Components

• The cardiovascular system consists of the heart, blood vessels (arteries, veins, and capillaries), and blood

Heart Anatomy

• The heart is a muscular organ that pumps blood throughout the body
• It has four chambers: the right atrium, right ventricle, left atrium, and left ventricle
• Valves, including the tricuspid, pulmonary, mitral, and aortic valves, ensure unidirectional blood flow

Blood Vessels

• Arteries carry oxygenated blood away from the heart, with the aorta being the largest artery
• Veins return deoxygenated blood to the heart, with the superior and inferior vena cava being the largest veins
• Capillaries are tiny vessels where oxygen and nutrient exchange occurs with tissues

Blood Composition

• Blood consists of plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
• Red blood cells contain hemoglobin, which binds to oxygen for transport
• White blood cells are involved in immune defense
• Platelets are essential for blood clotting

Blood Circulation

• Pulmonary circulation involves blood flow between the heart and lungs, where carbon dioxide is released, and oxygen is absorbed
• Systemic circulation involves blood flow between the heart and the rest of the body, delivering oxygen and nutrients

Cardiac Cycle

• The cardiac cycle includes diastole (relaxation) and systole (contraction) phases
• During diastole, the heart chambers fill with blood
• During systole, the ventricles contract, pumping blood into the pulmonary artery and aorta

Heart Rate and Blood Pressure

• Heart rate is the number of heartbeats per minute
• Blood pressure measures the force of blood against artery walls and is expressed as systolic/diastolic pressure

Regulation of Cardiovascular Function

• The autonomic nervous system regulates heart rate, contractility, and blood vessel tone
• Hormones like epinephrine (adrenaline) can increase heart rate and blood pressure
• Baroreceptors detect changes in blood pressure and trigger regulatory responses

Common Cardiovascular Diseases

• Atherosclerosis is the buildup of plaque in arteries, leading to reduced blood flow
• Hypertension is high blood pressure, which can damage blood vessels and organs
• Heart failure occurs when the heart cannot pump enough blood to meet the body's needs
• Arrhythmias are irregular heartbeats, which can affect blood flow
• Coronary artery disease (CAD) involves the narrowing or blockage of coronary arteries, often leading to heart attack

Diagnostic Tests

• Electrocardiography (ECG) records the heart's electrical activity to detect abnormalities
• Echocardiography uses sound waves to create images of the heart, assessing its structure and function
• Angiography involves injecting dye into blood vessels to visualize them using X-rays
• Blood tests can measure cholesterol levels, cardiac enzymes, and other markers of cardiovascular health

Risk Factors for Cardiovascular Disease

• Modifiable risk factors include smoking, high cholesterol, high blood pressure, obesity, physical inactivity, and diabetes
• Non-modifiable risk factors include age, sex, and family history

Maintaining Cardiovascular Health

• Regular exercise strengthens the heart and improves circulation
• A balanced diet low in saturated fats, cholesterol, and sodium helps maintain healthy blood pressure and cholesterol levels
• Avoiding smoking reduces the risk of atherosclerosis and other cardiovascular problems
• Managing stress can lower blood pressure and improve overall heart health
• Regular check-ups with a healthcare provider can help detect and manage cardiovascular risk factors early

Arteries

• Arteries have thick, elastic walls to withstand high pressure
• They branch into smaller arterioles, which regulate blood flow to capillaries

Veins

• Veins have thinner walls than arteries and contain valves to prevent backflow of blood
• Venules collect blood from capillaries and merge into larger veins

Capillaries

• Capillaries are the smallest blood vessels, with thin walls facilitating exchange of gases, nutrients, and waste
• Capillary beds connect arterioles and venules

Lymphatic System Interaction

• The lymphatic system helps maintain fluid balance by collecting excess interstitial fluid and returning it to the bloodstream
• Lymph nodes filter lymph and play a role in immune defense

Coronary Circulation

• Coronary arteries supply blood to the heart muscle itself
• Blockage of these arteries can lead to myocardial infarction (heart attack)

Pulmonary Arteries and Veins

• Pulmonary arteries carry deoxygenated blood from the heart to the lungs
• Pulmonary veins carry oxygenated blood from the lungs back to the heart

Blood Pressure Regulation

• Systolic pressure is the highest pressure when the heart contracts
• Diastolic pressure is the lowest pressure when the heart relaxes
• Blood pressure is influenced by cardiac output, blood volume, and peripheral resistance

Cardiac Output

• Cardiac output is the amount of blood pumped by the heart per minute
• It is calculated by multiplying heart rate by stroke volume

Stroke Volume

• Stroke volume is the amount of blood ejected by the heart with each beat
• It is influenced by preload, afterload, and contractility

Preload

• Preload is the volume of blood in the ventricles at the end of diastole
• Increased preload can increase stroke volume

Afterload

• Afterload is the resistance the heart must overcome to pump blood
• Increased afterload can decrease stroke volume

Contractility

• Contractility is the force of heart muscle contraction
• Increased contractility can increase stroke volume

Cardiovascular Control Center

• The cardiovascular control center in the brainstem regulates heart rate and blood pressure
• It receives input from baroreceptors, chemoreceptors, and higher brain centers

Chemoreceptors

• Chemoreceptors detect changes in blood oxygen, carbon dioxide, and pH levels
• They can trigger changes in heart rate and respiration

Hormonal Regulation

• Epinephrine and norepinephrine increase heart rate and contractility
• Antidiuretic hormone (ADH) increases blood volume and blood pressure
• Atrial natriuretic peptide (ANP) decreases blood volume and blood pressure

Valves of the Heart

• Tricuspid valve is located between the right atrium and right ventricle
• Pulmonary valve is located between the right ventricle and pulmonary artery
• Mitral valve is located between the left atrium and left ventricle
• Aortic valve is located between the left ventricle and aorta

Heart Sounds

• The "lub" (S1) sound is caused by the closing of the tricuspid and mitral valves
• The "dub" (S2) sound is caused by the closing of the pulmonary and aortic valves

Murmurs

• Heart murmurs are abnormal sounds caused by turbulent blood flow
• They can indicate valve problems or other heart defects

Conduction System

• The sinoatrial (SA) node is the heart's natural pacemaker
• The atrioventricular (AV) node delays the electrical signal, allowing the atria to contract before the ventricles
• The bundle of His and Purkinje fibers conduct the electrical signal to the ventricles

Arrhythmias

• Tachycardia is a fast heart rate
• Bradycardia is a slow heart rate
• Atrial fibrillation is an irregular and rapid atrial rhythm
• Ventricular fibrillation is a life-threatening irregular ventricular rhythm

Heart Failure

• Left-sided heart failure causes fluid buildup in the lungs
• Right-sided heart failure causes fluid buildup in the body

Cardiomyopathy

• Cardiomyopathy is a disease of the heart muscle
• It can be caused by genetic factors, infections, or other conditions

Congenital Heart Defects

• Congenital heart defects are abnormalities present at birth
• Examples include ventricular septal defect (VSD) and atrial septal defect (ASD)

Peripheral Artery Disease (PAD)

• PAD involves narrowing of arteries in the limbs, often causing pain and cramping
• It is commonly caused by atherosclerosis

Deep Vein Thrombosis (DVT)

• DVT is a blood clot in a deep vein, usually in the leg
• It can lead to pulmonary embolism

Pulmonary Embolism (PE)

• PE is a blood clot that travels to the lungs, blocking blood flow
• It is a life-threatening condition

Cardiac Rehabilitation

• Cardiac rehabilitation is a program to help patients recover from heart conditions
• It includes exercise, education, and counseling

Medications

• Anti-hypertensives lower blood pressure
• Statins lower cholesterol
• Anti-coagulants prevent blood clots
• Anti-arrhythmics regulate heart rhythm