Understanding the Cardiac Cycle and Cardiovascular Health

The Cardiac Cycle

The heartbeat is the movement that pumps blood through the body. It consists of two primary states:

• Systole: Coordinated rhythmic contraction.
• Diastole: Relaxation involving all four chambers of the heart.

Phases of the Cardiac Cycle

1. Atrial Systole: Both atria contract, mitral and tricuspid valves open, and both ventricles fill.
2. Ventricular Systole: Both ventricles contract, semilunar valves open, and blood is pushed through the aorta and pulmonary artery while mitral and tricuspid valves close.
3. Diastole: Atria and ventricles relax, semilunar valves close, and ventricles fill with blood.

The Double Circulatory System

This system keeps oxygenated and deoxygenated blood separate:

• Pulmonary Circuit: Pumps blood between the heart and lungs (right side).
• Systemic Circuit: Links the heart to the rest of the body (left side).

Cardiovascular Diseases (CVD)

These conditions affect the circulatory system, blood vessels, or the heart:

• Arteriosclerosis: Hard and thick artery walls resulting in a loss of elasticity. Caused by plaque (cholesterol, fat, and fibers), it decreases artery diameter and restricts flow. If plaque breaks off, it can cause an embolism.
• Hypertension (High Blood Pressure): High pressure at rest caused by the force of blood pushing against artery walls. Chronic conditions can damage arteries and overwork the heart. Risk factors include smoking, alcohol, obesity, and a sedentary lifestyle. Normal blood pressure is 120 mmHg (systolic) / 80 mmHg (diastolic).
• Myocardial Infarction (Heart Attack): The heart's blood supply is blocked, usually by a clot or obstruction in a coronary artery, preventing oxygen from reaching the myocardium.

Blood Diseases

• Anemia: Low levels of hemoglobin.
• Leukemia: Cancer affecting the blood or bone marrow.
• Haemophilia: Hereditary clotting disorders causing excessive bleeding.

Healthy Habits for the Circulatory System

• Moderate Daily Exercise: Aerobic activity benefits the heart, improves circulation, and aids in CVD prevention.
• Maintain a Calm Lifestyle: Chronic stress can lead to heart attacks.
• Hydration: Drink 2 liters of water per day to help dilute and eliminate waste.
• Balanced Diet: Avoid high-fat and high-salt diets to prevent obesity, arteriosclerosis, and hypertension.
• Avoid Smoking: Smoking increases blood pressure, heart stress, and the risk of arteriosclerosis.