Ch5 part 2 end 5-6e

Circulation OverviewSystemic and Pulmonary Circulation: Blood is pumped through systemic and pulmonary circuits to deliver oxygen and remove waste products from cells.Pulmonary Circulation Definition: Flow of blood between the heart and lungs.Pulmonary Arteries: Carry deoxygenated blood from the right ventricle to the lungs (distinct as arteries typically carry oxygenated blood).Gas Exchange: In the lungs, carbon dioxide is replaced by oxygen from inhaled air.Pulmonary Veins: Transport oxygenated blood from the lungs to the left atrium (only veins carrying oxygenated blood).

Systemic Circulation Definition: Blood flow to all body parts except the lungs.Oxygenated Blood: Flows from the left ventricle into the arterial system.Deoxygenated Blood: Returns through veins into the right atrium, leading back to pulmonary circulation.

Heartbeat and Conduction SystemHeartbeat: Refers to the heart's ability to pump blood effectively, relying on sequential contraction and relaxation.Electrical Impulses: Determine the heartbeat’s rate and rhythm. They originate from specialized myocardial tissues in the heart.Sinoatrial (SA) Node: Located in the right atrium, acts as the heart's natural pacemaker, starting each muscle contraction wave.Atrioventricular (AV) Node: Receives impulses from the SA node, located near the interatrial septum, transmitting them to the Bundle of His.Bundle of His: Fibers in the interventricular septum that carry impulses to the ventricles.Purkinje Fibers: Specialized fibers in the ventricular walls that ensure coordinated contraction of the ventricles, propelling blood into the aorta and pulmonary arteries.

Electrical Activity VisualizationElectrocardiogram (EKG/ECG): Depicts the electrical discharges of the heart.Sinus Rhythm: Normal heart rhythm represented by P wave, QRS complex, and T wave indicating atrial and ventricular activities.

Blood VesselsTypes of Blood Vessels: Arteries, capillaries, and veins.

Arteries Function: Carry blood away from the heart to various body regions.Structure: Composed of three muscular and elastic layers.Bright Red Blood: Indicates oxygen-rich arterial blood.Major Arteries:

  • Aorta: Largest vessel, originating from the left ventricle, distributing blood throughout the body.

  • Carotid Arteries: Supply blood to the head, dividing into internal and external carotid arteries.

  • Arterioles: Smaller branches leading to capillaries.

Capillaries Function: Smallest vessels, one epithelial cell thick, enable exchange of oxygen, nutrients, and waste between blood and body cells.

Veins Function: A low-pressure system returning deoxygenated blood to the heart.Structure: Thinner walls compared to arteries, contain valves that promote unidirectional blood flow.Major Veins:

  • Vena Cava: Largest veins (superior and inferior) returning blood to the right atrium.

Blood Pressure and PulsePulse: Rhythmic pressure from heart contractions against artery walls.Blood Pressure: Measurement of systolic (highest) and diastolic (lowest) pressures in arteries.

Blood CompositionBlood Types: Classified by antigens and Rh factors (e.g., A+, A-, B+, B-, O+, O-).Plasma: Comprises 55% of blood, mainly water, containing nutrients, hormones, and proteins.

Formed Elements:

  • Erythrocytes (Red Blood Cells): Oxygen transport via hemoglobin.

  • Leukocytes (White Blood Cells): Immune defense against pathogens.

  • Thrombocytes (Platelets):

    • Definition: Small cell fragments critical for blood clotting.

    • Production: Formed in the bone marrow from megakaryocytes.

    • Function: On injury, they aggregate at the site, adhere to the damaged surface, and release chemicals to promote clotting, preventing excessive blood loss. They also form a temporary barrier to further bleeding and support healing by regulating growth factors and tissue regeneration.

Cardiovascular HealthMedical Specialties: Cardiologists, hematologists, vascular surgeons focus on heart/blood disorders.Common Disorders:

  • Congenital Heart Defects: Abnormal structures present at birth.

  • Coronary Artery Disease (CAD): Atherosclerosis leading to insufficient oxygen supply.

  • Atherosclerosis: Buildup of plaque in arteries.

  • Ischemia: Reduced blood flow causing tissue oxygen deficiency.

  • Angina: Chest pain due to insufficient blood flow to myocardium, may precede heart attack.