Cardiovascular System All you Need to Know

‘Cardi’ means heart Myocardium = muscles of the heart Epicardium = most outer layer of the heart muscle Pericardium= the layer of heart muscle that envelops the entire heart but not so tightly that it can’t expand and collapse during contraction Endocardium= the muscle of the heart that lines the insde Cardiovascular activity= activity that requires the use of and strengthens/conditions the myocardium, and each component of the vascular system (arteries, veins, capillaries, etc.) Electrocardiogram (ECG)- a graphical representation of the heart’s electrical activity as the heart contracts

Anatomy of the Heart

Flow of Blood Through the Heart Begins with Pulmonary circulation: Circulation of blood through the right side of the heart while deoxygenated before being set off to the lungs Once Pulmonary circulation has completed it’s cycle, systemic circulation kicks in: Circulation of oxygenated blood through the left side of the heart and out to the rest of the body

Flow of Blood Blood enters into the right side of the heart through Superior and Inferior Vena Cava Right Atrium Tricuspid Valve Right Ventricle Left and Right Pulmonary Artery Left and Right Pulmonary Veins Left Atrium Bicuspid Valve Left Ventricle Aorta + Thoracic Aorta

Electrical Activity: What makes the blood pump The heart moves blood by way of contraction Atria contract from the top downward Ventricles contract from the bottom upwards In order to contract and push the blood in the proper direction, the heart receives electrical impulses that are controlled and passed along via Nodes and Fibres

Pathway of Impulses Sinoatrial Node (SA Node) = Pacemaker Atrioventricular Node (AV Node) Bundle of HIS (Splits to right and left bundles) Purkinje Fibres

Electrocardiogram

ECG- What Each Interval Means P wave= Atrial depolarization QRS complex= Ventricular T wave= Ventricular repolarization *Depolarization is the spread of the electrical impulse that leads to contraction *Repolarization is the relaxation phase where the muscle returns to rest *Atrial repolarization is not seen

Blood Pressure Systolic Blood Pressure 120mmHg -------------------- = --------- Diastolic Blood Pressure 80mmHg Systolic= Pressure in arteries during contraction (blood being pushed) Diastolic= Pressure in arteries during relaxation (blood filling)

Problems Stemming from or Related to Blood Pressure Hypertension- term used to describe high blood pressure; pressure reading is consistently 140/90mmHg or higher Atherosclerosis- gradual narrowing of the coronary arteries resulting from the accumulation of hard deposits of cholesterol Also termed Coronary Artery Disease (CAD) or Coronary Heart Disease (CHD) Leads to a myocardial infarction (heart attack)

Vascular System Vessels through which blood is passed to all areas of the body (the body’s blood transport system) Consists of large arteries, arterioles, capillaries, venules and large veins

Break it down Arteries = thick, muscular-walled vessels that carry blood away from the heart to the rest of the body; the vessels that produce a blood pressure reading; their elasticity allow them to stretch and recoil as blood passes through (important especially during diastolic phase) Arterioles = smaller branches of arteries; surrounded by rings of smooth muscle that contracts as these vessels continue to transport blood to organs/muscles in the body Arterioles will be triggered by chemical changes and the nervous system to open wider to feed a substantial blood supply to working muscles during exercise (autoregulation)

Capillaries = smallest vessels with the most important function; vessel through which the exchange of nutrients and gasses occur between the blood and the muscle/organ Venules = smaller branches of veins that help with the transportation of deoxygenated blood as it returns to the heart Veins = carry deoxygenated blood to the heart; the farther away from capillaries a vein is, the larger it gets (capillaries venulesveins)

From the Heart… Heart Heart Large artery (ex. Aorta) Arterioles Capillaries (gas exchange occurs) Venules Large vein (ex. Superior vena cava) Heart

Composition of Blood Once separated (ex. centrifuge) 55% Plasma consisting 90% water, 7% plasma proteins, 3% other (acids, salts, etc.) 45% Formed elements 99% red blood cells (erythrocytes), 1% white blood cells (leukocytes- disease defense)

Cardiac Output (Q) Formula: Q = HR x SV Cardiac output amount of blood pumped out of the left ventricle in one minute (L/min.) Rest approx. 5-6 L/min During exercise approx. 30 L/min Heart Rate (HR) monitored in beats per minute Stroke Volume (SV) amount of blood ejected in a single beat SV = LVESV - LVEDV