Biology 2 THE CARDIOVASCULAR SYSTEM CARDIOVASCULAR SYSTEM https

Biology 2 THE CARDIOVASCULAR SYSTEM

CARDIOVASCULAR SYSTEM � https: //www. youtube. com/watch? v=g. VY 04 N QUpxk � How does this video relate to the heart? � What happens to the man in the video?

SCHEME OF BLOOD CIRCULATION � Pulmonary circulation � Eliminates carbon dioxide via the lungs and oxygenates the blood � Contains � Systemic deoxygenated blood circulation � Delivers oxygen to all body cells and carries away wastes � Contains oxygen-rich blood

CIRCULATION � Without circulation, tissues would lack a supply of oxygen and nutrients, and wastes would accumulate � Necrosis = death of body tissue that occurs when not enough blood is flowing to the tissue

HEART SIZE & LOCATION � Average adult heart size is 14 centimeters long and 9 centimeters wide (fist size) � Housed within the mediastinum – location behind the sternum � Bordered laterally by the lungs � The base of the heart lies beneath the 2 nd rib � The apex (distal point of the heart) extends downward and to the left to the intercostal space between the 5 th & 6 th rib

HEART LOCATION

COVERINGS OF THE HEART � Pericardium- encloses the heart and the proximal ends of the large blood vessels to where it attaches � Outer fibrous pericardium attaches heart to surroundings � Double-layered sac � Visceral � AKA epicardium � Parietal � pericardium = innermost layer of sac pericardium = inner lining of fibrous pericardium Pericardial cavity- space between the visceral and parietal layers � Contains fluid that reduces friction as heart contracts

PERICARDIUM

PERICARDITIS � Swelling and irritation of the pericardium � Pericarditis often causes chest pain and sometimes other symptoms. The sharp chest pain associated with pericarditis occurs when the irritated layers of the pericardium rub against each other.

3 LAYERS OF THE HEART’S WALLS � Epicardium- outer layer � Also part of the visceral pericardium � Made of connective & adipose tissue � Protects heart by reducing friction � Myocardium- middle layer � Thick cardiac muscle tissue � Pumps blood out of the heart chambers � Endocardium� Epithelial inner layer and connective tissue layer � Contains elastic fibers, blood vessels, & Purkinje fibers

3 LAYERS OF HEART WALLS

3 LAYERS OF HEART WALLS

DOUBLE PUMP � The heart is divided into 4 hollow chambers � Atria- upper chambers have thin walls and receive blood returning to heart � Ventricles- lower chambers that receive blood from the atria and contract to force blood out of the heart into arteries � Septum- solid wall that separates the atrium and ventricle on the right from the atrium and ventricle on the left

CHAMBERS OF THE HEART

VALVES OF THE HEART � Atrioventricular valves (A-V valves)ensure one way flow of blood between atria and ventricles � Tricuspid valvelocated between the right AV � Bicuspid valve (AKA mitral valve)located between the

THE VENTRICLES � The right ventricle has thinner muscular walls as it only pumps blood a short distance to the lungs � The left ventricle is thick and must force the blood to all parts of the body against a greater resistance to flow

BLOOD FLOW � The right atrium receives blood from 2 large veins: superior vena cava and inferior vena cava � Superior vena cavareturns blood to heart from upper body � Inferior vena cavareturns blood to heart from lower body

BLOOD FLOW � Muscular wall of RV contracts, blood in chamber is under pressure, closing the tricuspid valve and forcing the blood out the pulmonary trunk, which divides into the pulmonary arteries � Pulmonary arterieslead to lungs

BLOOD FLOW � The LA receives blood from 4 pulmonary veins (2 from each lung) � The LV contracts, closing the bicuspid valve and pushing blood through the aortic valve into the aorta � Aorta – large artery that delivers blood to the body

SEMILUNAR VALVES � The pulmonary and aortic valves are called semilunar valves due to their half moon shape of their cusps

MITRAL VALVE PROLAPSE (MVP) � One or both of the cusps of the mitral valve stretches and bulges into the left atrium during ventriclar contraction � Sometimes blood flows back into the left atrium � Chest pain, palpitations, fatigue, anxiety � Sounds like a “click and a murmur” � 6% of the population � More susceptible to endocarditis, which can be caused by Streptococcus

MITRAL VALVE PROLAPSE � https: //www. youtube. com/watch? v=AHBzu 5 z h. Fu. A � https: //www. youtube. com/watch? v=Kmh. Kuf. T S 0 w. Q

BLOOD SUPPLY TO THE HEART � Right & Left Coronary Arteries- 1 st two branches of the aorta that supply blood to heart tissue � Feed the many capillaries of the myocardium � Cardiac veins- drain the blood that has passed through the myocardial capillaries (deoxygenated blood) � These veins join an enlarged vein on the heart’s posterior surface called the coronary sinusempties directly into the right atrium