Cardiovascular System Study Materials

CARDIOVASCULAR SYSTEM ♡ ● ● The heart is located in the pericardial cavity within the mediastinum The pericardial cavity is the only part of the mediastinum with a serous membrane SYSTEMS ● Consists of the heart and blood vessels entering and exiting it and the pericardium (serous membrane that surrounds the heart) ● Blood vessels are all connected to one another with organs in between, heart makes sure that the blood remains flowing between all these vessels ● Pulmonary means lung → pulmonary circulation → interaction between the heart and lung [right side of the heart] ○ Deoxygenated blood goes to the lungs to be reoxygenated ○ Then goes to systemic circulation ○ Less pressure in the right side of the heart because the blood only needs to go to the lungs (very close target organ) ● Systemic circulation → interaction between the heart and the body systems via the muscular arteries and veins [left side of the heart] ○ Distributes the newly oxygenated blood to the body systems ○ Needed for tissues to survive (cell death if there’s no oxygen) ○ More pressure and muscle in the left side of the heart because in a single contraction, blood needs to be moved around the whole body (position of the target organs and tissues in relation to the heart) ● Connected through the heart THE PERICARDIUM (membrane enclosing the heart) Fibrous pericardium ● Attaches to the roots of the great vessels, central tendon of the diaphragm ● Maintain the position of the heart, if it moves more it will affect the functioning of the lungs (affects how much oxygen can get in) ● Fused to the superior surface of the diaphragm (keeps the heart in place) ● Fibrous sac (similar to the fibrous capsule around joints) ● ● ● ● Inelastic - doesn't overfill and over pump (controls how much the heart can expand/fill) Provides a resistance to the heart so it allows the contraction to be more powerful, building the strength of the heart Most superficial layer of the pericardial sac Pathophysiology: if there’s a blockage, the heart going against resistance will be detrimental, muscle fibres will get thicker and the ventricles will get too thick because it’s full of muscle wall (muscle taking up ventricle space) = won’t pump enough oxygen around the body Serous pericardium ● Outer parietal layer ● Inner visceral layer ● Lubrication allows free movement of the heart within the fibrous pericardium (so the heart doesn't stick to the walls of the thoracic cavity or lung when expanding or contracting) THE HEART WALL Epicardium ● Visceral serous membrane (visceral pericardium) ● Adipose tissue (fat that surrounds the heart) Myocardium ● Contracts to pump the blood around the body and through the heart ● Thickest layer ● Made up of cardiac muscle Endocardium ● Innermost layer of the blood vessels is continuous with the heart chambers ● Lines interior heart chambers THE HEART - ● ● The heart is a pump Has 4 chambers ● ● Atrium = entrance Ventricles = more muscular chamber ● ● ● Venous blood on the right Arterial blood on the left No exchange of fluids of gases In anatomical position, this is how you would see the heart (mainly see the R ventricle) Apex is where you put the stethoscope - get the sounds from 2 sides of the heart (where the two ventricles come together) From the outside you can see the anterior interventricular artery THE HEART CHAMBERS Atria - Atrial walls are thin and smooth Pectinate muscle (contractions that help to drive blood from the atrium to the ventricle) The L and R atria are separated by the interatrial septum Ventricles - Ventricles have a thicker myocardium (than the atria because they have to pump blood further) - The L and R ventricles are separated by the Interventricular septum (sulcus sits on top of this) - Muscles of the ventricle wall have a honeycomb appearance = trabeculae carneae muscle (because of how it looks and the arrangement of fibres) → contraction of the ventricles, squeezing like ringing out a towel, wormlike contraction because of the arrangement of the muscle fibres - Left ventricle pumps blood to the rest of the body = thicker muscle