Recognise Healthy Body Systems - Cardiovascular System PDF

Preview

Summary

Summary of the cardiovascular body system....

Description

20 HLTAAP001 - RECOGNISE HEALTHY BODY SYSTEMS The Cardiovascular System Outline of system Size of heart: - Size – same as a males clenched fist - Weighs - about 300g - Is 12 cm long - 9 cm wide (at it’s broadest point - the base) - 6 cm thick (the apex) - Cone shaped

System is made up of: - Blood - Blood vessels Arteries Arterioles Veins Venules Capillaries - Heart Heart location and projection: • The heart rests on the diaphragm • Lies in the mediastinum • 2/3 of the heart lies left of the mediastinal line • 1/3 lying to the right

• • •

The base points superiorly and right The apex points inferiorly and left Imagine a cone shape laying on its side

Layers of the Heart The three layers of heart tissue: - Epicardium - Myocardium - Endocardium Pericardium Pericardium: Is the heart’s protective sac it is enclosed in. Consists of two parts: - Layer of fibrous pericardium - Layer of serous pericardium - Layer of fibrous pericardium: tough dense connective - Layer of serous pericardium: A thin delicate layer of tissue that holds the heart in position to the chest and pericardium. prevents overstretching of the heart. Anchors heart to Consists of two layers: diaphragm and sternum and provides protection from - Parietal layer: the outer layer the is fused to the injury infection. fibrous pericardium. - Visceral layer: inner layer also called the epicardium that forms part of the heart wall and overs the whole heart. Pericardial cavity: Lies between the parietal and visceral layers of the pericardium. Contains a thin secretion called pericardial fluid and reduces friction between the layers as the heart contracts. Allows for smooth heartbeat. Epicardium Epicardium: the outer most layer and is the visceral layer of the serous pericardium. Protects and supports the heart and gives the heart a smooth slippery surface. Myocardium Myocardium: Is the middle muscular layer and makes up the muscle bulk of the heart. Has involuntary contractions to make heartbeat and Propels blood forward through blood vessels. Endocardium Endocardium: Is the hearts innermost layer that consists of a layer of simple squamous epithelium on a thin layer of connective tissue. Is the smooth layer lining inside the heart that allows blood to flow smoothly and lines the heart valves and large vessels of the heart.

Chambers of the heart The heart has four chambers: - Two upper (superior) chambers: atria - Two lower (interior) chamber: ventricles Both atria and ventricles are divided into R and L sided chambers. R and L side of body is divided by a thick connective tissue called the septum. Veins of the heart All veins enter the heart. Veins enter only into the atria where blood drains from the veins into the atria. The veins of the heart consist of seven large veins, 3 entering the R atrium and 4 entering the L atrium. Atrial Veins: Left Atrium: Right Atrium: - Two left pulmonary veins (from the left lung) - Superior Vena Cava: (from head and upper body) - Two right pulmonary veins (from the right lung) - Inferior Vena: (from lower body) - They all carry oxygenated blood - Coronary sinus: (from the heart wall) - They all carry deoxygenated blood Arteries of the heart All arteries exit the heart consist of two large arteries: - Pulmonary artery - Aorta Blood is pumped through these arteries by the heart muscle pump. They exit from each of the ventricles. Ventricular Arteries: Pulmonary Artery: Aorta: - Exits from the right ventricle - Exists from the left ventricle - Branches into the right and left pulmonary arteries - Branches into arteries throughout the body - Continues on to the lungs - Carries oxygenated blood - Carries deoxygenated blood Heart valves The heart has 4 valves that lie at the entry and exit of the ventricles. They are made up of dense regular connective tissue covered by endocardium and are surrounded by fibrous rings that prevent the valves from over stretching. Consists of cusps that flap open and closed. Semi-lunar Valves: cusps resemble half moons Atrioventricular (AV) valves: - Tricuspid: between R atrium and R ventricle - Pulmonary Valve: between R Ventricle and Pulmonary - Bicuspid (Mitral): between L Atrium and L Ventricle artery - Aortic Valve: between L Ventricle and Aorta Blood supply to the heart Blood flows: forward through the body due to pressure gradients and one-way valves in the veins. Blood flows from an area of high pressure to low pressure. flows forward through the heart due to pressure gradients and the one way valves. Blood enters the R atrium from the SVC, IVC and coronary sinus > Then flows through open tricuspid valve into R ventricle > From R ventricle through the pulmonary artery > pulmonary circulation to the lungs > From the lungs blood flows into L atria through the R and L pulmonary veins > Passing into L ventricle through the open bicuspid valve > Through aortic valve into the aorta and out into systemic circulation through the body. Heart Sounds Heart sounds: Are caused by turbulence when heart valves shut. With each heartbeat 4 heart sounds are made . Only the first 2 can be heard with a stethoscope - S1 occurs when the AV valve closes (LUBB) - S2 occurs when the semi-lunar valves close (DUBB) The rhythm is lubb, dubb, pause, lubb, dubb, pause

Myocardial blood supply The myocardium has its own blood supply called the coronary circulation which uses coronary arteries to supply the myocardium with O2 and nutrients. They arise from the aorta just above the aortic semilunar valves. They coronary veins carry deoxygenated blood back into the atrium via the coronary sinus and into circulation. Coronary circulation R coronary artery supplies the R side of the heart. L coronary artery supplies the L side of the heart - The myocardium relies on a constant supply of oxygenated blood - If this blood flow is interrupted by a blockage the myocardium can be damaged (infarct) Blood Vessels Blood vessels are a closed transport system. Blood is propelled from the heart through the systemic circulation and pulmonary circulation: Arteries – Arterioles – Capillaries – Venules – Veins – Back to the heart Arteries carry blood away from the heart and veins carry blood to the heart. Anatomy of blood vessels Arteries and veins consist of 3 layers: Lumen: - Hollow centre of the vessel 1. Tunica interna - Inner layer - Blood flows in the lumen - Smooth endothelial lining - Is where blood is in contact with the - Assists in reducing friction endothelial lining - Larger in veins than in arteries 2. Tunica media - Smooth muscle and elastic fibres - The thickest layer 3. Tunica externa - Elastic and collagen fibres - Supports and protects the vessel Arteries - Walls of arteries are thicker than veins - Especially the tunica media - Need to be able to stretch to accommodate the surge of blood - The recoil assists in propelling blood along - Carry blood away from the heart - Contains 13% of blood volume - Pressure is greatest in the arterial system - All arteries except the pulmonary artery carries oxygenated blood Capillaries - 10 billion capillaries in the body - Found near every cell in the body - Walls composed of a single layer of endothelial cells - Exchange vessels for nutrients, O2 and CO2, and metabolic waste - Cells bathed in interstitial fluid - Products move between the capillaries and cells via interstitial fluid - Makes transport through capillary wall easy Capillary Exchange: arterial end - Blood flows from arteries through capillaries then into the venous system - Pressure gradients from plasma proteins, blood pressure and interstitial pressure influence movement into and out of capillary - Pressure is high in capillaries and low in interstitial fluid at arterial end - Fluid moves from an area of high pressure to low pressure - Fluid moves into interstitial fluid at arterial end, O2 and nutrients then diffuse into cells

Capillary Exchange: Venous End - Metabolic waste products diffuse out of cell into interstitial fluid - Pressure is low in capillary and high in interstitial fluid at venous end - Fluid moves from an area of high pressure to low pressure - Fluid and wastes diffuse into capillaries at the venous end

Veins - Thickest layer in veins tunica externa - Large lumen (bigger than arteries) - Contain 64% of blood volume - Contain valves that prevent back flow of blood - Pressure decreases in the venous system - They do not expand and recoil like arteries - Carry blood back to the heart - All veins except the pulmonary veins carry deoxygenated blood...