The Cardiovascular System home study course harmony house holistic therapy treatment centre and training academy www.harmony-house.org
1 Copyright 2010 by Mark and Katy Rogers All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the Copyright owner Harmony House, or any other persons who have been involved in working on this publication, cannot accept responsibility for any injuries or damage incurred as a result of following the information, exercises, or therapeutic techniques contained in this book.
2 Table of Contents The Cardiovascular System...3 Blood...3 Functions of blood...4 Blood Vessels...5 Arteries...5 Veins...5 Capillaries...6 Circulation...6 Pulmonary circulation...6 General or Systemic circulation...7 The portal circulation...7 The heart...8 Blood flow through the heart...9 The cardiac cycle...10 Blood pressure...11 Pulse rate...11 Blood Shunting...11 Inter-relationship with other systems...12
3 The Cardiovascular System Blood Blood is a fluid connective tissue containing cells that are suspended in a liquid called plasma. It is the medium in which all materials are transported to and from individual cells in the body. Blood is the main transport system of the body. Blood consists of two parts 55 % plasma and 45 % cells. Plasma is a clear, pale yellow slightly alkaline fluid consisting of :- 91 % water the remaining 9 % consists of dissolved blood proteins, waste, digested food materials, minerals salts and hormones. There are three main types of blood cells :- Erythroctyes are the red blood cells, they are formed in red bone marrow and contain the iron protein haemoglobin which contributes to the red colour of blood. Haemoglobin is the substance that enables erythrocytes to transport oxygen and carbon dioxide. Leucocytes are white blood cells. There are two types of leucocytes 1. Granulocytes these form 75% of white blood cells and they defend the system against viruses and bacteria. They can change shape and pass out of the blood vessels and into the surrounding tissue. 2. Non-Granulocytes (lymphocytes and monocytes) lymphocytes are responsible for making antibodies which help the body to resist infection. Monocytes engulf harmful bacteria, dead cells, and foreign material by a process known as phagocytosis Thrombocytes also known as platelets, they are formed in red bone marrow. They initiate the chemical reaction that leads to the formation of a blood clot. Platelets stop the loss of blood from an injured blood vessel in the following manner:- 1. Platelets gather where the blood vessel is injured. 2. The first platelets to arrive from a plug across the opening and release chemicals that convert fibrinogen (a coagulation factor) to fibrin 3. The fibrin forms a mesh of needle like fibres that trap platelets and other blood cells, to create an insoluble clot.
4 Functions of blood The four main functions of blood are:- Transport Substances are transported around the body by blood:- 1. Oxygen is carried from the lungs to the body s cells by the red blood cells 2. Carbon dioxide is carried from the body s cells to the lungs 3. Nutrients, such as glucose, amino acids, vitamins and minerals are carried from the small intestine to the cells of the body. 4. Cellular waste such as water, lactic acid and urea are carried away in the blood to be excreted 5. Hormones released by the endocrine system and which act as chemical messengers are carried to the target organs, to get them organs to perform important functions. Defence 1. White blood cells are called leucocytes, and help to destroy damaged and old cells. 2. They defend the system against viruses and bacteria. Some leucocytes are able to multiple by mitosis, thus they can stop the infection. Regulation Clotting 1. Body processes are regulated by hormones which are transported around the body by the blood. 2. Blood helps to regulate the temperature of the body by absorbing the heat generated by the liver and muscles. This is then transported around the body to help maintain a constant internal temperature of 36.8 C. 3. Blood helps to regulate the body s ph balance. Keeping it between 7.35 7.45 by chemical systems in the blood called buffers. 4. Normal fluid balance is maintained by the composition of the blood. Clotting is an effective method of controlling blood loss from blood vessels. When a blood vessel becomes damaged as in a cut. Thrombocytes or platelets form a clot around the damaged area to prevent the body to prevent the body losing too much blood and to stop bacteria entering.
5 Blood Vessels Blood is circulated around the body by the pumping action of the heart and is carried in blood vessels called arteries, veins and capillaries. Arteries carry blood away from the heart and veins carry blood to the heart. Capillaries form at the ends of arterioles and venules and provide the link between the circulatory system and the cells of the body. Both arteries and veins have three layers, outer, middle and internal. Because arteries carry blood under pressure, their walls are thicker and more elastic. Arteries Arteries carry blood away from the heart. Blood is carried under high pressure, thus they have thick, muscular, elastic walls to withstand the pressure. Arteries have no valves except at the base where they leave the heart. Arteries (except the pulmonary artery) carry oxygenated blood Arteries are generally deep seated, except where they cross over a pulse spot. Arteries subdivide to form smaller blood vessels called arterioles, these deliver blood to the capillaries. Veins Veins carry blood towards the heart. Blood is carried under low pressure Veins have thinner muscular walls Veins have valves at intervals along their length to prevent the backflow of blood. Veins (except for the pulmonary vein) carry deoxygenated blood. Veins are generally superficial not deep-seated Veins subdivide to form smaller blood vessels called venules, these continue on from capillaries and receive blood via capillaries.
6 Capillaries Capillaries are the smallest blood vessels Capillaries connect arterioles and venules, forming a network of blood vessels in the tissues The wall of a capillary is one cell thick, this allows the diffusion of dissolved substances to and from the tissues to occur. Capillaries have no valves Blood is carried under low pressure, but at a higher pressure than veins Capillaries supply the cells and tissues with nutrients Circulation The circulation of blood can be divided into two main parts:- Pulmonary circulation General or Systemic circulation Pulmonary circulation Pulmonary circulation concerns the flow of blood between the heart and the lungs. The left and right pulmonary arteries carry deoxygenated blood from the right ventricle of the heart to the lungs, where the carbon dioxide is removed and expired and is replaced by oxygen to give oxygenated blood The four pulmonary veins carry the freshly oxygenated blood back to the left atrium of the heart. It then passes through the bicuspid valve into the left ventricle ready to be pumped around the body.
7 General or Systemic circulation General or Systemic circulation involves the general flow of blood from the heart and the return of blood and lymph from the cells back to the heart. The function of systemic circulation is to bring nutrients and oxygen to all systems of the body and carry waste products away from the cells and tissues for elimination. Oxygenated blood passes from the left atrium of the heart through the bicuspid valve into the left ventricle and is pumped out of the heart to the cells of the body via the aorta (the main artery). Blood flows via the arteries to the head, arms and legs. The blood passes from artery to arterioles, these in turn feed the capillaries. It is here that diffusion passes the oxygen and nutrients to the cells and tissues, and where carbon dioxide and waste products are collected. The lymphatic system collects excess tissue fluid and any waste products too large to pass through the capillary wall. The capillaries then feed the venules with deoxygenated blood. The venules in turn feed the veins. The main veins of the body (the superior and inferior vena cava) return the deoxygenated blood and filtered lymph to the right atrium of the heart, where it passes through the tricuspid valve into the right ventricle of the heart. The portal circulation The portal circulation is part of the systemic circulation. It collects blood from the digestive organs and delivers this blood to the liver for processing via the hepatic portal veins. The liver plays and important role in maintaining the correct concentration of glucose, fat and protein in the blood, thus the blood from the digestive system goes via the liver so that these substances can be processed before the blood carries on in the systemic circulation.
8 The heart The function of the heart is to maintain a constant flow of blood throughout the body. The heart is located in the thorax, slightly to the left side, between the lungs. It is a hollow muscular organ, which acts as a pump. This pumping action is made up of a series of events known as the cardiac cycle. The heart is made up of three layer of tissue. Pericardium the outer layer. This a forms a double layer where the space between the two layer is filled with fluid to reduce friction when the heart moves during beating Myocardium the middle layer. This is made up of cardiac muscle which is under involuntary control producing the contractions that make up the heartbeat. Endocardium the inner layer. This forms the lining of the heart.
9 The heart is divided a left and right side by a muscular wall called the septum. This prevents blood from the left and right sides of the heart mixing. The right side of the heart deals with deoxygenated blood, while the left side deals with oxygenated blood. Each side is then divided again into an atrium as the upper chamber and a ventricle as the lower chamber. The atria are connected to the ventricles by valves. These valves allow blood to flow into the ventricle but stop it from returning to the atrium. The tricuspid valve connects the right atrium to the right ventricle The bicuspid valve connects the left atrium to the left ventricle The upper chambers the atria take blood in from the body from large veins and pump it to their lower chamber the ventricle. The ventricles also have valves that connect them to the arteries. The aortic valve connects the left ventricle and the aorta The pulmonary valve connects the right ventricle with the pulmonary artery Blood flow through the heart 1. Deoxygenated blood from the body enters the right atrium via the superior and inferior vena cava. When the right atrium is full the blood flows through the tricuspid valve into the right ventricle 2. When the right ventricle is full, it contracts and pushes the blood through the pulmonary valve into the pulmonary artery. The pulmonary artery divides into left and right branches and takes the blood to both the left and right lungs. Here the blood becomes oxygenated. The four pulmonary veins leave the lungs and transport the oxygenated blood back to the left atrium. 3. This stage takes place at the time as the process described in 1. When the left atrium is full blood flows through the bicuspid valve into the left ventricle. When the left ventricle is full it contracts and pushes the oxygenated blood through the aortic valve into the aorta and to all parts of the body except the lungs. The left ventricle s walls are thicker to provide the extra strength required to push blood out of the heart and around the body.
10 The cardiac cycle The cardiac cycle is a sequence of events that happens between consecutive heartbeats. The atria contract simultaneously and force blood into the relaxed ventricles. The ventricles then contract strongly and pump blood out of the heart and into the aorta and the pulmonary artery. During the ventricle contraction, the atria relax and fill up with blood again, and the process repeats.
11 Blood pressure Blood pressure is the amount of pressure exerted by blood on an arterial wall due to the contraction of the left ventricle. Systolic pressure is the maximum pressure associated with the contraction of the ventricles Diastolic pressure is the minimum pressure associated with the relaxation of the ventricles. Blood pressure can be measured using a sphygmomanometer Pulse rate The pulse is a pressure wave that can be felt in the arteries which corresponds to the beating of the heart. The pulse can be felt at any place where an artery is near the surface. Pulse rate is the number of time the heartbeats per minute. The normal resting pulse rate of an adult is 60 and 80 beats per minute. Blood Shunting Blood shunting is when blood is directed to those areas of the body that need it according to the physical demands on the particular system or organ. E.g after a meal blood is diverted to the digestive system to aid in the digestive process.
12 Inter-relationship with other systems The cardiovascular system links to the following other body systems. The skin blood rich in nutrients and oxygen is transported to the skin, nails and hair. The skeletal system red bone marrow produces red blood cells. The muscular system the heart is a muscular organ which continuously pumps blood around the body The lymphatic system helps the circulatory system to remove additional waste and fluid away from the tissues to maintain, blood volume, blood pressure and prevent oedema and fight infections. The respiratory system - in the lungs the respiratory system removes carbon dioxide from deoxygenated blood and adds oxygen to make it oxygenated blood. The nervous system the sympathetic nerves in the arterioles regulate blood pressure. The endocrine system hormones are transported by blood to their target organs The digestive system Nutrients broken down by the digestive system are transported to the liver where they can be processed.