Lesson_9_Cardiovascular

Lesson_9_Cardiovascular - Dr. Pamela VandeVord BME 5005...

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Unformatted text preview: Dr. Pamela VandeVord BME 5005 Objectives Following this lesson, you should be able to describe: 0 The heart — Anatomy — Blood flow - Blood vessels — Arteries, capillaries, and veins — Blood pressure ° The blood — Plasma — Cells of the blood Introduction The cardiovascular system has the extremely important responsibility of transporting blood with oxygen and nutrients out to all cells. It must also remove waste and carbon dioxide from the tissues. The main pump for the blood is the heart, and the vessels they move through are the arteries, arterioles, capillaries, and veins. _ I INTERSTITIAL : '.. molecules FLUID l I Tissue . cell Capillary Diffusion of Copyrrgl‘l‘l ":1 Tl'le MCGI'aw-Hlll companies llIC FerlnISSlOrl required for reproduction or UISpl-ay Lungs O2 absorbed f, whom i veins // CO2 released — \ . / *“H-xf -r ' " kt l / Pulmonary I: ' a}. ‘ I. " Ii circulation Pulmonary —\ arteries .\\ “ - I Systemic Systemic j ?_ BFTBTIES veins i \ rd _ _ “r \ r _ ‘r atrium ‘i. i i I “ll ‘ a. Left r Right - ' S i _ ventricle atrium 1“ . j - "p i\ ‘ . r“ _ tag ' . if, i ( Right ’ " ~ / \H ventricle 7 ' | ' \‘ \ \\ Systemic ‘ / I \ ‘3 \.\ circulation J J r' 7-“ A! 5.5"" . “It! II r . _ . A: {If If I \ “xx rgisv- r 3x l ' 02 released \‘ .' ' 21; CO2 absorbed *” Vic/’- All organs and tissue other than Iunus The Heart The heart is the Vital pump for all the blood in the body. It pumps the blood through two separate parts of the circulation: the pulmonary circulation (lungs) and the systemic circulation (all other tissues besides the lungs). It is necessary to pump blood to the pulmonary circulation so that oxygen can be absorbed and carbon dioxide can be released. This blood then gets pumped into the systemic circulation where it can deliver oxygen and uptake wastes like carbon dioxide. Heart Anatomy Aorta f I Pulmonary / artery LEFT a» ATRIUM t Pulmonary artery \ Superit\ vena cava \ _ RIGHT I, " ATRIUM\ Pulmonary ‘- . .r’ao v. l tr" ~ r‘ - "~7‘~Pulmonary veins :. . .‘ '7 ; -“"' veins Semilunar ‘ . ._ Semilunar valve . _ . \valve Atrioven- " '_ Atrioven- tricular '- tricular valve ' . valve Inferior Vena can RIGHT LEFT VENTRICLE VENTRICLE .I'Ltld I'J'I'f'H-‘usu JIMP'IIHI: Iru: The heart is divided into the right and left halves. Each half contains an atrium and a ventricle: so the four chambers are the right atrium, right ventricle, left atrium, and left ventricle. The atria pool blood for a little while before sending it into the ventricles. The ventricles send blood out of the heart, into either the pulmonary or systemic circulations. The right ventricle pumps blood into the pulmonary circulation (via the pulmonary artery), and the left ventricle pumps blood into the systemic circulation (via the aorta). Heart Anatomy :'-'.r.-.'-3--'. - Ihc r.L- .na Pulmonary — ' Aorta vein / . 1/ 5 // ,- Pulmonary .J 1 -. / // artery Superior - f/ _/ vena cave ._ '- ' " ,/ 'Lelt . ' ’ atrium lnteralrial ' ' - _ septum .- ' — Pulmonary ' vein atrium .‘ ‘ '- if Pulmonary '. N trunk Left Flight —’ . "' .. ventricle AV valve . '_ ' 'i fl. . r'llllrl I I - I '. I I ‘ :1 . Inferior ,3 ' . I - 'l .- , L f venacava ,/ 3 ' e't . '. ' - -‘ AV valve Flight—’ . ventricle ‘ lntervenlricrrlar Pulmonary and aortic valves septum In order to ensure the bloodis always going in the right direction, and there is no unwanted bac-kflow, one-way valves create the barriers. between the four chambers and the large vessels they pump into. The valves between the atria and ventricles are called atrioventricular valves (AV valves). The right AV valve is also called the tricuspid valve. The left AV valve can also be called the bicuspid valve or the mitral valve. The valves between the ventricles and the aorta/pulmonary artery are called the semilunar valves. The right ' semilunar valve is known as the pulmonic valve, and the left is the aortic valve. Blood Flow Pulmonary ‘ Circulation ’ Circulation The valves ensure the blood flows from the right atrium to the right ventricle, through the pulmonary artery into the lungs. The blood comes back from the lungs through the p ulmonary vein, and empties into the left atrium. From here, it goes into the left ventricle and is pumped into the aorta and the rest of the systemic circulation. The blood then returns through a large vein called the vena cava. Pulmonary Artery Pulmonary Vein Aorta Vena Cava Capillaries of superior upper body vena ca V3 Pulmonary Pulmonary Capillaries of right lung Pulmonary _ Pulmonary VEll‘l vein Left atrium Aorta Right atrium Inferior vena cava Capillaries of lower body “Mn Wl‘flw ng'nan, In: Contraction of Chambers 0 Heart is o Atria relaxed. _; / AV valves . W ff / contract. are open. .- k \ \ 2" l l SYSTOLE 0 Ventricles contract. Semilunar valves DIASTOLE are open. The heart chambers contract in a coordinated manner, with the atria contracting first, then the ventricles contracting together. When the ventricles are filling, and the atria are contracting, it is called diastole. Systole occurs during ventricular contraction. So when your blood pressure is taken, systolic pressure is the higher pressure (~120n'1n'1Hg), during the forceful ventricular contraction. Diastolic pressure is not as great (~80n1mHg), since the ventricles are resting and filling at this stage. Blood Vessels The blood vessels are the “pipes” that transport blood from the heart out to the rest of the body. Arteries and arterioles carry blood away from the heart, towards the circulation (pulmonary or systemic). Veins and venules carry blood towards the heart, away from the circulation (pulmonary or systemic). Between the arteries and veins, gases and nutrients are exchanged in capillary beds. Characteristics of Blood Vessels Epithelium — Epithelium -' - iii-j} muscle ARTERY , '-— Smooth fissue __ _ ARTERIOLE Direction of blood flow Basement / membrane In __...I Epithe- — - ‘_,fl ,5- _ <' Ilum Smooth —-' . CAPILLAfiv musc'e .. Connective Connective tissue VENULE Tissues —' VEIN Arteries and the smaller branches, arterioles, carry blood towards the tissue. Arteries are very elastic and have lots of smooth muscle around them. Capillaries do not have muscle around them. Instead, they have very thin walls so that gases and nutrients can diffuse across the walls into/out of the tissues. Veins are very compliant (they stretch), though they are not elastic (no recoil). They ensure blood keeps moving towards the heart thanks to the many one- way valves inside them. Arterial Pressure from Anefles Exitvia Because arteries are very elastic, arterioles they maintain the high pressure initially produced by the heart: the artery walls get stretched by the extra volume of blood, and then recoil, pushing the blood forward. This mechanism works -- similarly to that of a balloon r “’“it-hB'Ood filled with water then released, Blame Artery We, rem” untied: the water would be ” __ " " expelled from the balloon as the AM or WWW” WM, walls of the balloon recoil. Relative sizes and numbers of blood vessels 0. Velocity (cmfsec) Pressure (mm Hg) Blood Pressure 1 20 100 - 80 60 40 20 .. Diastolic pressure Systolic pressure 50' 40' 3O 20-- 10' 0 A0 rla Arteries Arterioles ’ Capillaries | Venules i Veins Venae cavae Here is a graph of blood pressure in the different blood vessels. As you can see, the high pressure can be maintained through the arteries. But notice that once the blood reaches the arterioles, which are not as elastic, the pressure drops significantly! By the time the blood reaches the capillaries, the pressure is almost zero, and velocity is also very small. The slow speed of the blood is important here to allow time for exchange of gases and nutrients. Arterioles Capillary bed o Arteriole dilated -'-'.\Ad:llu'_-'I'I'i‘l-I'lvfl, u':--;n"-'| III. e Arteriole constricted Although the arterioles are not very elastic, they control blood flow at the organ/tissue level. If a certain tissue does not need as much blood, the smooth muscle around the arteriole can constrict, limiting blood flow to that area. If a tissue/organ needs more blood, the smooth muscle surrounding the local arteriole can relax, letting blood flow freely to that tissue or organ. Capillary Exchange In the capillaries, fluids filled with nutrients need to leave the capillary, and fluids containing waste materials from the tissue must enter the capillary. This exchange of fluid depends on two pressures: blood pressure pushing out of the capillary and osmotic pressure pushing fluid into the capillary. The arterial end of the capillary has a relatively high blood pressure compared to the surrounding pressure wanting to enter the capillary via osmosis. Therefore, at the beginning of the capillary, the net movement favors fluid movement out towards the tissues. The end of the capillary now has very low volume, and therefore low blood pressure, so the osmotic pressure takes over, forcing fluids in. _____ ___ _ _p ,_ _ __ ___ — -- x- x‘r' “'-~——_ _ ___,__ _ "we" I ‘ ' 3‘7 3 Tissue cells ' - _7‘/< ___A __,.-<._‘fi_-¥ _A ##1,‘ _‘rh. _— - —— an“ Osmotic Osmotic 123%?! pressure Pressure V9210”? _ en 0 caplllarv i capiilarr )4 Blood Blood T" I Ii pressure pressure if} ' KW INTE RSTITIAL FLUID Net pgleflssure Net pressure \ _ _ _ “N In __________ w:- r- - —=<. __ ‘—~—/ 3..., 5:::-.I1.5J:JI.~-.:-'I 'u'flsulcr, .<:r'~='ri .'.'i ii ‘i. Veins After capillaries exchange fluids, the veins need to bring the leftovers back towards the heart. But remember that after the capillaries, we had very little, if not any blood pressure! So how can the veins pump the blood back towards the heart? The skeletal muscle pump: veins run between skeletal muscles, and when the muscles contract and widen, they push the blood along the veins by squeezing the walls of the vein inwards. Because the veins are fitted with one-way valves, the blood is sure to move in the right direction. This is why if a person is on bedrest or does not walk much, fluid can collect in the legs and feet. Direction of blood flow in vein Valve (closed) Skeletal Valve (open) muscle Withdraw blood .,.¢' Place in tube PLASMA 55% CONSTITUENT Salts Sodium Potassium Calcium Magnesium Chloride Bicarbonate Plasma proteins Albumin Fl brinogen Immunoglobulins (a nflbodles) MAJOR FUNCTIONS Solvent for carrying other substances Osmotic balance. pH butlerlng, and regulation oi membrane penneeblllty Osmotic balance pH butteran Clotting lmmun ity Substances transported by blood Nubiants [a.g.. glucose. fatty acids, vitamins) Waste products of metabolism Respiratory gases (til2 and 002} Hormones Fer '5'". Centrifuge CELLULAFI ELEMENTS 45% CELL TYPE NUMBER FUNCTIONS (per cu mm3 or blood} Erythrocytes 5—5 Transport oxygen {’96 blood GENE} million and help transport carbon dioxide Leukocytes Defense and [white 500040-000 immunity blood cells} ll ' ; .- . _ -. I Lym hot: 9 Basophll if .I p w . _ Eosirlophii _' Monocyte Neutrophil Platelets 1x- 250,000- , I, .;. 1.: a 40mm Blood clotting The Blood Although the blood may appear to be a homogenous red fluid to the naked eye, it is actually made of many things. The plasma, the fluid portion of the blood, contains many ions, nutrients, gases, and proteins, and makes up 55% of the blood volume. The other 45% is made of cells: mostly red blood cells which are responsible for oxygen transport, but also white blood cells that are important for immunity. In addition, platelets are cell fragments that used for clotting. Conclusions The heart is the major pump for the circulatory system, and has four chambers. It pumps blood into arteries, which carry the blood through arterioles, and into capillaries. Capillaries allow for gas and nutrient exchange before allowing blood to flow into the veins which return the blood back to the heart. The blood is made up of plasma, red blood cells, and white blood cells. Things to Remember! There are four chambers of the heart: right atrium, left atrium, right ventricle, and left ventricle The atria contract together, then the ventricles Arteries are highly elastic vessels that maintain blood pressure Arterioles control blood flow at the organ and tissue level Capillaries exchange fluid with the tissues Veins use the skeletal muscle pump to return blood to the heart ...
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This note was uploaded on 08/04/2010 for the course BME 5005 taught by Professor Vandvorde during the Spring '08 term at Wayne State University.

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Lesson_9_Cardiovascular - Dr. Pamela VandeVord BME 5005...

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