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Unit 4.docx

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University of Waterloo
BIOL 273
Catherine Studholme

UNIT 4 OVERVIEW OF THE CARDIOVASCULAR SYSTEMTHE HEARTA Role of the Cardiovascular System pg 463464Multicellular OrganismThe problem with being multicellular is that you are very bigOnly the surface layer is in contact with environment We require from the environmento Nutrients water gasRate of diffusion of oxygen and nutrients is limited by distance Overcome this diffusion limitation byo Cardiovascular system for transport of substances through the bodyo Transported by flow of blood through circulatory systemo Bulk flow rather than diffusionMaterials Transported From the external environment to tissues nutrients water gases Between tissues of body wastes nutrients hormonesFrom tissues to external environment metabolic wastes gases heat Major material transported oxygeno Many cells absolutely require oxygen to survive o Lack of oxygen causes irreparable damage o Brainmost oxygen dependent organ in the human bodyo 510 secs of interrupted blood flow loss of consciousness o 510 min interrupted blood flow permanent brain damage Components of the Cardiovascular System pg 464466 Components heart pump blood vessels vasculate blood cellsplasma fluidsBlood Vessels Arteries away veins towards o System of valves keep blood moving in one directiono Between arteriesveins are a network of capillaries Path of bloodaorta carries oxygenated blood from the heart o Arteries branch into series of smaller arteries that lead into capillaries still oxygenated thin walled vessels allow exchange of materialso Blood in capillaries move into smaller veinsthen larger veins muscle prevent exchange The HeartDivided functionally into two separate pumps that work in serieso LeftrightIn the body the separated pumps that work in serieso Atrium ventricleaortaarteriesIn the body the separate pumps are next to each other in one organ and pump together simultaneously Exit from heart highest pressure to blood vessels low pressureo Entrance from lowest pressure venae cavae to aortaWhy have two pumps in series o Pump 1 deoxygenated rightcontracts decreases in volumeIncreases the pressure Pumps blood into the lungs through arteries Blood picks up oxygen for transport to the rest of the body Lungs contain very many small capillaries to increase O 2transferSmall radius high surface area to increase resistance and decrease pressure Blood is oxygenated but it also has very low pressure How can it get to the rest of the body to deliver the oxygen PUMP 2o Pump 2 oxygenated left contracts decreases in volume Increases the pressure Blood flows to the rest of the body Organs of the body contain many capillary beds Small radius high surface to increase resistance and decrease pressure Blood is deoxygenated and arrives back at pump 1 with very low pressureo Pump 1 contracts decreases in volume and repeats as aboveo The pumps increase the pressure at critical points in the double cycleo Gives blood the pressure needed to make it to lungs or periphery and back even though it has to pass through capillary beds which cause decreased pressure External Anatomy of the HeartPericardiuma tough membranous sac surrounding the hearto Made up of two layers with a small amount of fluid between them that acts as a lubricant o Can become inflamed pericarditiso Amount of fluid between two layers increases and compresses the heart restricts its action Coronary arterieso Supplies blood to the hearto Heart has a very high oxygen demando Absolutely depends on adequate blood flow Lack of blood supply to the heart leads to a heart attack myocardial infarctiono This is damage or death of an area of the heart muscleo If the blood supply is cut off severely or for a long time there may be irreversible injury or death to muscle cellso How much heart muscle is damaged can lead to disability or death
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