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The Circulatory System Section 3.3 p. 135 - 140 Learning Outcomes • I can describe the role and function of the circulatory system • I can list and describe the individual organs that make up the circulatory system, and how they work together • I can describe the how circulatory system responds to changing conditions The Role of the Circulatory System •The circulatory system's job is to deliver nutrients and oxygen to the cells of the body, and to move waste products (CO2) to the necessary organs where they can be expelled from the body The Heart • The heart is the pump that powers the circulatory system • About the size of your fist • It consists of • Two different circuits • Right side receives deoxygenated blood from the body, and sends it to the lungs to become oxygenated • Left side receives oxygenated blood from the lungs, and then pumps it to the rest of the body • Atriums: Receive blood into the heart • Ventricles: When they contract they pump blood out of the heart Heart Heart Valves • Valves prevent the backflow of blood keeping it flowing in the right direction • 4 Valves present in the human body • They are forced open the Atrium contractions • Forced closed by the Ventricle contractions • The opening and closing of these valves is responsible for the lub/dub sound you hear • Deficiencies with those valves results in a heart murmur Blood Vessels in your body • These are tubes that carry blood to and from the Heart • Inside diameter is referred to as the lumen • 3 Main types • Arteries • Veins • Capillaries • If laid end to end, make up 60 – 100 thousand Km’s • Lymphatic Vessels, assist but are not part of the circulatory system Arteries • Artery: Thick walled blood vessels that carry blood away from the heart • Arteries branch off to form smaller vessels called Arterioles • Arterioles continue to branch off into smaller blood vessels until they become Capilleries Capillaries • Capillaries: Tiny blood vessels that connect arteries to veins; one cell layer thick and extremely narrow • Tiniest of the blood vessels • Gas (O2→CO2) and nutrient exchange occurs here due to the extremely thin walls due to diffusion • Form networks that allow cells to be no farther away than 2-3 cells • Exchange only occurs in the Capillaries • The narrowness forces the forces the blood cells to pass single file • Capillaries merge with others to form Veinules Veins • Veins: blood vessels that return blood from the body to the heart • Veins contain valves known as Veinous Valves • Just like the heart valves, these valves are designed to prevent backflow • They are needed due to low blood pressure in the veins • When they malfunction they create a condition referred to as varicose veins • Two main veins that return blood to the heart are the superior and inferior vena cava Blood pressure in your body • Is a measurement for the pressure required by the heart to pump blood from the left ventricle all the way back to the right atrium • Pressure will be highest in the arteries closest to the heart • Pressure will be the lowest at the veins (Vena Cava) returning blood back to the heart (the system provides just enough pressure to return the blood back to the heart • Arteries are used when measuring both blood pressure, and pulses for this reason Blood Pressure Continued • Blood pressure is expressed in units of mmHg (common unit for pressure) • Results in the measurement at two different time • Systolic: Ventricle contracted • Diastolic: ventricle relaxed • Normal body pressure is 120 mm/Hg over 80mm/Hg • Measured by a Sphygmomanometer (works by listening for sounds) • Pulse allow you to record heart beat, due to the elasticity and recoil of the blood flowing through an artery Blood • Is a fluid connective tissue that flow through the heart and blood vessels • Second largest example of connective tissue in your body (behind bones) • 4 Main Components • Plasma • Red Blood Cells • White Blood Cells • Platelets • 5-6 liters in the human body • Circulates the body approximately every minute Plasma • Plasma: is the liquid portion of the blood • Water accounts for 90% of the plasma makeup • Makes up about 60% of the blood • Suspended in the plasma are the cells (elements of the blood) Red blood cells • Make up 99% of the “Elements” in the plasma • They are what give blood it color • Referred to as Erythrocytes (red) • Are Disc Shaped • Both top and bottom have concave compressions Red Blood Cells Continued • Cells are unique in that they have no Organelles • Contain large amounts of Hemoglobin • Job is to carry O2, and to remove CO2 • Average life span is 120 days (4 months) • Break down quicker due to no nucleus White Blood Cells • Are specialized to fight infection • Play an important role in the immune system • Many different types (5 types) • Neutrophils engulf bacteria • This occurs when our inflammation response occurs • Your body responds to a cut/potential source of infection • Phagocytes such as neutrophils are sent to the compromised area • To encourage this blood vessels dilate (widen) to increase blood flow to the compromised site Platelets • Function is the formation of blood clots to stop bleeding, and allow healing to occur • Very Short life span • Only a week • Derived from larger cells known as Megakaryocytes