Transcript File
Blood, circulation, and the Heart. The beat goes on… Your Blood Vessels… • Many years ago, people thought we were just walking sacs of liquid, with blood just sloshing freely inside of us (Ugly bags of mostly water). • Eventually, however, it was discovered that blood flowed through a tubing system of arteries and veins all through our body. Arteries • Are the vessels that carry oxygenated blood away from our heart to our body or lungs. • One exception – the Pulmonary artery carries deoxygenated blood to the lungs. • Very Muscular, thick walls, under great pressure • Main artery leading from the heart is the ‘Aorta’. Veins • Are the vessels that carry deoxygenated blood back to our heart. • One exception – the pulmonary vein carries oxygenated blood from the lungs to the heart. • Thinner walls, stretchy, with valves to control back-flow of blood. • Under less pressure than arteries. • ‘Varicose Veins’ happen when valves break down. Capillaries • Arteries and Veins are connected by a system of very tiny blood vessels called capillaries. • These are so small, only one blood cell can fit through at a time. • Very thin walls that allow diffusion of nutrients and oxygen to the cells, and waste products out of the cells. • Every cell in your body needs access to a capillary. Only flow in one direction • Valves prevent the backflow of blood into our heart or in our veins. They are flaps that allow the flow of blood in only one direction. • Found in veins and in the heart. ARTERIES-ARTERIOLES(GET SMALLER) Capillaries to Body Cells – diffusion of nutrients and gases VEINS – BACK TO HEART Each cell in the body is serviced by a capillary where… - Carbon Dioxide (and other waste) is taken out, and replaced with Oxygen. - Nutrients enter the cells. • Artery walls are thick, muscular, and not very stretchy. They are designed to help push the blood flow along, and do not allow nutrients to pass through easily. • These vessels get continuously smaller (arterioles), until they become capillaries – which have very thin walls, and exchange nutrients and gases more easily to your cells. • The blood then drains into your veins which are much more stretchy and much less muscular than your arteries. • The blood is then pushed back to your heart by the movement of your muscles Eg. When you walk, your leg muscles push the blood back up to your heart. • The Valves make sure that the blood flows in only one direction – towards your heart. If one is standing or sitting too long without moving their legs, the valves can start to break down, blood starts pooling in the veins in the legs, and they get a condition known as -Varicose Veins. • Once the deoxygenated blood gets back to the heart, it is transported to the lungs, where it exchanges the Carbon Dioxide wastes for fresh Oxygen. It then goes back to the heart where it is pumped back to the body to revisit the cells. Back to heart (Left Atrium) To body (from left ventricle) Back to heart (right atrium) To lungs (from right ventricle) Blood • Blood is a very important fluid in your body. It transports Nutrients and Oxygen to the cells, and then transports Waste Products away from them to the appropriate organs for removal/excretion. • Men have approx. 5 L of blood in their bodies, and women have approx 4 – 5 L • If any part of the body is deprived of blood for any length of time, waste products build up in the cells, and they eventually die. What is Blood? • Blood is made up of two parts; a liquid part, and a solid part. • The Solid matter is mainly made up of tiny blood cells and platelets. • The liquid part is clear and yellowish, and is called ‘Plasma’. Plasma • Plasma is 92% water, and 8% dissolved solids: – Eg. Glucose – Amino Acids – Minerals/Vitamins – Carbon Dioxide Plasma also carries Blood Proteins – there are three types that we will learn about… • Antibodies – Fight infection – your body makes very specific antibodies for specific infections • Hormones – Direct certain actions and processes in your body eg. Thyroxin – controls how fast you burn energy (metabolism) Adrenalin – released when you need to respond quickly to something (fight or flight) • Clot forming Proteins – work to repair broken blood vessels. The Solid Part of Blood Conisists of… • Red Blood Cells - Carry oxygen to all cells in the body - Contain ‘Hemoglobin’ – the molecule in the red blood cells that ‘grabs’ the oxygen and ‘lets go’ of it in places where it is needed. - 1 hemoglobin can carry 4 oxygen molecules - In order to make Hemoglobin, your body needs iron, which you get from dark, green, leafy veggies like spinach and broccoli. • Red blood cells live for about 120 days, and when they die, they go to the liver to be recycled into ‘bile’. • The iron is removed and used in the new blood cells which are produced in the marrow of your bones. • Iron deficiency = anemia • Leukemia is ‘blood cancer’ which prevents you from properly making new blood cells. Treated with a ‘marrow transplant’. White Blood Cells (Leukocytes) • Work with antibodies to fight off invaders like viruses and bacteria. • There are different types – some made in the bones, spleen, and tonsils. Platelets • Collect where there is damage to blood walls (a cut) • Release chemicals that activate the ‘clot forming proteins’. • Hemophelia – your blood doesn’t clot properly.