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The Circulatory System Functions of the Circulatory system 1. 2. 3. 4. Transportation of water, Oxygen, CO2 Distribution of nutrients Maintenance of body temp Circulation of hormones BLOOD Average amount of blood in a human body (70kg) =5L Constituents of blood 1. 2. 3. 4. Plasma Erythrocytes (red blood cells) Leucocytes (white blood cells) Platelets PLASMA • Pale yellow liquid component of the blood • Contains - dissolved gases - nutrients - wastes - hormones (factor 8 for blood clotting) - RBC - WBC - Platelets Red Blood cells (Erythrocytes) • No Nucleus! • Responsible for transporting O2 and CO2 • Contains haemoglobin molecules that allow the bonding of oxygen to the cells to occur (with haemoglobin, blood can carry enough O2 to support life for around 5 mins, without Haemoglobin the blood could support around 5 seconds of life) White Blood cells (Leucocytes) • Protect the body against disease • Much fewer in numbers than RBC • Several Types (all contain nucleus) -Some engulf foreign particles, -Some produce anti bodies and form the basis of the immune system. Platelets Small fragments of bone marrow Primary function is to assist in the clotting of blood Chemical Composition of blood (per 1L) Blood in centrifuge TASK BLOOD CONSTITUENTS • Read pages 121 – 124 of Nelson Biology 1 & 2 • Summary of red blood cells, white blood cells, plasma and platelets • Review Questions 1 – 18 THE CIRCULATORY SYSTEM • Read pages 124 – 128 • Summary of subheadings in text book • Draw Diagram of the heart labelling all chambers, valves, arteries and veins • Review Questions 19 – 27 COMPLETE CHAPTER 5 GLOSSARY! THE CARDIO VASCULAR SYSTEM TYPES OF CIRCULATION OPEN vs CLOSED OPEN: e.g. Fish, insects, arachnids • Some animals do not have specialised fluid such as blood for transport, rather they use the fluid in between cells called Interstitial fluid •This is known as an Open circulatory system •There is still the presence of a heart in organisms with an open circulatory system •This fluid is used to carry everything from CO2, O2 – carbohydrates and Hormones CLOSED: e.g. Mammals, Marsupials, etc (see next slides) Chambers of the heart THE HEART AND THE FLOW OF BLOOD FOUR CHAMBERS: 2 atrium (top), 2 ventricles (bottom) FUNCTION: The heart pushes blood around the body by its chambers contracting and forcing blood into the next chamber The blood needs to be pumped between the lungs and the cells of the body to carry O2 to the cells, and CO2 back to the lungs Backflow of blood is stopped by the valves THREE MAJOR VALVES Tricuspid valve between R ventricle and R atrium Mitral valve between the L Atrium and L Ventricle Pulmonary valve between rest of the body and the L Ventricle Blood flow through the heart OXYGENATED BLOOD Flow of blood: (From the body) Anterior Vena cava / Pulmonary vein, Right Atrium, Right Ventricle, Pulmonary Artery, Gives CO2 to lungs LUNGS Collects O2 from lungs Left Atrium, Left Ventricle, Aorta / Pulmonary Artery (To the body) THE BLOOD VESSELS Arteries: Carry blood away from the heart (oxygenated) Arterioles: Small arteries Capillaries: small veins, extend circulatory network right in between cells Veins: Carry blood to the heart (de-oxygenated) Capillaries Arterioles Arteries Heart cell Veins STRUCTURE OF ARTERIES Arteries are more muscular and thicker than veins, this is because they swell as each wave of blood is ejected from the heart. They then recoil to propel elastically to push blood further on STRUCTURE OF VEINS The Lumen of a vein is much larger than that of an artery. (over 60% of blood is distributed in the veins as a reservoir, should extra volume be required (exercise) Veins have valves to help prevent backflow Veins rely on the contraction of skeletal muscles to help propel blood back to the heart against gravity (draw diagram) LUNG STRUCTURE The lungs are basically a series of air sacs that fill with air due to the pressure difference inside the lungs and outside the body The air travels through a series of passages Trachea Bronchus Bronchioles Alveoli (point of diffusion) GAS EXCHANGE IN MAMMALS •One of the main functions of the blood is to carry O2 to the cells and CO2 back to the lungs to be expelled •This is achieved via diffusion occurring in the Alveoli in the lungs (see below) •Blood pathways carry blood past the alveoli were there is a very thin membranous surface where the CO2 can diffuse out of the RBC and into the alveoli sacs, and O2 Diffuses from the alveoli sacs into the RBC CONDITIONS REQUIRED FOR DIFFUSION •Surface must be moist (gases dissolve in an out by dissolving into water) •Must be a thin permeable membrane •Must have a concentration gradient allowing passive diffusion CELL PERFORMANCE To function the cells require O2 for respiration The more O2 cells get, the harder they can work (e.g. high intensity exercise) Very fit athletes can posses several factors that increase the levels of respiration they can undertake 1. Large lungs to take in large amounts of CO2 2. High diffusion efficiency between the lungs and blood 3. High O2 carrying capacity in the blood (high RBC + hemoglobin count)