Year 8 Biology Lesson 6 - Circulatory System PDF

Year 8 Biology Lesson 6: Circulatory System Aka - The Cardiovascular System GLEERUPS 6,10 GLEERUPS 6,11  Lesson Objectives By the end of the lesson, you should be able to Describe the overall purpose and function of the Circulatory Syst...

Year 8 Biology Lesson 6: Circulatory System Aka - The Cardiovascular System GLEERUPS 6,10 GLEERUPS 6,11  Lesson Objectives By the end of the lesson, you should be able to Describe the overall purpose and function of the Circulatory System State the various components of blood and explain their functions. Relate the structure of arteries, veins and capillaries to their functions. Describe the structure and function of the heart. 2 Transport System The job of the circulatory system is to Transport essential things around the body. Protection System Some things it transports help to protect the body from illness and injury 3 Human Circulatory System Is made of: Blood Vessels that run through the entire body Blood, which flows through vessels Heart which ensures that blood keeps flowing through blood vessels 4  Layers of Learning Extra Facts and Details Red Blood Plasma Veins Cells Parts Arteries Capillaries White Blood Platelets Cells Layer 3 Layer 3 Layer 3 Blood Blood Heart Vessels Layer 2 Transport Protection Circulatory Layer 1 System Transport Functions Blood acts as a transport medium carrying various substances: ○ Digested food ○ Waste products (e.g. urea and carbon dioxide) ○ Oxygen 6 Protective Function – BLOOD CLOTTING ▸ When bleeding happens, blood can stick together to stop further bleeding. This is called blood clotting. ▸ Clotting (blodpropp) (or coagulation) seals the wound ○ preventing excessive loss of blood ○ stopping microorganisms from entering bloodstream 7  Protective Function – White Blood Cells ▸ Killing Diseases that get into the body (Ingesting and digesting of foreign particles) ▸ Production of antibodies (antikroppar) 8 Components of Blood Blood is a connective tissue consisting of cells floating in a liquid called plasma. An average person has about 5.5 litres of blood. 9 10 Blood Plasma (blodplasma) Pale yellowish liquid Consisting of about 90% water Contains important dissolved substances ○ Products of food digestion ○ Mineral salts ○ Waste products ○ Hormones 11 Red Blood Cells (röda blodkropp) Main function is to transport oxygen from the lungs to all cells in the body. 12  Red Blood Cells - how they carry oxygen Contain haemoglobin (a special protein containing iron) haemoglobin Combines with oxygen 13 Red Blood Cells - Facts Produced by bone marrow Lifespan: About 120 days About 2.4 million new Red Blood Cells are produced per second in human adults About 5 million red blood cells in each mL of blood 14 White Blood Cells Originate in bone marrow Larger than RBCs but are fewer in number Ratio of RBCs to WBCs = About 700:1 15  White Blood Cells Play an important role in defence of the body against diseases. 2 ways: ○ Ingest and digest foreign particles, e.g. bacteria ○ Produce antibodies (antikroppar) to protect body from disease-causing organisms 16 Platelets (blodplättar) Fragments of cytoplasm from bone marrow cells Involved in clotting of blood (blodpropp) 17 Blood Vessels (blodkärl) 18 19  Artery (artär) Carries blood away from the heart Mainly carries oxygen-rich blood Blood pressure is HIGHER than in vein, and blood flows faster 20 Artery (artär) Has THICKER, MORE elastic and muscular walls than vein ○ Helps to withstand high blood pressure in artery Elastic to help artery to stretch and recoil (i.e. spring back) to push blood ○ Results in pulses 21 Artery (artär) Has a SMALLER lumen (space) relative to diameter ○ helps to maintain the high blood pressure in the artery 22 Vein (ven) Carries blood towards the heart Mainly carries oxygen-poor blood Blood pressure is LOWER than in artery, and blood flows more slowly and smoothly Has THINNER, less elastic and muscular walls than artery 23 Capillary (kapillär) Microscopic blood vessel found between cells of all tissues Has thin wall consisting of only one layer of cells The wall has pores and is partially permeable thus allowing small substances to diffuse through quickly 24 Capillary (kapillär) Highly branched forming an extensive network providing a large surface area for exchange of materials between blood and cells 25 What does the blood contain VIDEO  Heart Located in thorax (bröstkorg) behind chest bone and between two lungs 27 Heart Made up of 4 chambers: ○ 2 upper atria (singular: atrium) (förmak) ○ 2 lower ventricles (kammare) 28  Heart Right side is separated from the left side of the heart by a muscular wall ○ septum ○ prevents mixing of oxygen-rich and oxygen-poor blood. 29 30  Path of Blood through Heart Atria have thinner walls to force blood into the ventricles. Right ventricle Left ventricle has thick muscular has thicker muscular walls to move blood walls than the right into the lungs. ventricle as it has to pump blood to the rest of the body.  Blood vessels associated with the heart pulmonary artery Aorta Largest artery, carrying oxygen-rich blood Carries oxygen-poor blood from the right ventricle from the left ventricle to the rest of the body. to the lungs. pulmonary artery (lungartär) superior (anterior) vena cava (hålven) pulmonary veins Returns oxygen-poor blood from the upper body to the right atrium. (lungven) Carry oxygen-rich blood from the lungs to the left atrium. inferior (posterior) vena cava (hålven) Returns oxygen-poor blood from the lower body to the right atrium.  7 Blood leaves the heart via the aortic arch and is Path of Blood through Heart pumped to rest of body 1 Oxygen-poor blood returns to the heart 4 Blood leaves the heart via the vena cava and enters lungs via the pulmonary arteries 2 Right atrium contracts and blood 5 Oxygen-rich blood from flows into right the lungs flows to left ventricle atrium via pulmonary veins 3 Right ventricle 6 Left ventricle contracts contracts and blood and blood flows towards leaves through aortic arch pulmonary arch Summary of Blood Flow Oxygen-rich blood Lungs → Pulmonary veins → Left atrium → Left ventricle → Aorta → Rest of body Oxygen-poor blood Rest of body → Vena cavae → Right atrium → Right ventricle → Pulmonary arteries → Lungs How does the bloodstream work VIDEO 35  Check Your Understanding What are the various components of blood and what does the each of them do? Compare the structure of arteries, veins and capillaries and how does these differences help in their functions? How does the various structures of the heart help in its functions? 36