The Function of circulation

1. The Function of circulation SBI3U Section 12.1 Pg 478-487

2. Main Functions of the Circulatory System • Transports gases (from respiratory system), nutrient molecules and waste materials (from digestive system) • Regulates internal temperature through expanding of capillaries causing heat to be released (flushing of skin) and transports chemical substances • Protects against blood loss from injury through clotting of blood • Protects against disease-causing microbes or toxic substances introduced into the body through the action of white blood cells

3. Major Components of Circulatory System Heart – muscular organ that pumps blood through the body Blood Vesseles – System of hollow tubes through which the blood moves Blood - Fluid that transports nutrients, oxygen, carbon dioxide and other materials throughout the body

4. Types of Circulatory Systmes Open Circulatory System – blood flows freely within the body cavity and make direct contact with organs and tissues mixing with the interstitial fluid creating a fluid called hemolymph Note: The interstitial fluid is fluid that surrounds the cells providing cells with nutrients and waste removal Closed Circulatory System - The blood is contained within vessels andseparate from other body tissues. The blood flows in a fixed path of circulation and is kept separate from the interstitial fluid

5. Blood Vessels • Arteries – Carries oxygenated blood away from the heart • Veins – Carries (in most cases) oxygen depleted blood towards heart • Capillaries – Single celled branching blood vessels that form a network between smaller diameter arteries (arterioles) and smaller diameter veins (venules). They allow for the transfer of gases, nutrients and other materials from the blood to the tissue cells

7. The Human Heart • The heart is located slightly to the left of the middle of the chest and is about the size of your fist • The walls of the heart are made out of cardiac muscles , which allow the heart to be resistant to fatigue due to the large number of mitochondria. • A good supply of oxygen rich blood also contributes to the hearts resistance to fatigue

8. Structure of the Heart • Has four chambers • Top chambers (atria) receive blood from body • Bottom Chambers (Ventricles) pump blood to body our lungs

9. Right Side of Heart • Right side of heart receives deoxygenated blood from body and pumps it out to the lungs • The superior vena cava collects oxygen poor blood from the tissues in the head, chest and arms • The inferior vena cava collects oxygen poor blood coming from elsewhere in the body • Oxygen poor blood flows into right atrium and then into right ventricle and out into the pulmonary trunk • It then enters the left and right pulmonary arteries and flows to the lungs for gas exchange

11. Left side of heart • Receives oxygen rich blood from the lungs which flows through the pulmonary veins to the left atrium • The pulmonary veins are the only veins that carry oxygenated blood • The left atrium pumps blood into the left ventricle which then leaves the heart through the aorta

13. Heart Valves • Atrioventricular Valve - A valve in the heart between the ventricle and atrium • Semilunar vale - A valve between the ventricle and the large arteries (it carries blood away from heart)

14. Mammalian Circulatory System • Blood that travels from heart to lungs carries deoxygenated blood containing a high concentration of waste carbon dioxide • Carbon dioxide diffuses from blood into lungs through capillaries in the alveoli and blood is oxygenated from the oxygen in lungs • Oxygenated blood moves back to the heart and is then pumped to the body tissues

17. Blood • Is considered to be a tissue because it consists of specialized cells and is a major component in the animals physical makeup • It is considered to be a connective tissue because it links all the cells and organs in the body Blood consists of two portions: Fluid Portion (Plasma) – consists of water, dissolved gases, proteins , sugars, vitamins, minerals and waste products Solid Portion - Consists of red blood cells, white blood cells and platelets which are produced in the bone marrow

19. Plasma • Is a clear yellowish fluid composed of 92% water and 7% blood proteins and 1% organic substances and inorganic ions (sodium, potassium, chloride and bicarbonate) Main blood proteins (also termed serum proteins): Albumin - contributes to oncotic pressure which helps transport molecules in the blood. (Note: Oncotic pressure occurs due to water from the interstitial fluid rushing into the blood vessels) Globulins - transports ions, hormones and lipids that aid in immune function Fibrinogen – Is essential for blood clotting

20. Red Blood Cells and Their Functions • Red blood cells (also called erthrocytes) are disk shaped, do not have a nucleus and are specialized for oxygen transport • Oxygen caring capacity of blood is dependent on the number of red blood cells and amount of hemoglobin each red blood cell contains • Hemoglobin has special properties that allow it to bind to oxygen and release oxygen to the cells that need it. It also transports carbon dioxide waste from cells

21. White blood Cells • White blood cells also called leukocytes appear to be colourless and have nuclei. They help fight infections Phagocytes - are white blood cells that engluf and destroy pathogens by a process called phagocytosis Five types of White blood cells: Neutrophils – Found in body tissues and blood and defend against bacterial and fungal infections. Their activity and death in large numbers forms pus. They are a type of phagocyte. Eosinophils- Found in the mucous lining of the digestive and respiratory tracts and deal mainly with parasitic infections

22. Basophils - Aid in immunity by secreting substances that attract phagocytes to destroy pathogens. They are responsible for allergic reactions through the release of the chemical histamine causing vasodilation Lymphocytes - Produce proteins called antibodies that incapacitate pathogens and allow them to be easily detected and destroyed Monocytes - Circulate in the bloodstream for only a few days before they become specialized as macrophages, which destroy bacteria. They are a type of phagocyte

23. Platelets and their Function • Platelets (also called thrombocytes) are membrane bound fragments of cells that don’t contain nuclei and break down in the blood within 7 to 10 days • They form when larger cells in the bone marrow break apart • They play a key role in clotting blood

25. Steps to blood clotting • When a blood vessel is broken chemicals are released that attract platelets to the site of the injury • Platelets rupture, releasing chemicals that combine with other chemicals in the plasma to produce the enzyme thromboplastin • As long as calcium ions are present, thromboplastin reacts with prothrombin (a protein made by the liver) to produce the enzyme thrombin • Thrombin reacts with fibrinogen to produce the protein fibrin which forms a mesh over the site of injury forming a clot

28. Temperature Regulation Vasodilation - is an increase in blood flow by widening (dilating) of blood vessels increasing the volume of blood near the bodies surface when the body becomes hot. As sweat evaporates heat is released . Vasoconstriction - is a decrease in the flow of blood by narrowing of the blood vessels near the surface of the skin reducing the amount of heat lost