D3.2 - Blood and Circulation (Updated 2024) PDF

D3.2 - Blood and Circulation I can… Describe the main components of blood and their role in transport, clotting and resisting the influence of pathogens (plasma, erythrocytes, platelets, leukocytes) Explain the role of blood in regulating body temperature Discuss associated disor...

D3.2 - Blood and Circulation I can… Describe the main components of blood and their role in transport, clotting and resisting the influence of pathogens (plasma, erythrocytes, platelets, leukocytes) Explain the role of blood in regulating body temperature Discuss associated disorders of the blood Blood Blood is considered to be a connective tissue because it links all cells and organs in the body ○ Connective tissue: Supports and connects different parts of the body (Ex. blood, bones) Blood Composition 1. Fluid portion Plasma 2. Solid portion Red blood cells (“erythrocytes”) White blood cells (“leukocytes”) Platelets Plasma Plasma: Fluid component of blood 55% of blood volume is plasma Consists of water, dissolved gases, proteins, sugars, vitamins, minerals, hormones, and waste products Carries all other blood cells Helps transport CO2 in blood Red Blood Cells (Erythrocytes) Erythrocytes are specialized for oxygen transport Its lack of a nucleus allows cells to carry hemoglobin molecules Hemoglobin is an iron-containing respiratory pigment required to bind oxygen “Folded disk” shape allows them to have much greater surface area than a spherical cell - can carry more oxygen Sickle Cell Anemia Sickle cell anemia is a genetic condition wherein red blood cells do not develop properly As a result, they can not bind hemoglobin, and are unable to efficiently carry oxygen White Blood Cells (Leukocytes) Leukocytes are also known as white blood cells ○ Make up 1% of blood volume Part of the immune system responses Contain a nucleus Much larger than red blood cells Double when your body is fighting an infection Different types of white blood cells include: monocytes, neutrophils, and lymphocytes Leukemia Cancer of bone marrow (where white blood cells are produced) Characterized by an abnormal increase in the production of immature white blood cells Leukemia weakens the immune system Also prevents blood from clotting normally, leading to frequent nosebleeds and bruising. Treatments: Blood transfusions, chemotherapy, bone marrow transplants Platelets Platelets are formed when larger cells in bone marrow break apart ○ Do not contain a nucleus ○ Break down quickly in blood Play a key role in blood clotting (prevents excessive blood loss) Stages of Blood Clotting 1. Injured blood vessel releases chemical messengers which attract platelets to the site. 2. Collecting platelets rupture and release substances that combine with other blood components to produce an enzyme called thromboplastin 3. With the help of calcium ions, thromboplastin reacts with prothrombin (a protein secreted by the liver), producing thrombin 4. Thrombin reacts with fibrinogen (a protein found within the plasma) to produce fibrin 5. Fibrin strands act as a sort of mesh, preventing blood cells from escaping and forming a clot Functions of Blood 1. Transport: Transports cells and other materials present in plasma (nutrients, waste, hormones, etc.) 2. Homeostatic regulation: Maintain temperature by balancing heat production and heat loss Vasodilation: Body’s internal temperature becomes too warm ○ Blood transports heat from where it’s formed by cellular respiration and muscular activity to blood vessels in skin ○ Nervous system causes vessels to dilate to increase amount of heat that can be lost from skin ○ Perspiration (sweat) can help body rid itself of excessive heat Vasoconstriction: Body’s internal temperature becomes too cold ○ Blood vessels near surface of skin are constricted in order to reduce amount of heat that is lost from skin ○ Shivering increases the production of heat by cellular metabolism Vasodilation and Vasoconstriction Can be influenced by… Blood pressure ○ High blood pressure is often a result of vasoconstriction ○ Low blood pressure is often a result of vasodilation Exercise ○ Promotes vasodilation in order to increase blood flow to tissues Alcohol and nicotine ○ Alcohol promotes vasodilation ○ Nicotine promotes vasoconstriction Hemophilia Hemophilia is a hereditary disease that results from insufficient clotting proteins in the blood This increases the risk of bleeding to death upon injury Those who have severe hemophilia have less than 1% of clotting protein in blood Can be treated by injecting with substance called “Factor VIII” (protein involved in coagulation) ○ Coagulation: Blood changing to a semi-solid/solid state