Blood Composition and Function Lectures 2023/2024 PDF

Composition and Function of Blood • • Lecture 2 • Chapter 6 Academic Year 2023 • Dr. Tarik AlShaibani What are the functions of blood? / · • ↑ Transportation: langs - Blood- Cells - Nutrients : When eaten absorbed oxygen, nutrients, wastes, carbon dioxide, nitrogen from amino Go...

Composition and Function of Blood • • Lecture 2 • Chapter 6 Academic Year 2023 • Dr. Tarik AlShaibani What are the functions of blood? / · • ↑ Transportation: langs - Blood- Cells - Nutrients : When eaten absorbed oxygen, nutrients, wastes, carbon dioxide, nitrogen from amino Good acids and hormones, lipoproteins HDL and estore] LDL low Jensity Release High density Wastes - · - : Hormones in CO2 are , nutrients are . blood + Stool transferred by blood - ↓ • • Bas Hemoglobin carries oxygen and CO2, (CO poisoning) S Defense: against invasion by platelet pathogens, and by clotting prevent [Thromboxin positive blood loss ( prothrombin and feedback] fibrinogen) 2 • ↑ Homeostasis Regulatory functions: body temperature, water-salt balance, blood pressure by plasma proteins, and body pH acid-base balance.(chemical buffers) Buffers ~ sponge example Hydrogen regulators are a a already is hidrogen when - T Transport • Blood is the primary transport medium. • Acquires oxygen in the lungs and distributes it to all cells, and in in its return trip, CO2 from cell to lungs. • Blood picks up nutrients from the digestive tract for delivery to tissues. • Blood also transport waste products, and excess nitrogen from the breakdown of protein, to the kidneys for elimination; ( maintaining Homeostasis). Loading… • Blood transport hormones to target organs or cells. • Lipoproteins as transport vehicles for hormones • special proteins such as HDL & LDL carry lipids or fats. • Hemoglobin (found in red blood cells) is specialized to carry oxygen to the cells and also carries CO2 as a waste product back to lungs. Defense • Blood defends the body against pathogen invasion and blood loss. • White blood Cells (WBC) are capable of engulfing and destroying pathogens by phagocytosis. • Other WBC produce and secrete antibodies (AB) • an antibody is a protein that combines with and disables specific antigens which then can be destroyed by phagocytes. • In injury, such as a cut in your hand, blood clots and defends against blood loss. Role of platelets. Without blood clotting we could bleed to death even from a small cut. REGULATION • Blood plays an important role in regulating the body’s Homeostasis. • Helps regulate body temperature by picking up heat from active muscles and transporting it around the body. • The liquid portion of blood (plasma) contains dissolved salts and proteins. These solutes create blood’s osmotic pressure which keeps the liquid content of the blood high. • Blood contains chemical buffers that stabilize blood pH i.e., the acid-base balance, and keeps it at a relatively constant 7.4. Loading… What is the composition of blood? • • – – – • – – – Remember: blood is a fluid connective tissue composed of: Formed elements: produced in red bone marrow (Stem cells) Red blood cells/erythrocytes (RBC), small but numerous (in millions in mm3) White blood cells/leukocytes (WBC), 3 times bigger but less in number (in thousands in mm3) Platelets fragments of cell (in hundred of thousands in mm3) Plasma: 91% water and 9% salts, and organic molecules (buffer) Plasma proteins are the most abundant molecules (albumin, globulin, fibrinogen made by liver, but gamma globulin is made by lymphocytes) (osmotic pressure) Also, glucose, amino acids, nutrients, urea. Composition of blood When blood transferred to a test tube and is prevented from clotting, it forms two layers. The transparent, yellow, top layer is plasma, the liquid portion of blood. The formed elements are in the bottom layer. The tables describe these components in detail. 1- Transport. 2-Protection. 3-Temp. regulation. 4-Clotting. 3 major types of plasma proteins • Albumins – most abundant and important for plasma’s osmotic pressure as well as transportation • Globulins – Alpha and Beta, ( transport substances) and Gamma globulins produced by lymphocytes ( anti bodies fight infections). • Fibrinogen – an inactive protein, important for the formation of blood clots Blood cells Loading… Hemoglobin Formation and Transport of gases • . Where do the formed elements come from and what are they? Red Blood Cells • RBCs are highly specialized for O2 transport. • Contain HEMOGLOBIN (Hb), a pigment with a high affinity for O2. Responsible for the red coloration of RBC’s and blood. The structure of red blood cells is important to their function Lack a nucleus and few organelles (e.g., no Mitochondria, anaerobic ATP production so not use the O2 they carry). O2Hb, and deoxyHb. Biconcave shape increases surface area. Greater surface area for the diffusion of gases into and out of the cells. Contains about 280 million hemoglobin molecules that bind 4 molecules of O2 each (one RBC can carry 1 Billion O2 molecules) HEMOGLOBIN • Hemoglobin contains two portions globin and heme. • The globin portion of Hb contains four highly folded polypeptide chains. • The heme part of Hb is an iron containing group of each polypeptide chain • The iron combines reversibly with O2. • Carbon monoxide (CO) has much stronger affinity for Hb than O2. • O2 binds to heme in the lungs and becomes OXYHEMOGLOBIN • In the tissues, Heme gives up O2 and becomes DEOXYHEOGLOBIN. How is Oxygen transported? • O2 is found in two forms in blood : • about 97% of the oxygen in blood is found as associated with hemoglobin which indicates hemoglobin saturation • 3% as dissolved oxygen in the plasma, which gives the oxygen partial pressure (PO2) How is carbon dioxide transported? • • CO2 is found in three forms in blood : In Plasma 68% as a bicarbonate ion in the plasma (this conversion takes place in RBCs by the enzyme. Carbonic anhydrase) In RBC • 25% in red blood cells (in Hb, CO2 combines with the terminal amino groups of globin molecules). Hb carrying CO2 is called (Carbaminohemoglobin ) • 7% as dissolved carbon dioxide in the plasma Buffered by amino acids of the globin portion of Hb Destiny of carbon Dioxide • In The Tissues • CO2 moves into RBC’s, it then combines with RBC’s water to form carbonic acid H2CO3. • An enzyme called carbonic anhydrase speeds the reaction. • Carbonic acid dissociates to form H+ and bicarbonate. • H+ then binds to globin, the protein portion of Hb. • Thus , Hb assists plasma proteins and salts in keeping the blood pH constant. • In the Lungs • The reaction is reversed, H+ ions and HCO 3 reunite to re-form carbonic acid with help of carbonic anhydrase enzyme • Producing CO2 and H2O. - Production of red blood cells • Produced in the red bone marrow • Lifespan of about 120 days ( 2 millions RBCs die/second) (RBC destruction and Hb release) • Old cells are destroyed by the liver and spleen (globin is converted into amino acids, Heme is converted into iron and chemical product excreted by liver into feces) • Erythropoietin (EPO) is a hormone released by kidney cells and moves to red marrow when oxygen levels are low Destiny of Red Blood Cells • Stem cells in the bone marrow called RBC stem cells divide and produce new cells that differentiate into mature RBCs. • In the process of maturation of RBCs, they acquire Hb and lose their nucleus and other internal organelles. • RBCs, therefore, are not able to carry out cellular respiration and rely on glycolysis and fermentation. • Due to lack of nucleus RBCs are unable to replenish important proteins and repair cellular damage. • Therefore, RBCS live only about 120 days • When RBCs age, they are phagocytized by white blood cells (macrophages) in the liver and spleen. • About 2 million RBCs are destroyed every second, and therefore an equal number must be produced to keep the RBCs number in balance ( homeostasis). • The globin portion of Hb is broken down into its component amino acids and recycled in the body. • The majority of iron is recovered and returned to the bone marrow for reuse. • The rest of the heme portion undergoes chemical degradation and is excreted by the liver and kidneys. What is blood doping? • • Erythropoietin: a kidney hormone stimulates bone marrow stem cells Any method of increasing the number of RBC’s to increase athletic performance • It allows more efficient delivery of oxygen and reducing fatigue • EPO is injected into a person months prior to an athletic event (before race, units of his blood is centrifuged and administered to him) • • Is thought to be able to cause death due to thickening of blood that leads to a heart attack Functions of White Blood Cells • Lecture 3 • Year 1 Academic year 2023/2024 • • Dr. Tarik Al Shaibani Where do the formed elements come from and what are they? • • • • • • • • White blood cells Derived from red bone marrow Large blood cells that have a nucleus Production is regulated by colony-stimulating factors(CSF), specific CSF for each WBC type. Can be found in the blood as well as in tissues Fight infection, cancer cells, and foreign proteins. They make an important part of the immune system. Some live days and others live months or years Phagocytosis (process/ lysosomes) and antigenantibody reaction. In a person with normal bone marrow, the number of WBC can double within hours, if needed. • WBC’s can squeeze through pores in the capillary wall; therefore, they are found in tissue fluid and lymph. • White Blood Cells fight infections, an important part in the immune system. That defend the body against pathogens, cancer cells, and foreign proteins. • Many WBCs live for few days, often they die while the fighting pathogens. Other live for months or even years. • A Pathogen is any foreign body ( an antigen) that causes a disease. Movement of WBC’s out of circulation Ways of White Blood Cells to fight infection • By Two Ways: • Phagocytosis: a projection from the white blood cell surrounds a pathogen and engulfs it. Then a vesicle containing the pathogen is formed inside the cell. Lysosomes attach and empty their digestive enzymes into the vesicle. The enzymes break down the pathogen. • Antibody Production: WBC’s produce antibodies (Ab’s). ABs are proteins that combine with antigens. The antigen-antibody pair is marked for destruction by phagocytes • • Thymus · · · · · · · · A 3% rate pass WBC's learn wisc's who The ones Thymus The ories Some WBC's for school about fail who T cells be will who pass retires for assigned fight can after lail antigens all called might initiate a . specific antigen . any antigen years : All WRC's are a T cells . coup. are trained . How are white blood cells categorized? • WBCs are categorized into Two Types: • 1) Granular Leukocytes or Granulocytes are a category of – – – – – white blood cells characterized by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes (PMN, PML, or PMNL) because of the varying shapes of the nucleus, which is usually lobed into three segments. Neutrophils : account for 50-70% of all WBC’s. Multitoned nucleus so the are called polymorph, so they are called polymorphonuclear leukocytes or polys. First to respond to bacterial infection. Eosinophils : have bilobed nucleus, red in color. Protection against large parasites ( parasitic worms) also involved in phagocytisis of allergens. Basophils: The least in number of the WBC’s. U-shaped nucleus. Dark-blue in color. In the connective tissues, basophils and mast cells, release histamine associated with allergic reaction. 2) Agranular Leukocytes or Agranulocytes Agranular – Do not have granules and have nonlobular nuclei. They sometimes called mononuclear leukocytes. They include: 1) Lymphocytes and 2) Monocytes Types of Agranular White Blood Cells (Agranulocytes) • • • • 1) Lymphocytes: form 25-35% of all WBC’s. Responsible for specific immunity to particular pathogens and toxins. They are of two types: B lymphocytes ( B cells) and T lymphocytes ( T cells). B cells mature and called Plasma cells which produce Antibodies. T cells are different types; cytotoxic T cells, helper T cells and memory T cells. Cytotoxic T cells directly destroy pathogens 2) Monocytes: Manooy • They are active phagocytes • Are the largest of the WBC’s. • After taking up residence in the tissues they differentiate into even larger macrophages. • If they take residence In the skin, they are called DENDERITIC differen is CELLS Their organ • • • name => in • Loading… - every . Neutrophils, macrophages and dendritic cells are all active phagocytes. Mono eats more though = • Macrophages and dendritic cells also stimulate other WBC’s, including lymphocytes, to defend the body. ↑ Backup • Composition of blood When blood transferred to a test tube and is prevented from clotting, it forms two layers. The transparent, yellow, top layer is plasma, the liquid portion of blood. The formed elements are in the bottom layer. The tables describe these components in detail. 1- Transport. 2-Protection. 3-Temp. regulation. 4-Clotting. • About 50-70% of all WBC’s Small percentage of WBC’s • Contain a multi-lobed nucleus • Upon infection they move out of circulation into tissues to use phagocytosis to engulf pathogens. Too much dead neutrophils called US. Small percentage of WBC’s Contain a U-shaped or lobed nucleus Together with Mast cells they release histamine (dilates BV, and constrict air tubes) related to allergic reactions Contain a bilobed nucleus Many large granules function in parasitic infections and play a role in allergies About 25-35% of all WBC’s Large nucleus that takes up most of the cytoplasm Develop into B (gives rise to Plasma cells) and T (gives rise to cytotoxic T cells) cells that are important in the immune system Relatively uncommon WBC’s (4-8%) Largest WBC with horseshoe-shaped nucleus Take residence in tissues and develop into macrophages (dendritic cell in the skin) Macrophages use phagocytosis to engulf pathogens, they also stimulate other WBC to defend the body. Platelets and blood Clotting • . Where do the formed elements come from and what are they? Platelets ( Thrombocytes) • Made of fragments of large cells called megakaryocytes made in the red bone marrow • About 200 billion are made per day. Platelet count is 150-300 thousands/ mm3. • Their function is to cause blood clotting, or Coagulation. • Blood proteins named prothrombin (Vit. K is necessary for its production) and fibrinogen are important for blood clotting by leading to the formation of fibrin threads that catch RBC’s. Blood Clotting • Function : The blood-clotting process helps the body maintain homeostasis in the cardiovascular system by ensuring that the plasma and formed elements remained within the blood vessels. • STEPS OF BLOOD CLOTTING: • 1) When a blood vessel is damaged, platelets clump at the site of the puncture and partially seal the leak; ( plug formation). As platelets aggregate, they release thromboxane, making the platelets stickier ( an example of positive feedback). • 2) platelets and the injured tissue release a clotting factor called PROTHROMBIN ACTIVATOR that converts in the plasma prothrombin to thrombin ( this step needs Calcium). Blood Clotting (Continue) • 3) Thrombin then acts as an enzyme that converts FIBRINOGEN to FIBBRIN • 4) step 3 results in the production of activated fibrin fragments which are then join end to end forming long threads of fibrin. • 4) Fibrin threads wind up around the platelets plug in the damaged area of the blood vessel and provide the framework for the clot. • 5) RBCs trapped within the fibrin threads make the clot appear red. Resolution of Clot • Once blood vessel repair starts, an enzyme called PLASMIN, destroys the fibrin network so tissue cells can grow. • After blood clots, a yellowish fluid called SERUM escapes from the clot. • Serum contains all the components of plasma except fibrinogen and prothrombin. • SERUM = plasma – fibrinogen and prothrombin How do platelets clot blood? Serum: is Plasma without Fibrinogen and prothrombin Plasmin: dissolves the blood clot The Effect of Aspirin • Aspirin inhibits the activity of THROMBOXANE making the platelets less likely to stick together Disorders Related to Blood Clotting • Thrombocytopenia : deficiency in platelets number due to either low production in bone marrow or increased breakdown of platelets outside the bone marrow. • If the lining of a blood vessel becomes roughened, as clot can form spontaneously inside an unbroken vessel, this clot is called THROMBUS, if it stays stationary in the blood vessel. • If the clot dislodges and travel in the blood, it is called EMBOLUS, if not treated blood flow to tissues can stop completely. • Hemophilia: is an inherited clotting disorder that causes deficiency in clotting factors, like factor VIII.