Blood (2).pptx

Blood [email protected]  Learning Outcomes List the key functions of blood Briefly describe how blood is transported List the constituents of the three components of blood (Red Blood Cells, ‘buffy coat’, and plasma’) Describe the structure and func...

Blood [email protected]  Learning Outcomes List the key functions of blood Briefly describe how blood is transported List the constituents of the three components of blood (Red Blood Cells, ‘buffy coat’, and plasma’) Describe the structure and function of each of those. Describe the production and destruction of Red Blood Cells Read: Chapter 17 (except transfusion): Marieb and Hoehn; Human Anatomy and Physiology (10th edition)  Blood is… The scientific study of blood, blood-forming tissues, and its associated disorders……. Haematology and Transfusion Science Blood is… A fluid connective tissue No collagen or elastic fibres But fibrin visible during clotting The only fluid tissue in the body ~8 % total body weight Blood volume ~5-6L male ~4-5L female pH 7.4 (7.35-7.45) © 2016 Pearson Education, Inc. Function of Blood… Major functions of Connective tissue: Binding and support Protecting Insulating What is transported Storing reserve fuel by the blood? Transporting substances (blood) Functions of Blood… Functions of blood distributes, regulates and Distribution protects Delivering oxygen from lungs, and nutrients from the gut to all body cells Transporting metabolic waste products from cells e.g.. Kidneys to urine Transporting hormones from endocrine glands to their target organs Regulatory functions Maintaining appropriate body temperature Maintaining normal pH in body tissues Maintaining adequate fluid volume in the circulatory system e.g. Blood proteins prevent excessive fluid loss Protection Preventing blood loss (clot formation for example) Prevent infections (antibodies, white blood cells and complement proteins are carried in the blood and these help fight infection)  Arteries and capillaries Heart = 2 pumps not 1 Arteries: carry oxygenated blood from heart to all parts of the body Get smaller the further away from heart – capillaries Connect to venules in tissues Blood gives up O2 and nutrients to tissue cells Picks up CO2 and metabolites for disposal  Venules and veins Venules - become bigger veins as they approach heart Blood pumped through heart to lungs Releases CO2 and picks up O2 Blood ….. Is a fluid connective tissue It distributes, regulates and protects It moves through elastic arteries and other blood vessels, helping the exchange of respiratory gases. Blood is composed of… Withdraw blood C………….. (spin) the and place in tube. blood sample. Figure 17.1 The major components of whole blood. © 2013 Pearson Education, Inc.  Plasma ~ 90% Water ~ 10% solutes Over 100 different dissolved solutes including: Of which 60% is plasma proteins albumin nutrients o Acts as a carrier enzymes & hormones molecule – shuttles other molecules electrolytes through the circulation respiratory gases o Acts as a blood buffer o Leucocytes, platelets (buffy coat) and erythrocytes… Together called the ‘formed elements’ Slightly unusual cells types Erythrocytes are not true cells (no n…… or o…………..) Neither are platelets (they are cell fragments) They survive in the blood for only a few days And they don’t divide (they are formed by stem cells in the bone marrow)  Red blood cells A mature red blood cell is referred to as an erythrocyte ‘Normal’ Red Blood Cell count: 4.2 – 6.1 million / µl 7-8 µm biconcave disks Increases surface area for gas exchange Plasma membrane, but no nucleus or organelles Lack of mitochondria mean energy is procedure anaerobically, and doesn’t use oxygen that it is carrying. Flexible and elastic - important because……? Effectively a bag packed full of oxygen carrying haemoglobin (97% vol) © 2016 Pearson Education, Inc. Full blood count Blood smear (film) What blood cells look like down the microscope: Blood smear x20, Leishman’s stain. Open Learn Virtual Microscope …and in the disease state Sickle cell Anemia Hypochromic microcytic anemia Haemoglobin 33% of red blood cell weight ~280 million haemoglobin molecules per cell Carries oxygen (O2) and carbon dioxide (CO2) globin and a non-protein Protein called component called haem (heme) Adult globin has 4 polypeptide chains (2 alpha and 2 beta chains = α2β2) Haemoglobin – haem Non-protein pigment containing iron (Fe+2) One haem to each globin chain So on molecule heamaglobin can combine with four O2 molecules = oxyhaemoglobin (ruby red coloured) Each red blood cell can carry 1 billion O2 molecules Oxygen released into tissues = deoxyhaemaglobin (dark red couloured) Why are red blood cells shaped as biconcave disks? A) That is incorrect, RBC are not biconcave B) To hold more oxygen C) Increased surface area D) For aerobic respiration  Anaemia O2 carrying capacity of blood is too low. Different types: Haemorrhagic – blood loss Iron deficiency / microcytic (lack of Hb leads to small cells) Pernicious – autoimmune destruction of gut cells that absorb Vit B12 required for RBC production Haemolytic – mismatched blood or infection lead to lysis of RBCs Hereditary – such as Sickle Cell  Abnormal hemoglobin structure can result in red cell defects such as sickle cell anemia. Single amino acid sustitution on β globin chain of haemaglobin β chains clump together in low oxygen conditions (exercise for example) resulting in the sickled shape. Sickled RBCs are fragile and repture easily, further restricting oxygen delivery Can lead to a sickle cell crisis © 2016 Pearson Education, Inc. Blood ….. When spun, has three layers Plasma – full of solutes (proteins, gases, nutrients) Buffy coat – white blood cells Red blood cells Bags of haemoglobin – an Oxygen carrying protein with iron A reduced ability to carry Oxygen leads to anaemia Haematopoiesis The production of blood cells Takes place in red b………… m………. Mostly in bones of the a……l skeleton All arise from hematopoietic stem cells An undifferentiated precursor cell – pluripotent stem cell Hormones and growth factors stimulate the formation of whatever cell type is needed. Erythropoiesis The production of red blood cells Remember! blast indicates an immature cell. cyte indicates a mature cell Erythropoiesis The production of red blood cells Erythrocyte derived from the pluripotent stem cell in the bone marrow The cells undergo gradual changes in the bone marrow Decrease of RNA and increase of haemoglobin Degeneration of the nucleus - eventual extrusion from cell Loss of cytoplasmic organelles, e.g. mitochondria Reduction in cell size with each cell division Process takes about 15 days until reticulocyte released, which takes a further two days to mature and degrade ribosomes Reticulocytes account for 1-2% RBC count, and indicate rate of production Around 2 million erythrocytes produced per ……….. (unit of time)  Hypoxia (hyp – low) (oxia - oxygen) Haemoglobin in the erythrocytes carries oxygen to the tissues Lack of oxygen = hypoxia Hypoxia is sensed by the kidneys Kidneys release Erythropoietin (EPO) EPO travels to bone marrow and upregulates RBC production More RBCs = no more hypoxia = no more EPO released Homeostasis – the principle of feedback Most systems are regulated by NEGATIVE FEEDBACK 3 Input: Information 4 Output: Information sent along afferent Control sent along efferent pathway to control Center pathway to effector. center. Afferent Efferent pathway pathway Receptor Effector 2 Receptor detects change. 5 Response of effector feeds IMB back to reduce AL the effect of 11 Stimulus A NC E stimulus and produces returns variable change in BALANCE to homeostatic variable. level. IMB AL AN © 2016 Pearson Education, Inc. CE Homeostasis – the principle of feedback Most systems are regulated by NEGATIVE FEEDBACK © 2016 Pearson Education, Inc. Fate and destruction RBCs live 100-120 days They cannot synthesise new protein. Why? Haemoglobin starts to degrade. Cells become less flexible and prone to being trapped in small vessels …..of which the spleen is full. What does the spleen look like? Engulfed and destroyed by macrophages Iron removed from haem and recycled, remainder degraded to bilirubin  Old RBCs become inflexible and become trapped in erythropoiesi spleen, liver and bone s marrow Macrophages phagocytose RBCs. Haemoglobin left over is broken down into heme and globin. Globin recycled into amino destruction acids and released back into blood stream. Iron removed, and released back into blood stream as needed. Remainder of the heme molecule degraded to biliverdin (green) then to Blood ….. Is produced from hematopoietic stem cells in bone marrow Through a process involving the production of Hb and the ejection of the nucleus Production is regulated through negative feedback in response to hypoxia Stimulated by erythropoietin Eventually, RBCs are degraded by macrophages when old primarily in the spleen, liver and bone marrow Many components are recycled, and those that are not are excreted via bile Leukocytes – White Blood Cells (WBCs) 1% of the total blood volume 5000 to 10,000 cells per drop (µl) of blood Total leucocyte count = 5-9 x 109 cells/mL Function – to combat pathogens Only 2% of WBCs are found in blood Leukopoiesis What is Leukopoiesis? All derived from hematopoietic stem cell (as are erythrocytes) In response to chemical signals such as interleukins and Colony Stimulating Factors (CSF) Differentiation of cells Granulocytes stored in bone marrow (10x more than in blood) 3x more WBCs produced than RBCs (shorter life span 0.25 – 9 days) Granulocytes (with granules) Agranulocytes (without granules) a) Neutrophils 50 - 70% d) Lymphocytes 20 - 25% b) Eosinophils 2 - 4% e) Monocytes 3 - 8% c) Basophils 0.5-1% Differential white blood cell count: Count one hundred white blood cells and evaluate what type they are % Absolute no. x109cells/L Neutrophils 50 -70 1.7 – 7.5 Lymphocytes 20 -25 1.0 – 3.2 Monocytes 3-8 0.2 – 0.6 Eosinophils 2-4 0.03 – 0.06 Basophils 0.5 - 1 0.02 – 0.29  Most abundant > least abundant Neutrophil> Lymphocytes> Monocyte>Eosinophil>Basophil Never Let Monkeys Eat Bananas Macrophage - Figure 21.2b Phagocytosis. 1 Phagocyte adheres to phagocytosis pathogens or debris. 2 Phagocyte forms pseudopods that Phagosome eventually engulf the (phagocytic particles, forming a vesicle) phagosome. Lysosome 3 Lysosome fuses with the phagocytic vesicle, forming a phagolysosome. Acid hydrolase enzymes 4 Lysosomal enzymes digest the particles, leaving a residual body. Figure 21.2a Phagocytosis. A macrophage (purple) uses its cytoplasmic extensions to pull rod-shaped bacteria 5 Exocytosis of the (green) toward it. Scanning electron vesicle removes micrograph (4800x). indigestible and residual material. Events of phagocytosis. © 2013 Pearson Education, Inc. Platelets Cytoplasmic fragments containing granules 2-4 μm diameter No nucleus Life-span 5-10 days 150,000 to 400,000 per µl blood! Important role to aid blood clotting and maintain ‘haemostasis’ Open Learn Virtual Microscope Platelets Fragments of megakaryocytes Repeated mitosis, and Mega – because they are big! 60 μm growth without Bud off and mature for 4-5 days in the bone cytokinesis marrow before being released into the circulation Thrombopoietin hormone regulates production Haemostasis 1. Damage causes vasoconstriction – reduces blood flow and loss 2. Platelets cling on to exposed collagen fibres from blood vessels von Willebrand factor (plasma protein) activates platelets, which swell, change shape & become sticky. A platelet plug is formed 3. A fibrin mesh traps blood forming a clot. Clotting factors help turn plasma from a liquid to a gel Prothrombin activator ‘activates’ prothrombin to thrombin (an enzyme) Thrombin converts soluble fibrinogen to insoluble fibrin.