Marieb Human Anatomy & Physiology Chapter 17: Blood PDF

Marieb Human Anatomy & Physiology Twelfth Edition Chapter 17 Blood Damian Warner – Olympic Decathlon Gold Medalist Tokyo...

Marieb Human Anatomy & Physiology Twelfth Edition Chapter 17 Blood Damian Warner – Olympic Decathlon Gold Medalist Tokyo 2020 Copyright © 2025 Pearson Education, Inc. All Rights Reserved Why This Matters Understanding the anatomy and physiology of blood helps you to advise patients on activities to prevent blood clots during hospital stays. What Does Blood (“River of Life”) Do Blood exits heart via arteries. Arteries branch repeatedly until they become capillaries, servicing all tissues. Carries oxygen and nutrients. Waste materials and oxygen deficient blood flow into veins carrying blood back to the heart. Informedhealth.org Chapter Opener 17 Copyright © 2025 Pearson Education, Inc. All Rights Reserved 17.1 Functions of Blood Functions include – Transport – Regulation – Protection Copyright © 2025 Pearson Education, Inc. All Rights Reserved Transport Transport functions include: – Delivering O2 and nutrients to body cells – Transporting metabolic wastes to lungs and kidneys for elimination – Transporting hormones from endocrine organs to target organs Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation Regulation functions include: – Maintaining body temperature by absorbing and distributing heat – Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions – Maintaining adequate fluid volume in circulatory system Copyright © 2025 Pearson Education, Inc. All Rights Reserved Protection Protection functions include: – Preventing blood loss ▪Plasma proteins and platelets in blood initiate clot formation – Preventing infection ▪Agents of immunity are carried in blood – Antibodies – Complement proteins – White blood cells Copyright © 2025 Pearson Education, Inc. All Rights Reserved 17.2 Composition of Blood (1 of 2) Blood is a fluid tissue in body Type of connective tissue – Matrix is nonliving fluid called plasma – Cells are living blood cells called formed elements ▪Cells are suspended in plasma ▪Formed elements – Erythrocytes (red blood cells, or RBCs) – Leukocytes (white blood cells, or WBCs) – Platelets (cell fragments) Copyright © 2025 Pearson Education, Inc. All Rights Reserved 17.2 Composition of Blood (2 of 2) Spun tube of blood yields three layers: – Erythrocytes on bottom (~45% of whole blood) ▪Hematocrit: percent of blood volume that is RBCs – Normal values: Males: 47% ± 5% Females: 42% ± 5% – WBCs and platelets in Buffy coat (< 1%) ▪Thin, whitish layer between RBCs and plasma layers – Plasma on top (~55%) Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.1 The Major Components of Whole Blood Copyright © 2025 Pearson Education, Inc. All Rights Reserved Physical Characteristics and Volume Blood is a sticky, opaque fluid with metallic taste Color varies with O2 content – High O2 levels show a scarlet red – Low O2 levels show a dark red pH 7.35–7.45 Makes up ~8% of body weight Average volume: – Males: 5–6 L – Females: 4–5 L Copyright © 2025 Pearson Education, Inc. All Rights Reserved Blood Plasma Blood plasma is straw-colored sticky fluid – About 90% water Over 100 dissolved solutes – Nutrients, gases, hormones, wastes, proteins, inorganic ions – Plasma proteins are most abundant solutes ▪Remain in blood; not taken up by cells ▪Proteins produced mostly by liver ▪Albumin: makes up 60% of plasma proteins – Functions as carrier of other molecules, as blood buffer, and contributes to plasma osmotic pressure Copyright © 2025 Pearson Education, Inc. All Rights Reserved Table 17.1 Composition of Plasma Copyright © 2025 Pearson Education, Inc. All Rights Reserved Formed Elements Formed elements are RBCs, WBCs, and platelets Only WBCs are complete cells – RBCs have no nuclei or other organelles – Platelets are cell fragments Most formed elements survive in bloodstream only few days Most blood cells originate in red bone marrow and do not divide Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.2 Blood Cells Copyright © 2025 Pearson Education, Inc. All Rights Reserved 17.3 Erythrocytes Copyright © 2025 Pearson Education, Inc. All Rights Reserved Structural Characteristics (1 of 2) Erythrocytes are small-diameter (7.5 μm) cells that contribute to gas transport Cell has biconcave disc shape, is anucleate, and essentially has no organelles Filled with hemoglobin (Hb) for gas transport RBC diameters are larger than some capillaries Contain plasma membrane protein spectrin and other proteins – Spectrin provides flexibility to change shape Copyright © 2025 Pearson Education, Inc. All Rights Reserved Structural Characteristics (2 of 2) Superb example of complementarity of structure and function Three features make for efficient gas transport: – Biconcave shape offers huge surface area relative to volume for gas exchange – Hemoglobin makes up 97% of cell volume (not counting water) – RBCs have no mitochondria ▪ATP production is anaerobic, so they do not consume O2 they transport Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.3 Structure of Erythrocytes (Red Blood Cells) Biconcave Shape Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.4 Structure of Hemoglobin Copyright © 2025 Pearson Education, Inc. All Rights Reserved Function of Erythrocytes (2 of 2) Each Hb molecule can transport four O2 Each RBC contains 250 million Hb molecules O2 loading in lungs – Produces oxyhemoglobin (ruby red) O2 unloading in tissues – Produces deoxyhemoglobin, or reduced hemoglobin (dark red) CO2 loading in tissues – 20% of CO2 in blood binds to Hb, producing carbaminohemoglobin Copyright © 2025 Pearson Education, Inc. All Rights Reserved Production of Erythrocytes (1 of 3) Hematopoiesis: formation of all blood cells Occurs in red bone marrow; composed of reticular connective tissue and blood sinusoids – In adult, found in axial skeleton, girdles, and proximal epiphyses of humerus and femur Hematopoietic stem cells (hemocytoblasts) – Stem cell that gives rise to all formed elements – Hormones and growth factors push cell toward specific pathway of blood cell development – Committed cells cannot change New blood cells enter blood sinusoids Copyright © 2025 Pearson Education, Inc. All Rights Reserved Production of Erythrocytes (2 of 3) Stages of erythropoiesis – Erythropoiesis: process of formation of RBCs that takes about 15 days – Stages of transformations 1. Hematopoietic stem cell: transforms into myeloid stem cell 2. Myeloid stem cell: transforms into proerythroblast 3. Proerythroblast: divides many times, transforming into basophilic erythroblasts 4. Basophilic erythroblasts: synthesize many ribosomes, which stain blue Copyright © 2025 Pearson Education, Inc. All Rights Reserved Production of Erythrocytes (3 of 3) Stages of erythropoiesis (cont.) 5. Polychromatic erythroblasts: synthesize large amounts of red-hued hemoglobin; cell now shows both pink and blue areas 6. Orthochromatic erythroblasts: contain mostly hemoglobin, so appear just pink; eject most organelles; nucleus degrades, causing concave shape 7. Reticulocytes: still contain small amount of ribosomes 8. Mature erythrocyte: in 2 days, ribosomes degrade, transforming into mature RBC – Reticulocyte count indicates rate of RBC formation Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.5 Erythropoiesis: Formation of Red Blood Cells Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation and Requirements of Erythropoiesis (1 of 5) Too few RBCs lead to tissue hypoxia Too many RBCs increase blood viscosity > 2 million RBCs are made per second Balance between RBC production and destruction depends on: – Hormonal controls – Dietary requirements Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation and Requirements of Erythropoiesis (2 of 5) Hormonal control – Erythropoietin (EPO): hormone that stimulates formation of RBCs ▪Always small amount of EPO in blood to maintain basal rate ▪Released by kidneys (some from liver) in response to hypoxia – At low O2 levels, oxygen-sensitive enzymes in kidney cells cannot degrade hypoxia-inducible factor (HIF) – HIF can accumulate, which triggers synthesis of EPO Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation and Requirements of Erythropoiesis (3 of 5) Hormonal control (cont.) – Causes of hypoxia: ▪Decreased RBC numbers due to hemorrhage or increased destruction ▪Insufficient hemoglobin per RBC (example: iron deficiency) ▪Reduced availability of O2 (example: high altitudes or lung problems such as pneumonia) Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation and Requirements of Erythropoiesis (4 of 5) Hormonal control (cont.) – Too many erythrocytes or high oxygen levels in blood inhibit EPO production – EPO causes erythrocytes to mature faster ▪Testosterone enhances EPO production, resulting in higher RBC counts in males Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.6 Erythropoietin (EPO) Mechanism for Regulating Erythropoiesis Copyright © 2025 Pearson Education, Inc. All Rights Reserved Clinical – Homeostatic Imbalance 17.1 Some athletes abuse artificial EPO – Use of EPO increases hematocrit, which allows athlete to increase stamina and performance Dangerous consequences: – EPO can increase hematocrit from 45% up to even 65%, with dehydration concentrating blood even more – Blood becomes like sludge and can cause clotting, stroke, or heart failure Copyright © 2025 Pearson Education, Inc. All Rights Reserved Regulation and Requirements of Erythropoiesis (5 of 5) Dietary requirements for erythropoiesis – Amino acids, lipids, and carbohydrates – Iron: available from diet ▪65% of iron is found in hemoglobin, with the rest in liver, spleen, and bone marrow ▪Free iron ions are toxic, so iron is bound with proteins: – Stored in cells as ferritin and hemosiderin – Transported in blood bound to protein transferrin – Vitamin B12 and folic acid are necessary for DNA synthesis for rapidly dividing cells such as developing RBCs Copyright © 2025 Pearson Education, Inc. All Rights Reserved Fate and Destruction of Erythrocytes (1 of 2) Life span: 100–120 days RBCs are anucleate, so cannot synthesize new proteins, or grow or divide Old RBCs become fragile, and Hb begins to degenerate Can get trapped in smaller circulatory channels, especially in spleen Macrophages in spleen engulf and breakdown dying RBCs Copyright © 2025 Pearson Education, Inc. All Rights Reserved Fate and Destruction of Erythrocytes (2 of 2) RBC breakdown: heme, iron, and globin are separated – Iron binds to ferritin or hemosiderin and is stored for reuse – Heme is degraded to yellow pigment bilirubin ▪Liver secretes bilirubin (in bile) into intestines, where it is degraded and leaves body in feces – Globin is metabolized into amino acids ▪Released into circulation Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.7 Life Cycle of Red Blood Cells Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (1 of 13) Most erythrocyte disorders are classified as either anemia (lacking blood) or polycythemia (many blood cells) Anemia – Blood has abnormally low O2-carrying capacity that is too low to support normal metabolism – Sign of problem rather than disease itself – Symptoms: fatigue, pallor, dyspnea (difficulty breathing), and chills – Three groups based on cause ▪Blood loss ▪Not enough RBCs produced ▪Too many RBCs being destroyed Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (2 of 13) Anemia (cont.) – Blood loss ▪Hemorrhagic anemia – Rapid blood loss (example: severe wound) – Treated by blood replacement ▪Chronic hemorrhagic anemia – Slight but persistent blood loss Example: hemorrhoids, bleeding ulcer – Primary problem must be treated to stop blood loss Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (3 of 13) Anemia (cont.) – Not enough RBCs being produced ▪Iron-deficiency anemia – Can be caused by hemorrhagic anemia, but also by low iron intake or impaired absorption – RBCs produced are called microcytes Small, pale in color Cannot synthesize hemoglobin because there is a lack of iron – Treatment: iron supplements Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (4 of 13) Anemia (cont.) – Not enough RBCs being produced (cont.) ▪Pernicious anemia – Autoimmune disease that destroys stomach mucosa that produces intrinsic factor – Intrinsic factor needed to absorb B12 – B12 is needed to help RBCs divide – Without B12 RBCs enlarge but cannot divide, resulting in large macrocytes – Treatment: B12 injections or nasal gel – Can also be caused by low dietary intake of B12 Can be a problem for vegetarians Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (5 of 13) Anemia (cont.) – Not enough RBCs being produced (cont.) ▪Renal anemia – Caused by lack of EPO – Often accompanies renal disease Kidneys cannot produce enough EPO – Treatment: synthetic EPO Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (6 of 13) Anemia (cont.) – Not enough RBCs being produced (cont.) ▪Aplastic anemia – Destruction or inhibition of red bone marrow – Can be caused by drugs, chemicals, radiation, or viruses Usually cause is unknown – All formed element cell lines are affected Results in anemia as well as clotting and immunity defects – Treatment: short-term with transfusions, long-term with transplanted stem cells Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (7 of 13) Anemia (cont.) – Too many RBCs destroyed: ▪Premature lysis of RBCs – Referred to as hemolytic anemias ▪Can be caused by: – Incompatible transfusions or infections – Hemoglobin abnormalities: usually genetic disorder resulting in abnormal globin Thalassemias Sickle-cell anemia Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (8 of 13) Anemia (cont.) – Too many RBCs destroyed: ▪Thalassemias (sea blood) – Typically found in people of Mediterranean ancestry – One globin chain is absent or faulty – RBCs are thin, delicate, and deficient in hemoglobin – Many subtypes that range in severity from mild to extremely severe Very severe cases may require monthly blood transfusions Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (9 of 13) Anemia (cont.) – Too many RBCs destroyed: ▪Sickle-cell anemia – Hemoglobin S: mutated hemoglobin Only 1 amino acid is wrong in a globin beta chain of 146 amino acids – RBCs become crescent shaped when O2 levels are low Example: during exercise – Misshaped RBCs rupture easily and block small vessels Results in poor O2 delivery and pain Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (10 of 13) Anemia (cont.) – Too many RBCs destroyed: Sickle-cell anemia (cont.) – Prevalent in black people of the African malarial belt and their descendants – Possible benefit: people with sickle cell do not contract malaria Kills 1 million each year Individuals with two copies of Hb-S can develop sickle-cell anemia Individuals with only one copy have milder disease and better chance of surviving malaria Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (11 of 13) Anemia (cont.) – Too many RBCs destroyed: Sickle-cell anemia (cont.) – Treatment: acute crisis treated with transfusions; inhaled nitric oxide – Prevention of sickling: Hydroxyurea induces formation of fetal hemoglobin (which does not sickle) Stem cell transplants Gene therapy Nitric oxide for vasodilation Copyright © 2025 Pearson Education, Inc. All Rights Reserved Figure 17.8 Sickle-Cell Anemia Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (12 of 13) Polycythemia – Abnormal excess of RBCs; increases blood viscosity, causing sluggish blood flow – Polycythemia vera: Bone marrow cancer leading to excess RBCs ▪Hematocrit may go as high as 80% ▪Treatment: therapeutic phlebotomy – Secondary polycythemia: caused by low O2 levels (example: high altitude) or increased EPO production Copyright © 2025 Pearson Education, Inc. All Rights Reserved Erythrocyte Disorders (13 of 13) Polycythemia (cont.) – Blood doping: athletes remove, store, and reinfuse RBCs before an event to increase O2 levels for stamina Copyright © 2025 Pearson Education, Inc. All Rights Reserved 17.4 Leukocytes Copyright © 2025 Pearson Education, Inc. All Rights Reserved General Structure and Functional Characteristics (1 of 2) Leukocytes, or WBCs, are only formed element that is complete cell with nuclei and organelles Make up