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Midterm

BIOL 4260 Midterm: Objectives_Chpt_21_Blood

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Department
Biology
Course
BIOL 4260
Professor
Thimmiah
Semester
Fall

Description
Objectives - Blood Overview: Blood Composition and Functions 1. Describe the composition and physical characteristics of whole blood. Explain why it is classified as a connective tissue. • Blood is the only fluid bodily tissue • Type of connective tissue o Matrix is nonliving fluid called plasma o Cells are living blood cells called formed elements ▪ Cells are suspended in plasma ▪ Formed elements= Erythrocytes/ RBCs, Leukocytes/ WBCs, platelets • Erythrocytes on bottom yield 45% of blood o Hematocrit= percent of blood that is RBCs • WBC ands platelets in Buffy Coat o Thin whitish layers between RBCs and plasma layers • Plasma on top 2.Describe the functions of blood. • Functions of blood= transport, regulation and protection o Transport= delivering O2 and nutrients to body cells ▪ Transporting metabolic wastes to lungs and kidneys for elimination ▪ Transporting hormones from endocrine organs to target organs o Regulation= maintaining body temperature by absorbing and distributing heat ▪ Maintaining normal pH using buffers, using alkaline reserve of bicarbonate ions ▪ Maintaining adequate fluid volume in circulatory system o Protection ▪ Preventing blood loss- plasma proteins and platelets in blood initiate clot formation ▪ Preventing infection- agents of immunity are carried in blood (antibodies, complement proteins, WBC) Blood Plasma 3. Discuss the composition and functions Albumin, Na+, Globulin and Fibrinogen of plasma. • Albumin= 60% of plasma proteins functions as carrier of other molecules, as a blood buffer, and contributes to plasma osmotic pressure????????????????????????? • Na+????? • Globulin Formed Elements 4. Describe the structure, function, and production of erythrocytes. • Structural Characteristics of Erythrocytes o Erythrocytes are small diameter (7.5 Mm) cells that contribute to gas transport o Cells have biconcave disc shape, is anucleate, and essentially has no organelles o Filled with hemoglobin (Hb) for gas transport o RBC diameters are larger than some capillaries o Contain plasma membrane protein spectrin and other proteins ▪ Spectrin provides flexibility to change shape o Superb example of Complementarity of structure and function o 3 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) ▪ RBC have no mitochondria- ATP production in anaerobic so they don’t consume the O2 they transport • Functions of Erythrocytes o RBCs are dedicated to respiratory gas transport o Hemoglobin binds reversibly with oxygen o Hemoglobin consists of red heme pigment bound to the protein globin ▪ Globin is composed of 4 polypeptide chains • 2 alpha and 2 beta chains ▪ A heme pigment is bonded to each globin chain • Gives blood red color • Each heme’s central iron atom binds one O2 o Each Hb molecule can transport 4 O2 atoms o Each RBC contain 250 Hb molecules o O2 loading in lungs ▪ Produces oxyhemoglobin (ruby Red) o O2 unloading in tissues ▪ Produces deoxyhemoglobin/ reduced hemoglobin (dark red) o CO2 loading in tissues ▪ 20% CO2 in blood binds to Hb, producing carbaminohemoglobin • Production of Erthrocytes o Hematopoiesis: Formation of all blood cells o Occurs in red bone marrow; composed of reticular connective tissue and blood sinusoids ▪ In adult, found in axial skeleton, girdles, and proximal epiphysis of humerus and femur o 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 o New blood cells enter blood sinusoids • Stages of Erythropoiesis o Erthropoiesis: process of formation of RBCs that takes about 15 days o 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 main ribosomes, which stain blue 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 ribosoms 8. Mature erythrocyte in 2 days, ribosome’s degrade, transforming into mature RBC o Reticulocyte count indicates rate of RBC formation o • Regulation and Requirements of Erythropoiesis o Too few RBCs lead to tissue hypoxia o Too many RBCs increase blood viscosity o > 2 million RBC are made per second o Balance between RBC production and destruction depends on… ▪ Hormonal control ▪ Dietary requirements… o 1) Hormonal Control- Erythropoietin (EPO)- hormone that stimulates formation of RBCs ▪ Always small amount of EPOs 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 ▪ Causes of hypoxia: • Decreased RBCs due to hemorrhage or destruction • Insufficient Hb per RBC (Ex: iron deficiency) • Reduced availability of O2 (Ex: high altitude or lung problems such as pneumonia) • Too many erythrocytes or high oxygen levels in blood inhibit EPO production • EPO causes erythrocytes to mature faster o Testosterone enhances EPO production, resulting in higher RBC counts in males o • Clinical- homeostatic Imbalance o Some athletes abuse artificial EPO- use of EPO enhances hematocrit, which allows athlete to increase stamina and performance o Dangerous consequences= EPO can increase hematocrit from 45% to up to 65%, with dehydration, concentrating blood level even more ▪ Blood becomes like sludge and can cause clotting, stroke and heart failure • Regulation and Requirement of Erythropoiesis o Dietary requirements for EPO ▪ AAs, lipids, and carbohydrates ▪ Iron: available from diet • 64% of iron is found in hemoglobin, with the rest in the liver, spleen and bone marrow • Free iron ions are toxic so it is bound with proteins o Stored in cells as ferritin and hemosiderin o Transported in blood bound to transferrin ▪ Vitamin B and folic acid are necessary for DNA synthesis for rapidly dividing cells such as RBCs • Fate and Destruction of Erythorcytes o Life span: 100-120 days o RBCs are anucleate, so cannot synthesize new proteins, grow, or divide o Old RBCs become fragile, and Hb begins to degenerate o Can get trapped in smaller circulatory channels, especially in the spleen o Marcophages in the spleen engulf and breakdown dying RBCs o RBC breakdown: Heme, iron and globin are separated ▪ Iron binds to ferridin or hemosiderin and is stored for reuse ▪ Heme is degraded to yellow pigment by bilirubin • Liver secretes bilirubin (in bile) into intestines, where it is degraded to pigment urobilinogen o Urobilinogen is transformed into brown pigment stercobilin that leaves the body in feces ▪ Globin is metabolized into amino acids • Released into circulation 5. Describe the chemical makeup of hemoglobin. • Hemoglobin binds reversibly with oxygen o Hemoglobin consists of red heme pigment bound to the protein globin ▪ Globin is composed of 4 polypeptide chains • 2 alpha and 2 beta chains ▪ A heme pigment is bonded to each globin chain • Gives blood red color • Each heme’s central iron atom binds one O2 o Each Hb molecule can transport 4 O2 atoms o Each RBC contain 250 Hb molecules o O2 loading in lungs ▪ Produces oxyhemoglobin (ruby Red) o O2 unloading in tissues ▪ Produces deoxyhemoglobin/ reduced hemoglobin (dark red) o CO2 loading in tissues ▪ 20% CO2 in blood binds to Hb, producing carbaminohemoglobin 6. Describe the erythropoietin (the organ and factors that help its synthesis. Pros and cons of its effect). o 1) Hormonal Control- Erythropoietin (EPO)- hormone that stimulates formation of RBCs ▪ Always small amount of EPOs 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 ▪ Causes of hypoxia: • Decreased RBCs due to hemorrhage or destruction • Insufficient Hb per RBC (Ex: iron deficiency) • Reduced availability of O2 (Ex: high altitude or lung problems such as pneumonia) • Too many erythrocytes or high oxygen levels in blood inhibit EPO production • EPO causes erythrocytes to mature faster o Testosterone enhances EPO production, resulting in higher RBC counts in males o • Clinical- homeostatic Imbalance o Some athletes abuse artificial EPO- use of EPO enhances hematocrit, which allows athlete to increase stamina and performance o Dangerous consequences= EPO can increase hematocrit from 45% to up to 65%, with dehydration, concentrating blood level even more ▪ Blood becomes like sludge and can cause clotting, stroke and heart failure • Regulation and Requirement of Erythropoiesis o Dietary requirements for EPO ▪ AAs, lipids, and carbohydrates ▪ Iron: available from diet • 64% of iron is found in hemoglobin, with the rest in the liver, spleen and bone marrow • Free iron ions are toxic so it is bound with proteins o Stored in cells as ferritin and hemosiderin o Transported in blood bound to transferrin 7. Give examples of disorders caused by abnormalities of erythrocytes. Explain what goes wrong in each disorder. _ All the different types of Anemia, Polycythemia, Sickle cell anemia and Thalassemia • Erythrocyte Disorders o Most erythocyte disorder are classified as either anemia or polycythemia o Anemia ▪ Blood has abnormally low O2 carrying capacity that is too low to support normal metabolism ▪ Sign of a problem rather than disease itself ▪ Symptoms: fatigue, pallor, dyspnea and chills ▪ 3 groups based on cause • Blood loss • Not enough RBCs produced • Too many RBCs being destroyed o Blood Loss ▪ Hemorrhagic anemia • Rapid blood loss (ex: with severe wound) • Treated by blood replacement ▪ Chronic Hemorrhagic Anemia • Slight but persistent blood loss (ex: hemorrhoids, bleeding ulcer) • Primary problem must be treated to stop blood loss ▪ Anemia- not enough RBC is being produced • Iron deficiency anemia o Can be caused by hemorhagic anemia, but also by low iron intake or impaired absorption o RBCs produced are called microcytes ▪ Small and pale in color ▪ Cannot synthesize Hb because there is a lack of iron o Treatment: Iron supplements • Pernicious Anemia o Autoimmune disease that destroys stomach mucosa that produces intrinsic factor o Instrinsic factor needed to absorb B o B12 is needed to help RBCs divide o Without B12, RBCs enlarge but cannot divide resulting in large macrocytes o Treatment: B12 injections or nasal gel o Can also be caused by low dietary intake of B12 ▪ Can be a problem for vegetarians • Renal anemia- o Caused by lack of EPO o Often accompanies renal disease- kidneys cannot produce enough EPO o Treatment: Synthetic EPO • Aplastic Anemia o Destruction or inhibition of red bone marrow o Can be caused by drugs, chemicals, radiation, or viruses ▪ Usually cause is unknown o All formed element cell lines are effected ▪ Results in anemia as well as clotting and immunity defects o Treatment: Short term with transfusions, long term with transplanted stem cells • … Premature lysis of RBCs o Referred to as hemolytic anemia’s o Can be caused by ▪ Incompatible transfusions or infections ▪ Hemoglobin abnormalities: usually genetic disorder resulting in abnormal globin • Thalasemias • Sickle cell anemia o Thalasemias- typically found in people of Mediterranean ancestry ▪ One globin chain is absent or faulty ▪ RBCs are thin, delicate, and deficient in Hb ▪ Many subtypes range from mild to extremely severe • Very severe cases require monthly blood transfusions o Sickle Cell Anemia ▪ Hemoglobin S: mutated hemoglobin • Only 1 amino acid chain is wrong in 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 ▪ Prevalent in black people of the African malarial belt and their descendents ▪ Possible benefit: people with sickle cell don’t contract malaria • Kills one million each year • Individuals with two copies of Hemoglobin S can develop sickle cell anemia • Individuals with only one copy have milder form and lesser chance of contracting malaria ▪ Treatment: acute crisis treated with transfusions: inhaled nitric oxide ▪ Prevention of sickeling: • Hydroxyuren induces formation of fetal Hb, which doesn’t sickle • Stem cell transplants • Gene therapy • Nitric oxide for vasodilation ▪ th ▪ 6 AA Glu replaced with Val o 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 (ex: high altitude) or increased EPO production ▪ Blood doping: athletes remove, store, and reinfuse before an event to increase O2 level for stamina 8. List the classes, structural characteristics, normal percentages, and functions of leukocytes. • Leukocytes: General Structure and Characteristics o Leukocyte, or WBCs, are only formed in complete cells with nuclei and organelles o Make up 1% of total blood volume o 4,800 or 10,000 WBCs per ML blood o Function in defense against disease ▪ Can leave capillaries via diapedesis ▪ Move through tissue spaces by amoeboid motion and positive chemotaxis o WBCs count over 11,000 per ML blood?? ▪ Increase in normal response to infection o Leukocytes grouped into 2 categories ▪ Granulocytes- contain visible cytoplasmic granules ▪ Agranulocytes- do not contain visible cytoplasmic granules • Decreasing abudance in blood= Never Let Monkeys Eat Bananas • Granulocytes: 3 types o Neutrophils, eosinophils, basophils o Larger and shorter lived than RBCs o Contain lobed, rather than circular nuclei o Cytoplasmic granules stain specifically with Wright’s stain o All are phagocytic to stom degree o Neutrophils= most numerous WBCs (50-70%) ▪ About twice the size of RBCs ▪ Granules stain with both acidic and basic dyes ▪ Granules contain either hydrolytic enzymes or antimicrobial proteins, defensins ▪ Also called polymorphonuclear leukocytes (PMNs or polys) because nucleus is lobular • Cell has anywhere from 3-6 lobes ▪ Vary phagocytic- referred to as “bacteria slayers” • Kill microbes by process “respiratory bust”—cells synthesize potent oxidizing substances (bleach or hydrogen peroxide) ▪ Defensin granules merge with phagosome- form “spears” that pierce holes in membrane of ingested microbe o
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