Biology 2313 Week 2 Notes
Biology 2313 Week 2 Notes Biology 2313
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This 11 page Class Notes was uploaded by Ednjon Parilla on Friday September 2, 2016. The Class Notes belongs to Biology 2313 at University of Texas at El Paso taught by Dr. Zaineb Al-Dahwi in Fall 2016. Since its upload, it has received 42 views. For similar materials see Human Anatomy & Physiology II in Science at University of Texas at El Paso.
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Date Created: 09/02/16
Chapter 17: Blood (Continued) Function of RBC Components of Hemoglobin Polypeptide chains (globin part) = 2 beta chains and 2 alpha chains o Center of each chain is the heme pigment o Contains iron which is the most important part! Allows oxygen to reverse bind to the hemoglobin Iron atom is located in the center; can bind up to 4 oxygen atoms o Oxygen binds to hemoglobin = Oxyhemoglobin Can also be un-binded to release oxygen into tissues = Deoxidized Hemoglobin (reduced hemoglobin) o Carbon Dioxide can also bind to hemoglobin but not to the iron atom like oxygen. Binds to amino acids; becomes Carbaminohemoglobin Production of RBC (takes place in red marrow) 1) Hemocytoblast: stem cell that produces blood cells, undergoes multiple divisions Becomes either: o Myeloid stem cell; leads to all blood cells except lymphoids o Lymphoid stem cell 2) Committed Cell (Proertyhroblast) Appearance of surface receptors on membrane o Hormone factors differ (certain pathways lead to the formation of certain type of blood cell) Produced by kidney (red blood cell formation) 3) Basophilic Eryhtroblast (Early) Important in producing ribosomes (which makes proteins) 4) Polychromatic Erythroblast Increase of hemoglobin (iron accumulation) 5) Orthochromatic Erythroblast Change of color in cytoplasm Breakdown of organelles in cell (including the degeneration of the nucleus; gives the RBC its concave shape) o All organelles ejected out of the RBC 6) Reticulocyte No organelles Contains small networks of ribosomes Completes hemoglobin formation Digests ribosomes with enzymes already in the RBC (takes 2 days to digest) 7) Erythrocyte! Negative Feedback Mechanism (what happens in a decreased # of RBCs) 1) Stimuli (in this case Hypoxia = no oxygen for tissues, increased demand of RBC) Decrease in # of red blood cells (blood loss) Decrease in hemoglobin (anemia) Decreased availability of oxygen (EX: caused by high altitude) o Promoting increased RBC 2) Erythropoietin Made in the kidney Activates committed cell Increases RBC count Oxygen availability increases Life Cycle of RBC Spleen = graveyard of RBC RBC arrives at the spleen where it is engulfed by macrophages o Leads to recycling of RBC material Recycling Mechanisms Become fragile after 120 days RBC is broken down into heme and globin o Globin breaks down into amino acids back into blood circulation o Heme is broken down into iron and pigment Free iron atoms are toxic to the body Needs to bind to carrier protein in order to be transported If stored, needs to be surrounded by a protein Usually in the liver (sometimes spleen) o Binds to fertin, hemosiderin, and more (become Iron Protein Complexes) After liver, binds to Transferrin back into blood circulation as needed for erythropoiesis Heme breaks apart into biliverdin, which is then reduced to Bilirubin (pigment) Bilirubin is picked up by the liver and secreted into bile in the intestine Here it is metabolized into Stercobilin by bacteria secreted in feces Amino acids, iron, and folic acid are absorbed from the intestine enter the blood circulation WHITE BLOOD CELLS (Complete Cells) General Facts Contains all organelles Protects against bacteria, viruses, and parasites Capable of protection through circulation but also through tissue Leukocyte Extravasation: exit of white blood cell from circulation o Form cytoplasmic extensions to allow movement in between tissues; amoeboid motion o Positive Chemotaxis: the movement of white blood cells toward the released attractants Divided into 2 types: Granulocytes Agranulocytes Major difference between the two types: Granulocytes have visible granules (membrane bound sacs containing digestive enzymes) Agranulocytes do not have VISIBLE granulocytes Order from highest to lowest percentage of WBC types at the body’s normal condition: Neutrophils [G] Lymphocytes [A] Monocytes [A] Eosinophils [G] Basophils [G] Granulocytes General 1) Nucleus is multi-lobed (connected by “cord-like” nuclear strands) 2) Spherical shape cell 3) Visible cytoplasmic granules Neutrophils 3 to 6 lobes in nucleus 2 types of cytoplasmic granules o Large Granules: contain lysosomes o Small Granules: contains “toothpick-like” antimicrobial proteins which promote holes (destroys) the microbial agents (bacteria) When there is an increase in # of neutrophils in blood Meningitis, Appendicitis, and others come about Granules absorb both the acidic + basic portions of stains which brings its name; neutral = neutron Functions o Phagocytosis Engulfs the bacterial agent and acts on it by using digestive enzymes from lysosomes (in general) Pierces holes in bacteria agents o Respiratory Burst Mechanism where oxygen is converted to hydrogen peroxide Plays an important role in the immune system; is a crucial reaction that occurs to degrade internalized particles and bacteria Eosinophils 2 lobes in nucleus Orange-ish granules o Absorbs the acidic portion of stain which is the eosin; ergo its name Associated with parasitic infections o Under normal conditions eosinophils are 2 to 4% of white blood cells With a parasitic infection it increases to 20% and higher Small Cell o Parasites are larger than the eosinophil In order to perform phagocytosis, the eosinophil gets close to the parasite and releases digestive enzymes specialized for promoting damage to the parasite’s wall Basophils Multi-lobed; usually takes the “S” shape Dark purple color of granules o Absorbs basic portion of stain; basophil Granules contain Histamine o Expresses a receptor on membrane for binding to an antibody Promotes activation of the basophil Releases histamine (causes the allergic reaction) This happens after attaching through the receptor Agranulocytes General 1) Do not have multi-lobed nuclei 2) No visible granules (under light microscope; visible under electomicroscope) Lymphocyte Huge nucleus that almost fills the entire cell, leaves small rim of the cytoplasm Two Types: o B Lymphocyte o T Lymphocyte Formation o Both arise from lymph nodes o Start with hemocytoblast (stem cell) lymphoblast (committed cell) prolymphocyte which splits into 2 types: Precursor B Lymphocyte Stays in the red bone marrow and matures there Precursor T Lymphocyte Moves from red bone marrow to the thymus gland and matures there o After growth completion of lymphocyte B Lymphocyte Moves to blood circulation where it could encounter an antigen. If that happens it will proliferate into 2 daughter cells. æ Plasma Cell: daughter cell that forms antibodies (proteins; cannot destroy) o Antibodies bind to antigen to mark it for destruction by the T lymphocytes æ Memory B Cell T Lymphocyte Encounter antigen and performs a cell-to-cell attack! Not a protein! æ It can attack a virus cell or cancer invaded cell Monocyte Kidney-shaped nucleus; horseshoe shape No visible granules Important in defending against viruses o Provides function in the circulation but can exit the circulation as well Once it leaves the monocyte becomes a Macrophage Changes into star-shape; cytoplasmic extensions are formed æ Makes it capable of catching antigens in the tissue, engulf it, digest it, and presents the peptide fragments to the T lymphocytes æ Activation of internal enzymes occurs Production of White Blood Cells (Leukopoiesis) Glycoproteins promote the production of WBCs Colony Factors: production; granulocyte stimulating factors Interleukins: inducing or activating the production of different WBCs o Usually numbered (ex: interleukin #5 = eosinophil Formation of Neutrophils, Eosinophils, and Basophils 1) Hemocytoblast 2) Myeloid Stem Cell 3) Myoblast (committed cell) 4) Promyelocyte Synthesis + accumulation of enzymes, production of special chemicals 5) _________ (type such as eosinophilic or neutrophilic or basophilic) Myelocte Appearance of “duck-like” granules; chemicals are now surrounded by a membrane (granule) 6) _________ Band Cell Nucleus changes into a new shape Spends a short amount of time in red bone marrow o Leaves the circulation and finishes the formation of the nucleus and ceratin type of WBC Formation of Monocyte 1) Hemocytoblast 2) Myeloid Stem Cell 3) Myelomonoblast (committed cell) 4) Promonocyte 5) Monocyte Which then becomes a macrophage ONLY when it leaves circulation and moves into the tissues Formed Elements Platelets: Incomplete cell, cellular fragment (aka cytoplasmic fragment) of Megakayoctye o Flat disk-like structure o Contains 2 regions in which the color is lighter on the outside and darker on the inside. o Contains chemicals Calcium, ADP, Serotonin…