Blood Worksheet I Key

Blood Worksheet I KEY BLOOD FACTS Blood is the only liquid tissue in our body. o It is a type of connective tissue.   About 8 % of your body weight is blood. You have about 5 liters in your body (1.5 gallons). Blood temperature is about 100°F. o It is a conduit of heat exchange. We can divert flow of blood from one part of the body to another to change its temperature. If we put it to the surface, heat will be exchanged with the environment and we will (cool down/warm up). If we keep blood away from the surface, heat will be maintained, and we will (cool down/warm up). Blood pH is between 7.35-7.45. o On the (acidic/alkaline) side of neutral. o This is advantageous because most of the foods we bring in are slightly (acidic/alkaline). FUNCTIONS Function Example/Description Delivers oxygen and nutrients to tissues Transports metabolic wastes From oxygen rich - Largest of these is CO2 Nitrogenous wastes -  - oxygen poor areas; ex. glucose Transports hormones Maintains body temperature Maintains body pH - Flow from one part to the next determines temperature - Blood carries buffers (bicarbonate) - Exchange between different fluid compartments (interstitial space, cells cytoplasm) Prevents blood loss - Clotting factors Prevents infection - Specialized cells help to prevent infection Maintains fluid volume 1 BLOOD COMPONENTS Includes formed elements, which make up approximately 46%, and plasma, which makes up approximately 54%. Formed Elements Erythrocytes Leukocytes Type of Cell Red blood cells (RBC’s) Living or Non-living? Not living (lost nucleus and most of their organelles to make space for an oxygen carrying protein) True living cells Carry respiratory gases (Oxygen and CO2) Immune system – help prevent infection by attacking foreign substances 45% Less than 1% Function Percentage of blood Platelets Fragments (pieces that have broken off) White blood cells Not living Blood clotting All formed elements are produced in the (red/yellow) bone marrow. Blood hematocrit: shows us the percentage of each component of our blood Plasma Water Makes up 90% of the volume Solutes Proteins (clotting), biggest compositional protein is albumin, globulins, Nutrients (glucose), Electrolytes (calcium, sodium, potassium), Respiratory gases (O2 and CO2) 2 ERYTHROCYTES Size Small (smaller than WBC’s) Shape Biconcave Nucleus Contain: Hemoglobin, antioxidant enzymes Anucleate (no nucleus) (breakdown free radicals) Humans have, on average, five million red blood cells per milliliter of blood. o We have 5000 milliliters of blood in the body. Men have more than women due to multiple factors. o Men  5.1-5.8 million/mL o Women  4.7-5.2 million/mL (menstrual cycle) Approximately 250 million hemoglobin molecules per RBC. o Each heme binds to one oxygen, so four oxygen molecules per hemoglobin. o A single RBC can carry one billion oxygen molecules. o There are five million billion oxygen molecules per milliliter of blood. HEMOGLOBIN Composed of globin protein bound to heme pigment. Globin is a complex protein, which means it has more than one subunit. Heme pigment is what makes blood red.  Globin Protein : 4 polypeptide chains o 2 alpha o 2 beta Each subunit binds to one heme pigment.  Heme Pigment : Contains oxygen-binding iron. Each heme can bind to one oxygen molecule. 3 OXI vs. DEOXY-HEMOGLOBIN Hemoglobin can shift between having oxygen and not having oxygen. o When oxygen is bound  Oxihemoglobin  Binding of oxygen to hemoglobin makes it bright red. o When oxygen is not bound  Deoxyhemoglobin  Lack of oxygen binding to hemoglobin makes it dark red. This is a transporter mechanism for moving oxygen throughout the body. o Hemoglobin loves oxygen. o Once oxygen starts to bind to hemoglobin, it is more likely to bind additional oxygen. o It likes to stay completely saturated (having 4 oxygen molecules bound). A patient is struggling when their oxygen saturation gets below 90%. Oxygen dissociation curve  CARBAMINOHEMOGLOBIN Hemoglobin also carries carbon dioxide. Only about 20% of the carbon dioxide carried in the blood is bound as carbaminohemoglobin. o The rest is transported in the plasma. Carbon dioxide doesn’t bind to the heme, it binds to the globin. HEMATOPOESIS (production of blood cells) The production of blood cells. This is an ongoing process. We produce about one ounce of blood cells per day. o Each ounce will contain about 100 billion cells. o The composition of these cells will vary from one day to the next based on our body’s needs. Example: fighting infection = white blood cells, start running = red blood cells All blood cell production occurs in the bone marrow. 4 ERYTHROPOIESIS (production of red blood cells) Hemocytoblast, a pluripotent cell (undifferentiated and can give rise to a number of different things), is stimulated to start dividing (by a signal!) and produces another pluripotent cell called a myeloid stem cell. Myeloid stem cell divides to become a proerythroblast. The proerythroblast, which is the first committed cell (meaning it can only become RBC), becomes an early erythroblast. Early erythroblast becomes late erythroblast. Late erythroblast becomes normoblast. Normoblast loses cellular organelles and nucleus and starts to accumulate hemoglobin to become a reticulocyte. Reticulocytes mature in bloodstream (away from the bone marrow) to become erythrocytes. Reticulocytes & erythrocytes are not living! They have lost their nucleus and organelles. Because of this, they have to be replaced often. This process takes somewhere between 3-5 days & produces about 2 million erythrocytes per second. REGULATION OF ERYTHROPOIESIS 5 Regulator Action/Description Erythropoietin When our blood is (low/high) on oxygen, the kidneys start to produce this. The body monitors oxygen level, not RBC count. It is a hormone, which has receptors on hemocytoblasts, and it initiates their division process. Testosterone This is another reason why men have more red blood cells than women. Increased muscle mass results in an increased need for oxygen, and thus more red blood cells. Works through the kidneys by stimulating them to release erythropoietin. B Vitamins Iron Dietary Nutrients Especially B12 and folic acid. During pregnancy, a woman has to produce red blood cells to carry oxygen for both herself and the baby. This is why she needs supplements. We have to have iron to create hemoglobin. We get it in the food we eat. If we don’t need it immediately, it is stored in cells as ferritin and hemosiderin. When transported in the blood, its called transferrin. If we’re making any sort of cell, we have to have nutrients. o Ex. Proteins, lipids, carbohydrates. ERYTHROCYTE LONGEVITY 6 Last between 100-120 days. (4 months max) These cells ultimately start to get old, and macrophages consume them and break them apart. This process occurs primarily in the spleen. (can happen other places) As we break down old red blood cells, we recycle their parts. o Heme is split from globin. o Iron stripped off of heme and is stored as ferritin and hemosiderin. o Some of that iron is broken down and turned into bilirubin.  Bilirubin is picked up by the liver and used as one of the ingredients to make bile. Bile is secreted into the small intestine to help us with digestion.  Pigment degraded and expelled as feces. o Globin, a protein, broken down to component amino acids.  Can then be used to make other proteins. ERYTHROCYTE DISORDERS Anemias o Either low number of or abnormal (sickle cell) red blood cells that reduce the oxygen carrying capacity of the blood. Polycythemias o Over production of red blood cells. o So many red blood cells that the blood has trouble moving through the tiny capillaries.  Blood is a “sludge”. DIAPEDESIS Some blood cells have the ability to leave blood vessels and enter the interstitial fluid. (Red/White) blood cells cannot do this, but some (red/white) blood cells can. (not all!) LEUKOCYTES Complete, living cells which have nuclei and organelles. Display positive chemotaxis, which means they are chemically attracted to certain areas. 4800-10800 per mL of blood. A simple blood test can be used to tell whether we have bacterial or viral infection. o Viral = white blood cell generally goes down o Bacterial = white blood cell goes up There are 5 different types. Some contain granules which store things such as enzymes. Granulocytes 7 Neutrophils Function Phagocytic cells which function in the inflammatory response Characteristics Most numerous; Has a lobed nucleus Percentage of white blood cells 50-70% Basophils Granules full of histamine (a vasodilator), attracts other white blood cells Eosinophils Attacks parasitic worms Two-lobed nucleus 0.5-1% 2-4% Agranulocytes Lymphocytes Function Characteristics Types Percentage of white blood cells Monocytes Become macrophages (special phagocytic cells) when they leave the blood stream (diapedese) – alters when it leaves Immunity Large nucleus which makes up most of the cell, found primarily in lymphatic tissue (generally not circulating through blood) Largest; U-shaped nucleus o T- lymphocytes = attack virally infected cells or tumors o B-lymphocytes = secrete antibodies N/A 25% 3-8% LEUKOPOIESIS (production of white blood cells) Hemocytoblast is stimulated and gives rise to two different stem cells. 8 o Myeloid stem cells: give rise to  All granulocytes & Monocytes o Lymphoid stem cells: give rise to  Lymphocytes  GRANULOCYTE LEUKOPOIESIS (Some/All) granulocytes produced through this lineage. The specific type that are produced is based on the need of the body. Myeloid stem cells become myeloblasts. Myeloblasts, the first committed cells, accumulate lysosomes (granules) to become promyelocytes. Promyelocytes differentiate into myelocytes. Cell division stops and nuclei arch to form band cells Nuclei constrict and segment to become mature granulocytes. Lasts: between half a day and 90 days. Even though it’s a real cell, it doesn’t last very long.  AGRANULOCYTE LEUKOPOIESIS Monocytes Myeloid stem cells become monoblasts. 9 Monoblasts become promonocytes. Promonocytes leave bone marrow and matures to become monocytes in lymph tissues. Lasts: months Lymphocytes Lymphoid stem cells become lymphoblasts. Lymphoblasts become prolymphocytes. Prolymphocytes leave bone marrow and become lymphocytes in lymphatic tissue. Lasts: from weeks to decades (70 yrs) REGULATION OF LEUKOPOIESIS Interleukins o Chemical messengers usually released when we’re fighting an infection. o When a cell is attacked by a virus, it releases these to protect neighboring cells. Colony-stimulating factors (CSFs) o (Increases/Decreases) white blood cell count. LEUKOCYTE DISORDERS Leukemia o Cancerous condition of white blood cells. Infectious mononucleosis 10 o Increase in agranulocytes. o Caused by exposure to the epistene-barre virus. Leukopenia o (Increase/Decrease) in white blood cell production. o Immune system is compromised. PLATELETS Anucleated cytoplasmic fragments of megakaryocytes. Contain granules which have clotting factors. THROMBOPOIESIS (production of platelets ) Hemocytoblasts give rise to myeloid stem cells. Myeloid stem cells become megakaryoblasts, which are the first committed cell in this lineage. Megakaryoblasts undergo repeated mitosis but no cytokinesis (divides nuclear portion, but not cytoplasm) to form megakaryocytes. Cytoplasmic extensions of megakaryocyes break off to become platelets. REGULATION OF THROMBOPOIESIS Thrombopoietin o A hormone which stimulates production of platelets. 11