CHAPTER 17: THE BLOOD Flashcards
LIST THE FUNCTIONS OF WHOLE BLOOD
Transportation: transporting O2 and nutrients to body cells, transporting metabolic wastes to the kidneys and lungs for elimination, transporting hormones from endocrine organs to target cells/organs.
Regulation: maintains body temperature by absorbing and distributing heat, maintains PH using a buffer system (carbonic acid and bicarbonate), maintains adequate fluid volume in the circulatory system
Protection: prevents blood loss by using plasma protein and platelets to form clots, prevents infection by using immune cells like antibodies, complement proteins, and white blood cells
WHAT ARE THE COMPONENTS OF BLOOD
plasma and formed elements (erythrocytes, leukocytes, platelets)
WHAT IS PLASMA MADE OF? WHATS IT’S CONSISTENCY LIKE?
is a straw-coloured non-living substance that is made up of around 90% water. The remaining 10% is made up of over 100 different solutes (that remain in blood, not taken up by the cells). Plasma proteins are the most abundant solutes and are mostly made in the liver.
WHAT ARE THE 2 MOST ABUNDANT PLASMA PROTEINS IN PLASMA
Albumin: makes up 60% of plasma proteins. Works as a blood buffer, contributes to osmotic pressure in blood, and transports molecules in blood
Globulin: makes up 36% of plasma proteins, acts as immune modulators and as a transport protein.
DESCRIBE THE COMPONENTS OF A CENTRIFUGED TEST TUBE
– hematocrit: is the bottom layer of the centrifuged blood containing erythrocytes. Is the most dense component and makes up 45% of whole blood.
– buffy coat: is the thin middle layer containing leukocytes and platelets. Is <1% of whole blood
– plasma: is the top layer that contains plasma, it is the least dense layer and is 55% of whole blood.
RELATE THE STRUCTURE OF AN ERYTHROCYTE TO IT’S FUNCTION
Biconcave shape: the shape allows for the cell to have more surface area relative to volume. This makes it so more O2 can diffuse in and out of the cell.
Lack of organelles and nuclei make it so RBC’s can hold more hemoglobin (makes up 97% of cell volume not including water). This increases and maximizes the oxygen carrying capacity of each cell, however RBC lifespan is sacrificed. Each RBC has 250 million hemoglobin molecules. Absence of mitochondria prevents cell from eating up the oxygen its transporting.
Diameter: is relatively thin, this makes it easier for gas to diffuse in and out of the cell.
WHAT IS HEMATOPOIESIS? WHERE DOES IT OCCUR?
process of blood cell formation, this occurs in the red bone marrow (axial skeleton, girdles, proximal epiphysis of humerus and femur)
WHAT ARE HEMATOPOIETIC STEM CELLS?
stem cells that give rise to blood cells, growth factor and hormones pushes cells towards a specific pathway (to become a specific type of blood cell). Once it is committed, it cannot change pathways (ex. Once a RBC, always a RBC)
WHAT IS ERYTHROPOIETIN? HOW IS IT STIMULATED?
is a hormone that stimulates erythropoiesis (RBC production). It is produced by kidney cells when they become hypoxic (o2 deprived). Constant low levels of EPO maintain the basal rate of RBC production.
DESCRIBE THE STAGES OF HEMATOPOIESIS STARTING FROM PRODUCTION IN BONE MARROW TO DESTRUCTION FROM MACROPHAGES
1). Stem cell: hematopoietic stem cells → myeloid stem cell → proerythroblast (committed cell)
2). Developmental stage: → basophilic erythroblast (mass production of ribosomes occur, iron also begins to accumulate in the cell) → polychromatic erythroblast (accumulation of iron leads to mass synthesis of hemoglobin) → orthochromatic erythroblast (the mass production of hemoglobin causes organelles and nucleus to be ejected in order to make more space for elevated protein levels)
3). Reticulocyte: reticulocyte (immature erythrocyte, lack of organelles and nuclei causes the cell to cave in on itself causing the biconcave shape. A few ribosomes remain hence the name, and makes some last minute hemoglobin)
The entire process from start to reticulocyte takes around 15 days, then the reticulocyte is ejected into the blood. Over the next 2 days the remaining reticulocytes will degrade. Reticulocyte count is a good way to measure the rate of RBC production.
4). Erythrocyte: mature RBC filled to the brim with hemoglobin and with maximized oxygen carrying capacity .
5). Destruction: RBC life span is around 100-120 days, this is because the lack of nucleus causes the cell to be unable to synthesize proteins, grow, or divide. The hemoglobin starts to degenerate (o2 carrying capacity decreases). and the RBC becomes fragile. RBCs can be easily trapped in smaller circulatory pathways esp. In the spleen. Macrophages engulf dying RBC’s.
Heme, globin, and iron are all separated. Heme becomes pigment bilirubin (bilirubin is secreted into the intestines by the liver where it eventually becomes the brown pigment that leaves the body via feces), iron is stored for later use, globin is metabolized into amino acids (released into circulation).
WHAT ARE THE ADDITIONAL REQUIREMENTS FOR HEMATOPOIESIS?
Erythropoiesis is regulated by hormonal and dietary requirements/factors. Erythropoietin is triggered by hypoxia of kidney cells, too many RBCs trigger EPO inhibition. Testosterone also speeds up erythropoiesis, this is why RBC count is higher in males.
Dietary requirements include amino acids, iron, lipids, carbohydrates, as well as vitamin b12 and folic acid for DNA synthesis for rapid production of RBCs.
WHAT ARE SOME ERYTHROCYTE RELATED DISEASES? WHAT CAUSES THEM?
Anemia: very low oxygen carrying capacity
Polycythemia: excess RBCs leading to more blood viscosity and sluggish blood flow.
STATE THE COMPONENTS, FUNCTIONS, AND ULTIMATE FATE OF A HEMOGLOBIN MOLECULE
Components: heme, iron, 4 polypeptide chains (2 beta and 2 alpha)
Function: O2 transport (it binds reversibly)
Fate: once the RBC dies at around 100-120 days, the hemoglobin will start to degrade and each of the 3 components are separated (heme, globin, and iron). Heme is converted into bilirubin which is secreted by the liver (in bile) into the intestines, it then becomes a brown pigment that is excreted in the feces. Iron is stored for later use, and globin is metabolized into amino acids which then enter blood circulation.
WHAT IS THE ORDER OF ABUNDANCE FOR LEUKOCYTES? NAME THEIR PRECENTAGE TOO.
neutrophil (50-75%), lymphocyte (25%), monocytes (3-8%), eosinophil (2-4%), basophil (<1%)
HOW ARE LEUKOCYTES CLASSIFIED? NAME THE LEUKOCYTES WITHIN THOSE CATEGORIES.
Granulocytes: contain obvious and visible cytoplasmic granules (neutrophils, eosinophils and basophils)
Agranulocytes: do not contain visible/obvious granules (lymphocytes and monocytes)
STATE THE FUNCTION OF NEUTROPHILS
-Are the most abundant WBC (50-70%)
- cytoplasmic granules can stain with both acidic and basic dyes,
- are also referred to as polymorphonuclear lymphocytes because they are lobular, they can contain anywhere from 3-6 lobes.
- Are also twice the size of a RBC. Are very phagocytic and contain hydrolytic enzymes, antimicrobial proteins called defensins. Produced germ killing oxidizing substances like bleach and hydrogen peroxide.
STATE THE FUNCTION OF EOSINOPHILS
Eosinophils: account for 2-4% of WBC’s. They contain 2 lobes connected by a broad band, almost resembling earmuffs. The red staining granules contain digestive enzymes that are released on large parasitic worms that are too large to be phagocytized.
STATE THE FUNCTION OF BASOPHILS
are the rarest WBC, accounting for 0.5-1% of all of them. The nucleus is a deep purple and has 2 constrictions. The deep purple-black granules contain histamine (chemical that acts as a vasodilator and attracts WBC’s to inflamed sites)
STATE THE FUNCTION OF LYMPHOCYTES
are the second most abundant leukocyte, accounting for around 25% of them. There are 2 major types of lymphocytes. They are also the only lymphocyte made in lymphoid tissue, and are prominent in lymphatic areas.
– T-lymphocytes: are also referred to as killer T cells. They target virus infected and tumor cells.
– B-cells: create antibodies from plasma proteins
STATE THE FUNCTION OF MONOCYTES
are the largest leukocyte, and account for around 3-8% of them. They are very phagocytic and are referred to as macrophages when they enter tissues, they are very mobile. They target chronic infections, intracellular bacteria, and viruses.
WHAT ARE SOME LEUKOCYTE RELATED DISEASES? WHAT CAUSES THEM?
Leukopenia: underproduction of leukocytes
Leukemia: overproduction of abnormal leukocytes, usually comes from clones of a single abnormal cell.
WHAT IS HEMOSTASIS?
Hemostasis: is a cascade of events that prevents blood loss hence the name (hemo=blood, stasis=stop).
WHY ISN’T BLOOD ALWAYS CLOTTING?
The only reason blood isn’t constantly clotting is because of anticoagulants, those being heparin (inhibits thrombin by increasing the activity of antithrombin 3), nitric oxide, prostacyclin) these dominate in the blood when it isn’t damaged.
WHAT ARE THE STEPS OF HEMOSTASIS?
Vascular spasm, platelet plug formation, coagulation, clot retraction, fibrinolysis
