bio 213 chapter 18 objectives

Stating the chemical composition, location in blood, and function of albumin and fibrinogen

(54%) regulate osmotic pressure of plasma •one of the plasma proteins and produced by liver and synthesized mainly by hepatocytes (liver cells) • Function: o It helps maintain proper blood osmotic pressure; which is an important factor in the exchange of fluids across capillary walls o transport proteins for several steroid hormones and for fatty acids 2: 7%; key for blood clotting(forms fibrin thread of blood cloth) -produced by the liver both are found in the plasma of blood.

Stating the percentages plasma, red blood cells, white blood cells, and platelets in whole blood

Blood is more denser and viscous than water with an alkaline range of 7.35 - 7.45 and constitutes about 8% of body weight • Average size of 5 - 6 liters (1.5 gal) in man and 4 - 5 liters (1.2 gal) in woman • Blood plasma - 55% • Formed elements - 45% o RBC - >99% of 45% WBCs and platelets in Buffy coat (< 1%)

Defining erythropoiesis

Erythropoiesis starts in the red bone marrow with a precursor cell called a pro erythroblast. The proerythroblast divides several times, producing cells that begin to synthesize hemoglobin. Ultimately, a cell near the end of the development sequence ejects its nucleus and becomes a reticulocyte. Loss of the nucleus causes the center of the cell to indent, producing the RBC's distinctive biconcave shape. Reticulocytes, which are about 34 percent hemoglobin and retain some mitochondria, ribosomes, and endoplasmic reticulum, pass from red bone marrow into the bloodstream. Reticulocytes develop into erythrocytes (mature RBCs) within 1 or 2 days after their release from red bone marrow.

Describe hemopoiesis and state where formed elements are produced.

Formation of blood cells from hemopoietic stem cells in red bone marrow controlled by hormones -Erythropoietin, thrombopoietin, cytokines, and other hemopoietic growth factors -Pluripotent stem cells give rise to two kinds of stem cells Myeloid stem cells - differentiate into precursor cells (blasts) for RBCs, platelets, three kinds of granulocytes, and monocytes Lymphoid stem cells - differentiate into precursor cells (lymphoblasts) for two kinds of lymphocytes in red bone marrow, then complete development in lymphatic tissues

Explaining the regulation of erythropoiesis

If the oxygen-carrying capacity of the blood falls because erythropoiesis is not keeping up with RBC destruction, a negative feedback system increases RBC production. The controlled condition in this particular feedback loop is the amount of oxygen delivered to the kidneys (and thus to body tissues in general). Cellular oxygen deficiency, called hypoxia, may occur if too little oxygen enters the blood. Hypoxia stimulates the kidneys to increase the release of the hormone erythropoietin. Erythropoietin circulates through the blood to the red bone marrow, where it speeds the development of proerythroblasts into reticulocytes. As the number of circulating RBCs increases, more oxygen can be delivered to body tissues.

dietary nutrients needed for red blood cell production to occur

Iron, folic acid, protein, vitamin B12

Describe the red blood cell life cycle including the fate of hemoglobin in old, worn-out red blood cells,

Macrophages in the spleen, liver, and red bone marrow phagocytize ruptured and worn-out red blood cells, splitting apart the globin and heme portions of hemoglobin. 2) Globin is broken down into amino acids, which can be reused by body cells to synthesize other proteins. 3) Iron removed from the heme portion associates with the plasma protein transferrin, a transporter for iron in the bloodstream. 4)The iron-transferrin complex is then carried to red bone marrow, where RBC precursor cells use it in hemoglobin synthesis. Iron is needed for the heme portion of the hemoglobin molecule, and amino acids are needed for the globin portion. Vitamin is also needed for synthesis of hemoglobin. 5) Within red bone marrow, erythropoiesis (red blood cell production) releases red blood cells into the circulation. 6) When iron is removed from heme, the non-iron portion of heme is converted to biliverdin, a green pigment, and then into bilirubin, a yellow-orange pigment. Bilirubin enters the blood and is transported to the liver. Within the liver, bilirubin is secreted by liver cells into bile, which passes into the small intestine and then into the large intestine. 7) In the large intestine, bacteria convert bilirubin into urobilinogen. Excreted as waste.

Describe red blood cell anatomy and the structure and function of hemoglobin

Mature cells are biconcave discs that lack nuclei and other major organelles, so cannot undergo mitosis or extensive metabolic activities Contain oxygen-carrying hemoglobin -Gives RBCs their red color -Globin part of molecule is four-polypeptide chain protein -that can bind and transport carbon dioxide Heme part of molecule is ringlike nonprotein pigment with iron that binds to oxygen (to transport oxygen from the lungs to the body's tissues and then transport carbon dioxide out of the tissue back to the lungs) Produced and enter circulation at same rate destroyed (about 2 million per second)

polycythemia

an abnormally increased concentration of hemoglobin in the blood, through either reduction of plasma volume or increase in red cell numbers. It may be a primary disease of unknown cause, or a secondary condition linked to respiratory or circulatory disorder or cancer

sickle-cell disease

an inherited group of disorders, red blood cells contort into a sickle shape. The cells die early, leaving a shortage of healthy red blood cells (anemia), and can block blood flow causing pain (crisis)

Comparing the structure of reticulocytes and erythrocytes

reticulocytes are round with a nucleus and organelles. Erythrocytes are biconcave with no nucleus or organelles. reticulocytes and erythrocytes are each normally found in circulating blood

Describe formed elements

• Formed elements are cells and cell fragments that make up 45% of whole blood. • Normally 99% of formed elements are red blood cells and the remaining components are white blood cells and platelets. RBC and WBC are whole cells while platelets are cell fragments.

the hematocrit

• Is the percentage of total blood volume occupied by RBC (40% hematocrit means our blood is composed of 40% RBC) o Normal range for men is 40 - 54, average 47% o Normal range for women is 38 - 46, average 42% • The hormone testosterone stimulates the synthesis of erythropoietin (EPO), the hormone that stimulates the production of RBC. Since testosterone is higher in males, hematocrit is also higher • Significantly low hematocrit is indicative of anemia • Significantly high hematocrit is indicative of polycythemia

Defining plasma

• The extracellular fluid found in vessels; blood minus the formed elements. • It is a straw colored fluid that remains on top of blood after centrifuging it. • 91.5% water, 7% protein and 1.5% solutes It acts as a solvent for important proteins, nutrients, electrolytes, gases, and other substances essential to life. (allows blood to flow freely through blood vessels)

Summarize the general characteristics of blood by: Describing its functions

• Transportation - of hormones, oxygen and nutrients to cells and heat and waste from cells • Regulation - maintenance of homeostasis via circulating blood. • Protection - clots can be formed in times of injury to protect against excessive loss of blood. WBC function as phagocytes