Lecture 21Outline of Last Lecture I. The eyeII. Accessory structures of the eyeIII. Visual pathwayIV. The earV. Introduction to the circulatory systemOutline of Current Lecturei. The bloodii. Plasmaiii. Blood cellsCurrent LectureI. The Blooda. Blood: the fluid within the blood vessels and heartb. Said to be a kind of connective tissue with cells that are separated by a surrounding material (matrix)c. Develops from mesenchyme tissue like connective tissued. Makes up 7-8% of 6h4 body by weighte. Consists of 2 partsi. Cellsii. Plasmaf. Once centrifuged:i. Plasma is on topii. Red blood cells on the bottomiii. In between is a gray later called the “buffy coat”= white blood cells + plateletsII. Plasmaa. Makes up about 55% of the volume of bloodb. Hematocrit: the volume percent of red cells in bloodc. plasma is made up of many things such as:i. small molecules1. water, ions, small nutrient molecules, small waste molecules, oxygen, vitamins, and hormonesii. blood proteins (3 main classes)1. albumin: maintains a high osmotic pressure in blood, so the tissue fluid that is forced out at the capillaries will subsequently re-enter them 2. globulins: a. gamma globulins: include antibodiesb. alpha and beta globulins: some transport iron, others carry copper or lipids3. fibrinogen: when activated, becomes fibrin, the main element of a blood clotIII. Blood Cellsa. “disposable” cells of the bodyBIOLOGY 315 1st Editionb. Short lived, constantly being replaced with new cells from the bone marrow (the blood-cell forming organ)c. 3 types of blood cellsi. Erythrocytes1. Red blood cells2. Transport oxygen a. Pick up oxygen at lung capillariesb. Other capillaries to supply the tissues of the body3. Shaped like bi-concave discs, 8 micrometers in diameter a. Because they are all the same size, they can be used to estimate the sizes of surrounding structures 4. Stain orang-pink5. Most abundant of the blood cell types6. Technically not cells, because lack a nucleus and organelles 7. Cytoplasm contains a lot of hemoglobin8. Live an average of 120 days 9. Reticulocytes: the first 2 days of erythrocytes, have not yet lost all their ribosomes a. Become more abundant under circumstances that demand an increase in erythrocyte production b. Abnormally rare when blood-cell production slowsc. Clinician can count reticulocytes to estimate rates of erythrocyte formation and to help diagnose disease states ii. Platelets1. Smaller than red or white blood cells , 2-5 micrometers2. Not complete cells, cell fragments3. Form by breaking off of large cells in the bone marrow called megakaryocytes 4. No nucleus, few organelles, central part contains granules 5. Peripheral cytoplasm contains circular bundles of microtubules that maintain the platelets shape6. Stick to rough surfacesa. Sticky property comes from thick glycocalyx (cell coat)7. Function: adhere in large numbers to any tears in the lining of blood vessels, close the tears to stop the bleeding, start the blood clotting process by releasing a clot-signaling substance called thromboplastin8. Some of the granules in platelets release serotonin (lessens blood flow to damaged vessels by signaling these vessels to constrict)9. Do not adhere to the lining of healthy vesselsiii. Leukocytes1. White blood cells2. True cells- have nuclei and typical organelles3. functions in defense against infection a. combat infection in the connective tissues outside the vessels4. do not function in the blooda. leave the circulatory system through the capillary walls 5. crawl like an amoeba when in the connective tissue6. rarer than erythrocytes7. 5 types of white blood cellsa. Divided into 2 groups: granular leukocytes and agranular leukocytesb. Granular leukocytes : neutrophils, eosinophils, basophilsi. 9-12 micrometers in diameterii. Live for a short time, about 10 days1. The first 12 hours are in the bloodstreamiii. Have distorted nucleus with bulges called lobes1. The nucleus stops controlling the cells and shuts downiv. All are phagocytic v. Neutrophils1. Most abundant of the leukocyte types2. About 60% of all white blood cells3. Long nucleus with between 2-6 lobes, connected bynarrow threads of chromatin4. Granules are of 2 distinct types, both of which are lysosome-like a. Specific granules: stain very light pinkb. Azurophilic granules: less abundant, and stain purplec. Together make a light purple color d. Both contain assortments of enzymes whichbreak down bacterial walls in numerous ways 5. Specialized for phagocytizing bacteria6. Secrete toxins into surrounding matrix that kill nearby bacteria 7. Secrete networks of proteins to trap bacteria and kill them with bactericidal chemicals 8. Most active in early stages of infection9. Band neutrophils: immature neutrophils, nucleus isnot yet condensed, has band-like horseshoe shapevi. Eosinophils 1. Rarer than neutrophils 2. Nucleus often has 2 lobes connected by a thick band 3. Contains many enzymesa. Some of which form a big protein crystal 4. The granules are similar to lysosomesa. Lack only the few lysosomal enzymes that specifically attack bacteria 5. Phagocytize antigen antibody complexesa. Antibodies of allergy that are attached to the allergen molecules that stimulate allergyi. Turn off allergic reactions6. Destroy parasitic worms 7. An elevated number of eosinophils in the blood canindicate that person has allergies or parasitesvii. Basophils 1. The rarest of all white blood cells2. Nucleus is elongated and bent3. S shaped or omega shaped4. Granules are large, stain dark purple, and often obscure the nucleus5. Contain histamine and heparina. Signaling the inflammation of allergy b. Control the late stages of the allergy reaction 6. Attract eosinophils to allergy sites so the eosinophils can then shut down the allergic reaction c. Agranular leukocytesi. Lymphocytes1. Second most common class of white blood cellsa. 20-35% of all leukocytes2. Cytoplasm is basophilic 3. Nucleus has a large amount of condensed chromatin 4. Come in all sizes, determined by the amount of cytoplasm present 5. Participate in the specific immune response, meaning that each lymphocyte cell recognizes and attacks its own specific type of foreign molecule 6. Basis of our immune system7. 2 main substances a. Called T and B cellsi. Differ in function but not in structure8. Not phagocytic ii. Monocytes1. Largest blood cells2. Blue cytoplasm and purple nucleus3. Nucleus of monocytes is often bowed (C-shaped) and chromatin is never as highly