University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2020
Views:

313

Pages:

33
Author:

Hundebuchesn

Blood Cells Blood •It is specialised type of connective tissue •Composition: Variety of cells suspended in a fluid medium called plasma Sheet note 1 § Blood is considered a specialized type of connective tissue Functions of blood •Transports nutrients and respiratory gases • Transports waste products to organs and tissues where they can be recycled or released Sheet note 2 • Transports hormones • Transports immune cells throughout the body By vasoconstriction &vasodilation • Helps regulate body temperature - Blood is slightly alkaline • Maintains of acid-base and osmotic balance Characteristics •pH of 7.4 •Colour is dependent on amount of oxygen More oxygen= brighter the red Less oxygen= duller the red •5-6 litres of blood in an average adult moves unidirectionally within the closed circulatory system Physical Characteristics Fluid –Living 45% v Cells (formed elements) –RBC Erythrocytes(carry oxygen) –WBC Leukocytes (immune) –Platelets Thrombocytes(clotting) Buffy coat –Non living (Matrix) 55% v Plasma (pale yellow fluid) –90% water –10 % (electrolytes, nutrients, proteins (albumin), waste (CO2, ammonia, urea), gases, hormones) HEMATOCRIT: Ratio of the volume of RBCs to the volume of whole blood Example: a hematocrit value of 40% means that there are 40 ml of RBCs in 100 ml of whole blood Normal hematocrit: Males=40-53% Females= 36-48% Sheet note #2 • In medical books, always we see the venous blood in a blue color? Does it really blue? ofcourse NOT, blood either in arteries or veins is always red, but the amount of redness differs depending on the amount of O2 • The 45% is divided to Around 44% erythrocytes Less then 1% WBCs In order to study the physical characteristics of the blood we should take a blood sample and put it in the centrifuge then the blood will be separated into 3 layers that are arranged according to the density Centrifuged blood sample Sheet note #3 Using centrifugation which separates the components depending on density Plasma Essentially aqueous solution of inorganic salts which is constantly exchanged with extracellular fluid of body tissue Plasma also contains à Plasma Proteins of 3 main types A- Albumin B- Globulin C- Fibrinogen Plasma proteins collectively exert a colloid osmotic pressure within the circulatory system which helps regulate the exchange of aqueous solutions between plasma and ECF Albumins: constitute the bulk of plasma proteins Bind insoluble metabolites such as fatty acids and serve as transport proteins Globulins: includes the antibodies of immune system transport protein Fibrinogen: soluble protein which polymerises to form the insoluble protein fibrin during blood clotting Blood cell types Three major classes: 1- Red Blood Cells (RBCs) (erythrocytes) 2- White Blood Cells (WBCs) (leukocytes) 3- Platelets (Thrombocytes) # RED bone marrow All are formed in the bone marrow a process known as Haemopoiesis Erythrocytes: involved in transport of (O2 and CO2) Function exclusively within the vascular system Leukocytes: Important part of defence and immune system Act mainly OUTSIDE blood vessels in the TISSUES Platelets: play a vital role in the control of bleeding (haemostasis)by: 1- Plugging the defects in blood vessels 2- Actvating the blood clotting cascade Methods used to study blood and bone marrow Sheet note 4# contain different stains (acidic&basic stains) To make a smear on a glass slide à after fixation à stained by a polychromatic stain (Giemsa, Wright, Leishman) à distinctive staining characteristics ( according to the affinity of the various cellular organelles to the different stains employed) Blood film Blood smear Spreader A- Basophilia (deep blue): affinity for the basic dye methylene blue characteristic of DNA in nucleus and RNA in the cytoplasm eg. Ribosomes B- Azurophelia (purple): affinity for azur dyes, typical of lysosomes (azurophilic granules in leucocytes) C- Eosinophilia (pink): affinity for acidic dye (eosin) particular feature for hemoglobin within erythrocytes Thes granules don’t have affinity for acidic or basic dyes D- Neutrophilia (salmon pink/ lilac): characteristic of the specific cytoplasmic granules of neutrophil leucocytes (the dye is NOT of neutral PH) The name, neutrophil, derives from staining characteristics on hematoxylin and eosin (H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink(pale pink) sheet #5 Erythrocytes Erythrocytes (RBCs) • Small, pink biconcave discs •7-8 µm in diameter •Transport oxygen and CO2 • cytoplasm is full of hemoglobin molecules •Have no nuclei or organelles •Pick up O2 at lung capillaries and release it at body tissue capillaries Male: 4.5-5.5 million/mm3 Female:4-5 million/mm3 The amount of RBCs is higher in males Because they have androgen hormone which stimulates the production of these cells Sheet note #6 During their maturation process, the erythrocytes extrude their nuclei, and the mature RBCs enter the bloodstream, without their nuclei Eosinophilia/ acidophiliadue to their High content of Hemoglobin (which is a basic protein) The pale staining of the central region is a result of its biconcave disc shape Biconcave shape provides 20-30% greater surface area than a sphere relative to cell volume, thus significantly enhancing gas exchange The biconcave shape along with the fluidity of the plasma membrane (50% proteins) permits erythrocytes to bend and adapt to the small diameters and irregular turns of capillaries (34μM in diameter RBCs have smooth membrane without pointed projections Normochromic RBCs the central region is very thin—> less HB—> less dye—> pale central region Erythrocyte consists of an outer plasma membrane enclosing hemoglobin and a limited number of enzymes necessary for maintenance of plasma membrane integrity and gas transport functions Immediately beneath the plasma membrane is a meshwork of proteins(Spectrin and Ankyrin) forming a cytoskeletonà responsible for the biconcave shape of erythrocyte This submembranous meshwork: • Stabilizes the membrane • Maintains the cell shape • Provides the cell elasticity required for passage through capillaries The cell membrane is highly selective and flexible • Size 7-8 µm in diameter (7.5 µm) • Thickness 2.6-µm thick at the rim, but only 0.75-µm thick in the centre Erythrocytes can be used asa size reference for other cell types Fate: Survive for ~100-120 days in the circulation. Worn out RBCs are removed by macrophages of the spleen, bone marrow and liver. (without organelles à erythrocytes are unable to replace necessary enzyme and membrane proteins) LM: Blood film stained with Leishman: Ø Rounded Ø Non nucleated Ø Acidophilic (with pale central area) Appear like this because the RBC is 100% composed of Hb EM: • Have no nucleus or organelles • Filled with hemoglobin Electron dense and homogenous Rouleaux appearance occurs to some extent in all films Sheet note #7 It may appear in LM because of artifact during preparation Rouleaux formation: • RBCs may adhere to one another loosely in stacks called Rouleaux (pile of coins) • In slow (not in normal) circulation Due to surface tension caused by their biconcave surface (reversible) Reticutocytes Are the immature form, in which erythrocytes are released into the circulation from the bone marrow They still contain sufficient : mitochondria ribosomes Golgi To complete cytoskeleton and the remaining 20% of haemoglobin synthesis Final maturation into erythrocytes occurs within 24-48 hours of release The rate of release of reticulocytes into the circulation generally equals the rate of removal of spent erythrocytes by the spleen and liver Reticulocytes constitute slightly less than 1% of circulating red blood cells The presence of these cells in a signi In routinely stained blood smears: reticulocytes canNOT be easily distinguished from mature erythrocytes. When fresh blood is incubated with basic dye ((brilliant cresyl blue)), a blue-stained reticular precipitate is formed in the reticulocytes due to the interaction of the dye with ribosomal RNA remnants, the technique is called supravital staining Reticulocytosis An increase in the number of reticulocytes is considered an abnormality but the cell itself is not an abnormal erythrocyte Abnormalities of Erythrocytes Change from the normal • Size • Shape • Staining properties of erythrocytes are important indicator of disease. However, some of these abnormalities may be found in healthy individuals Anemia,in Abnormal sizes: iron deficency Microcytes(<6 µm) Macrocytes(>9 µm) Anisocytosis(different sizes) (abnormal variations of the size) Abnormal staining: Hypochromia: Denotes a decrease in the intensity of staining Indicates a decreased amount of hemoglobin Frequently accompanies microcytosis Hypochromic microcytic anemia Even here there Is anemia,why? Because increase in size means decrease in number( net decrease in Hb amount) • Anemia because of folic acid&B12 deficiency Abnormal shapes: Due to changes either in the cell membrane or Hb content Spherocytes Ovalocytes Poikilocytes The cells may show blunt/ pointed projections from their surfaces Sickle cell anemia results from abnormal hemoglobin Sickle cell One of the most sever changes in shape occurs during SICKLING of RBCs in sickle cell anemia where erythrocytes take on the form of crescents Crenation of red cells: if normal cells are placed in a hypertonic solution, water is abstracted from the cells leaving it shrunken and bearing numerous projection from its surface Howell-Jolly bodies: nuclear fragments left over from the nucleated precursors of the red cells Anemia: a decrease in the total number of RBCs (and/or hemoglobin) Polycythemia: an increase in the total number of RBCs People living at high altitudes usually have higher RBC count as a response tolower oxygen levels. Physiological conditions Athletes whose demand for oxygen is more elevated, also have higher RBC counts. Leukocytes Leukocytes • Originate in the bone marrow and released continuously into the blood • Travel in bloodstream but function mainly OUTSIDE blood vessels (in loose CT) • Leukocytes form a mobile army that helps protect the body from damage by bacteria, viruses, parasites, toxins and tumor cells • 5 types organized into 2 groups depending on nuclear shape and cytoplasmic granules –Granulocytes (single, multi-lobed nucleus) I. Neutrophils II. Eosinophils III. Basophils –Agranulocytes (mononuclear leukocyte) I. Lymphocytes II. Monocytes Leukocytes, or WBCs, are nucleated and subdivided into granulocytes and agranulocytes, depending on the presence or absence of specific granules in their cytoplasm These specific granules stain red with acidic stain such as eosin These specific granules stain with basic stain Lymphocyte play a key role in all immune responses, in contrast to the other leukocytes their activity is always directed against specific foreign agents All the leukocytes perform their function in the tissues and merely use the blood asa vehicle for transit between sites of formation, storage,activity Neutrophils and monocytes are highly phagocytic and engulf micoorganisms, cell debris in a non-specific manner. Cytoplasmic granules Specific granules Secondary granules Non-specific granules Azurophilic granules Lysosomes Primary granules Granulocytes • Cytoplasmic granules (containing enzymes or chemicals) àmakes cytoplasm look grainy • Single multi-lobed nucleus (segmented) • All are phagocytic; they engulf and consume foreign cells and material • 3 main types: Small granules, pale pink/salmon pink Large granules, Red Large granules, blue Neutrophil • The most common leukocyte in blood • constitute 40-75% of circulating leukocytes • Characterised by the shape of the nucleus which contains small lobed connected by thin filaments • When mature there are usually 5 lobes connected by fine strands of nuclear material. In less mature neutrophils the nucleus is less lobulated • 2-5 lobes in nucleus connected by “threads” of nuclear material (polymorphs) • Light pink cytoplasm • Called neutrophils because cytoplasm takes up red (acidic) and blue (basic) stains equally The lobes number depends on the maturity of the cell • 1. 2. 3. Specialized for responding to: bacterial invasions Acute infections acute pyrogenic infections Sheet note #8 Pyogenic infection : infection in which pus fever isPyrogenic=inducing produced Pyrogenic infection:infection that produces and pus fever • Neutrophils are short-lived cells with a half-life of 6-8 hours in blood and a life span of 1-4 days in connective tissues before dying by apoptosis. Neutrophils are the first WBCs that leave the blood in large numbers to reach the site of inflammation Cells of acute infection 1-The most abundant 2-The most motile 3-Neutrophil chemotactic factors (chemotaxins) are the first released Sheet note #9 In female pateints with XXX 2 Barr bodies are seen In females, the inactive X chromosome (Barr body) may appear as a drumstick-like appendage on one of the lobes of the nucleus (about 3% of neutrophils in peripheral blood) Granules in neutrophils • Specific granules (secondary) • Azurophilic granules (primary) (most numerous) (less numerous) Small in size Somewhat larger in size -Lysozyme: act against cell wall -Myeloperoxidase (bacteriocidal) -Phagocytin (bactericidal) -Acid hydrolase -Lactoferrin (bacteriostatic) Sheet note #10 -Defensins Important to -Collagenase break down collagen (barely visible by light in ECM allowing the miscroscopy) WBCs to leave circulation to the site of infection Different names for neutrophils: They have different number of lobes Polymorphs They participate in the bacterial infection during their maturation Pus cells which produces pus after bacterial death Microphages They are small and have phagocytic activity Cells of acute inflammation The ability of neutrophils to survive in an anaerobic environment is highly advantageous, because they can kill bacteria and help clean up debris in poorly oxygenated regions, for example, damaged or necrotic tissue lacking normal microvasculature

Blood Cells

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