Blood Cells in the body are fixed within tissues and must have nutrients and oxygen brought to them...
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Transcript of Blood Cells in the body are fixed within tissues and must have nutrients and oxygen brought to them...
Blood• Cells in the body are fixed within tissues and
must have nutrients and oxygen brought to them and waste removed.
• The blood is classified as a fluid matrix connective tissue– The cells and cell fragments are the formed
elements and the matrix of the blood is fluid (plasma).
– Formed elements make up about 45% and plasma 55% of the total blood volume.
– Blood volume: 4-5 L in females, 5-6 L in males.
Blood Functions• Distribution and transportation
– Respiration
– Nutritive
– Excretory
– Negative Aspects
• Regulation and Maintenance
– Hormonal regulation
– Thermoregulation
– pH / acid-base balance
– Fluid volume
• Protection
– Clotting
– Immunity
Major Components of the Circulatory System
• Two divisions: Cardiovascular and lymphatic systems.– Cardiovascular: Heart, blood vessels
• Heart• Vessels
– Lymphatic: lymphatic vessels and lymphoid tissues in spleen, thymus, tonsils, and lymph nodes.
• The fluid portion of the blood (plasma) passes through the capillary walls under hydrostatic pressure (interstitial fluid).
• Some interstitial fluid returns to the blood and some enters the lymphatic system
– Lymphatic vessels carry interstitial fluid now called lymph back to the venous blood.
– Lymph nodes along the way filter and cleanse the blood before it is returned.
Erythrocytes• Structure
– Biconcave, anucleate– 4.8 million/mm3 in
women. – 5.4 million/mm3 in men.– 7.5 um in diameter
• Components– Hemoglobin– Lipids, ATP, carbonic
anhydrase• Function
– Transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs
Hemoglobin
• Consists of: – 4 globin molecules: 2 alpha and 2 beta chains
• 280 million per RBC.• Transport carbon dioxide (carbonic anhydrase involved), nitric
oxide.
– 4 heme molecules: Transport oxygen• Iron is required for oxygen transport
Erythropoiesis
• Production of red blood cells
– Stem cells proerythroblasts early erythroblasts intermediate late reticulocytes
• Erythropoietin: Hormone to stimulate RBC production
Anemias • Result of either a decrease in hemoglobin / RBC or in the
number of RBCs.
• Symptoms: pale, lethargic, shortness of breath, tired.
• Aplastic anemia: inability of red bone marrow to produce RBCs
• caused by: damage to Red bone marrow, Iron of Folate deficiency
• Pernicious anemia - Vitman B12 deficiency
• Hemorhagic anemia - results from loss of blood
• Hemolytic anemia - erythrocytes rupture or are destroyed at an increased rate.
• Thalasemia - defective hemoglobin production
Formed Elements• Red blood cells (erythrocytes)• White blood cells (leukocytes)
– Granulocytes• Neutrophils
• Eosinophils
• Basophils
– Agranulocytes • Lymphocytes
• Monocytes
• Platelets (thrombocytes)
Production of Formed Elements
• Hematopoiesis or hemopoiesis: Process of blood cell production
• Stem cells: All formed elements derived from single population– Proerythroblasts: Develop into red blood cells– Myeloblasts: Develop into basophils,
neutrophils, eosinophils– Lymphoblasts: Develop into lymphocytes– Monoblasts: Develop into monocytes– Megakaryoblasts: Develop into platelets
Neutrophil
• Appearance– 2-5 lobes – 10-12 um– 54-62% of white cells
• Characteristics– Fights bacterial and
fungal infections– Contains peroxidases and
defensins– Numbers increase with
meningitis and appendicitis
Eosinophil
• Appearance– Bilobed nucleus– Red granules– 11-14 um– 1-3% of white blood cells
• Characteristics– Fights parasitic infections.– Releases anti-
inflammatory chemicals.– Secretes enzymes that
break down clots.
Basophils
• Appearance– Two indistinct lobes– Blue-purple granules– 10-12 um– Less than 1% of WBC
• Characteristics– Release histamine– Chemoattractant for other
WBCs– Releases heparin to
prevent clots.Basophil Eosinophil
Monocyte
• Apearance
– Nucleus round, kidney or horseshoe shaped
– 12-20 um
– 3-9 % of WBC
• Characteristics
– Transforms into macrophages
Lymphocyte
• Appearance– Round nucleus– 6-14 um– 25-33% of WBC
• Characteristics– Found in lymphoid tissue– Provides specific immune
response• T - lymphocytes
• B - lymphocytes
Hemostasis
• Arrest of bleeding• Events preventing excessive blood loss
– Vascular spasm: Vasoconstriction of damaged blood vessels
– Platelet plug formation – Coagulation or blood clotting
Thrombocytes
• Cell fragments pinched off from megakaryocytes in red bone marrow
• Important in preventing blood loss
– Platelet plugs
– Promoting formation and contraction of clots
Coagulation
• Stages
– Activation of prothrombinase
– Conversion of prothrombin to thrombin
– Conversion of fibrinogen to fibrin
• Pathways
– Extrinsic
– Intrinsic
Blood Grouping
• Determined by antigens (agglutinogens) on surface of RBCs
• Antibodies (agglutinins) can bind to RBC antigens, resulting in agglutination (clumping) or hemolysis (rupture) of RBCs
• Groups– ABO and Rh
Rh Blood Group
• First studied in rhesus monkeys• Types
– Rh positive: Have these antigens present on surface of RBCs
– Rh negative: Do not have these antigens present
• Hemolytic disease of the newborn (HDN)– Mother produces anti-Rh antibodies that cross
placenta and cause agglutination and hemolysis of fetal RBCs
Diagnostic Blood Tests
• Type and crossmatch
• Complete blood count
– Red blood count
– Hemoglobin measurement
– Hematocrit measurement
• White blood count
• Differential white blood count
• Clotting