22. Blood Flashcards
General characteristics of blood
Type of fluid connective tissue
8% of body mass
4-6 liters in average person
General function of blood
Carries nutrients, respiratory gases, waste products, and signaling molecules (hormones) between cells of the body
Blood components
Plasma (55% consisting of water proteins and other solutes like electrolytes, nutrients, waste)
Buffy coat (less than 1% consisting of platelets and leukocytes
Erythrocytes (44%)
Characteristics of blood plasma
90% water, but contains many molecules
3 main protein types: albumin, globulins, fibrinogen
Albumin
Most abundant of blood plasma, retains water in blood
Globulin
Antibodies (immunoglobulins) in plasma and produced by WBC’s to identify pathogens
Also transport lipids
Fibrinogen
Protein In blood plasma
Help with clot formation
Characteristics of erythrocytes (RBCs)
Red blood cells (and platelets) are not true cells
Transport oxygen to tissues via hemoglobin
Carry carbon dioxide to lungs
Originate in red bone marrow
Average lifespan of 120 days
Why are RBCs and platelets not true cells
Lack nuclei and organelles
Platelets are cell fragments
Erythrocytes life cycle
Form in red bone marrow
Circulate in bloodstream for 120 days
Are phagocytized in liver and spleen
Heme components recycled
Membrane proteins and globulin proteins broken down and recycled
What is sickle cell anemia?
Defect in hemoglobin molecule in blood cells
Homozygous recessive for hemoglobin gene
Cells deform and can block vessels preventing blood flow
Symptoms of sickle cell anemia
Shortness of breath, fatigue, dizziness, pain in abdomen and chest
What is malaria
Disease caused by parasite that invades and destroys red blood cells
Typically transmitted by mosquitoes
Common in tropical and subtropical regions
Heterozygote advantage of malaria with sickle cell anemia
Hh - have only one recessive allele for sickle cell
Do not have symptoms of sickle cell anemia
Skiffle cell alleles persist because heterozygotes have “resistance” to parasite
Characteristics of ABO blood types
RBCs have surface antigens that project from plasma membrane
WBCs produce antibodies to surface antigens not found on RBCs (antibodies in plasma will identify foreign blood surface antigens to be eliminated)
Surface antigens of ABO blood types
All RBCs have O antigen
Antigens A and B may or may not be present in individuals
Presence of A or B antigens determines ABO blood type
Blood transfusions
Receiving incompatible blood causes agglutination (clumping) and hemolysis (destruction)
Type AB blood- no antibodies, universal recipient
Type O blood- no A or B surface antigens, universal donor
Rh antigen
Another common RBC surface antigen
Rh positive- surface antigen present
Rh negative- surface antigen not present
Antibodies produced to Rh antigen if you are negative and receive Rh positive blood
Characteristics of leukocytes
Less numerous than RBCs
Provide defense against infection and disease
Travel in blood stream but function outside of blood vessels
Categorized into granulocytes and agranulocytes (distinction based on appearance, not function or origin)
Granulocytes
Have cytoplasmic granules
Includes neutrophils, eosinophils, and basophils
Agranulocytes
Cytoplasmic granules so small, they’re not visible under microscope
Includes lymphocytes and monocytes
Characteristics and function of neutrophils
Multilobed nuclei
Pale granules in cytoplasm
Function: enter tissue spaces to phagocytize infectious pathogens (particularly bacteria)
Characteristics and function of eosinophils
Bi-lobed nuclei
Reddish-orange granules in cytoplasm
Function: phagocytize antigen-antibody complexes and release chemical mediators that attack parasitic worms
Characteristics and function of basophils
Bi-lobed nuclei
Dark purple granules in cytoplasm
Function: release histamine (vasodilator) and heparin (anti-coagulant) during inflammatory or allergic reaction
Characteristics and function of lymphocytes
Large spherical nucleus that fill up most of cell
3 types: T-lymphocytes, B-lymphocytes, and natural killer cells
Function: found in lymph glands and lymphatic tissue; attack pathogens and abnormal, infected cells; produce antibodies
Characteristics and function of monocytes
Kidney shaped nucleus
Function: exit blood vessels and become macrophages; phagocytize pathogens (bacteria, viruses); and engulf cellular debris, dead cells
Characteristics of platelets (thrombocytes)
Irregular, membrane-bound cellular fragments of cells called megakaryocytes
Megakaryoctyes found in red bone marrow
Parts of megakaryocytes pinch off and enter blood
Form clots with fibrin in response to damage
Thrombocytopenia
Low platelet count
Causes diminished clot formation and internal bleeding
Hematopoiesis
Blood cell formation
Occurs in red bone marrow
All blood cells come from hemopoietic stem cells
Hemopoietic stem cells can produce either myeloid (all other cells) or lymphoid stem cells (lymphocytes)
Disorders of the blood
Anemia, polycythemia, leukemia
Anemia
Excessively low erythrocytes or hemoglobin concentrations
Diminished oxygen carrying capacity of blood
Many causes- blood loss, iron deficiency, genetic defect of hemoglobin
Causes tiredness, paleness, shortness of breath
Polycythemia
Abnormal excess of erythrocytes in blood
Can result from cancer of the bone marrow
Increase viscosity of blood which can cause blockage in small vessels
Leukemia
Cancer resulting in uncontrolled proliferation of WBCs in bone marrow
Can be acute (rapidly advancing) or chronic (slowly advancing)
Cancer cells crowd bone marrow and slow production of normal blood cells
