Chapter 15 - blood Flashcards
describe blood plasma
90% water. 6-8% proteins by weight. nutrients (glucose, lipids, amino acids). wastes (urea, lactic acid).
describe erythrocyte amount, anatomy, and primary function
5 million per microliter. no nucleus; no organelles; biconcave disk. transport O2 and CO2
describe leukocytes amount, anatomy, and primary function
4k-10k per microliter. ? defend body against pathogens
describe platelets amount, anatomy, and primary function
100k-500k per microliter. cytoplasmic fragments; granules. hemostasis
why are erythrocytes shaped as biconcave disk
for a large surface-to volume ratio for efficient diffusion. the shape is flexible
do erythrocytes have organelles
No nucleus or organelles: no mitochondria, no oxygen consumption, receive energy through glycolysis only. 2 ATPs per glucose molecule
describe life cycle of erythrocytes
no nucleus, DNA, RNA, or protein synthesis. no division of mature RBCs. short life span = 120 days. replace 2-3 million RBCs/sec. old erythrocytes are filtered and recycled by spleen (and liver)
how do erythrocytes develop
all blood cells develop from the hematopoietic stem cells in red bone marrow. erythrocyte synthesis is stimulated by erythropoietin (secreted by kidneys)
name 3 dietary requirements for normal erythrocyte production
iron: component of hemoglobin (heme portion). folic acid: necessary for DNA replication and thus cell proliferation. vitamin b12: necessary for DNA replication and thus cell proliferation
compare spleen and liver in recycling erythrocytes
spleen filters and removes old erythrocytes. liver metabolizes and recycle by-products from breakdown of erythrocytes
describe steps in spleen handling of erythrocytes
spleen filters blood. spleen macrophages phagocytose old, worn out RBCs. globin subunits are broken into amino acids. hemoglobin is catabolized: iron is removed and recycled, heme -> bilirubin. bilirubin is released into bloodstream. travels to liver for further metabolism. products of bilirubin catabolism are (1) secreted in bile and travel to intestinal tract for elimination, and (2) released into bloodstream and excreted in urine
what happens to iron have hemoglobin catabolization
efficiently recycled for synthesis of new hemoglobin. transported in blood bound to transferrin: from GI tract to bone marrow. from liver to bone marrow. Iron is stored in liver( bound to ferritin)
what is anemia
any condition where capacity for carrying oxygen is reduced
what is hemolytic anemia
excessive destruction of RBCs; in malaria, sickle cell anemia
what is renal anemia
decreased erythropoietin production
what do leukocytes do
function in defense of body: part of the immune system. defend against pathogens. identify and destroy cancer cells. perform phagocytosis of debris from dead or injured cells
describe neutrophils
most numerous WBCs. represent 50-80% of leukocytes in blood. phagocytic cells. circulate for 7-10 hours. migrate to tissues, live for a few days. first line of defense during infections
describe eosinophils
represent 1-4% of leukocytes. defend against parasitic invaders. granules contain toxic molecules that attack parasites
describe monocytes
represents 5% of leukocytes. migrate to tissues and become macrophages (very powerful phagocytes). involved in immune surveillance: wandering macrophages and resident macrophages
describe basophils
the rates WBCs representing less than 1% of all leukocytes. non-phagocytic cells. mediate inflammation and allergic reactions by releasing histamine and heparin
describe lymphocytes
2nd most numerous WBC. represents 30% of leukocytes and 99% of interstitial fluid cells. there are 3 types: B cells T cells and natural killer cells
describe B cells
upon contacting antigen –> activated B cells –> plasma cell. plasma cells secrete antibodies (immunoglobulins). antibodies mark invaders for destruction
describe T cells
directly damage foreign cells. attack infected, mutant, or transplanted cells. develop into cytotoxic T cells that destroy target cells: this takes several days, secretory products form pores in the target cell’s membrane, lysis occurs
describe platelets
not true cells. they’re cell fragments: no nucleus has organelles and granules. they break off from megakaryocytes in red bone marrow and enter circulation. they’re important in blood clotting
name the 3 steps in hemostasis
- vascular spasm 2. platelet plug 3. formation of a blood clot
what is vascular spasm
damage to blood vessel: vessel constricts to minimize blood loss. this leads to intrinsic vascular responses and sympathetic discharge to the area
what is a platelet plug
aggregation of platelets at site of damage. further decreases blood loss. necessary for subsequent clot production. initiated by exposure of subendothelial collagen to von willebrand factor (vWf) present in plasma
describe formation of a blood clot
clotting is coagulation. blood is converted into solid gel called a clot or thrombus. occurs around a platelet plug. it is the dominant hemostatic defense mechanism. involves multiple clotting factors and a chemical reaction (coagulation cascade).
what is end result of blood clot formation
fibrinogen –> fibrin (loose) –> fibrin (mesh) –> fibrin clot= blood clot
describe clotting factors
they’re produced by liver and secreted in inactive form. they become activated during coagulation cascade. plasma without clotting factors = serum. hemophilia is a genetic disorder with deficiency in clotting factor. usually factor VIII
what is Von Willebrand’s disease
reduced levels of vWf. decreased platelet plug formation
what does vitamin K deficiency cause
decreased synthesis of clotting factors
