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HSF > HSF 2 - Unit 1 Histology: Erythrocytes > Flashcards

HSF 2 - Unit 1 Histology: Erythrocytes Flashcards

1
Q

what kind of tissue is blood?

A

a specialized connective tissue in fluid, its extracellular matrix is plasma

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2
Q

what does blood transport?

A

it is the primary vehicle for transport of nutrients, O2, CO2, waste products, and hormones

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3
Q

blood functions in _______ and _______

A

thermoregulation and homeostasis

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4
Q

what is the average volume of blood in adults?

A

5 liters

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5
Q

what is plasma?

A

a liquid, extracellular matrix, about 55% of the blood’s volume. made of 91-92% water, 1-2% electrolytes (Na, Ca, K, HCO3), 7-8% protein

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6
Q

what is serum?

A

plasma without the clotting factors

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7
Q

what are albumins?

A

bulk of plasma proteins, all synthesized in the liver that function as transport of proteins for insoluble metabolites (Fatty acids); are also responsible for maintaining colloid osmotic pressure in blood vessels

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8
Q

what are globulins?

A

large molecules, used as transport proteins for lipids and heavy metal ions; largest fraction are immunoglobulins which are antibodies synthesized by plasma cells

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9
Q

what are fibrinogens?

A

they are the largest plasma proteins, soluble, and synthesized by the liver; they polymerize to form insoluble fibrin during clotting
prothrombin-thrombin catalyzes fibrinogen-fibrin

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10
Q

what are the formed elements?

A

red blood cells plus white blood cells and platelets

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11
Q

what is hemapoiesis?

A

the formation of RBCs, WBCs, and platelets in bone marrow

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12
Q

what is hematocrit?

A

the volume of RBCs, 42-45% based on sex

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13
Q

what is PCV?

A

packed cell volume; hematocrit without/with buffy coat

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14
Q

what is the buffy coat?

A

WBCs and platelets; 1-2%

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15
Q

what is a blood smear?

A

drop of blood is smeared, air dried, stained with modified Romanovsky method; used to look at blood under microscope

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16
Q

what is erythropoiesis?

A

red cell production

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17
Q

what is myelopoiesis?

A

white cell production

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18
Q

what is the process of hemopoiesis under control of?

A

erythropoietin, which is secreted by the kidney

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19
Q

how does hemopoiesis begin?

A

pluripotential stem cell which differentiates into several unipotential stem cell lines (=CFUs)

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20
Q

where does hemopoiesis occur and how many RBCs are put out per day?

A
  • in adults: vascular sinuses of bone marrow of flat bones of the skull, ribs, sternum, vertebrae, pelvis, and some long bones
  • estimated 2.5 billion RBCs daily
  • in fetus: first occurs in blood islands in wall of yolk sac during 1st trimester, in second occurs in liver and lymphatic tissue, during last month of pregnancy is in the bone marrow; after birth gets restricted to marrow cavities
  • number of active sites decreases with age
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21
Q

red marrow

A

active and contains large numbers of mature RBCs

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22
Q

yellow marrow

A

inactive and fatty

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23
Q

what are the overall trends in erythropoiesis as it progresses?

A

progressive decrease in the cell size, loss of nucleus and organelles, increase in hemoglobin

24
Q

what is the process of erythropoiesis?

A

stem cell (CFU-E) - proerythroblast - erythroblast/normoblast - reticulocyte - mature RBC

25
Q

what do mature RBCs consist of?

A

outer cell membrane containing cytoplasm, Hb, and few enzymes, lack mitochondria

26
Q

how are RBCs removed from circulation when they become senescent?

A

liver and spleen

27
Q

how do RBCs get energy?

A

anaerobic glycolysis

28
Q

what is the lifespan of RBCs?

A

about 120 days

29
Q

what are Howell-Jolly bodies?

A

occasional, basophilic nuclear remnants visible within the cytoplasm

30
Q

what are reticulocytes?

A

immature RBCs with stippled cytoplasm due to rRNA remaining; they are slightly larger than mature RBCs

31
Q

what is reticulocytosis?

A
  • an increase in the reticulocytes in circulation; associated with chronic blood loss, hemolytic anemia (“left shift”)
  • also seen in severe or chronic infections
32
Q

what is megaloblastic anemia?

A

large numbers of erythrocyte precursors are in peripheral blood; have been released before fully mature

33
Q

how large are erythrocytes? what is their shape?

A

6-8 micrometers; biconcave discs (causes some deformability, allows more surface area for gas exchange)

34
Q

what is the main structural protein in RBCs? what does it do?

A

spectrin; provides both resiliency and deformability, binds to inner surface of plasma membrane

35
Q

what do erythrocytes do?

A

involved in O2 and CO2 transport; contain large amounts of Fe containing pigment (Hemoglobin)

36
Q

what is hemoglobin’s structure?

A

4 polypeptide chains associated with 4 Fe-containing heme groups

37
Q

why is iron deficiency an issue?

A

RBCs become small and result in a type of anemia (microcytic), also stain very pale (hypochromic)

38
Q

what causes sickle cell anemia?

A

single amino acid substitution of valine for glutamic acid at position 6 of beta globulin chain, which causes a change in the 3D structure of Hb molecule to make the overall cell “sickle” shaped, more fragile, easily damaged and can cause damage to endothelial cells of capillary walls due to rough edges

39
Q

what is the connection between sickle cell anemia and malaria?

A

heterozygotes for the sickle cell trait have some resistance to malaria, which is caused by an intracellular blood parasite (Plasmodium spp.), while homozygous for the disease have severe problems and no advantage

40
Q

how large are platelets? what is their alternative name?

A

2-4 micrometers in diameter, also called thrombocytes

41
Q

what are platelets?

A

small, non-nucleated cells containing organelles that are formed from large, polyploid cells in bone marrow, megakaryocytes

42
Q

what are megakaryocytes?

A

up to 100 micrometers in diameter, with single, multi-lobed nucleus

43
Q

what do platelets do?

A

function in blood clotting, form physical plugs at the site of a vascular damage; can be impaired by some drugs

44
Q

how do platelets develop?

A

they tear off from pleated demarcation channels in the cytoplasm of megakaryocytes

45
Q

what is coagulation and why does it occur?

A

is a result of a cascade interaction between plasma proteins and coagulation factors that occurs only when endothelial lining of vessel is injured

46
Q

what are the different pathways of coagulation?

A

extrinsic and intrinsic; they are convergent

47
Q

what is the extrinsic pathway?

A

faster coagulation, initiated by release of tissue thromboplastin as a result of tissue damage

48
Q

what is the intrinsic pathway?

A

slower coagulation, initiated by exposure of collagen; requires numerous clotting factors and has a longer cascade reaction (von Willebrand’s factor, factor VII)

49
Q

when a wall of blood vessel breaks…

A

tissue injury results-

1) releases thromboplastin, initiates extrinsic pathway - also exposes collagen, initiates intrinsic pathway
2) platelets mechanically adhere to exposed collagen; also release serotonin (vasoconstrictor for smooth muscle in vessel to minimize blood loss)

50
Q

where do extrinsic and intrinsic pathways converge?

A

at the point where factor X is activated, converge to form a common pathway

51
Q

what does the converging of the extrinsic and intrinsic pathways result in?

A

conversion of prothrombin to thrombin, converts soluble fibrinogen into insoluble fibrin which traps platelets and RBCs

52
Q

what stops clotting?

A

exhaustion of fibrinogen and removal of thrombin from blood during conversion of fibrinogen to fibrin, anticoagulants antithrombin III and heparin

53
Q

why do we want to stop inappropriate clot formation?

A

can result in heart attack, stroke, DIC

54
Q

what is hemophilia?

A
  • a deficiency in clotting factors so blood can’t clot; defect in intrinsic pathway
  • sex-lined in males; present on X chromosome
55
Q

hemophilia A

A

deficiency of clotting factor VIII

56
Q

hemophilia B

A

factor IX deficiency

57
Q

hemophilia C

A

factor XI deficiency

HSF (23 decks)

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