S1B3 - Bsf1: Blood Histology

Front 1

What are the "formed elements" of blood?

Back 1

RBCs, WBCs, and platelets.

Front 2

Describe the appearance and components of a test tube containing anticoagulent and blood after it has settled.

Back 2

Red precipitate at the bottom is RBCs (45%), a thin light layer above that (~1%) which represents the leukocytes, and a yellowish fluid layer on top which is the plasma (~55%).

Front 3

What is the buffy coat?

Back 3

It is the thin ligh layer of leukocytes between RBCs and plasma in blood that has been allowed to settle in a test tube with anticoagulent.

Front 4

What is hematocrit?

Back 4

The volume of formed elements (RBCs, WBCs, and platelets) per unit volume of blood. Females normally = 35-45%; males normally = 40-50%.

Front 5

List the functions of blood.

Back 5

Blood carries nutrients from the gastrointestinal tract to all cells of the body; Cellular waste is carried to specific organs involved in its elimination; Oxygen is distributed throughout body; Carbon dioxide is transported to the lungs for elimination; Hormones are distributed to their target organs; Blood is involved in body temperature regulation; Blood helps maintain body fluid acid-base balance and osmotic balance.

Front 6

What are the components of blood plasma?

Back 6

~90% water and ~7% plasma proteins, with a variety of substances (e.g. inorganic salts, hormones, vitamins) comprising the remaining 3%.

Front 7

What is blood serum?

Back 7

It is the fluid portion of blood remaining after a clot forms, i.e. plasma minus fibrinogen and other clotting proteins.

Front 8

What is albumin's role in blood?

Back 8

Critical in establishing the blood colloid osmotic pressure, a force responsible for maintenance of blood and interstitial fluid volumes.

Front 9

Where are α- and β- globulins produced? What is their function?

Back 9

They are produced in the liver. They transport substances in the blood (lipid-soluble vitamins, metal ions).

Front 10

Where do γ- globulins arise from? What do they include?

Back 10

Arise from plasma cells and include antibodies.

Front 11

What are two major clotting proteins? Where are they produced?

Back 11

Prothrombin and fibrinogen. Clotting proteins are produced in the liver.

Front 12

What do complement proteins do?

Back 12

Initiate both inflammation and destruction of foreign microorganisms.

Front 13

What do chylomcrons do?

Back 13

Transport triglycerides to liver.

Front 14

What does VLDL do?

Back 14

Transport triglycerides from liver to body cells.

Front 15

What does LDL do?

Back 15

Transport cholesterol from liver to body cells.

Front 16

In a peripheral blood smear, what would you expect to see?

Back 16

Only erythrocytes, granulocytes, and agranulocytes (occassionally reticulocytes and band neutrophils).

Front 17

What is hematopoiesis?

Back 17

Development of blood cells.

Front 18

Where is hematopoietic tissue in an embryo?

Back 18

Initially the yolk sac, then also liver, spleen, and bone marrow.

Front 19

Where is hematopoietic tissue located after birth?

Back 19

Red bone marrow and some lymphatic tissues.

Front 20

What is the difference between red and yellow bone marrow?

Back 20

Red bone marrow is where hematopoeisis occurs. Yellow bone marrow is where hematopoeisis has ceased and become occupied with adipose. Nearly all marrow of infants is red, the long bones of adults become yellow.

Front 21

List typical dyes used for blood smears.

Back 21

Methylene blue – stains acidic cellular components blue. Eosin – stains alkaline components pink. Azures – formed by oxidation of methylene blue; azurophilic (“azure-loving”) structures in blood cells bind azures, resulting in a distinct red to violet appearance. Lysosomes of leukocytes often appear as azurophilic granules.

Front 22

What is the shape of RBC optimized for?

Back 22

Surface to volume ration for exchange of gases.

Front 23

What is the lifespan of a RBC?

Back 23

120 days.

Front 24

What is the size of a RBC?

Back 24

6-8 µm diameter, 2 µm thick.

Front 25

What is the long filamentous protein that makes up the cytoskeleton of RBC with actin?

Back 25

Spectrin.

Front 26

Which protein secures the cytoskeleton of RBCs to plasmalemma proteins?

Back 26

Ankyrin.

Front 27

What is hereditary spherocytosis?

Back 27

It is a pathology in which a mutation in one of the cytoskeletal proteins results in RBCs that are spherical in shape with reduced pliability. Ankyrin is the most commonly mutated cytoskeletal protein, although the pathology has also been related to mutations in spectrin and other proteins. The affected RBC has a normal appearance upon its initial release into the circulation, but reduced membrane stability leads to loss of membrane fragments. Eventually the RBCs take on a spherical shape (also not uniform in size). These RBCs are destroyed in the spleen.

Front 28

What accounts for the acidophilic staining of RBCs?

Back 28

Hemoglobin.

Front 29

List major proteins of RBCs.

Back 29

Hemoglobin, carbonic anhydrase, band 3, and proteins involved in glucose metabolism.

Front 30

Why is hemoglobin ideal for transporting respiratory gases between the lungs and the rest of the body?

Back 30

In areas of high O2 concentration (e.g. lungs), iron (of the heme group) binds to O2 and the globin releases CO2; in areas with low O2 concentrations, the O2 is released and CO2 binds to the globin.

Front 31

What is sickle cell anemia?

Back 31

A single amino acid substitution in one of the globin chains results in the sickle cell hemoglobin (HbS). The HbS molecules polymerize upon deoxygenation, causing distortion of the RBC such that it takes on a sickle shape. Repeated bouts of sickling results in membrane damage to the RBC.

Front 32

What is carbonic anhydrase?

Back 32

A RBC enzyme that forms carbonic acid from CO2 and water. Most CO2 is carried to the lungs in the form of bicarbonate (HCO3-).

Front 33

What is band 3?

Back 33

A RBC integral membrane protein transporter that exchanges an intracellular bicarbonate ion for an extracellular Cl-. Also serves as the binding site for ankyrin.

Front 34

Who is a universal acceptor?

Back 34

Individuals with blood group AB, they have no A or B antibodies because they have A and B antigens.

Front 35

Who is a universal donor?

Back 35

Individuals with blood group O, they have neither antigen A or B (they have no antigens for antibodies to react to).

Front 36

When are Rh antibodies produced?

Back 36

When an Rh- individual is exposed to Rh+ blood they will produce antibodies against it. A second exposure can trigger serious immune response.

Front 37

What is erythropoiesis?

Back 37

The process of RBC formation (250 billion mature RBCs per day!)

Front 38

What is erythropoietin?

Back 38

Serum glycoprotein hormone that stimulates erythropoiesis (induces formation of CFU-E and stimulates mRNA coding for globin), synthesized by fibroblast-like cells in the interstitium of kidney cortex and outer medulla.

Front 39

What is CFU-E?

Back 39

Colony forming units - erythrocyte, formed from pluripotential cells in response to erythropoeitin.

Front 40

What are the precursors to erythrocytes in the proper order?

Back 40

Proerythroblast -> Basophilic erythroblasts -> Polychromatophilic erythroblasts -> Orthochromatophilic erythroblasts (normoblasts) -> Reticulocytes -> Erythrocyte. PBPORE

Front 41

Describe proerythroblasts?

Back 41

Large cells (~16µm diameter) with a basophilic cytoplasm (due to polyribosomes) and large nucleus. No hemoglobin is present.

Front 42

Describe basophilic erythroblasts?

Back 42

These cells (~14µm diameter) have a somewhat smaller nucleus than proerythroblasts. Some hemoglobin is present in the cytoplasm at this stage.

Front 43

Describe polychromatophilic erythroblasts?

Back 43

Nuclear chromatin is coarser and cytoplasm can be variable in color. Cytoplasm staining characteristics are due to a decreasing amount of basophilic polyribosomes in tandem with gradually increasing amounts of acidophilic hemoglobin.

Front 44

Describe orthochromatophilic erythroblasts?

Back 44

(Normoblasts) Cells progressed to this stage are smaller (~10µm diameter) with a much smaller, condensed nucleus. Hemoglobin has continued to accumulate, and the hemoglobin-rich cytoplasm now appears acidophilic with only a hint of basophilia.

Front 45

Describe reticulocytes?

Back 45

This cell is formed when the orthochromatophilic erythroblast extrudes its nucleus. Reticulocytes still have some polyribosomes, which can be observed with cresyl blue stain. Becomes erythrocyte once it loses all its polyribosomes. They are not typically identifiable in routine blood stains.

Front 46

What is diapedesis?

Back 46

Process by which leukocytes leave the bloodstream by passing between capillary endothelial cells to enter connective tissue.

Front 47

What are specific granules?

Back 47

Granules in granulocytes that have specific functions for the type of leukocyte in which they are found. They bind either acidic or neutral components of the stain.

Front 48

What are azurophilic granules?

Back 48

Granules in granulocytes that are primarily lysosomes. These granules stain deep violet.

Front 49

What is the difference between granulocytes and agranulocytes?

Back 49

Granulocytes have specific and azurophilic granules, agranulocytes do not have specific granules but do have azurophilic granules.

Front 50

List the different granulocytes.

Back 50

Neutrophils, eosinophils, and basophils.

Front 51

Describe a neutrophil.

Back 51

Nucleus arranged in 3 lobes (2-5), with lightly eosinophilic cytoplasm. Granules not obvious because of small size.

Front 52

What is the lifespan of a neutrophil?

Back 52

~8 days, and are in the bloodstream for only about 9-10 hours.

Front 53

What is the function of neutrophils?

Back 53

They are important in combating bacterial infections. Their specific granules contain enzymes and other agents needed in defense against bacterial infection. They phagocytose bacterial.

Front 54

What are chemotactic agents?

Back 54

These are released at the site of bacterial invasion and attract neutrophils to the site.

Front 55

List different mechanisms used to destroy phagocytized bacteria.

Back 55

Enzyme activity, formation of oxygen free radicals (highly toxic to bacteria), exposure to lactoferrin (molecule that binds strongly to iron, which is a necessary nutrient of bacteria).

Front 56

What is pus formed from?

Back 56

Accumulation of dead bacteria, dead neutrophils and cell debris.

Front 57

Describe an eosinophil.

Back 57

Bilobed nucleus, large eosinophilic granules. Major basic protein that make up crystalline core of granules are reason for eosinophilia.

Front 58

What is the function of eosinophils?

Back 58

Receptor binding (of histamine, leukotrienes, or eosinophil chemotactic factor) induces migration fo eosinophils to the site of parasitic worm invasion, allergic reaction, or inflammation.

Front 59

What is major basic protein involved in?

Back 59

Killing parasitic worms.

Front 60

What are some of the enzymes that surround the crystalline core of eosinophilic granules for?

Back 60

Inactivation of inflammatory response initiators such as histamine or leukotrienes.

Front 61

Describe a basophil.

Back 61

They have a lobed nucleus, but lobes are usually masked by the basophilic specific granules present in the cytoplasm. The intensely-stained, violet-colored specific granules are less numerous and more irregularly shaped than granules of other granulocytes.

Front 62

What is the function of basophils?

Back 62

They have specific granules that contain heparin, histamine, or chemotactic factors.

Front 63

What is heparin?

Back 63

An anticoagulant.

Front 64

What is histamine?

Back 64

Substance that causes vasodilation, bronchial smooth muscle contraction, and leakiness of blood vessels.

Front 65

What is chemotactic factors?

Back 65

They attract eosinophils and neutrophils to the site of the specific granule release.

Front 66

What is IgE?

Back 66

A class of immunoglobulin produced by plasma cells in response to certain antigens. They bind to receptors on basophils (or mast cells) with no apparent consequence. However, the next time the same antigen enters the body, it binds to the IgE molecules on the basophil surface and initiates a response sequence.

Front 67

What occurs when an antigen binds to an IgE molecuels bound to a basophil?

Back 67

This sequence is inititated: Contents of specific granules are released into the extracellular space; Leukotrienes are synthesized by the basophils;= The heparin, histamine, and chemotactic factors released have the effects described earlier; Leukotrienes have similar effects to histamine, but their action is slower and more prolonged.

Front 68

What type of cells are similar to mast cells?

Back 68

Mast cells, they have same type of granules and function, but arise from different precursors.

Front 69

What is the order of granulocytopoiesis?

Back 69

Myeloblast -> Promyelocytes -> Myelocytes -> Band cell -> mature granulocyte.

Front 70

What is a myeloblast?

Back 70

Earliest recognizable precursor to granulocytes (may be any of the three lineages). They have a large, light nucleus and a basophilic cytoplasm.

Front 71

What are promyelocytes?

Back 71

After myeloblast and before myelocyte in granulocytopoiesis, these are cells with some azurophilic granules in a distinctly basophilic cytoplasm.

Front 72

What cells are specific granules first recognized?

Back 72

Myelocytes, these are the first cells which can be distinguished as three separate populations.

Front 73

What is a band cell?

Back 73

(Stab cell) an intermediate stage of neutrophilic granulocyte in which the nucleus appears as a "horseshoe" or curved rod. Identifibable in peripheral blood smears.

Front 74

List the different agranulocytes?

Back 74

Lymphocytes and monocytes.

Front 75

Describe a lymphocyte.

Back 75

Round cells with a dense, round nucleus. Small lymphocytes are by far the most common in circulating blood and appear as ~6-8µm diameter cells with a thin rim of basophilic cytoplasm surrounding the predominant nucleus. Medium and large lymphocytes are up to 18µm in diameter and are thought to represent lymphocytes that have been activated by specific antigens.

Front 76

What are the 3 categories of lymphocytes?

Back 76

T cells, B cells, and Null cells.

Front 77

Which lymphocytes are responsible for the cellular immune response?

Back 77

T cells, matured at the thymus it requires presence of living cells.

Front 78

What cells primarily kill virus-infected cells?

Back 78

Natural killer cells. NK cells as well as circulating stem cells are null cells.

Front 79

Describe a monocyte?

Back 79

The largest circulating blood cell (~12 to 20µm in diameter). Monocytes typically have a large, eccentric kidney-shaped nucleus that stains light due to the less condensed chromatin. Cytoplasm stains lightly basophilic; azurophilic granules are present.

Front 80

How do monocytes develop?

Back 80

Monoblast -> Promonocyte (divides twice) -> Monocyte

Front 81

What is the function of monocytes?

Back 81

Monocytes migrate into connective tissue where they differentiate into macrophages.

Front 82

Where are megakaryocytes found?

Back 82

Bone marrow (not present in peripheral blood).

Front 83

Describe a megakaryocyte.

Back 83

The mature megakaryocyte is a giant cell (up to 150µm in diameter) with a plethora of membrane invaginations throughout the cytoplasm. These cells appear to be multinucleate but actually have a single, large lobulated nucleus.

Front 84

Where do platelets come from?

Back 84

Demarcation membranes – membrane invaginations present in the megakaryocyte cytoplasm, representing areas that will be shed as platelets.

Front 85

What is the function of platelets?

Back 85

To control hemorrhage of damaged blood vessels. Platelets become activated and release the contents of their granules when they contact subendothelial collagen, an event that occurs only if a vessel endothelial lining is disrupted. Platelets adhere to the damaged site and to each other, forming a platelet plug.