Blood Cells

Front 1

1. Describe the general functions of blood.

Back 1

ł Blood functions in the distribution of gases - oxygen and carbon dioxide, metabolites, nutrients, hormones, inflammatory mediators etc.

Front 2

2. Describe the classes of blood cells.

Back 2

Three general classes of blood cells: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets

ł Erythrocytes: red blood cells are biconcave discs without a nucleus. They contain hemoglobin which gives blood it's red color, and are responsible for gas transport to and from tissues.

ł Leukocytes: cells specialized for immune defense against foreign antigens. There are several classes, all ameboid shaped with a nucleus, including lymphocytes, granulocytes, monocytes, and macrophages.

ł Platelets: these are cell fragments specialized for clotting. Like RBCs, they lack nuclei.

Front 3

3. Define hematocrit and describe how it is used diagnostically.

Back 3

ł Hematocrit: the ratio of the volume of red blood cells to the total volume of blood.
ł Hematocrit is a diagnostic tool done through centrifuging blood that has been treated with an anticoagulant (to prevent clotting). RBCs are the most abundant cell type, averaging
~ 5m per microliter blood. Hematocrit of blood is about 45 %. Changes in the volume of hematocrit signifies changes in the size of RBCs or their number in blood, and is used as a simple diagnostic criteria for diseases e.g. vitamin deficiency or anemia.

Front 4

4. Describe the major histological features of blood cells.

Back 4

Erythrocytes:
ł have biconcave disk shape - high S.A to volume ratio hence short gas diffusion distance
ł they lack nuclei
ł stain denser on outside than inside
ł ~7.5 micrometers in diameter
ł highly deformable

Platelets:
ł lack nuclei
ł 2-3 micrometers in diameter

Leukocytes:
Sub-classed based on nuclear morphology and intracellular vesicle content into polymorphonuclear granulocytes (Eosinophil, basophil, neutrophil) vs. mononuclear agranulocytes (lymphocytes and monocytes)

Polymorphonuclear Granulocytes
ł they contain specialized secretory vesicles which store different types of secretory substances, and are subclasses (again) based on staining characteristics of their specific granule content.
ł granulocytes are all about same size
ł each has irregularly shaped, multilobed nucleus (polymorphonuclear)
ł Classes of granulocytes: Eosinophil: - bind acidic dyes like eosin, Basophil - bind basic dyes like methylene blue, Neutrophil - salmon colored specific granules. do not bind acidic or basic dyes,

Mononuclear Agranulocyte
ł don't contain secretory vesicles
ł have round or slightly indented nucleus ł two types: lymphocytes and monocytes
ł Lymphocytes - small (7-9 micrometer diameter), have round nucleus and thin rim of basophilic cytoplasm, Activated lymphocytes larger (up to 13 micrometers)
ł Monocytes - relatively large (12-17 micrometers) in diameter, oval to kidney shaped nucleus irregularly located in cytoplasm, basophilic cytoplasm

Front 5

5. Explain the major functions of each of the blood cells.

Back 5

Erythrocytes: aka RBCs are oxygen and carbon dioxide transporters through binding of hemoglobin to these gases.

Platelets: function in blood clot formation. They have specialized granules which contain adhesive proteins, and growth factors which stimulate platelet adhesion at site of injury.

Leukocytes: include a variety of cell classes that function in immune defense in different ways.
ł Granulocytes: white blood cells with secretory vesicles that provide rapid
and generalized response to presence of foreign antigens. Release degradative enzymes, toxins and cytokines from granules to kill foreign organisms.
>> Neutrophils: function in acute inflammatory response against bacteria
>> Eosinophils: function in inflammatory response against large parasites (ex. worms)
>> Basophils: bind to immunoglobin E (IgE) antibodies
ł Lymphocytes: white blood cells that participate in highly specific
adaptive immune response. B cells produce specific antibodies which recognize antigens. T cells recognize specific antigens through T cell receptors, and differentiate into effector cells which kill antigen.
ł Monocytes: precursors to tissue macrophages, which ingest and destroy foreign particles.

Front 6

6. Differentiate between intravascular and extravascular functions of blood cells.

Back 6

Erythrocytes and platelets carry out their functions in the blood vascular compartment, while leukocytes are transient 'passengers' in the blood. They function defensively outside in the tissues.