about blood cells

8/4/2019 About Blood Cells

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Included on this page are micrographs that were selected to illustrate the features mostoften used to identify the various blood cells. Not every cell you see in the lab will look

exactly like these, but if you look for the features pointed out with each micrograph, youshould be able to make proper identifications during differential white blood cell counts

or during a lab exam.

GRANULOCYTES:NEUTROPHIL - EOSINOPHIL - BASOPHIL

AGRANULOCYTES:LYMPHOCYTE - MONOCYTE

ERYTHROCYTE

THROMBOCYTES - PLATELETS

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NEUTROPHIL

This granulocyte has very tiny light staining granules (thegranules are very difficult to see). The nucleus is frequently

multi-lobed with lobes connected by thin strands of nuclear

material. These cells are capable of phagocytizing foreign cells,toxins, and viruses.

When taking a Differential WBC Count of normal blood, this

type of cell would be the most numerous. Normally, neutrophilsaccount for 50-70% of all leukocytes. If the count exceeds this amount, the cause isusually due to an acute infection such as appendicitis, smallpox or rheumatic fever. If the

count is considerably less, it may be due to a viral infection such as influenza, hepatitis,

or rubella.

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EOSINOPHIL

This granulocyte has large granules (A) which are acidophilic andappear pink (or red) in a stained preparation. This micrograph

was color enhanced to illustrate this feature. The nucleus often

has two lobes connected by a band of nuclear material. (Does it

looks like a telephone receiver?) The granules contain digestiveenzymes that are particularly effective against parasitic worms in

their larval form. These cells also phagocytize antigen - antibody

complexes.
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These cells account for less than 5% of the WBC's. Increases beyond this amount may be

due to parasitic diseases, bronchial asthma or hay fever. Eosinopenia may occur when the

body is severely stressed.

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BASOPHIL

The basophilic granules in this cell are large, stain deep blue to

purple, and are often so numerous they mask the nucleus. Thesegranules contain histamines (cause vasodilation) and heparin

(anticoagulant).

In a Differential WBC Count we rarely see these as they representless than 1% of all leukocytes. If the count showed an abnormally high number of thesecells, hemolytic anemia or chicken pox may be the cause.

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LYMPHOCYTE

The lymphocyte is an agranular cell with very clear cytoplasmwhich stains pale blue. Its nucleus is very large for the size of the

cell and stains dark purple. (Notice that the nucleus almost fills

the cell leaving a very thin rim of cytoplasm.) This cell is muchsmaller than the three granulocytes (which are all about the same

size). These cells play an important role in our immune response.

The T-lymphocytes act against virus infected cells and tumorcells. The B-lymphocytes produce antibodies.

This is the second most numerous leukocyte, accounting for 25-35% of the cells counted

in a Differential WBC Count. When the number of these cells exceeds the normal

amount, one would suspect infectious mononucleosis or a chronic infection. Patients withAIDS keep a careful watch on their T-cell level, an indicator of the AIDS virus' activity.

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MONOCYTE
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This cell is the largest of the leukocytes and is agranular. Thenucleus is most often "U" or kidney bean shaped; the cytoplasm is

abundant and light blue (more blue than this micrograph

illustrates). These cells leave the blood stream (diapedesis) tobecome macrophages. As a monocyte or macrophage, these cells

are phagocytic and defend the body against viruses and bacteria.

These cells account for 3-9% of all leukocytes. In people with malaria, endocarditis,

typhoid fever, and Rocky Mountain spotted fever, monocytes increase in number.

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ERYTHROCYTE

The background cells in this micrograph are erythrocytes (red

blood cells). These cells are non-nucleated, biconcave discs that

are filled with hemoglobin. The primary function of these cells isto carry oxygen from the lungs to the body cells.

Woman usually have 4-5 million erythrocytes per cubic

millimeter of blood, men have 5-6 million. If this number isconsiderably higher, polycythemia may be the cause. If the number is considerably less,

the person has anemia.

Sickle cell anemia is an inherited condition which results in some

erythrocytes being malformed. The gene for this condition causesthe hemoglobin to be incorrectly formed, which in turn causes

some erythrocytes to take on a crescent shape. These cells are not

able to carry adequate amounts of oxygen to cells.

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THROMBOCYTES - PLATELETS

Platelets, which are cell fragments, are seen next to the "t's"
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above. (Many of the other micrographs on this page contain them as well.) Platelets are

important for proper blood clotting.

Each cubic millimeter of blood should contain 250,000 to 500,000 of these. If the numberis too high, spontaneous clotting may occur. If the number is too low, clotting may not

occur when necessary.

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Riding On The Red-road

Red blood cells perform the most important blood duty. A single drop of bloodcontains millions of red blood cells which are constantly traveling through your

body delivering oxygen and removing waste. If they weren't, your body wouldslowly die.

Red blood cells are red only because they contain a protein chemical calledhemoglobin which is bright red in color. Hemoglobin contains the element Iron,making it an excellent vehicle for transporting oxygen and carbon dioxide. Asblood passes through the lungs, oxygen molecules attach to the hemoglobin. Asthe blood passes through the body's tissue, the hemoglobin releases the oxygento the cells. The empty hemoglobin molecules then bond with the tissue's carbondioxide or other waste gases, transporting it away.

Over time, the red blood cells get worn out and eventually die. The average lifecycle of a red blood cell is 120 days. Your bones are continually producing newblood cells, replenishing your supply. The blood itself, however, is re-circulatedthroughout your body, not being remade all of the time.

Since the human body is continually making more blood, it is safe for healthyadults to donate blood. The blood is then stored for use in emergency situations.Initially after giving blood, the donor may feel some momentary lightheadedness


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due to the loss of oxygen-rich red blood cells and blood sugar. The body quicklystabilizes itself.

Battling Blood Cells

Whenever a germ or infection enters the body, the white blood cells snap toattention and race toward the scene of the crime. The white blood cells arecontinually on the lookout for signs of disease. When a germ does appear, thewhite blood cells have a variety of ways by which they can attack. Some willproduce protective antibodies that will overpower the germ. Others will surroundand devour the bacteria.

The white blood cells have a rather short life cycle, living from a few days to afew weeks. A drop of blood can contain anywhere from 7 000 to 25 000 whiteblood cells at a time. If an invading infection fights back and persists, that numberwill significantly increase.

A consistently high number of white blood cells is a symptom of Leukemia, acancer of the blood. A Leukemia patient may have as many as 50 000 whiteblood cells in a single drop of blood.

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