Classes of Blood Cells

8/2/2019 Classes of Blood Cells

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CLASSES OF BLOOD CELLS

LEUCOCYTES

Leukocytes are part of the defense mechanisms of the body.

Leukocytes move. This characteristic allows them to leave the capillaries through theintercellular spaces of the wall (diapedesis). Using amoeba like movements they move

towards microorganisms or harmful particles that are in the tissues. Afterwards they

move out of the capillaries and into the tissue.

Size: > of 7.5mm of diameter Count: between 5,000/mm and 9,000/mm

They are derived from the mother cell called hemocitoblast (whitish appearance)

They are formed partly from bone marrow (myeloid tissue) and partly from lymphaticganglia (lymphatic tissue). Once they are produced, they are transported through the

blood to different locations within the organism where they function.

Granulocytes are leukocytes that have small grains and vesicles in the cytoplasm which

give them a rough or granular appearance. These grains are known as lisosomes, whichare intracellular enzyme bags that digest or degrade cellular proteins and other discarded

materials.

Types of granulocytes: Neutrophils, Eosinophils the Basophils.

Although the leukocytes are considered blood cells their actions are produced in thetissues.

Agranulocytes (without grains) are the monocytes and the lymphocytes.

Granular leukocytes

NEUTROPHILS

First line of defense. They use phagocytosis.

Neutrophils are known by other names like: Polimorphonuclear cells (many forms),

Neutrophils in bands (Bands) and Segmented Neutrophils (Segmented). The origin of the

name is due to the unusual form of their nucleus.

The most numerous of all the leukocytes (60 - 70% of the total of WBC).


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Originate from the mother cell and complete the process of maturation in the bonemarrow.

They require 12 to 14 days to be functional.

In a healthy organism (immunosuficient) about 100 million new mature neutrophils arerelease into the blood circulation (bone marrow) on a daily basis. Their life expectancy is

12 to 18 hours.

Once in the blood they move with amoeba like movements. They penetrate the

endothelial layers of the capillaries and liberate their desired effect into the interstitial

fluids.

The grains are responsible of completing the phagocytic process. In the cytoplasm of the

mature neutrophil there is a large amount of grains of two types that contain diverse

enzymes. The enzymes help degrade the different components from the foreign invaders

that were digested.

Each neutrophil is capable of producing a single episode of phagocytic destruction beforeits energy source is exhausted and it dies. The energy supplement is small and they do

not posses an internal mechanism to produce energy (suicidal mission).

Neutrophils are responsible for providing continuous, instantaneous and non-specific

protection against the invasion of microorganisms. The total number and percentage of

WBC that are mature neutrophils is an indicator of the susceptibility of the client to have

infection.

The differential in a white blood cells count indicates that most of the neutrophils

released to the blood from the bone marrow are segmented and the smaller percentage is

with bands.

Some infectious conditions cause the population of neutrophils in the blood to change

from segmented to less mature. This indicates that a persons bone marrow cannotproduce sufficient mature neutrophils to match the continuous presence of infectious

microorganisms. Due to this situation immature neutrophils are freed into the blood

stream (condition known asDeviation to the left).

Immature neutrophils (non-functional cells) cannot provide phagocytosis of foreign

materials; therefore, the organism does not benefit from them. They dont have the

capacity to mature in the blood.

EOSINOPHILS

They make up from 1 to 2% of the total of the leukocytes (except in allergic reactions

where their number increases considerably).


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Weak phagocytic cells.They work mainly in reactions that destroy or eliminate parasitic larvae in human beings.

They participate in inflammatory reactions related to allergies in sensitive people. Their

grains contain diverse substances that produce diverse actions. Some are vasoactiveamines that produce inflammatory reactions.

The actions of these amines can cause some indirect effects of malaise and damagerelated to exposure to allergens in sensitive people.

Another function is the regulation of inflammatory reactions in body tissues.

The grains of eosinophils also contain special enzymes that degrade vasoactives amines

and other agents released by basophils. These enzymes limit the activity of amines and

thus the extension of inflammation (inflammatory reactions).

BASOPHILS

These are the rarest granulocites and the smallest ones.

Constitute up 0.5% of the total of leukocytes.

Derive from the myeloid mother cells and are released to bone marrow after a shortperiod of maturation.

Related to the signs and symptoms of the inflammation process.

They dont have amoeba-like movements or any phagocytic action.

They contain great amounts of grains that contain heparin as well as diverse vasoactives

amines like histamine, serotonin, cinines and leucotrins.

Inmunoglobulin E (IgE) is attached to the surface of the membrane.

Histamine contracts smooth muscle of venules, inhibiting the blood flow through small

veins and diminishes venous return. This effect makes blood more concentrated in

capillaries and in small arterioles thus increasing the hydrostatic pressure within blood

vessels.

Cinines produce slow vasodilatation of arterioles and together with serotonin increases

the capillary permeability. This way plasma is filtered towards the interstitial space.

Basophils are very important in generation of acute inflammatory reactions.


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NOT-GRANULAR LEUKOCYTES

MONOCITES - Macrophages

Monocites are an intermediate type of cells, from the bone marrow. They are releasedinto the circulation before they are completely functionally mature.

They constitute of 2 - 4% of the total of leukocytes.

When mature monocytes emigrate to the tissues they become MACROPHAGES (final

stage). The monocytes are not completely functional until they mature.

They are big in size and capable of recognizing their own cells and foreign cells.

They have diverse aspects depending on the tissue in which they are located.

o Lung alveolar macrophageo Conjunctive tissue histiociteo Brain microglial cello Liver cell of Kupffero Peritoneum Peritoneal macrophageo Bone osteoclasto Joints Type A synovial cellso Kidney mesangial cell

The duration (life expectancy) of a macrophage depends on the substance that surrounds

it during the phagocytosis process.

Macrophages in the tissues have a life expectancy of a few months or even years. Theyare the greatest leukocytes and they contain fine grains and a single nucleus. They have

great cytoplasmic extensions that help them in physical entrapment of foreign proteins.

Functions:

o Phagocytosiso Repair of injured tissueso Processing of antigenso Secretion of chemical substances that regulate immunity process

Each macrophage participates in many phagocytic processes during their life.


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LYMPHOCYTES

Lymphocytes originate from mother cells in the bone marrow.

During the fetal development the bone marrow releases immature and undifferentiatedlymphocytes (not specialized) into the blood. Some of these move to the thymus wherethey acquire the ability to distinguish between their own cells and foreign cells.

In the thymus lymphocytes are differentiated in B Lymphocytes and T Lymphocytes.

Once T cells have differentiated in the thymus they are released into the blood and

distributed in lymphatic tissue, especially in lymphatic nodules. About 70% of

circulating lymphocytes are T cells.

Lymphocytes that dont move into the thymus travel in the blood to other locations,

probably to the fetal liver where they are differentiated into B cells. Once they acquirethe ability to distinguish between their own cells and foreign cells then they are ready fortheir special role as part of the immune response. After that process is completed the B

cells enter the blood and are distributed into the lymphatic tissues.

B cells represent about 30% of the circulating lymphocytes.

In the process of differentiation and maturation thousands of different types oflymphocytes T and B are produced. Each type has a special zone for the receptors that

combine with specific antigens to provide specific-resistance to disease.

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Classes of Blood Cells