Introduction WBCs Leukocytes are colourless nucleated cell elements Larger and lesser in number Important in defence mechanism of body WBCs vs RBCs Larger in size Irregular Nucleated ID: 326354
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Slide1
White blood cellsSlide2
Introduction:
WBCs
/ Leukocytes are colourless nucleated cell elements.
Larger and lesser in number.
Important in defence mechanism of body.
WBCs
vs
RBCs:
Larger in size.
Irregular.
Nucleated.
Many types.
Some are granulated.
Shorter life span.Slide3
Classification:
Granulocytes:
Depending on staining properties
1. Neutrophils. Granules taking both acidic and basic stains.
2. Eosinophils. Acidic stain.
3. Basophils. Basic stains.
Agranulocytes
:
Plain cytoplasm without granules.
1. Monocytes.
2. Lymphocytes.Slide4
Neutrophils:
Also called polymorphs.
Fine small granules in cytoplasm.
Take acidic and basic stain.
Nucleus is multilobed.
Number of lobes depend on age of the cell.
Younger cells= nucleus is not lobed.Older neutrophills= 2-5 lobes.Diameter of cells is 10-12 micron.Ameboid in shape.Slide5
Eosinophils:
Larger coarse granules.
Stain pink or red with eosin.
Bilobed
/ spectacle shaped nucleus.
Diameter 10-14 micron.Slide6
Basophils:
Coarse granules in cytoplasm.
Stain purple blue with
methylene
blue.
Nucleus is
bilobed.Diameter 8-10 micron.Slide7
Monocytes:
Largest leukocytes with 14-18 micron diameter.
Nongranulated.
Nucleus is round, oval, horseshoe shaped, bean shaped or kidney shaped.
Nucleus is either in center or pushed to one side.
Large amount of cytoplasm.Slide8
Lymphocytes:
Nongranulated cytoplasm.
Nucleus is oval, bean shaped or kidney shaped.
Nucleus occupies whole cytoplasm.
A rim of cytoplasm may or may not be seen.Slide9
Types of lymphocytes:
Divided on basis of size and function:
1. Size:
Large lymphocytes: Younger cells. Diameter 10-12 micron.
Small lymphocytes: older cells. Diameter 7-10 micron.
2. Function:
T lymphocytes. Cellular immunity.B lymphocytes. Humoral immunity.
NORMAL WBC COUNT:
Total WBC count: 4,000- 11,000 Slide10
Variation in
wbc
count:
Leukocytosis
:
Increase in total WBC count. Can be physiological and pathological.
Leukopenia:Decrease in total WBC count. Pathological.Granulocytosis:Abnormal increase in number of granulocytes.
Granulocytopenia
:
Abnormal reduction in number of granulocytes.
Agranulocytosis
:
Absolute lack of granulocytes. Acute pathological condition.Slide11
Physiological variations:
Age:
Infants= 20,000/ cu mm
Children= 10,000-15,000/ cu mm.
Adults= 4,000-11,000/ cu mm of blood.
Sex:
More in males than females.Diurnal variation:Minimum in early morning. Maximum in afternoon.Exercise:
increase slightly.
Sleep:
decrease.
Emotional conditions:
increase.
Pregnancy:
increase.
Mensturation
:
increase.
Parturition:
increase.Slide12
Pathological variations:
Leukocytosis
:
Increase in total leukocytes.
Leukemia
:
Uncontrolled increase in WBCs. Cancer.Leukopenia
:
Decrease in total WBC count.
Neutrophelia
Increase in
neutrophil
count
Eosinophilia
Increase in
eosinophil
count
Basophilia
:
increase in basophile count
Monocytosis
:
increase in monocyte count. Slide13
lymphocytosis
:
Increase in total lymphocytes.
Neutropenia
:
decrease in
neutrophil count.Eosinopenia. Decrease in eosinophil
count.
Basopenia
:
Decrease in basophile count.
Monocytopenia
:
Decrease in monocyte count
Lymphocytopenia
:
Decrease in lymphocytes.Slide14
Life span of white blood cells:
Not constant. Depends upon body demand.
May be half day to 3-6 months.
Functions of
WBCs
:
Defence of body.Protection from invading organisms.Each type of WBC act in different way.Slide15
Properties of white blood cells:
1. Diapedesis:
Squeezing of
WBCs
through narrow blood vessels.
2.
Ameboid movement:Neutrophils, monocytes and lymphocytes.3. Chemotaxis:Attraction of
WBCs
towards injured tissues by chemical substances released at injury site.
4. Phagocytosis:
Neutrophils and
monocytes
engulf foreign bodies.Slide16
Neutrophils:
Defence mechanism of body.
Provide first line of defence along with
monocytes
.
Free cells wander freely through tissues.
Their granules contain enzymes:Proteases, myeloperoxidases, elastases and
metalloproteinases
.
They destroy the micro-organisms.
Have antibody like anti-microbial peptides:
Cathelicidins
and
defensins
Membrane contains NADPH
oxidase
.
Activated by toxic metabolites released from infected tissues.
Responsible for bactericidal action of neutrophils.
Secrete platelet-activating factor:
Aggregation of platelets during injury to blood vessels to prevent excessive blood loss.Slide17
Mechanism of action of neutrophils:
Released from blood at injury site.
New cells are produced at the progenitor cells.
Move by diapedesis towards injury site due to chemotaxis (chemo attractants).
They surround the area and adhere to infected tissues.
Chemo attractants increase the adhesive nature of neutrophils.
Make them sticky and attach firmly to infected area.1 neutrophil = 15-20 micro-organisms at the same time.
They engulf the bacteria and destroy by phagocytosis.Slide18
Respiratory burst:
Rapid increase in oxygen consumption during phagocytosis by neutrophils and other phagocytic cells.
NADPH
oxidase
is responsible for this phenomenon.
Radical oxygen is formed O
2- combines with 2H+ -> H2O2O
2
- and H
2
O
2
have potent bactericidal action.Slide19
Pus and pus cells:
Dead
WBCs
, bacteria, foreign bodies and cellular debris form whitish yellow fluid at site of injury.
Toxins from bacteria kill
WBCs
which are collected at the centre of infected area.Dead cells + plasma leaked from vessels + liquified tissue cells + RBCs ( from damaged capillaries) = PUS. Slide20
Eosinophils:
Defensive cells against parasites.
Parasitic infections -> large number of
eosinophils
produced and move towards infection site.
Count also increase during allergic reactions like asthma.
Detoxification, disintegration and removal of foreign proteins.Slide21
Mechanism of action:
Lethal substances released from granules and released at the time of exposure to parasites and foreign proteins are:
1.
Eosinophil
peroxidase
.helminths., bacteria and tumor cells.2. Major basic protein.
Helminths
. ballooning
3.
Eosinophil
cationic protein.
10 times more toxic. Complete distension. Neurotoxin.
4.
Eosinophil
derived neurotoxins.
Myelinated nerve fibers.
5. Cytokines.
Interleukin 4 & 5. increase inflammatory process by activating
eosinophils
. Also kill invading organisms.Slide22
Basophils:
Their number increase during healing process.
Allergy or acute hypersensitivity reactions.
Ig
E receptors on
basophil
membrane.Rupture and release from their granules:1. Heparin:Prevent intravascular blood clotting.2. Histamine, slow reacting substances of anaphylaxis,
bradykinin
and
seratonin
:
Acute
hypersensitivityy
reactions
Proteases and
myeloperoxidase
:
Destruction of micro organisms.
4. Cytokine:
Accelerate inflammatory responses and kill micro organisms.Slide23
Mast cells:
Found along blood vessels.
Prominently seen in skin, mucosa of lungs, GIT, mouth, conjunctiva and nose.
They don’t enter the blood stream.
Develop in bone marrow and mature in tissues.
Play important role in hypersensitivity reactions.
After activation, release chemical mediators into the interstitium.1. Preformed mediators:Already formed and stored in
secretory
granules.
2. Newly generated mediators:
Absent during resting condition and produced during activation.Slide24
Monocytes:
Largest, motile phagocytic cells. Wander freely through all tissues of the body.
Provide first line of defence along with neutrophils.
They secrete:
Interleukin 1
Colony stimulating factor
Platelet activating factor.Precursors of macrophages.Mature monocytes remain in blood for few hours then enter the tissues to form macrophages.
E.g
=
kuffer
cells, alveolar and spleen macrophages.Slide25
Lymphocytes:
Immune cells
2 types:
T lymphocytes:
Cellular immunity
B
lumphocytes.Humoral immunitySlide26