Blood – Part 2 - Mount Carmel Academy
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Transcript Blood – Part 2 - Mount Carmel Academy
WBCs are classified into
two major groups,
depending on whether or
not they contain visible
granules in their
cytoplasm.
1. Granulocytes – Granule
containing WBCs.
2. Agranulocytes – Lack
visible cytoplasmic
granules.
Granulocytes – Granule
containing WBCs.
› Have lobed nuclei
Typically consist of several rounded nuclear
areas connected by thin strands of nuclear
material.
› The granules in their cytoplasm stain
specifically with Wright’s stain.
› Granulocytes include the:
1. Neutrophils
2. Eosinophils
3. Basophils
Multilobed nucleus.
Very fine granules that
respond to both acid
and basic stains.
The cytoplasm as a
whole stains pink.
Avid phagocytes at
sites of acute infection.
Blue-red nucleus.
› Resembles an old
fashioned telephone
receiver.
Large brick-red
cytoplasmic granules.
Their number increases
rapidly during allergies
and infections by
parasitic worms
(ex: tapeworms and
flatworms)
Rarest of the WBCs.
Contain large histaminecontaining granules that
stain dark blue.
› Histamine – Inflammatory
chemical that makes
blood vessels leaky and
attracts other WBCs to
the inflammatory site.
Agranulocytes – lack visible
cytoplasmic granules.
› Their nuclei is closer to the norm – that is
spherical, oval, or kidney shaped.
› The agranulocytes include:
1. Lymphocytes
2. Monocytes
Have a large, dark
purple nucleus that
occupies most of
the cell volume.
Slightly larger than RBCs.
Tend to take up residence
in lymphatic tissues, where
they play an important role
in the immune response.
Largest of the WBCs.
Except for their more abundant
cytoplasm and indented nucleus, they
resemble large lymphocytes.
When they migrate into the tissues, they
change into macrophages with huge
appetites.
Macrophages are very important in
fighting chronic infections.
Platelets – One of the
irregular cell fragments of blood.
› Not cells in the strict
sense; They are fragments of bizarre
multinucleate cells called megakaryocytes.
Megakaryocytes rupture releasing thousands
of anucleate “pieces” that quickly seal
themselves off from the surrounding fluids.
Appear as darkly
staining, irregularly
shaped bodies
scattered among the
other blood cells.
Needed for the
clotting process.
Hematopoiesis –
Blood cell formation.
› Occurs in red bone
marrow.
This tissue is found chiefly in the:
1.
2.
3.
4.
Flat bones of the skull and pelvis
Ribs
Sternum
Proximal epiphyses of the humerus and femur
› After the cells mature, they are discharged
into the blood vessels surrounding the area.
All the formed elements arise from a
common type of stem cell, the
hemocytoblast.
› Hemocytoblasts resides in the bone marrow.
› Their development differs and once a cell is
committed to a specific blood pathway it
cannot change.
Because they are anucleate,
RBCs are unable to synthesize
proteins, grow, or divide.
As they age, RBCs become
more rigid and begin to fragment, or fall
apart in 100-120 days.
Their remains are eliminated by phagocytes
in the liver, spleen, and other body tissues.
Lost cells are replaced by the division of
hemocytoblasts.
The developing RBCs divide many times
and then begin synthesizing huge amounts
of Hb.
› When enough Hb
has been accumulated, the nucleus
and most organelles
are ejected and the
cell collapses inward.
The entire developmental process from
hemocytoblast to
mature RBC takes 3-5 days.
The rate of erythrocyte
production is controlled
by a hormone called
erythropoietin.
› Normally a small amount
of erythropoietin circulates in the blood at all
times, and RBC are formed at a fairly constant
rate.
› The kidneys play the major role in producing this
hormone.
If blood levels of O2 begin to decline, the kidneys
step up their release of erythropoietin.
An excessive amount of O2 in the bloodstream,
depresses erythropoietin release.
The formation of leukocytes is stimulated
by two hormones:
1. Colony Stimulating Factors (CSFs)
2. Interleukins
The production of
platelets is accelerated by the hormone
thrombopoietin.