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Blood
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Functions
A. Transport: gasses, nutrients, wastes, hormones,
antibodies etc.
B. Defense:
Leukocytes- white blood cells (neutrophils,
eosinophils, basophils, monocytes, lymphocytes)
Antibodies: small proteins in blood
Complement: small proteins in blood
C. Regulation
1) Platelets form blood clots during injury &
prevents excess blood loss.
2) Regulate body temperature w/
constricting/dilating blood vessels (circulation flow)
3) Salts & proteins keep content of water in
plasma high (osmosis)- maintains blood pressure
4) Regulates pH & electrolytes in blood &
interstitial fluid.
Serum:
Blood plasma after
clotting factors
have been removed
Plasma
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A. Consists of inorganic & organic molecules dissolved
in water.
55% of blood volume. water (90-92%), salts,
gasses, hormones, vitamins, nutrients, cholesterol,
antibodies. etc.
B. plasma proteins:
1. albumin: 60%,most abundant & smallest.
Mainly to maintain correct osmotic pressure of blood.
2. globulin:
a) immunoglobuins= antibodies.
b) Transport globulins: bind to insoluble
substances that may be filtered out of kidney.
3. Fibrinogen inactive clotting factor . Activated
form: fibrin.
Figure
20.1b The Composition of Whole Blood
Plasma Proteins
Albumins
(60%)
Major contributors to osmotic
pressure of plasma; transport
lipids, steroid hormones
Globulins
(35%)
Transport ions, hormones, lipids;
immune function
Fibrinogen
(4%)
Essential component of clotting
system; can be converted to
insoluble fibrin
Regulatory
proteins
(1%)
Other Solutes
Electrolytes
Normal extracellular fluid ion
composition essential for vital
cellular activities
Ions contribute to osmotic
pressure of body fluids
Major plasma electrolytes
are Na, K, Ca2, Mg2, Cl,
HCO3, HPO4, SO42
Organic
nutrients
Used for ATP production, growth,
and maintenance of cells; include
lipids (fatty acids, cholesterol,
glycerides), carbohydrates
(primarily glucose), and amino
acids
Organic
wastes
Carried to sites of breakdown or
excretion; include urea, uric acid,
creatinine, bilirubin, ammonium
ions
Enzymes, proenzymes,
hormones
A. Hemaotpoiesis- making of formed
elements. Takes place in red bone marrow.
A pluripotent stem cell in red bone
marrow 2 multipotent stem cells.
A multipotent stem cell maintains its
population by replicating itself. Some of those new
cells
will differentiate into other
types of stem cells. When a stem cell differentiates, it
commits
itself to a single
developmental pathway.
Leukemia: cancer of white blood cells.
Too much production in bone marrow, but cells put
out into
blood are immature and
not functional. Disrupts formation of normal blood
cells.
Figure 20.8 The Origins and Differentiation of Formed Elements
Pluripotential
Stem Cells
Red bone marrow
Lymphoid Stem Cells
Myeloid Stem Cells
Progenitor Cells
Blast Cells
Myeloblast
Proerythroblast
Monoblast
Lymphoblast
Myelocytes
Erythroblast stages
Band Cells
Ejection of
nucleus
Promonocyte
Megakaryocyte
Prolymphocyte
Reticulocyte
Erythrocyte
Red Blood Cells
(RBCs)
Platelets
Basophil
Eosinophil
Neutrophil
Granulocytes
Monocyte
Lymphocyte
Agranulocytes
White Blood Cells (WBCs)
Hematopoiesis
“Process of making formed elements (all blood cells)”
Multipotent
Figure 20.1c
Platelets
The Composition of Whole Blood (Part 2 of 2)
White Blood Cells
Neutrophils
(50–70%)
Red Blood Cells
Eosinophils
(2–4%)
Monocytes
(2–8%)
Basophils
(1%)
Lymphocytes
(20–30%)
Figure 20.2a Histology of Red Blood Cells
Blood smear
LM  477
When viewed in a standard
histological blood smear, red blood
cells appear as two-dimensional
objects because they are flattened
against the surface of the slide.
1. Erythrocytes
a) Small biconcave disks- shape gives it flexibility to move through
small capillaries and a large
surface area
(for
diffusion of gasses)
b) rouleau: stack of RBC’s in small spaces
c) Enucleated- Survive 120 days in circulation, Destroyed in liver &
spleen.
d) Hemoglobin: (Hb) Four subunit protein. Each subunit contains 1
heme group. Each heme group contains an iron (Fe) atom which
binds to oxygen. This is why we need iron in the diet! 280 million
molecules of Hb in one RBC!
- Anemia: condition where blood lacks enough healthy red
blood cells or hemoglobin.
- Causes of anemia: disease (eg. malaria), genetic disorder,
low iron in diet.
e) Hematocrit: % of RBC’s in blood. Normally about 45% for men
and 40% for women
f) ABO blood typing & Rh factor (D antigen)
Figure 20.2bc Histology of Red Blood Cells
0.45–1.16 m
Red blood cells
SEM  1838
A scanning electron
micrograph of red blood cells
reveals their three-dimensional
structure quite clearly.
2.31–2.85 m
7.2–8.4 m
A sectional view of a red blood cell
Figure 20.2d
Histology of Red Blood Cells
Red blood
cell (RBC)
Rouleau
(stacked RBCs)
Nucleus of
endothelial cell
Blood vessels
(viewed in
longitudinal
section)
Sectioned capillaries
LM  1430
When traveling through relatively narrow capillaries,
erythrocytes may stack like dinner plates, forming a
rouleau.
Figure 20.3 The Structure of Hemoglobin
 chain 1
 chain 1
 chain 2
Heme
 chain 2
Hemoglobin
molecule
Heme
Blood types- Erythrocyte antigens
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Leukocytes (WBCs)
Fight infection- in blood, lymph nodes, lymph & other lymphatic tissues.
a) granular leukocytes
1.neutrophils*
Polymorphonuclear (PMN), mobile, phagocytic,
2. eosinophils*: pink, kidney shaped nucleus, fights parasites. Involved in allergy,
3.basophils*: dark granules, bilobed nucleus, mediates allergy, histamine production,
b) agranular leukocytes
1. monocytes*: in blood, immature. Large nucleus with a notch.
Migrates to tissues.
- In the tissues, it matures into macrophage.
Phagocytic, non-specific.
2. lymphocytes: B & T cells. Specific immunity. Has “memory”.
- large round nucleus. Very little cytoplasm visible.
- cannot tell difference between T and B cell based
on morphology
- B cells antibodies, has memory
- T cells Kill virally infected cells, cancer cells.
Recognizes foreign tissues,
Has memory
-Helper T cells: coordinates all arms of
immunity (nonspecific cells, B
cells & T cells). HIV kills helper T cells. The person becomes
immunocompromised.
Figure 20.5 Histology of White Blood Cells
RBC
RBC
RBC
RBC
RBC
Neutrophil
LM  1500
Eosinophil
LM  1500
(see
Basophil
LM  1500
Monocyte
neutrophil in action)
LM  1500
Lymphocyte LM  1500
Leukocytes
Figure 20.7 Structure of a Blood Clot
Platelets
Blood clot
Network of fibrin Trapped RBCs in
fibers
fibrin strands
See video
on clotting
SEM  4675