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The only fluid tissue in the human body
Classified as a connective tissue
Components of blood
◦ Living cells
 Formed elements: basophils, eosinophils, erythrocytes,
lymphocytes, megakaryocytes, monocytes, neutrophils
◦ Non-living matrix
 Plasma: primarily water, non-cellular; the fluid matrix
of blood
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If blood is centrifuged
1. Erythrocytes sink to the
bottom (45% of blood, a
percentage known as the
hematocrit)
2. Buffy coat contains
leukocytes and platelets
(less than 1% of blood)

Buffy coat is a thin, whitish
layer between the erythrocytes
and plasma
3. Plasma rises to the top
(55% of blood)
1
3
2 1
1
1
Found in Plasma
Nutrients:
• Glucose, fatty acids
• vitamins
• amino acids
Gases:
O2 , CO2
Ions:
• Sodium
• Potassium
• Calcium
Three major categories of
Formed Elements:
• Erythrocytes
• Leukocytes
• Platelets
Figure 10.1 (2 of 2)
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Color range
◦ Oxygen-rich blood is scarlet red
◦ Oxygen-poor blood is dull red
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pH must remain between 7.35–7.45
Blood temperature is slightly higher than
body temperature at 100.4°F
In a healthy man, blood volume is about 5–6
liters or about 6 quarts
Blood makes up 8% of body weight
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Composed of approximately 90% water
Includes many dissolved substances
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◦
◦
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Nutrients
Salts (electrolytes)
Respiratory gases
Hormones
Plasma proteins
Waste products
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Plasma proteins
◦ Most abundant solutes in plasma
◦ Most plasma proteins are made by liver
◦ Various plasma proteins include
 Albumin—regulates osmotic pressure
 Clotting proteins—help to stem blood loss when a
blood vessel is injured
 Antibodies—help protect the body from pathogens
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Acidosis
◦ Blood becomes too acidic
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Alkalosis
◦ Blood becomes too basic
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In each scenario, the respiratory system and
kidneys help restore blood pH to normal
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Erythrocytes
◦ Red blood cells (RBCs)
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Leukocytes
◦ White blood cells (WBCs)
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Platelets
Cell fragments
1.
2.
3.
4.
5.
6.
Which body organ plays the main role in
producing blood proteins?
What are the three major categories of formed
elements?
What determines whether blood is bright red
(scarlet) or dull red?
What is the blood volume of an average-sized
adult?
Name as many different categories of
substances carried in plasma as you can.
Define formed elements. Which category is
most numerous? Which makes up the buffy
coat?
Figure 10.2
Table 10.2 (1 of 2)
Table 10.2 (2 of 2)
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Erythrocytes (red blood cells or RBCs)
◦ Main function is to carry oxygen
◦ Anatomy of circulating erythrocytes
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Biconcave disks
Essentially bags of hemoglobin
Anucleate (no nucleus)
Contain very few organelles
◦ 5 million RBCs per cubic millimeter of blood
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Hemoglobin
◦ Iron-containing protein
◦ Binds strongly, but reversibly, to oxygen
◦ Each hemoglobin molecule has four oxygen binding
sites
◦ Each erythrocyte has 250 million hemoglobin
molecules
◦ Normal blood contains 12–18 g of hemoglobin per
100 mL blood
Hemoglobin transports oxygen in the blood as well as a small
amount of carbon dioxide.
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Homeostatic imbalance of RBCs
◦ Anemia is a decrease in the oxygen-carrying ability
of the blood
◦ Sickle cell anemia (SCA) results from abnormally
shaped hemoglobin
◦ Polycythemia is an excessive or abnormal increase
in the number of erythrocytes
Table 10.1
Figure 10.3
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Leukocytes (white blood cells or WBCs)
◦ Crucial in the body’s defense against disease
◦ These are complete cells, with a nucleus and
organelles
◦ Able to move into and out of blood vessels
(diapedesis)
◦ Can move by ameboid motion
◦ Can respond to chemicals released by damaged
tissues
◦ 4,000 to 11,000 WBC per cubic millimeter of blood
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Abnormal numbers of leukocytes
◦ Leukocytosis
WBC count above 11,000 leukocytes/mm3
Generally indicates an infection
◦ Leukopenia
 Abnormally low leukocyte level
 Commonly caused by certain drugs such as
corticosteroids and anticancer agents
◦ Leukemia
 Bone marrow becomes cancerous, turns out excess
WBC
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Types of leukocytes
◦ Granulocytes
 Granules in their cytoplasm can be stained
 Possess lobed nuclei
 Include neutrophils, eosinophils, and basophils
◦ Agranulocytes
 Lack visible cytoplasmic granules
 Nuclei are spherical, oval, or kidney-shaped
 Include lymphocytes and monocytes
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List of the WBCs from
most to least abundant
◦ Neutrophils
◦ Lymphocytes
◦ Monocytes
◦ Eosinophils
◦ Basophils

Easy way to remember
this list
◦ Never
◦ Let
◦ Monkeys
◦ Eat
◦ Bananas
Hemocytoblast
stem cells
Lymphoid
stem cells
Myeloid
stem cells
Secondary stem cells
Erythrocytes
Basophils
Platelets
Eosinophils
Lymphocytes
Monocytes
Neutrophils
Figure 10.4
Hemocytoblast
stem cells
Figure 10.4, step 1
Hemocytoblast
stem cells
Lymphoid
stem cells
Secondary stem cell
Figure 10.4, step 2
Hemocytoblast
stem cells
Lymphoid
stem cells
Secondary stem cell
Lymphocytes
Figure 10.4, step 3
Hemocytoblast
stem cells
Lymphoid
stem cells
Myeloid
stem cells
Secondary stem cells
Lymphocytes
Figure 10.4, step 4
Hemocytoblast
stem cells
Lymphoid
stem cells
Myeloid
stem cells
Secondary stem cells
Erythrocytes
Basophils
Platelets
Eosinophils
Lymphocytes
Monocytes
Neutrophils
Figure 10.4, step 5
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Types of granulocytes
◦ Neutrophils
 Multilobed (3-7 lobes) nucleus with fine granules
 Act as phagocytes at active sites of infection
 Name means “neutral-loving”
◦ Eosinophils
 Large brick-red cytoplasmic granules
 Found in response to allergies and parasitic worms
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Types of granulocytes (continued)
◦ Basophils
 Have histamine-containing granules
 Initiate inflammation
 Releases a vasodilator; least abundant WBC
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Types of agranulocytes
◦ Lymphocytes
 Nucleus fills most of the cell
 Play an important role in the immune response
◦ Monocytes
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Largest of the white blood cells
Function as macrophages
Important in fighting chronic infection
Phagocyte in chronic infections
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Platelets
◦ Derived from ruptured multinucleate cells
(megakaryocytes) ancestral cell of platelets
◦ Needed for the clotting process
◦ Normal platelet count = 300,000/mm3
7.
8.
9.
10.
11.
12.
What is the role of hemoglobin in the red blood
cell?
Which white blood cells are most important in
body immunity?
If you had a severe infection, would you expect
your WBC count to be closest to 5,000, 10,000
or 15,000/mm3.
Little Lisa is pale and listless. What disorder of
erythrocytes might she be suffering from?
Define anemia, and give three possible causes.
Name the granular and agranular WBCs. Give
the major function of each type in the body.