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Blood
Objectives
• Describe the functions of blood
• Describe blood plasma
• Explain the functions of red blood cells, white
blood cells, and platelets
• Summarize the process of blood clotting
What is Blood?
• Blood is a type of
connective tissue
containing dissolved
substances and
specialized cells
• Human body contains
4-6 liters of blood
(about 8% total body
mass)
Functions of Blood
• Collects O2 from lungs,
nutrients from digestive
tract, and waste
products from tissues
• Helps maintain
homeostasis
– Ex: body temperature
• Helps fight infections
• Forms clots to repair
damaged blood vessels
Blood Plasma
• Plasma – straw-colored
fluid that makes up 55% of
blood
– other 45% is cells
• Plasma is 90% water
• Other 10% is…
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Dissolved gases
Salts
Nutrients
Enzymes
Hormones
Waste products
Proteins called plasma
proteins
Blood Plasma Proteins
• Three Groups:
– Albumins
• Transport fatty acids, hormones, vitamins
• Regulate osmotic pressure and blood volume
– Globulins
• Transport fatty acids, hormones, vitamins
• Some fight viral and bacterial infections
– Fibrinogen
• Responsible for the ability of blood to clot
Blood Cells
• Three Types of Blood Cells:
– Red Blood Cells
– White Blood Cells
– Platelets
Red Blood Cells
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Most numerous cells in the blood
Mature red blood cells have no nuclei
Also called erythrocytes
Red blood cells transport oxygen
Get their color from hemoglobin
Hemoglobin is an iron-containing
protein that binds to oxygen in the
lungs and transports it to tissues
throughout the body where the oxygen
is released
• Red blood cells last about 120 days
– Old red blood cells are destroyed by the
liver and spleen
White Blood Cells
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Also called leukocytes
Do not contain hemoglobin
Have nuclei
White blood cells guard against
infection, fight parasites, and attack
bacteria
• Phagocytes are a type of WBC that
engulfs and digests bacteria and
other microorganisms
• Lymphocytes are a type of WBC that
produce antibodies to fight viral
infection and produce immunity to
many diseases
• Antibody is a protein that destroys
pathogens (disease-causing agents)
Platelets and Blood Clotting
• Blood clotting is made
possible by plasma
proteins and cell
fragments called platelets
• Platelets are cell
fragments released by
bone marrow that help in
blood clotting
• A platelet is fragment of
cytoplasm enclosed in a
piece of cell membrane
Platelets and Blood Clotting
• When platelets come into
contact with the edges of a
broken blood vessel, their
surfaces become sticky
• They then release proteins
called clotting factors
• The platelets are then
converted into fibrin filaments,
which produce a blood clot
Blood Types
• Human blood type is
classified by the antigens
on the surface of red
blood cells
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Type A
Type B
Type AB
Type O
• Type A blood cells also
have Type B antibodies
– If a Type A person receives
Type B blood, the body will
reject it
Notes Review
• What are the functions of blood?
– Collects O2 from lungs, nutrients from digestive
tract, and waste products from tissues
– Helps maintain homeostasis
– Helps fight infections
– Forms clots to repair damaged blood vessels
Notes Review
• Describe blood plasma.
– Plasma is straw-colored fluid that makes up 55%
of blood
– Plasma is 90% water and 10% dissolved
substances
Notes Review
• Explain the functions of each type of blood
cell.
– Red blood cell: transports oxygen
– White blood cell: guards against infection, fights
parasites, and attacks bacteria
– Platelets: help in blood clotting
Notes Review
• Summarize the process of blood clotting.
– When platelets come into contact with the edges
of a broken blood vessel, their surfaces become
sticky
– They then release proteins called clotting factors
– The platelets are then converted into fibrin
filaments, which produce a blood clot