Transcript Chapter 10 Blood Fall 2010

Blood
Chapter 10
Blood - River of Life
• The only fluid tissue in the human body
• Contains both cellular and liquid components
• Classified as a connective tissue
– Living blood cells: erythrocytes, leukocytes and platelets are
called formed elements
– Plasma is the non-living matrix and fibrous proteins are only
visible during clotting
Blood Composition
• If we spin a sample of blood
in a centrifuge
• The heavier formed
elements will be at the
bottom
– Mostly composed of
erythrocytes - RBCs
• The less dense plasma
remains at the top
• A thin whitish layer in the
middle is called the buffy
coat
– Contains leukocytes and
platelets
Blood Composition
• 55% is blood
plasma
• 45% is
erythrocytes
• 1% is the buffy
coat (platelets
and leukocytes)
Blood Characteristics
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•
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Sticky, opaque fluid
Scarlet red – oxygen rich blood
Dark red – oxygen poor blood
Volume = 8% of your body weight
– 4-5 L in females & 5-6 L (1.5 gallons) in males
• More dense than water
• Slightly basic with a pH between 7.35-7.45
• Temperature is slightly higher than body
temperature (100.4)
Blood - River of Life
•
Functions of blood
1. Distribution
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–
Delivering oxygen and nutrients
Transporting wastes and hormones
2. Regulation
–
Maintaining adequate fluid volume, normal pH, body
temperature
3. Protection
–
Prevent infections and blood loss by forming clots
Blood Plasma
• Composition of plasma
– Mostly water (90%)
– Over 100 different
dissolved solutes (10%)
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•
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Plasma proteins
Nutrients
Electrolytes (ions)
Respiratory gases
Hormones
Metabolic wastes
Formed Elements
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Erythrocytes = red blood cells (RBCs)
Leukocytes = white blood cells
Platelets = cell fragments
Two of the three are not even true cells
– Erythrocytes have no nuclei or organelles
– Platelets are cell fragments
Erythrocytes – Red Blood Cells (RBCs)
• Small cells that are shaped like
biconcave discs with depressed
centers
• Lack a nucleus (anucleate) and have
no organelles
• Contain the protein hemoglobin that
gives them their red color and carries
the oxygen
• Cannot grow or divide (amitotic)
• Most numerous cells in the blood
• 12 – 18 g of hemoglobin per 100 mL
of blood
The Fate of the RBCs
• Life span of 100 to 120 days
• Without a nucleus they are unable to divide, grow, or
synthesize proteins and eventually begin to wear out
• Eliminated by macrophages in the spleen or liver
Erythrocyte Disorders
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Anemia
–
Condition in which the blood has
abnormally low oxygen carrying
capacity
–
Symptoms include fatigued, pallor,
shortness of breath and cold chills
Three types of anemia:
1.
Insufficient number of RBC
(Hemorrhagic or hemolytic anemia)
•
Results from blood loss, excessive
RBC destruction and bone marrow
failure
Erythrocyte Disorders
2.
Low hemoglobin count (Irondeficiency anemia)
•
Results from inadequate intake of
iron-containing foods in diet
3. Abnormal hemoglobin (Sickle-cell
anemia)
•
Results from having an abnormal
hemoglobin shape that causes
the RBC to be crescent shaped;
they tend to rupture easily and
dam up small blood vessels;
usually genetic
Leukocytes (1%)
• White blood cells (WBCs)
• Complete cells
– Contain nuclei and organelles
– No hemoglobin
• Live for days, months or
years
• The “mobile army” of the
circulatory system
– Defend against bacteria,
viruses, parasites, toxins and
tumor cells
• Formed in bone marrow
Leukocytes
• Classified in two categories based on visible granules
– Granulocytes
• Neutrophils
• Eosinophils
• Basophils
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•
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– Agranulocytes
• Lymphocytes (B and T)
• Monocytes
From most abundant to least abundant
Neutrophil  Lymphocyte  Monocytes  Eosinophils  Basophils
Never let monkeys eat bananas
Normal WBC levels = 4,000 - 11,000 cells/mm3
Granulocytes
• Neutrophils (50-70% of WBCs)
– Most numerous
– Fine granules that stain lilac
– Body’s bacteria slayers by
phagocytosis
– Numbers increase explosively
during an acute bacterial infection
such as appendicitis and
meningitis.
– Positive chemotaxis - chemically
attracted to sites of inflammation
Granulocytes
• Eosinophils (2-4% of WBCs)
– Deep red nucleus with two lobes
– Large, coarse granules stain brick
red
– Granules are packed with lysosomes
and digestive enzymes
– Attack parasitic worms such as
flatworms and roundworms that are
too large to be phagocytized
– Gather around and release enzymes
– Also play a role in allergies and
asthma
Granulocytes
• Basophils (rare-1% of WBCs)
– Deep purple nucleus
– Large, coarse histamine
containing granules that stain
purplish black
• Histamine is an inflammatory
chemical that acts as a vasodilator
(dilate blood vessels) and attracts
other WBCs to the inflamed site
• Antihistamines counter this effect
• INFLAMMATION!
Agranulocytes
• Lack visible granules
• Similar in structure but different in functions
• Lymphocytes (25% of WBCs)
– Large dark purple spherical nucleus that occupies
most of the cell
– Most of them are found in the lymphoid tissues
where they play a crucial role in immunity
– T lymphocytes – function in the immune response by
acting directly against virus-infected cells and tumor
cells
– B lymphocytes – give rise to plasma cells which
produce antibodies (immunoglobulins) that are
released to the blood
Agranulocytes
• Monocytes (3-8% of WBCs)
– Largest leukocytes
– Blue cytoplasm and a dark purple nucleus
– Differentiate into macrophages which are
active phagocytes
– Crucial in the body’s defense against
viruses, bacteria and chronic infections such
as tuberculosis
– Also activate lymphocytes to mount the
immune response
Leukocyte Disorders
– Leukemia
• Cancer involving white blood cells
– Serious acute forms usually affect children
– Chronic leukemia affects elderly people
• Tremendous numbers of leukocytes are produced that are
nonfunctional and cannot defend the body
• Red bone marrow becomes totally occupied by cancerous
leukocytes and flood the bloodstream
• Symptoms include severe anemia, bleeding problems, fever,
weight loss, bone pain
• Leukemia is fatal without treatment usually due to internal
hemorrhages and infections
Platelets
• Not real cells
• Made of cytoplasmic fragments of other blood cells
• Contain an array of chemicals that act in the clotting process when a
blood vessel is broken
• Stick to the damaged area and form a temporary plug that helps
seal the break
• Degenerate in about 10 days
• Normal platelet count is between 150,000 – 400,000 per microliter
Hemostasis
• Stoppage of blood flow in a broken blood
vessel by a series of reactions
• Fast, localized and controlled process
– Occurs in 3-6 minutes
• Three steps occur in rapid sequence to
form a clot
1.
2.
3.
Vascular spasms (vasoconstriction)
Platelet plug formation
Coagulation (blood clotting)
Undesirable Clotting
• Thrombus
– A clot in an unbroken blood vessel
– If the clot is large enough it may block circulation and lead to
death of the tissues
– Can be deadly in areas like the heart
Undesirable Clotting
• Embolus
– If the thrombus breaks away and floats freely in the bloodstream
– Not a problem until becomes trapped in narrow blood vessel
then it becomes an embolism
• Pulmonary embolism - trapped in the lungs
• Cerebral embolism – clot in the brain (can cause a stroke)
Bleeding Disorders
• Hemophilia (Bleeder’s Disease)
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Hereditary bleeding disorders
Symptoms begin early in life
Lack normal clotting factors
Prolonged bleeding into tissues that can be life threatening
Transfusions of fresh plasma can manage the condition
Human Blood Groups
• People have different blood
types and transfusion of
incompatible blood can be
fatal
• Erythrocytes contain highly
specific proteins on their
external surface which identify
each of us as unique from all
others
• Proteins serve as antigens a substance that the body
recognizes as foreign
Human Blood Groups
• The immune system
makes antibodies against
the other types of RBCs.
• If a RBC with a foreign
antigen was present the
antibodies in the serum
would cause the RBCs to
clump and be destroyed
Human Blood Groups
• There are at least 30 varieties
of red blood cell antigens in
humans
• The presence or absence of
each antigen allows each
person’s blood cells to be
classified into several different
blood groups
• The most vigorous transfusion
reactions are caused by
antigens determining the ABO
blood group and Rh blood
group
Transfusions
• The circulatory system is
designed to minimize the
effects of blood loss
• Large losses of blood have
serious consequences
– Loss of 15 to 30 percent
causes weakness and pallor
– Loss of over 30 percent
causes severe shock, which
can be fatal
• Transfusions are the only
way to replace blood quickly
Transfusions
• When mismatched blood is infused a
transfusion reaction occurs
• The donor’s red blood cells are
attacked by the recipient’s plasma
antibodies and clump (agglutination)
• Agglutination of the foreign RBCs
clogs small blood vessels and begin
to rupture (lyse) or are destroyed by
phagocytes
• Transfusion reactions can cause
fever, chills, low blood pressure, rapid
heartbeat, nausea, vomiting and
general toxicity
ABO Blood Groups
• Based on the inheritance
of the presence or
absence of two antigens
– Type A and Type B
• Blood type can be type A,
B, AB, or O
– Type O = lack of both
antigens (most common)
– Type AB = presence of both
A and B antigens (least
common)
– Type A = presence of type
A antigen
– Type B = presence of type
B antigen
ABO Blood Groups
• Unique to the ABO blood groups is the presence in the
plasma of antibodies that act against RBCs carrying
antigens that are not present on a person’s own red
blood cells
ABO Blood Groups
• A person with neither the A or the B (type O) possesses
both anti-A and anti-B antibodies
• A person with type A blood would have anti-B antibodies
• A person with type B blood would have anti-A antibodies
• Neither antibody is produced by type AB individuals
Rh Blood Groups
• Rh antigen (agglutinogen D) was originally
identified in rhesus monkeys
• Most Americans are Rh+ (85%); they carry
the D antigen
• Unlike ABO, there are no anti-Rh
antibodies formed in the blood of Rh • If a Rh - person receives Rh+ blood the
immune system begins producing
antibodies against the foreign antigen
• Red blood cells do not get destroyed the
first transfusion but the second time a
reaction occurs and the RBCs would be
attacked
Rh Dangers During Pregnancy
• Dangerous when the mother is Rh – and
the baby is Rh +
• First pregnancy usually proceeds without
problems but the mother’s immune
system gets exposed and starts making
antibodies
• If she is treated with RhoGAM (anti-Rh
antigens) before or shortly after she gives
birth her immune system will be blocked
• If she is not treated and becomes
pregnant with a Rh+ baby, her antibodies
will pass through the placenta and destroy
the baby’s RBCs – a condition known as
hemolytic disease of the newborn
Blood Typing
• Blood is “typed” by using antibodies that will cause blood with
certain proteins to clump (agglutination) before giving a transfusion
• It is crucial to determine the blood group of both the donor and the
recipient before blood is transfused
• Blood samples are mixed with anti-A antigen serum and anti-B
antigen serum
• Cross matching tests for agglutination of the donor RBCs by the
recipients serum
Blood Typing
• A person’s ABO and Rh blood type are usually reported
together like O+ or A• People with type O are universal donors because they
do not have either A or B antigens
• People with type AB are universal recipients because
they do not have any antibodies against either A or B
antigens
Genetics of Blood Typing
• Blood type is established by specific genes inherited
– One blood type gene from your mother and one from your father
• Two genes determine the blood type by causing the
presence or absence of the Type A and Type B antigen
molecules on the red blood cells.
• The blood type gene has three different versions of alleles:
– IA results in A antigen on the red blood cells
– IB results in B antigen on the red blood cells
– i does not result in either antigen
Genetics of Blood Typing
• Everyone has two copies of these genes, so there are
six possible combinations of alleles (called genotypes):
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IA IA and IA i
IB IB and IB i
IA IB
ii
Type A blood
Type B blood
Type AB blood
Type O blood
• In a heterozygous IA i person, which allele is dominant, IA
or i? Explain your reasoning.
Genetics of Blood Typing
• Each biological parent gives one of their two ABO alleles
to their child.
• For example, a mother who is blood type O has
genotype ii and can only give an i allele to her son or
daughter.
• A father who is blood type AB could give either an IA or
an IB allele to his son or daughter.
• This couple could have children of either blood type A (i
from mother and IA from father) or blood type B (i from
mother and IB from father).
•
Genetics of Blood Typing
Genetics of Blood Typing
1. Determine the possible genotypes & phenotypes
with respect to blood type for a couple who's blood
types are homozygous A & heterozygous B.
Genotypes: 50% IAIB; 50% Iai
Phenotypes: type AB and A (heterozygous)
Genetics of Blood Typing
2. What are the possible blood types of a child who's
parents are both heterozygous for "B" blood type?
Phenotypes: Type B and Type O
Genetics of Blood Typing
3. What are the chances of a man with Type AB and a
woman with Type A having a child with Type O?
Answer: 0%
Genetics of Blood Typing
4. A test was done to determine the biological father
of a child. The child is blood type A and the mother
is blood type B. Male #1 has a blood type O &
male #2 has blood type AB. Which male is the
biological father?
Child ‘s blood type A
Mother’s blood type B
Possible offspring of
woman & male # 1
Possible offspring of
Woman & male # 2.
Child is type A so
male # 1 cannot be the
father, but male # 2
could be.
Blood Typing