Download Blood Cells - Dr Magrann

BLOOD
Blood is not an epithelial tissue, and it’s not loose or dense connective tissue; it’s
classified as a “special connective tissue”. You have about 5 liters of blood, but that is
only half of the body fluid. The other half includes fluid around each cell, and joint
fluids, etc.
PLASMA  EXTRACELLULAR FLUID
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SYNOVIAL FLUIDS, JOINTS, CSF
Blood consists of the following:
A. Plasma
B. Red blood cells
C. White blood cells
D. Platelets
Plasma is what the blood cells float around in. If you spin a blood sample in a test tube,
the red blood cells sink to the bottom, and you’ll see the yellow plasma on top. Some
people who need blood just need the packed RBCs, others need the plasma, and some
need whole blood, which is both plasma and RBCs. The plasma also carries around the
platelets and some white blood cells.
PLASMA CONTENTS
1. Water (90%)
2. Dissolved substances (10%)
a. Proteins
i. Albumin (egg white). Most common protein in blood (needed for
homeostasis of blood volume and blood pressure)
ii. Antibodies
iii. Clotting factors; main one is called fibrin.
iv. Lipoproteins (move fats through blood: HDL, LDL)
b. Nutrients
i. Glucose (main energy source)
ii. Amino Acids (builds proteins)
c. Wastes (urea)
d. Gases (O2, CO2, Nitrogen)
e. Electrolytes = ions (Na+, K+, Cl-, Ca++)
BLOOD CELLS
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1. ERYTHROCYTES (Red blood cells): These are among the smallest cells in the
body. There are about 5 million of them in each of us. Their structure is simple;
like a doughnut with the hole not fully cut out.
a. These are among the smallest cells in the body
b. They have no nucleus
c. Biconcave to increase surface area
d. Filled with hemoglobin (Hgb), which carries O2 throughout the body.
Oxygenated Hgb is bright red, deoxy Hgb is deeper red, almost a bluishpurple.
e. Hemoglobin consists of 2 alpha units and 2 beta units. Hemoglobin
abnormalities are classified by which unit is deformed. The heme group is
where the oxygen molecule binds. An iron (Fe++) molecule is in the
middle, which attracts the oxygen to the heme group.
f. Average life span is 120 days. Old ones are destroyed in the spleen and
liver, and Hgb and iron are recycled.
g. In one day, 100 billion of these cells are destroyed, and 100 billion are
made: where?
h. Red bone marrow.
DISORDERS OF RBCs
 POLYCYTHEMIA is too many red blood cells; can cause blood clots. Need to donate
blood frequently.
 ANEMIA: Anemia can be caused by many things:
– Too few RBC’s
– Iron deficiency
– Hemorrhagic anemia (person lost blood)
– Hemolytic anemia (immune disorder, infection, blood transfusion)
 G6PD deficiency
– Hemoglobin abnormalities
 Pernicious anemia (lack of vitamin B12 or intrinsic factor)
 Thalassemia
 Sickle cell disease
 Megaloblastic anemia (pernicious anemia)
 ANEMIA: Any condition of RED BLOOD CELLS in which the blood’s capacity for
carrying oxygen is diminished.
HYPOXIA is lack of oxygen to tissues.
It can be caused from:
Ischemia (reduced blood flow to a tissue)
Malfunctioning hemoglobin
Increasing altitude
 Characteristic sign of anemia: see reticulocytes in the blood (immature red blood cells).
Remnants of the nucleus are still in the cell.
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DETAILS ABOUT SOME TYPES OF ANEMIA
Hemolytic anemia (immune disorder, infection, blood transfusion)
Hemolysis means rupture of RBC’s. Hemolytic anemia can be hereditary (born with the genes
that cause the disease) or acquired. Hereditary factors include immune disorders and G6PD
deficiency. Acquired causes include infections (malaria), and receiving the wrong blood type in a
transfusion.
G6PD deficiency (hereditary, X-linked; almost all are males)
G6PDH is an enzyme which is important for RBC metabolism. G6PD is the most common
human enzyme defect. A person with this would have a hard time maintaining iron in a
reduced state, and they develop hereditary (NOT acquired) hemolytic anemia in response
to a number of causes, most commonly infection or exposure to certain medications,
chemicals, or ingestion of fava beans.
HEMOGLOBINOPATHIES (HEMOGLOBIN ABNORMALITIES)
Pernicious anemia (Megaloblastic anemia)
 Caused by lack of vitamin B12 or intrinsic factor
 When a person has gastric bypass surgery, the stomach is no longer able to produce
intrinsic factor, which is needed to absorb vitamin B12, which is needed to make
hemoglobin in RBC’s.
 Without this vitamin, the blood cells are fewer and much larger than normal
(megaloblastic). The surgery patient must take vitamin B12 shots or sublingual
supplements for the rest of their life.
Thalassemia
A hereditary form of anemia where the RBCs have abnormal hemoglobin that deforms the cells
into many types of unusual shapes, including spherocytes (small and round), target cells (looks
like a target) and tear drops.
Sickle cell disease
 A hereditary mutation resulting in one valine amino acid substituted for glutamic
acid.
 Present in African Americans more than in other groups, and is always
characterized by sickled erythrocytes.
 The sickle shape helps prevent malaria infections, but it also causes blood clots.
BLOOD TESTS FOR RBCs
RBC, Hgb, Hct
 Red blood cell (RBC) count is a count of the actual number of red blood cells per
volume of blood. Both increases and decreases can point to abnormal conditions.
 Hemoglobin (Hgb) measures the amount of oxygen-carrying protein in the blood.
 Hematocrit (Hct) measures the percentage of red blood cells in a given volume of
whole blood.
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HEMATOCRIT
A quick screening test for anemia is the hematocrit.
A drop of blood is drawn up a small glass capillary tube and the tube is centrifuged to
pack the red blood cells at the bottom with the plasma on top.
Hematocrit measures the percentage of blood volume that consists of erythrocytes.
The hematocrit is the ratio of packed red blood cells to total blood volume.
 Normal is about 45% (46% for men and 38% for women.)
BLOOD TYPING: The ABO SYSTEM
Blood typing is the technique for determining which specific protein type is present on
RBCs.
Only certain types of blood transfusions are safe because the outer membranes of the red
blood cells carry certain types of proteins that another person’s body will think is a
foreign body and reject it.
These proteins are called antigens (something that causes an allergic reaction). There are
two types of blood antigens: Type A and Type B.
A person with Type A antigens on their blood cells have Type A blood.
A person with Type B antigens have Type B blood.
A person with both types has type AB blood.
A person with neither antigen has type O blood.
If a person with type A blood gets a transfusion of type B antigens (from Type B or Type
AB, the donated blood will clump in masses (coagulation), and the person will die.
The same is true for a type B person getting type A or AB blood.
Type O negative blood is called the universal donor, because there are no antigens, so
that blood can be donated to anyone. Type AB positive blood is considered the universal
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acceptor, because they can use any other type of blood. This blood type is fairly rare.
The rarest blood type is AB negative.
RH FACTOR
There is another term that follows the blood type. The term is “positive” or “negative”.
This refers to the presence of another type of protein, called the Rh factor. A person with
type B blood and has the Rh factor is called B-positive.
A person with type B blood and no Rh factor is called B-negative.
The reason this is so important is that if an Rh- mother has an Rh+ fetus in her womb
(from an Rh+ father), her antibodies will attack the red blood cells of the fetus because
her body detects the Rh protein on the baby’s red blood cells and thinks they are foreign
objects. This is called Hemolytic Disease of the Newborn (HDN).
This can be prevented if the doctor knows the mother is Rh- and the father is Rh+,
because that means the baby has a 50% chance of being Rh+ like the father.
Therefore, anytime a mother is Rh-, even if the mother says the father is Rh-, you can’t
be sure who the father is, so they will proceed as though the baby may be Rh +.
They will give her an injection of a medicine (rhogam) that will prevent her immune
system from attacking the baby.
Rhogam
 Rhogam is given at 18 weeks into the pregnancy and again within 72 hours after
giving birth.
 It is usually given within 2 hours after giving birth since you can’t trust the patient
to return after they leave the hospital.
 The first baby is not at risk; during the first birth, the placenta tears away and
that’s when the baby’s blood cells get into the mother’s bloodstream.
 She then forms antibodies against the Rh factor, which are ready to attack the
second fetus.
 The baby does not make the Rh factor until about 18 weeks into the pregnancy.
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LEUKOCYTES (White blood cells): There are different kinds; all fight infection.
1) BASOPHILS: Few in body. Their blue granules are filled with histamines, which help
fight infection by vasodilation, increasing the number of WBCs to the infection site.
Antihistamines interfere with the function of basophils. When a basophile leaves the
circulation to enter the tissues, it becomes a MAST CELL.
2) EOSINOPHILS: Function to fight allergies and parasitic infections. During these
conditions, their numbers increase.
3) NEUTROPHILS: The most abundant type of WBC. They are the first to respond to
infection. They phagocytize (eat) bacteria and also destroy bacterial toxins in body
fluids. Nucleus – has two to six lobes
 Neutrophils are the white blood cells that contribute to immunity mainly by
engulfing BACTERIA and foreign bodies (thorns, dirt, etc) in a process called
phagocytosis.
 They release the contents of their lysosomes onto the invader, dissolving it.
 When a bacterium has a capsule, it makes it hard to phagocytize, so the neutrophil
requires opsonization by antibodies.
 Some bacteria have evolved a slippery capsule around them as a defense against
phagocytosis. The neutrophil cannot engulf this type of bacteria. Neither can a
macrophage.
 When an antibody attaches to this type of bacteria, the neutrophil can now grab onto
the antibody like a handle, enabling it to phagocytize the bacteria.
 This process of facilitation of phagocytosis is called OPSONIZATION.
 When the invader has the antibody attached to it, it is called an ANTIGENANTIBODY COMPLEX.
 If a bacterium does not have a capsule, the neutrophil can destroy it without
opsonization. The antibody can also destroy the bacterium by itself by popping the
cell membrane.
 But when a capsule is present, the neutrophil and antibody work best together.
 Neutrophils are also the ones that primarily destroy the dissolved toxins that
bacteria secrete into body fluids.
4) MONOCYTES: Like neutrophils, they phagocytize (eat) bacteria, old cells, and
foreign bodies. They have more types of lysosome enzymes than neutrophils so they are
better at killing difficult pathogens.They also use antibodies for opsonization.
 When they leave the bloodstream and enter the tissues, they are called
MACROPHAGES.
5) LYMPHOCYTES: Effective in fighting infectious organisms like body cells infected
with viruses They act against a specific foreign molecule (antigen)
Two main classes of lymphocyte
– B cells – Originate in the bone marrow, mature into plasma cells. A
mature plasma cell fights infection by producing antibodies
– T cells – Originate in the thymus gland. They attack foreign cells directly
(including organ transplants!)
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B CELLS: – mature into plasma cells
 PLASMA CELLS secrete antibodies; the antibodies are what kill the
attacking cell. Antibodies attack in two ways:
– They attach to bacteria and pop the cell membrane
– They attach to encapulated bacteria to help neutrophils phagocytize them.
Mononucleosis: Epstein Barr virus attacks B lymphocytes. It is characterized by
inflammation of lymph vessels (lymphangitis). Lymphangitis: lymph vessel
inflammation; usually from infection. Infected lymphocytes have a
characteristic scalloped edge where they touch RBC’s
T CELLS
1. Coordinate the immune response by recruiting other white blood cells
2.They can directly destroy bacteria by popping their cell membrane.
3.They can also destroy body cells infected with viruses.
4. T cells attack foreign cells directly by popping the cell membrane.
5.They do not need to phagocytize the invading cell. They do not need the assistance
of antibodies.
6.T-cells can therefore kill a body cell that has become infected with viruses.
7.T cells are the cells that attack organ transplants!
8.Immunosuppression drugs are designed to inhibit the action of T cells.
9.T cells are attacked by the HIV (AIDS) virus.
10.The thymus gland secrets certain hormones which can cause T cells to become
immunocompetent (makes the cells mature and start to work)
There are several types of T cells. The main types are
 Cytotoxic (Killer) T cells
– Go out and directly kill bacteria or infected host cells
 Helper T cells
– Release chemicals called “cytokines” to stimulate the B cells to produce
antibodies against the bacteria. Cytokines also call in more white blood
cells of all types to join in the war.
 Suppressor T cells
Stop the immune process when it is over, and also "tell" some B-Cells to "remember"
how to destroy that specific pathogen. Those B-cells then become Memory B-Cells. They
can react to the same pathogen faster, the next time it invades. Memory B-cells already
have the proper antibodies stored up for that pathogen.
Summary
 A pathogen somehow gets past the body's physical and chemical barriers and the
inflammation response.
 The pathogen is engulfed by a macrophage (or neutrophil).
 The macrophage releases the contents of its lysosomes onto the bacterium and
dissolves most of it. There are still some pieces of the bacterium’s cell membrane
left. The macrophage then forces the surface proteins of the bacterium (antigens)
to it's own cell surface.
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 Helper T-Cells touch these surface antigens, make a copy of their shape, and
present them to B-cells to make antibodies against them.
 These Helper T-Cells begin to multiply and have two main roles.
 The first is to activate B-Cells and "tell" them how to neutralize the pathogen by
presenting the pieces of the bacterium cell membrane so the B-cells can make
antibodies.
 The B-Cells (now called Plasma cells because they have been activated)
begin to multiply and produce the antibodies to neutralize this specific
pathogen.
 The second role of Helper T-Cells is to activate the Killer T-Cells.
 Killer T-Cells can either destroy the pathogen itself (bacteria), or destroy the
entire body cell which is infected (viruses).
 When the immune response is over, Suppressor T-Cells stop the process and also
"tell" some B-Cells to "remember" how to destroy that specific pathogen. Those
B-cells now become Memory B-Cells.
DISORDERS OF WBCs
 LEUKEMIA: Cancer of the blood is called leukemia. It actually only involves
the white blood cells. Something goes wrong in one stem cell, and it starts making
huge amounts of clones of itself which don’t work right and not enough normal
white blood cells are made. Therefore, the body cannot fight infection. It’s better
to send a young cell with no weapons to the war than to send nothing at all!
There are many types of leukemias.
Think of Leukemia as too few mature white blood cells.
– Classified as lymphoblastic (too many immature lymphocytes) or
– myeloblastic (too many immature neutrophils)
 People with severe leukemia may need a bone marrow transplant.
 First, all of their WBC’s have to be killed off with a medicine because they are
mostly malfunctioning anyway.
 A donor has a small cylinder of bone removed from their hip. This is ground up
and given by i.v. to the recipient.
 The new WBC’s may kill the patient or it may save their life. It is done as a last
resort.
WBC Count
 White blood cell (WBC) count is a count of the actual number of white blood
cells per volume of blood. Both increases and decreases can be significant.
 White blood cell differential looks at the types of white blood cells present. There
are five different types of white blood cells, each with its own function in
protecting us from infection. The differential classifies a person's white blood
cells into each type: neutrophils (also known as segs, PMNs, granulocytes, grans),
lymphocytes, monocytes, eosinophils, and basophils.
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Terms
 Excess neutrophils: neutrophilia
 Few neutrophils: neutropenia
Antibodies
 Antibodies (also known as immunoglobulins, abbreviated Ig) are proteins made
by plasma cells.
 They are used to identify and neutralize foreign objects, such as bacteria and
viruses.
 They are typically made of basic structural units—each with two large heavy
chains and two small light chains—to form a unit shaped like the letter “Y”
 The tips of the “Y” have receptors that are specific for a particular antigen.
 The stem of the “Y” can be grasped by a phagocyte.
 The small region at the tip of the protein is extremely variable, allowing millions
of antibodies with slightly different tip structures, or antigen binding sites, to
exist.
 This region is known as the hypervariable region. Each of these variants can bind
to a different target, known as an antigen.
 This huge diversity of antibodies allows the immune system to recognize an
equally wide diversity of antigens.
 IMMUNITY: B Cells that have matured into plasma cells which have made
antibodies are now called Memory lymphocytes, after their first war.
Most people are sick more often as children than as adults in their 20s through 30s
because we build up many varieties of MEMORY LYMPHOCYTES during childhood,
providing immunity from more and more antigens during adulthood.
PLATELETS (very small compared to all other blood cells). These are pieces of
another cell found in the red marrow called a MEGAKARYOCYTE. Pieces break off
of a megakaryocte and are known as platelets. When a platelet encounters a broken
blood vessel it releases a substance that clots blood. Platelets are responsible for clot
formation. Cell fragments break off from megakaryocytes. Platelets need certain proteins
in the plasma called CLOTTING FACTORS in order for them to become activated and
form a clot. The main clotting factor is called FIBRIN.
VITAMIN K
 Found in green, leafy vegetables
 Needed for blood clotting factors.
 Some types of rat poisons work by eliminating the blood clotting ability.
 In case of accidental ingestion of rat poison, a child needs an I.V. of vitamin K.
 It works for accidental poisoning in dogs, too!
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Aspirin
 One baby aspirin a day can help prevent blood clots.
 It blocks the ability of an enzyme called COX (cyclo-oxidase) to make a
substance called prostaglandin.
 Prostaglandins are needed for inflammatory reactions. COX inhibitors, such as
aspirin, block the inflammatory process, so any pain caused by inflammation
would diminish.
 However, they also INCREASE blood clotting time.
DISORDERS OF PLATELETS
 THROMBOCYTOPHILIA: Excess platelets
 THROMBOCYTOPENIA: Too few platelets
 HEMOPHILIA is a hereditary disease of males, where they are unable to clot
properly because they are missing some clotting factors. When they get even a
slight bump or bruise they have to have an intravenous infusion of clotting factors
or they will bleed to death. This is probably the disease that was in the genes of
Henry VIII, which caused all of his male children to become weak and die in
infancy.
A thrombus is a blood clot in a vessel.
An embolism is a thrombus that broke away and travels in the blood stream. It usually
lodges in a smaller blood vessel and blocks circulation distal to that point.
Prothrombin Time (PT) and Partial Thromboplastin Time (PTT)
 The PTT test is used to investigate unexplained bleeding or clotting. It may be
ordered along with a PT (Prothrombin Time) test to evaluate hemostasis (the
process of clot formation). The PTT evaluates the coagulation factors XII, XI, IX,
VIII, X, V, II (prothrombin), and I (fibrinogen). A PT test evaluates the
coagulation factors VII, X, V, II, and I (fibrinogen). By evaluating the results of
the two tests together, a doctor can gain clues as to what bleeding or clotting
disorder may be present.
 These tests are used to monitor heparin anticoagulant therapy. Heparin is a drug
that is given intravenously (IV) or by injection to prevent and to treat blood clots.
IV’s are also flushed with heparin to prevent clot formation. When it is
administered for therapeutic purposes, it must be closely monitored. If too much
is given, the treated person may bleed excessively; with too little, the treated
person may continue to clot.
Complete Blood Count (CBC)
 The complete blood count or CBC test is used as a broad screening test to check
for such disorders as anemia, infection, and many other diseases. It is actually a
panel of tests that examines different parts of the blood and includes the
following:
 White blood cell (WBC) count
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White blood cell differential
Red blood cell (RBC) count
Hemoglobin
Hematocrit
platelet count , PT, PTT
Mean corpuscular volume (MCV)
Mean corpuscular hemoglobin (MCH)
Mean corpuscular hemoglobin concentration (MCHC)
Red cell distribution width (RDW)
Life span, from longest-lived to shortest-lived: lymphocytes, erythrocytes, platelets,
neutrophils.
Septicemia
 Septicemia (aka bacteremia) is the condition when bacteria invade the body and
circulate in the blood.
 Bacteria can enter the bloodstream as a severe complication of infections (like
pneumonia or meningitis), during surgery (especially when involving mucous
membranes such as the gastrointestinal tract), or due to catheters and other foreign
bodies entering the arteries or veins (including intravenous drug abuse).
 Bacteremia can have several consequences. The immune response to the bacteria
can cause sepsis and septic shock, which has a relatively high mortality rate (kills
1 person in 5). Bacteria can also use the blood to spread to other parts of the body
(which is called hematogenous spread), causing infections away from the original
site of infection. Examples include endocarditis or osteomyelitis.
 Treatment is with antibiotics, and prevention with antibiotic prophylaxis can be
given in situations where problems are to be expected.
HEMATOPOIESIS: The making of blood.
The plasma proteins are made in the liver.
The blood cells are made in the red bone marrow.
RED BONE MARROW
Most blood cells mature in the red bone marrow. When they are mature, they are
released into the bloodstream. When they are old, they are destroyed in the spleen and
liver.
Cell Lines in Blood Cell Formation
 All blood cells originate in bone marrow
 All originate from one cell type – blood stem cell
– Erythroblasts – give rise to red blood cells
– Lymphoblasts – give rise to lymphocytes
– Myeloblasts – give rise to all other white blood cells
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1. ERYTHROBLASTS, which mature into RETICULOCYTES, a RBC with bits
of nucleus material,which later resolves to make more room for hgb. It is now
called an ERYTHROCYTES. If the body makes too few erythrocytes it can lead
to one form of ANEMIA.
2. LYMPHOBLASTS give rise to lymphocytes
3. MYELOBLASTS: These are the stem cells that mature into the specific leukocytes:
Neutrophil, macrophage, eosinophil, basophil, platelets. Leukemia is cancer of the
stem cells. See all these different types of stem cells? That’s about how many types
of leukemia there are.
IMMUNE SYSTEM
INFLAMMATORY REACTION: When you get stuck by a thorn or inhale a cold
virus, the body goes through a series of events called an inflammatory reaction.
Four outward signs:
1. Redness
2. Heat
3. Swelling
4. Pain
Redness is caused from the blood vessels dilating to allow more blood flow to the area.
Within the blood are platelets to clot the blood, proteins to repair the damage, and
macrophages, which are white blood cells that eat up the foreign body, bacteria, or the
dead cells.
Heat is caused because of the extra amount of warm blood flow to the area.
Swelling is caused from the plasma that leaks out of the swollen blood vessels.
Pain is caused from the pressure of the extra fluid pressing on nerves in the area.
ADAPTIVE IMMUNITY
 Two types of Adaptive Immunity
– ACTIVE immunity
 Naturally Acquired
 Artificially Acquired
– PASSIVE immunity
 Naturally Acquired
 Artificially Acquired
ACTIVE IMMUNITY
 Naturally Acquired
– The body is naturally exposed to an infectious agent and launches an
immune reaction
 Artificially Acquired
– The person is injected with a weakened (attenuated) or killed organism, as
found in a vaccination
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Naturally acquired active immunity
This is when the body is exposed to an infectious agent and produces antibodies which
specifically attack that infectious agent so the person never gets that disease again. The
plasma cells secrete these antibodies which will continue to circulate sometimes for
years, ready to attack that type of bacteria and cause them to pop like a balloon before the
body can become sick.
– You catch a cold and eventually get better. You can never get the same cold virus
twice because you will have become immune to it. Your next cold is from a different
virus. There are hundreds of thousands of cold viruses; that’s why there is no cure
for the common cold.
– Another example is when an unvaccinated child is exposed to the measles at school
and gets the disease, but never gets the disease again.
However, there are some diseases that you don’t want to get, even once, such as polio,
diphtheria, tetanus, and influenza, because the first exposure could kill or disable you.
For these diseases, we have vaccines which are made of those organisms which have
been altered (attenuated) so that the body recognizes them as foreign, but they can’t cause
disease. That way, if the person is exposed to the real organism later, the antibodies are
already there to kill it off without the body getting sick.
Artificially acquired active immunity
– An example is when a child is vaccinated against measles as a baby, so when
he gets to school and is exposed to the disease, he doesn’t get sick.
PASSIVE IMMUNITY
 Naturally Acquired
– Example is the passing of antibodies from mother to infant in breast milk
 Artificially Acquired
– Example is when a person receives an infusion of antibodies from
someone else.
ALLERGIES are from a hypersensitivity to substances such as pollen or animal hair that
would not ordinarily cause a reaction. There are two types of allergic responses:
1. Immediate allergic response occurs within seconds of contact with the thing
causing the allergy. This is the case with anaphylactic allergies, where someone
who is allergic to seafood or peanuts can actually die within minutes because the
allergic reaction is so severe the throat swells shut and they can’t breathe . They
need an injection immediately of something that will stop the reaction.
2. Delayed allergic response is when the body’s first exposure to the substance will
not cause a reaction, but all exposures afterward will trigger the response. An
example is poison ivy. You won’t itch the first time you touch it.
AUTOIMMUNE DISEASE is a hereditary problem where the body thinks its own
tissues are foreign bodies, and it constantly tries to kill off its own tissues.
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