Transcript Chapter-6-lecture

Chapter 6
Cardiovascular
System: Blood
Points to Ponder
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What type of tissue is blood and what are its components?
What is found in plasma?
Name the 3 formed elements in blood and their functions.
How does the structure of red blood cells relate to their
function?
Describe the structure and function of each white blood cell.
What are disorders of red blood cells, white blood cells and
platelets?
What do you need to know before donating blood?
What are antigens, antibodies and blood transfusions?
How are ABO blood types determined?
What blood types are compatible for blood transfusions?
What is the Rh factor and how is this important to pregnancy?
How does the cardiovascular system interact with other
systems to maintain homeostasis?
6.1 Blood: An overview
Functions of Blood
1.
Transportation:
- Oxygen (from lungs), nutrients (from digestion), wastes
(from tissue fluid), carbon dioxide (from tissue fluid) and
hormones (influence cellular metabolism)
2. Defense:
- against invasion by pathogens
- Some cells phagocytize and destroy pathogens
- Others secrete antibodies into the blood
- Antibodies incapacitate pathogens so they can be
destroyed
3. Regulatory functions:
- body temperature  pick up heat from active muscle and
transport around or out of the body
- water-salt balance and body pH (blood contains buffers)
6.1 Blood: An overview
Composition of Blood
• Remember: blood is a fluid connective tissue
• Formed elements: Cells and cell fragments
– produced in red bone marrow via stem cell differentiation
– Cells and cell fragments:
• Red blood cells/erythrocytes (RBC)
• White blood cells/leukocytes (WBC)
• Platelets
• Plasma: liquid medium
– suspends the formed elements, carries substances,
distributes the heat generated by metabolism and muscle
contractions
– 91% water and 9% salts and organic molecules
• Salts act as buffer to help maintain the pH of the blood
• Organic molecules = glucose and amino acids for the cells
– Plasma proteins are the most abundant molecules
6.1 Blood: An overview
3 major types of plasma proteins
• Produced by the Liver
• Functions
1. Maintain homeostasis
• take up and release hydrogen ions
2. Establish osmotic pressure between blood and tissue fluid
• Force that prevents excessive loss of plasma from the capillaries
into tissue fluid
• Albumins – most abundant
• Function: plasma’s osmotic pressure and transportation
• Globulins –
• Function: transportation of hormones, cholesterol, and iron
• Fibrinogen –
• Function: formation of blood clots
6.1 Blood: An overview
Formed Elements
6.2 Blood: Red blood cells and transport of oxygen
Structure and Function of Red Blood Cells
• Lack a nucleus  Biconcave shape increases surface area
• Lack most organelles  including mitochondria
– ATP produced anaerobically so they don’t consume any oxygen that
they transport
• Contain about 280 million hemoglobin molecules that bind 4
molecules of O2 each
– Globin: 4 tertiary polypeptides
– Heme: iron-containing group Iron combines reversible with oxygen
6.2 Blood: Red blood cells and transport of oxygen
How is carbon dioxide transported?
• 68% as bicarbonate ions in the plasma
– this conversion of CO2 takes place in RBC’s by carbonic
anhydrase
– H+ binds to amino acids of the globin to assist in keeping
the pH of the blood constant
– At lungs carbonic anhydrase in RBCs reverse this reaction
to expel CO2 from the blood
• 25% bound to hemoglobin in red blood cells
• 7% as carbon dioxide dissolved in the plasma
Production of red blood cells
• Produced in red bone
marrow
• Lifespan = 120 days
• Erythropoietin (EPO)
– Excreted by kidney cells
– Moves to red marrow when
oxygen levels are low
– Stimulates the stem cells to
produce more RBCs
• Old cells are destroyed by
the liver and spleen
– Hemoglobin
• Globin: broken down into
amino acids and recycled
• Iron is recovered and
reused
• Heme undergoes chemical
degradation and is excreted
6.2 Blood: Red blood cells and transport of oxygen
What is blood doping?
• Any method of increasing the number of RBC’s
to increase athletic performance
• It allows more efficient delivery of oxygen and
reducing fatigue
• EPO is injected into a person months prior to an
athletic event
• Is thought to be able to cause death due to
thickening of blood that leads to a heart attack
6.2 Blood: Red blood cells and transport of oxygen
What disorders involve RBC’s?
• Anemia –
– a condition resulting from too few RBC’s or hemoglobin
that causes a run-down feeling
– Maybe due to decrease levels of iron, vitamins B12 and
B vitamin folic acid
• Sickle-cell anemia –
– genetic disease that causes RBC’s to be sickle shaped
– tend to rupture as they pass through the narrow
capillaries
• Hemolytic disease of the newborn –
– condition with incompatible blood types
– leads to rupturing of blood cells in a baby before and
continuing after birth
6.3 White blood cells and defense against disease
White blood cells (leukocytes)
• Derived from red bone marrow
• Large blood cells that have a nucleus
• Production is regulated by colony-stimulating factor
(CSF)
• Can be found in the blood and tissues
• Fight infection and part of immune system
– Phagocytosis:
• engulf pathogen and fuses with lysosome where enzymes digest
the pathogen to debris that leaves the cell
– Antibodies:
• proteins that combine with antigens and mark them for destruction
• Some live days and others live months or years
6.3 White blood cells and defense against disease
Movement of WBC’s out of
circulation
6.3 White blood cells and defense against disease
How are white blood cells
categorized?
• Granular – contain noticeable granules,
lobed nuclei
– Eosinophil
– Basophil
– Neutrophil
• Agranular – no granules, nonlobed nuclei
– Lymphocyte
– Monocyte
6.3 White blood cells and defense against disease
Neutrophils
• About 50-70% of all
WBC’s
• Contain a multi-lobed
nucleus
• Upon infection they
move out of circulation
into tissues to use
phagocytosis to engulf
pathogens
• Large numbers result
in pus
6.3 White blood cells and defense against disease
Eosinophils
• Small percentage of
WBC’s
• Contain a bilobed
nucleus
• Many large granules
function in parasitic
infections and play a
role in allergies
6.3 White blood cells and defense against disease
Basophil
• Small percentage of
WBC’s
• Contain a U-shaped or
lobed nucleus
• Release histamine
related to allergic
reactions
– Dilate blood vessels and
constricts the air tubes
that lead to lungs
6.3 White blood cells and defense against disease
Lymphocyte
• About 25-35% of all
WBC’s
• Large nucleus that takes
up most of the cytoplasm
• Develop into B and T
cells that are important
in the immune system
– B-cells protect us by
producing antibodies that
mark pathogens for
destruction
– T-cells directly destroy
pathogens
6.3 White blood cells and defense against disease
Monocyte
• Relatively uncommon
WBC’s
• Largest WBC with
horseshoe-shaped
nucleus
• Take residence in
tissues and develop
into macrophages
• Macrophages use
phagocytosis to
engulf pathogens
6.3 White blood cells and defense against disease
How do blood cell leave circulation?
6.3 White blood cells and defense against disease
What disorders involve WBC’s?
• Severe combined immunodeficiency disease (SCID)
– an inherited disease in which stem cells of WBC’s lack an
enzyme that allows them to fight any infection
• Leukemia
– a groups of cancers that affect white blood cells in which
cells proliferate without control
• Infectious mononucleosis
– also known as the “kissing disease” occurs when the
Epstein-Barr virus (EBV) infects lymphocytes resulting in
fatigue, sore throat and swollen lymph nodes
6.4 Platelets and blood clotting
Platelets (thrombocytes)
• Made of fragments of large cells called
megakaryocytes made in the red bone marrow
• About 200 billion are made per day
• Function in blood clotting
– Blood proteins thrombin and fibrinogen (produced in the
liver) are important for blood clotting by leading to fibrin
threads that catch RBC’s
• Thrombin: acts as an enzyme that severs two short amino acid
chains from each fibrinogen molecule
• Activated fragments join end to end, forming long threads of fibrin
• Fibrin threads wind around the platelets plug and provide framework
for the clot
• Plasmin enzyme: destroy fibrin network and restores
the fluidity of plasma after repair is complete
6.4 Platelets and blood clotting
6.4 Platelets and blood clotting
What disorders involve platelets?
• Thrombocytopenia –
– a disorder in which the number of platelets is too low due
to not enough being made in the bone marrow or the
increased breakdown outside the marrow
• Thromboembolism –
– when a clot forms and breaks off from its site of origin
and plugs another vessel
• Hemophilia –
– a genetic disorder that results in a deficiency of a clotting
factor so that when a person damages a blood vessel
they are unable to properly clot their blood both internally
and externally
6.4 Platelets and blood clotting
Health Focus: What do you need to
know about donating blood?
• Donating blood is a safe and sterile procedure
• You will donate about a pint of blood
• You will replace the plasma in a few hours and the cells in a
few weeks
• A few people may feel dizzy afterwards so sit down, eat a
snack and drink some water
• Your blood will at least be tested for syphilis, HIV antibodies
and hepatitis and if any of them come back positive you will
be notified
• Your blood can help save many lives
• You should not give blood if:
– You have ever had hepatitis, malaria or been treated for syphilis or
gonorrhea within 12 months
– If you risk for having HIV or have AIDS
6.5 Blood typing and transfusions
Terminology for ABO blood typing
• Antigen - a foreign substance, often a
polysaccharide or a protein, that stimulates an
immune response
• Antibody – proteins made in response to an
antigen in the body and bind to that antigen
• Blood transfusion – transfer of blood from one
individual into another individual
• Involves determining the
– ABO blood group
– Rh- or Rh+
6.5 Blood typing and transfusions
The A, B, AB or O blood type
• Presence and/or absence of 2 blood antigens, A
and B
• Type of antibodies present
• Antibodies are only present for those antigen
lacking on the cells because these proteins
recognize and bind the protein they are named after
6.5 Blood typing and transfusions
How can you remember what each
blood type means?
• Blood types are named after the protein antigens that
are present on the surface of their cell, except type O
that entirely lacks A and B proteins
• Blood types only have antibodies to antigens they do not
have on the surface of their cells
• For example: Type A blood
– Have A proteins on its surface
– Has B antibodies
• What can you say about someone with type AB blood?
6.5 Blood typing and transfusions
6.5 Blood typing and transfusions
How can you determine if blood types
are compatible for a blood transfusion?
1. Consider the antigens found on the blood
transfusion recipient
2. Consider the antibodies found in the donor blood
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If the antibodies in the donor blood can recognize
the antigen on the recipient’s blood then the blood
will agglutinate (clump) and cause rejection
6.5 Blood typing and transfusions
Testing your understanding
• Can a person with blood type O accept blood
type A without agglutination occurring? Why or
why not?
• Why can people with AB blood type accept
more blood types than people with type O, A or
B?
• Which blood type is able to be used most often
as a donor blood type? Why?
6.5 Blood typing and transfusions
What about Rh blood groups?
• The Rh factor is often included when
expressing a blood type by naming it positive
or negative
• People with the Rh factor are positive and
those without it are negative
• Rh antibodies only develop in a person when
they are exposed to the Rh factor from
another’s blood (usually a fetus)
6.5 Blood typing and transfusions
When is the Rh factor important?
• During pregnancy under these conditions:
– Mom: Rh– Dad: Rh+
– Fetus: Rh+ (possible with the parents above)
• In this case above some Rh+ blood can leak from the fetus to
the mother during birth causing the mother to make Rh
antibodies
• This can be a problem if the mother has a second fetus that
is Rh+ because she now has antibodies that can leak across
the placenta and attack the fetus
• This condition is known as hemolytic disease of the newborn
that can lead to retardation and even death
6.5 Blood typing and transfusions
Visualizing how hemolytic disease of
the newborn happens?
6.5 Blood typing and transfusions
How can hemolytic disease of the
newborn be prevented?
• Rh- women are given an injection of anti-Rh
antibodies no later than 72 hours after birth to an
Rh+ baby
• These antibodies attack fetal red blood cells in
the mother before the mother’s immune system
can make antibodies
• This will have to be repeated if an Rh- mother has
another Rh+ baby in case she has later
pregnancies
Heart, blood vessels and blood work with other
systems to maintain homeostasis