Download Chapter 19

Cardiovascular System: Blood
19-1
Plasma
• Liquid part of blood.
– Colloid: liquid containing suspended substances that
don’t settle out of solution
– 91% water. Remainder proteins, ions, nutrients,
waste products, gases, regulatory substances
• Proteins:
– Albumins: viscosity, osmotic pressure, buffer,
transports fatty acids, free bilirubin, thyroid
hormones
– Globulins: transports lipids, carbohydrates,
hormones, ions, antibodies, and complement
– Fibrinogen: blood clotting
19-2
Plasma, cont.
• Ions: involved in osmosis, membrane potentials,
and acid-base balance
• Nutrients: glucose, amino acids, triacylglycerol,
cholesterol, vitamins
• Waste Products:
– Urea, uric acid, creatinine, ammonia salts.
Breakdown products of protein metabolism
– Bilirubin. Breakdown product of RBCs
– Lactic acid. End product of anaerobic
respiration
• Gases: oxygen, carbon dioxide, and inert nitrogen
• Regulatory substances: hormones, enzymes
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Formed Elements
• Red blood cells (erythrocytes). Biconcave discs,
anucleate, contain hemoglobin; transports oxygen
and carbon dioxide.
• White blood cells (leukocytes)
– Granulocytes: cytoplasm contains large
granules; have multi-lobed nuclei. Three
distinctive types: neutrophils, eosinophils,
basophils
– Agranulocytes: cytoplasm contains small
granules and nuclei that are not lobed. Two
distinctive types: lymphocytes and monocytes
• Platelets (thrombocytes). Cell fragment. Form
platelet plugs, release chemicals necessary for
blood clotting.
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19-5
Hematopoiesis
19-6
Red Blood Cells
• Found in higher
concentration in
male than in female
plasma
• Components
– 1/3 Hemoglobin
– 2/3 Lipids, ATP,
carbonic anhydrase
19-7
Hemoglobin
19-8
Hemoglobin Composition
• Four globin molecules (polypeptide chains):
Transport carbon dioxide (carbonic anhydrase
involved), nitric oxide. NO brought from lungs to
tissues, induces smooth muscles to relax, lowering
BP.
• Four heme molecules, each containing one iron
atom: transport oxygen
• Iron required for oxygen transport. Iron absorbed
in upper small intestine; absorption increased by
stomach acid and vitamin C. Iron lost in urine,
feces, menstrual fluid.
19-9
Erythropoiesis
• RBCs last 120 days in circulation (enucleated)
• Production of red blood cells
– Stem cells → proerythroblasts → early erythroblasts →
intermediate erythroblasts → late erythroblasts → reticulocytes
• Erythropoietin: hormone stimulates RBC production;
produced by kidneys in response to low blood O2 levels.
19-10
Hemoglobin Breakdown
19-11
White Blood Cells
• Protect body against microorganisms and remove
dead cells and debris
• Movements
– Ameboid: pseudopods
– Diapedesis: cells become thin, elongate and move
either between or through endothelial cells of
capillaries
– Chemotaxis: attraction to and movement toward
foreign materials or damaged cells. Accumulation of
dead white cells and bacteria is pus.
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• Neutrophils: after leaving bone
marrow, stay in circulation 10-12
hours then move into other
tissues. Become motile,
phagocytize bacteria, antigenantibody complexes and other
foreign matter. Secrete lysozyme.
Last 1-2 days. Account for 6070% of the WBC.
• Eosinophils. Leave circulation
and enter tissues during
inflammatory response. Prevalent
in allergic reactions. Destroy
inflammatory chemicals like
histamine. Release chemicals that
help destroy tapeworms, flukes,
pinworms, and hookworms.
Account for 2-4% of the WBC.
19-13
•Basophils: least common. Leave circulation and
migrate through tissues, play a role in both
inflammatory response and allergic reactions.
Produce histamine and heparin. Account for less
than 1% of the WBC.
•Lymphocytes: produced in red bone marrow but
then migrate to lymphatic tissues and proliferate.
Responsible for antibody production. Studied
extensively with the immune system. Account for
20-25% of the WBC.
•Monocytes: remain in circulation for 3 days, leave
circulation and become macrophages. Phagocytic
cells. Can break down antigens and present them to
lymphocytes for recognition. Account for 3-8% of
the WBC.
19-14
Platelets
• Cell fragments pinched off
from megakaryocytes in
red bone marrow
• Important in preventing
blood loss
– Platelet plugs
– Promoting formation and
contraction of clots
19-15
Hemostasis
• Arrest of bleeding
• Events preventing excessive blood loss
– Vascular spasm: Vasoconstriction of damaged
blood vessels. Can occlude small vessels.
Caused by thromboxanes from platelets and
endothelin from damaged endothelial cells.
– Platelet plug formation
– Coagulation or blood clotting
19-16
Platelet Plug Formation
1.
2.
3.
4.
Platelet adhesion. Occurs
when von Willebrand factor
connects collagen and
platelets.
Platelet release reaction.
The release of ADP,
thromboxanes, and other
chemicals that activate other
platelets. They in turn
undergo the release reaction:
cascade effect.
Platelet aggregation.
Activated platelets express
surface receptors that bind
fibrinogen (protein found in
plasma). Fibrinogen forms a
bridge between platelets:
platelet plug.
Expression of coagulation
factor V and phospholipids.
Important for coagulation
19-17
Coagulation
• Stages
– Activation of prothrombinase
– Conversion of prothrombin to
thrombin
– Conversion of fibrinogen to
fibrin
• Coagulation factors.
– Proteins found in plasma.
– Circulate in inactive state until
tissues are injured.
– Damaged tissues and platelets
produce chemicals that begin
activation of the factors.
• Pathways
– Extrinsic
– Intrinsic
• Result: blood clot. A network of
threadlike fibrin fibers, trapped
blood cells, platelets and fluid
19-18
Blood Grouping
• Transfusion: transfer of blood or blood
components from one individual to another
• Infusion: introduction of fluid other than
blood
• Determined by antigens (agglutinogens) on
surface of RBCs
• Antibodies (agglutinins) can bind to RBC
antigens, resulting in agglutination
(clumping) or hemolysis (rupture) of RBCs
• Groups: ABO and Rh
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ABO Blood Groups
19-20
Agglutination Reaction
19-21
Transfusion
• Type A blood has anti-B antibodies; Type B blood
has anti-A antibodies
• Suggested that these antibodies are present
because of exposure to A and B antigens on
bacteria and food
• Donor: gives blood. Recipient: receives blood
• Type O as “universal donor”. Can actually cause
transfusion reactions because of antibodies in O
blood plasma
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Rh Blood Group
• First studied in rhesus monkeys
• Types
– Rh positive: Have these antigens present on surface of RBCs
– Rh negative: Do not have these antigens present
• Hemolytic disease of the newborn (HDN)
– Rh positive fetus, Rh negative mother.
– Late in pregnancy, Rh antigens of fetus cross placenta (through a
tear in placenta or during delivery); mother creates antiRh
antibodies (primary response)
– Second Rh positive pregnancy might initiate secondary response
and HDN (potentially fatal to fetus since antibodies to its RBCs
would cross the placenta from the mother to the fetus, destroying
fetal RBCs).
– Injection of RhoGAM. Contains antibodies against Rh antigens.
Antibodies attach to any fetal RBCs and they are destroyed.
19-23
Erythroblastosis Fetalis
19-24
Diagnostic Blood Tests
• Type and Crossmatch: determination of ABO
and Rh blood types. Red cells tested against
antibodies
• Complete Blood Count
– Red Blood Count: number of RBCs/ microliter of
blood
– Hemoglobin Measurement: grams of hemoglobin/100
mL of blood. For a male, 14-18, female 12-16 g/100
mL
– Hematocrit Measurement: percent of blood that is
RBCs
– White Blood Cell Count: 5,000-10,000 /microliter of
blood
19-25
Hematocrit
19-26
• Differential White Blood Count: determines
percentage of each of the five types of WBC
–
–
–
–
–
Neutrophils: 60-70%
Lymphocytes: 20-30%
Monocytes: 2-8%
Eosinophils: 1-4%
Basophils: 0.5-1%
• Clotting
– Platelet Count: 250,000- 400,000/microliter
– Prothrombin Time Measurement: measures how long
it takes for blood to start clotting. 9-12 seconds. To test,
thromboplastin is added to whole plasma
• Blood Chemistry: composition of materials
dissolved or suspended in the plasma. Used to
assess functioning of many body systems
19-27