Chapter 18

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Chapter 18
Cardiovascular
System: Blood
Blood functions
• Transportation: circulates its components
throughout the body (systemic and lungs) for
cellular exchange (gases, nutrients, wastes)
• Regulation: body temperature (98.6F) ,
pH(*7.3-7.4), fluid balance (colloid osmotic
pressure)
• Protection: immune components, platelets,
plasma proteins
*Bicarb (HCO3-) ion in blood, respiratory
and urinary systems assist
Blood Components 1
• Plasma – 55% of whole blood
92% Water, 7% plasma proteins;
and 1% dissolved solutes (electrolytes,
nutrients, wastes, gases)
• plasma proteins: 58% albumin, 37% α, β and γ
globulins; 4% fibrinogen and 1% regulatory
proteins
electrolytes: cations (Na+, K+, Ca2+, H+); anions
(Cl-, OH-, HCO3-, HPO42-)
Nutrients: Glucose, amino acids, lipids, lactic
acid
Wastes, gases: urea, ammonia, lactic acid, etc.
Blood Components 2
• Formed elements – 45% of whole blood
RBC: Erythrocytes - no nuclei, no organelles;
filled with hemogloblin (O2 carrying capacity)
Hematocrit: 38% - 56% (females-males)
most numerous of formed elements: 4x106/ml6x106/ml
*WBC: Leukocytes – immune cells; 4.5x103/ml11x103/ml; granulocytes, monocytes &
lymphocytes
Platelets: cellular particles formed from megakaryocytes; blood clotting functions.
• Most WBC’s are in the tissues not the blood.
Fig. 18.1
Blood Components 3
• Formed elements:
RBC’s – erythrocytes (nonnucleated) 44%;
biconcave disc shape; rouleau formation
Hemoglobin (HGb) - red pigmented protein: two
alpha (α) chains and two beta (β) chains: globins
Each chain contains a porphyrin ring (lipid heme)
with an Fe2+ molecule at its center.
Each Fe2+ weakly binds an O2 molecule.
CO2 binds to the globin molecules (not to heme)
Fig. 18.5
Erythrocytes
Hemoglobin
Blood Components 4
• Formed elements
RBC production is controlled by EPO
(erythropoietin), a hormone produced by the
kidney.
The kidney detect low O2 levels in the blood &
release EPO stimulating bone marrow
production of RBC’s.
Negative feedback mechanism: stimulus,
receptor (kidney), control center (kidney), effector
(red bone marrow), controls production of
erythrocytes.
Fig. 18.7
Plasma 1
• Plasma is a colloid with dispersed plasma
proteins, and dissolved electrolytes, gases,
nutrients, waste products.
Serum is the solution portion of whole blood
without the clotting proteins.
• Plasma proteins
Albumin – smallest & most numerous;
most significant in exerting osmotic pressure
in maintaining blood volume.
Carrier protein for transport of hormones,
lipids, medications
Plasma 2
• Plasma proteins
Globulins – globular proteins are the second
most abundant; various size and forms:
alpha (α) and beta (β) forms are carriers of ions,
metals and hormones. β is larger than α.
gamma (γ) globulins are the immune system’s
humoral defense known also as antibodies or
immunoglobulins.
Fibrinogen – much less abundant than the
previous listed plasma proteins; instrumental in blot
clot formation (with other less abundant clotting
factors).
Plasma 3
• Plasma proteins
Regulatory proteins – least numerous; enzymes,
hormones
• Electrolytes
Cations and anions are instrumental in
maintaining fluid balance between the tissues: cells
and interstitial fluids, and blood volume.
They actively regulate the function of nervous
and muscular tissues.
• Nutrients & wastes: nutrients absorbed by the
body are used for building & repair; wastes are
removed from the body. Both are transported by
the blood.
Hemopoiesis 1
• Hemocytoblast (red bone marrow):
stem cell – produces all blood cell types
(pluripotent)
1) myeloid line stimulated by multi-CSF (colony
stimulation factors) growth factors:
Megakaryocytes (platelets) : (Thrombopoietin)
Erythrocytes (RBC’s): (*EPO, a hormone)
Leukocytes (granulocytes, monocytes): GM-CSF
(progenitor cell) , G-CSF (myeloblast), M-CSF
(monoblast)
*Blood O2 levels stimulate the kidneys to
release erythropoietin; negative feedback control.
Hemocytoblast
Hemopoiesis 2
• Hemocytoblast (bone marrow):
2) lymphoid line: directly from stem
cell (hemocytoblast) to lymphoid stem cell
which generate: B-lymphoblast, T-lymphoblast and
NK (Natural Killer) cell.
• Erythropoeisis, recycling & destruction: atmospheric
O2 levels help determine O2 blood levels by EPO
stimulation regulated by neg. feedback loop.
Lifespan of RBC ~120 days.
Components – heme, iron and globulins
metabolized and recycled or eliminated as wastes.
Erythrocyte Formation (Erythropoiesis)
Granulocytes & Agranulocytes
Hemopoiesis 3
• Erythropoeisis, recycling & destruction:
Iron – minor losses in wastes, it is stored in the
liver by ferritin and hemosiderin.
Heme – converted to biliverdin then to bilirubin
by macrophages; transported to liver & excreted in
bile, converted to urobilinogen in small intestines.
Most is converted to stercobilin in large intestines
(giving feces its characteristic color). Some is
reabsorbed & converted to urobilin and excreted by
the kidneys (giving urine its characteristic color).
Globins – broken down to amino acids and
recycled.
Disorders of erythrocytes
• Anemias: several types with diminished O2
carrying capacity of RBC/ # of RBC’s.
Aplastic a.: defective formation of RBC’s & HGb
Pernicious a.: Intrinsic factor defect = Vit B12
deficiency.
Sickle cell a.: autosomal recessive; misshapen
cells @ low O2 tension, leads to hemolysis.
• Polycythemia: various types; increased viscosity of
blood due to an increased hematocrit.
Disorders of leukocytes 1
• Leukopenia
decreased number of WBC’s per unit of blood.
Increases the risk of infection;
decreases ability to fight an infection
indicative of a pathological condition
• Leukocytosis
elevated number of WBC’s per unit of blood
indicative of recent infection or stress
• Differential count: the number of each type of WBC
per unit of blood; the normal count of various types
changes with the various causes of pathology.
Disorders of leukocytes 2
• Differential count
all values are in units: “x103/µl blood”
WBC count norm: 4.5 - 11
neutrophils: 1.8 – 7.8
lymphocytes: 1 – 4.8
monocytes: 0.1 – 0.7
eosinophils: 0.1 – 0.4
basophils: 0.02 – 0.05
Acute ailments usually cause an increase in
neutrophils (neutrophilia) with an increase of
immature neutrophils (bands) in circulation (left
shifted differential).
A decrease in neutrophils (neutropenia) may be
due to anemia, cancer therapy, etc.
Disorders of leukocytes 3
• Differential count
Lymphocytosis is an increase in lymphocyte
count usually due to viral infections, chronic
bacterial infections, multiple myeloma and some
types of leukemias.
Lymphocytopenia is a decrease in lymphocyte
count below normal range. This may be due to HIV,
other types of leukemias, or sepsis.
Eosinophilia (increase in # of eosinophils) is seen
in allergic reactions, parasite infection, autoimmune
disorders.
Disorders of leukocytes 4
• Differential count
Monocyte #’s increase with chronic
inflammatory conditions and Tuberculosis infection.
They decrease with chronic steroid therapy.
Basophils increase with disorders causing
proliferation of formed elements by bone marrow
overproduction. Cytoplasmic granules contain
histamine (inflammatory) and heparin (anticoagulant) They decrease due to stress, and acute
allergic reactions.
Platelet formation (Thrombopoieses) 1
Platelet formation (Thrombopoieses) 2
• Thrombocytes
membrane bound cell fragments.
Circulate in blood for approx. 8 days then
broken down & recycled.
Numbers range from 150 x 103 to
400 x 103/ml
Stress can increase the #’s.
Decrease in platelet count, thrombocytopenia
is due to drug therapy, TB, leukemia, metastatic
cancer.
Platelet formation (Thrombopoieses) 3
Platelet formation (Thrombopoieses) 4
Blood Types 1
Surface Antigens
molecules present on the membrane of RBC’s.
known also as agglutinogens
two classifications: ABO and Rh groups
• *ABO group: consists of two surface antigens, A &
B; the presence or absence of either or both
determines the blood type of this group.
Types: A (only A present); B (only A present)
AB (both present); O (neither present)
• Plasma contains antibodies (agglutinins) which
react with ‘non-self’ antigens.
• *Important with blood transfusions
Blood Types 2
• Plasma
Agglutinins: Type A – anti B; Type B – anti A;
Type AB – no antibodies
Type O – anti A and anti B antibodies
• *Rh group: consist of surface antigen D on RBC’s
its the presence or absence determines
the blood type of this group.
Types: Rh+ (D is present); Rh–
(absent D)
• Plasma: Agglutinins: Type Rh+: no anti D antibodies
Type Rh-: anti D antibodies only after exposure
to Rh+ blood.
• *Important during pregnancy.
Hemostasis
Blood clotting Cascade 1
• Intrinsic (tissue factor) pathway
factors activated by damage to vessel wall:
platelets adhere and release factor XII
f. XII activates f. XI; f. XI activates f. IX;
f. IX + Ca2+ & platelet factor 3
pf3 activates f. VIII.
F. VIII activates f. X = Common pathway
• Extrinsic (contact activation) pathway
damaged tissues outside the vessel releases:
(Tissue Thromboplastin)f. III; f. III + Ca2+ & f. VII
activates f. X = Common pathway
Blood clotting Cascade 2
• Common pathway
f. X + f. II + f. V & Ca2+ & pf. 3 = prothrombin
activator which
activates prothrombin (f. II) to Thrombin
which converts f. I (soluble fibrinogen) to fibrin
(insoluble)
fibrin + Ca2+ activates f. XIII which cross-links
fibrin monomers into a fibrin polymer mesh
stabilizing the clot.
Fibrinolysis: within 2 days of clot formation, this
process occurs by plasmin degrading the mesh. Clot
retraction precedes this by actinomyosin (a platelet
protein) contraction.
Blood clotting disorders
• Failure to clot:
bleeding disorders; several variants
genetic mutations: Hemophilias A & B (females
usu. carriers: sex-linked)
Vitamin K deficiency (usu. newborns)
platelet deficiency: Thrombocytopenia
• Hypercoagulation:
genetic, environmental, drug related causes.
Symptoms: DVT, embolus; life threatening
• Which of the following is involved in all three
phases of hemostasis?
a) Ca+2 ion b) thrombin c)platelets d) fibrin
• The myeloid line of blood cells does not include:
a) monocytes b) basophils c)NK cells d) RBC’s
• Blood typing includes all of the following except?
a) RBC antigens b)agglutinins c)WBC antigens
• Which is not present in plasma?
a) fibrinogen b) albumin c) hemoglobin
d) γ globulins
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