Blood
Functions
1. Transport gases
2. Regulates pH by removing acids
generated in tissues
3. Protection
– Clotting factors to prevent fluid loss
– WBC and Antibodies to fight pathogens
– Stabilizes body temp
Blood Volume and Composition
• Blood volume is 8% of body weight
• Average adult has 5 liters of blood
• Blood is 45% cells
– hematocrit or packed cell volume
– 99% are red blood cells, remainder white blood
cells and blood platelets
• Blood is 55% plasma
– water, amino acids, proteins, carbohydrates,
lipids, vitamins, hormones, electrolytes, wastes
Blood Plasma
• Clear, straw colored liquid portion of blood
where proteins and platelets are suspended
• Components
–
–
–
–
–
92% water
Plasma proteins
Gases and nutrients
Nonprotein nitrogen substances
amino acids, urea, uric acid, creatine, creatinine
• Plasma electrolytes
– sodium, potassium, calcium, magnesium, chloride,
bicarbonate, phosphate, sulfate
Plasma Proteins
• Globulins
– 36% of plasma proteins
– alpha, beta, gamma globulins
• Fibrinogen
– 4% of plasma proteins
– primary role in blood clotting
Figure 14.3
Red Blood Cells
• Erythrocytes
– Life span of 120 days
• Small, biconcave discs
• Cells are 1/3 hemoglobin
• Mature cells lack nuclei, cannot divide or
synthesize proteins
• Red blood cells lack mitochondria and
produce ATP through glycolysis only
Red Blood Cell Destruction
• Damaged or worn cells rupture in the spleen
or liver.
• Macrophages phagocytize and destroy cells.
• Hemoglobin is broken down into globin and
heme which decomposes into biliverdin.
• Biliverdin is converted to bilirubin and
excreted in bile.
• Iron is carried on transferrin and store in the
liver as ferritin.
Figure 14.5
Erythropoiesis
• Erythrocytes are produced in the red bone
marrow.
• Average life span is 120 days.
• Erythropoietin operates in a negative feedback
mechanism to maintain red blood cell
homeostasis.
• When oxygen concentrations in the blood are
low, erythropoietin is released.
Anemia
Sickle cell anemia
Sickle Cell anemia
• Herediatry disease of RBC where there is an
incorrect AA incorperated in hemoglobin
• Causing the cell to “sickle”
• Blocks circulation in small vessels and
0xygen is not carried efficiently
• Results…joint pain, organ damage
Dietary Factors
• Vitamin B12
– required for DNA synthesis
– intrinsic factor necessary for absorption
• Folic acid
– required for DNA synthesis
• Iron
– required for hemoglobin synthesis
• Vitamin C
– increases absorption of iron
White Blood Cells
•
•
•
•
Leukocytes
5,000-9,000 cubic mm of blood
Protect against disease
Granulocytes
– granular cytoplasm
– neutrophils, eosinophils, basophils
• Agranulocytes
– lack cytoplasmic granules
– monocytes, lymphocytes
Neutrophils
• Granules stain light
purple in acid-base
combination stains
• First white blood
cells at arrive at
infection
• ~70% of WBC
Figure 14.9
• Nasal and oral
cavity
inflammation
Eosinophils
• Some mild
allergic reactions
• Defend against
parasitic worm
infection
• 1-3%
Figure 14.10
Basophils
• Granules stain
deep blue in basic
stain
• Nuclei have two
lobes
Figure 14.11
Basophils
• Migrate to
damaged tissue
• Allergic rxns:
Release histamine
to promote
inflammation and
heparin to inhibit
blood clotting
• less than 1% of
leukocytes
Agranulocytes
• Monocytes
– largest cells
– leave
bloodstream
and become
macrophages
– 3% to 9% of
the leukocytes
– FXN:
phagocytosis
Agranulocytes
• Lymphocytes
– Aka: T cells and
B cells
– important in
immunity
– Help prevent
cancer
– 35% to 33% of
leukocytes
Figure 14.13
Leukocytes
• Protect against
infection
– phagocytize bacteria
– produce proteins that
destroy foreign
particles
• Diapedesis:
leukocytes can
squeeze between
cells and leave the
circulation
Figure 14.14
Figure 14.15
Leukocytes
• Positive chemotaxis: damaged cells release
chemicals that attract leukocytes
• Inflammation delays spread of microorganisms
Blood Platelets
• Thrombocytes
• Arise from megakaryocytes in the red bone
marrow
• Platelets are small and lack a nucleus
• Assists in blood clotting: Help repair
broken blood vessels
• Release serotonin
Plasma Proteins
• Albumins
– 60% of plasma proteins
– maintain osmotic pressure, bind and transport
molecules
Figure 14.16
Blood Gases and Nutrients
• Blood gases
– oxygen and carbon dioxide
• Nutrients
– amino acids, simple sugars, nucleotides, lipids
– Lipids include triglycerides, phospholipids,
cholesterol transported as lipoproteins
• chylomicrons, VLDL, LDL, HDL
Hemostasis
• Stoppage of bleeding to prevent blood loss
• Blood vessel spasm
– vasospasm due to smooth muscle contraction
– direct stimulation of vessel wall and pain reflexes
Hemostasis
• Platelet plug
formation
– platelets become
spiny and sticky
and plug the
vascular break
Figure 14.17
Blood Coagulation
•
•
•
•
Complex cascade of events
Utilizes clotting factors
Vitamin K is necessary for clotting factors
Major event is conversion of soluble plasma
protein fibrinogen to insoluble treads of
fibrin
Extrinsic Clotting Mechanism
• Triggered when blood contacts damaged
blood vessel wall or tissue outside blood
vessels
• Damaged tissue releases thromboplastin
• Thromboplastin activates clotting cascade
• These reactions with calcium release
prothrombin
• Prothrombin is converted into thrombin
• Thrombin converts fibrinogen to fibrin
Extrinsic Clotting Mechanism
• Fibrin threads stick to exposed damaged
blood vessels.
• Meshwork traps blood cells and platelets.
• This produced a blood clot.
• The amount of prothrombin activator is
proportional to the degree of tissue damage.
• Blood clotting is self-initiating, a positive
feedback system.
Clot Limitation
• Blood flow keeps thrombin concentration
low
• Antithrombin limits thrombin formation
• Thrombus: a clot abnormally forming in a
vessel
• Embolus: a dislodged clot carried by the
bloodstream
• Embolism: embolus blocking blood flow
Intrinsic Clotting Mechanism
• All components found in the blood
• Activation of Hageman Factor initiates
intrinsic clotting
• Cascade of activation in the presence of
calcium produces prothrombin activator
• Prothrombin and fibrin are formed as in the
extrinsic pathway
Figure 14.19
Fate of Blood Clots
• Blood clot retraction occurs pulling torn
vessel ends together.
• Serum is squeezed out.
• Platelet-derived growth factor repairs wall.
• Plasminogen is absorbed by fibrin.
• Plasminogen activator converts
plasminogen to plasmin.
• Plasmin digests the clot.
Prevention of Coagulation
• Endothelial cells produce prostacyclin
which inhibits platelet adherence.
• Antithrombin inactivates thrombin.
• Basophils and mast cells release heparin
which interferes with the formation of
prothrombin activator.
Antigens and Antibodies
• Blood cell compatibility is based on clumping or
agglutination
• Transfusion reaction: a reaction between red
blood cell antigens or agglutinogens and protein
antibodies or agglutinins in the plasma
• Antigens include those of the ABO group and the
Rh group
Figure 14.22
ABO Blood Group
• Based on red blood
cell membrane
antigen A and
antigen B
ABO Blood Group
• Four possible
combinations
– Type A contains
antigen A
– Type B contains
antigen B
– Type AB contains
antigens A and B
– Type O contains no
antigens
Figure 14.21
ABO Blood Group
• Anti-A and anti-B antibodies are produced
when an antigen is absent from the cell
membrane
– Type A plasma contains anti-B antibodies
– Type B plasma contains anti-A antibodies
– Type AB plasma contains anti-A and anti-B
antibodies, universal recipient
– Type O plasma contains no antibodies,
universal donor
Rh Blood Group
• Rh positive
indicates presence
of antigen D, one
of the Rh antigens
• Rh negative
indicates absence
of Antigen D
Figure 14.23
Rh Blood Group
• Rh antigens, like
A and B antigens
are inherited and
present from birth
• Anti-D antibodies
and not produced
until after an
individual is
sensitized to D
antigen
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