Lecture notes for Chapter 19
• Movement of substances throughout the body utilizes vessels, pumps and fluid
• The CVS has a pump, the heart, vessels, arteries, veins, capillaries and fluid, blood
– Blood contains nutrients, waste products, gases and other dissolved substances, like
hormones
– Blood is in a contain system, inside the body and is not thought about until we see
it outside the body
– Loss of only 15-20% of blood can lead to death
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The lymphatic system does not contain a pump but has numerous vessels called
lympatics which contain a fluid called lymph.
– Lymph transports excess fluid that the CVS can’t pick up in the periphery and has
an important role in immunity (to be discussed in chpt. 22)
– Lymph nodes and organs are sites of large numbers of immune cells and are found
all over the body
Functions of blood
1. Transportation of dissolved substances, gases, nutrients, waste, hormones, enzymes
2. Regulation of pH and ion concentrations
3. Clotting, prevents excess fluid loss
4. Defense against pathogens and toxins-antibodies and immune T cells
5. Thermoregulation-vasocontriction and vasodilation
composition
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Fig. 19.1 p. 641, 2 parts
– Plasma is liquid portion and contains plasma proteins like albumin, globulins
(Abs), fibrinogen and enzymes
– Formed elements are cells or cell fragments
• RBCs, erythrocytes, make up the bulk of the formed element and function in
oxygen transport
• WBCs, leukocytes, are 5 types and are in small %
• Plateletes, thrombocytes, are cell fragments that are necessary for proper blood
clotting
Blood cell formation
Hemopoiesis or hematopoiesis- Fig. 19.10 p. 659 is the process of blood cell formation
from a stem cell in the bone marrow
– The hemocytoblast differentiates into a myeloid or lymphoid stem cell. Under the
influence of hormones, these 2 stem cell lines give rise to each of the types of
blood cells
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Blood characteristics and collection
• Whole blood can be collected from an arterial puncture or from venipuncture.
Capillary sticks also provide a small amount of blood
• Blood is about 38 degrees C (100.4 degrees F), has a pH of 7.35-7.45 and is thicker
than water (due to the plasma proteins)
• Men have 5-6 liters of blood while women have 4-5 liters
RBCs
• 99.9% of formed elements are RBCs, a hematocrit measures formed elements in blood
and therefore indicates RBC volumes (260 million in 1 drop of blood)
• RBCs are biconcave discs (fig. 19.2) that have to maintain this structure in order to
pass through capillaries
• Contain hemoglobin (Hb, 280 million Hb per RBC, fig. 19.3) and when bound to
oxygen as oxyHb, is bright red. Hb is made up of 4 globular proteins and each has a
heme unit that contains an iron (Fe2+) molecule. O2 binds to Fe2+. Hb can also bind
a small amount of carbon dioxide forming carbaminoHb
RBCs (cont.)
• Poor oxygen transport can lead to anemia (which is characterized by lethargy,
weakness and even death)
• Anemia results when RBCs are in low number (thalassemia) or if Hb is improperly
formed (sickle cell disease Fig. 19.4) or iron is deficient in diet
• RBCs only life for 120 days because they lack nuclei, ribosomes and mitochondria
RBC recycling
• Fig. 19.4 p. 647
– RBCs are formed in bone marrow and enter blood
– After 120 days cells are phagocytyzed by macrophages in liver and spleen
– Heme unit is released and the Fe2+ is transported (transferrin) back to the bone
marrow for use in formation of new RBCs
– The empty heme becomes biliverdin (green color) and than is converted to bilirubin
(orange-yellow color) in the liver.
– Bilirubin is excreted in bile, transformed and released in the feces and the urine
Erythropoiesis
• Fig. 19.5 and 19.10
– Hemocytoblast in red bone marrow becomes myeloid stem cell
– Myeloid stem cell becomes proerythroblast under the influence of hormone, EPO
(erythropoietin) from kidney which goes through changes and becomes a
reticulocyte (anucleated) and then a mature RBC in the blood vessel
– Need amino acids, Fe, vitamins B12, B6 and folate for proper RBC formation
– Blood doping and utilization of EPO by athletes is an illegal and dangerous
practice (puts strain on heart)
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Blood types
RBCs have surface markers called antigens or agglutinogens that are used to type
blood
4 blood types, A, B, AB, O indicated by presence of a specific antigen
Antibodies or agglutinins are used to detect antigens and cause agglutination
(clumping of cells) to occur when bound to a specific antigen (figs. 19.6 & 19.7)
Rh compatability (Rhesus factor) is important if mother is Rh negative and child is Rh
positive. Mother can produce antibodies that will attack 2nd Rh + child’s RBC and
produce a condition called hemolytic disease of the newborn or erythroblastosis fetalis
(pp. 653-654)
WBCs
• These are found in much fewer numbers but are important in defense and removal of
damaged or abnormal cells
• Table 19.3 summarizes 5 types and functions
– Never Let Men Eat Beans (order of abundance in blood)
– Granulocytes=NEB, agranulocytes=LM
– Found in blood but spend most time in tissues
– Phagocytic cells=NEM
– Immune cells=L
– Inflammatory cells=B
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WBCs (cont.)
Differential counts measure #s of different types of WBCs in blood specimen
– Leukopenia=decrease in WBC #s ex. Lymphopenia=decrease in lymphocytes
– Leukocytosis=increase in WBC #s, moderate leukocytosis occurs during infection,
leukemia is a dramatic leukocytosis
WBC development
Fig. 19.10 hematopoiesis of blood cells
– All WBCs come from the hemocytoblast in red bone marrow
– Different hormones stimulate the 5 types
• Myeloid stem cell gives rise to N,E,B,M when stimulated by multi-CSF, GMCSF, G-CSF, M-CSF
• Lymphoid stem cell gives rise to L, lymphocytges then differentiate into T or B
cells in different sites of body
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Platelets
• In mammals these are anucleated, cell fragments derived from myeloid stem cells
under the stimulation of TPO (thrombopoietin) to produce megakaryocytes that
fragment into 4000 plateletes
• In nonmammalian species these are called thrombocytes (nucleated)
• More platelets are found in blood than WBCs but much fewer than RBCs
– Thrombocytopenia (decrease in numbers and bleeding in GI tract and skin occurs)
and thrombocytosis (during infection, inflammation and cancer)
Platelets (cont.)
• Hemostasis=cessation of bleeding due to the production and release of clotting factors
from platelets
• 3 phases (figs. 19.11 & 12) vascular, platelet, coagulation
– 1. Vascular-vascular spasm occurs in injured blood vessel to decrease the diameter
of the vessel at the site of injury. Changes in the endothelium of the vessel wall
cause the release of chemical factors and hormones to speed up repair processes
and to make the wall sticky
Hemostasis (cont.)
– 2. Platelet phase-platelets attach to the sticky endothelial membranes forming a
platelet adhesion. More and more platelets are attracted and attach to the p.
adhesion to form a p. plug. Platelets become activated and release many factors
including clotting factors and calcium.
– 3. Coagulation phase-blood clotting requires clotting factors released by platelets
and 11 other proteins, calcium and vitamin K. Fibrin is formed which covers the
platelet plug, blood cells are attracted to destroy pathogens and a blood clot forms.
Hemostasis (cont.)
• Clot retraction-pulls edges of torn vessel together to seal off wound
• Fibrinolysis-clot dissolves during repair process
• abnormal hemostasis
– Embolus=abnormal mass in bloodstream (bloodclots can be emboli, like air
bubbles or other substances) embolism-blockage of a vessel that that interrupts
circulation depriving tissue of oxygen and leading to a MI or stroke
– Thrombus-stationary clot that has attached to vessel wall
– Anticoagulants=blood thinners (heparin, coumadin, aspirin
– Hemophilia=little production of clotting factor therefore “free bleeders”
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