Shier, Butler, and Lewis:  Hole’s Human Anatomy and Physiology, 10th ed.                                                           

Chapter 14:  Blood

Chapter 14:  Blood

I.  Blood and Blood Cells

A.  Introduction
1.  Blood is three to four times more viscous than water.
2.  Most blood cells form in red bone marrow.
3.  Types of blood cells are red blood cells and white blood cells.
4.  Cellular fragments of blood are platelets.
5.  Formed elements of blood are the cells and platelets.
B.  Blood Volume and Composition
1.  Blood volume varies with body size, changes in fluid and electrolyte concentrations, and the amount of adipose tissue.
2.  Blood volume is about 8% of body weight.
3.  An average-size adult has 5 liters of blood.
4.  Hematocrit is the percentage of blood cells in a blood sample.
5.  A blood sample is usually 45 % cells and 55 % plasma.
6.  Plasma is a mixture of water, amino acids, proteins, carbohydrates, lipids, vitamins, hormone, electrolytes, and cellular wastes.
7.  Less than 1% of formed elements of blood are white blood cells and platelets and 99% are red blood cells.
C.  The Origin of Blood Cells
1.  Blood cells originate in red bone marrow from hemopoietic stem cells.
2.  A stem cell can differentiate into any number of specialized call types.
3.  Colony-stimulating factors are growth factors that stimulate stem cells to produce certain cell types.
4.  Thrombopoietin stimulates the production of megakaryocytes.
D.  Characteristics of Red Blood Cells
1.  Red blood cells are also called erythrocytes.
2.  Red blood cells are biconcave in shape.
3.  The biconcave shape of red blood cells allow them to have an increased surface area for the transport of gases. 
4.  Hemoglobin is an oxygen carrying protein in red blood cells.
5.  Each red blood cell is about one-third hemoglobin by volume.
6.  Oxyhemoblobin is hemoglobin combined with oxygen.
7.  Deoxyhemoglobin is hemoglobin that has released oxygen.  
8.  Red blood cells extrude their nuclei as they mature.
9.  Because red blood cells lack mitochondria they must produce ATP through glycolysis.  
10.  As red blood cells age, they become rigid and are more likely to be damaged and removed by enzymes in the liver and spleen.
E.  Red Blood Cell Counts
1.  A red blood cell count is the number of RBCs in one mm3 of blood.
2.  A healthy adult male has a red blood cell count between 4,600,00-6,200,000 cells per mm3.
3.  A healthy adult female has a red blood cell count between 4,200,000-5,400,000 cells per mm3.
4.  A healthy child has a red blood cell count between 4,500,000-5,100,000 cells per mm3 
5.  The number of red blood cells reflects the blood’s oxygen carrying capacity.
F.  Red Blood Cell Production and Its Control
1.  Erythropoiesis is red blood cell production.
2.  Initially, red blood cell formation occurs in the yolk sac, liver and spleen.  
3.  After an infant is born, red blood cells are produced almost exclusively in the red bone marrow.
4.  Stem cells is red bone marrow give rise to erythroblasts that give rise to erythrocytes.
5.  Reticulocytes are immature red blood cells that still contain endoplasmic reticulum.
6.  The average life span of a red blood cell is 120 days.
7.  Erythropoietin controls red blood cell production and is released primarily from the kidneys.
8.  When oxygen levels fall, erythropoietin is released and red blood cell production increases.
G.  Dietary Factors Affecting Red Blood Cell Production
1.  Two vitamins needed for red blood cell production are vitamin B12 and folic acid.
2.  Two B-complex vitamins are needed for DNA synthesis.
3.  Intrinsic factor is needed for the absorption of vitamin B12.
4.  Iron is required for hemoglobin production.
5.  Anemia is a reduction in the oxygen-carrying capacity of the blood.
H.  Destruction of Red Blood Cells
1.  Damaged red blood cells rupture as they pass through the spleen or liver.
2.  In the liver and spleen, macrophages destroy worn out red blood cells.
3.  Hemoglobin molecules are broken down into globin and heme groups.
4.  Heme decomposes into iron and biliverdin.
5.  Ferritin is an iron-protein complex that stores iron in the liver.
6.  Biliverdin is converted to bilirubin.
7.  Bilirubin and biliverdin are excreted in bile.
I.  Types of White Blood Cells
1.  White blood cells are also called leukocytes.
2.  White blood cells function to protect against diseases.
3.  Two hormones that stimulate white blood cell production are interleukins and CSFs.
4.  Granulocytes have granules in their cytoplasm.
5.  Examples of granulocytes are neutrophils, basophils, and eosinophils.
6.  Agranuloctyes lack cytoplasmic granules.
7.  Examples of agranuloctyes are monocytes and lymphocytes.
8.  Neutrophil granules appear light purple in an acid/base stain.
9.  Neutrophils have nuclei that are lobed. 
10.  Neutrophils phagocytize bacteria, fungi, and some viruses.
11.  Neutrophils account for about 54%-62% of white blood cells in a blood sample.
12.  Eosinophil granules stain red in an acid stain.
13.  The nucleus of an eosinophil is usually bilobed.
14.  Eosinophils moderate allergic reactions and defend against parasitic worm infestations.
15.  Eosinophils make up 1%-3% of the total number of circulating white blood cells.
16.  Basophil granules stain blue in a basic stain.
17.  Basophils migrate to damaged tissues where they release histamine and heparin.
18.  Heparin functions to prevent blood clots.
19.  Histamine promotes inflammation.
20.  Basophils usually account for less than 1% of leukocytes.
21.  The largest of the white blood cells are monocytes.
22.  The nuclei of monocytes are spherical, kidney shaped or oval.
23.  Monocytes can leave the blood stream to become macrophages.
24.  Monocytes usually make up 3%-9% of white blood cells in a blood sample.
25.  A typical lymphocyte contains a large, spherical nucleus surrounded by a thin rim of cytoplasm.
26.  The major types of lymphocytes are T cells and B cells.
27.  T cells attack microorganisms, tumor cells, and transplanted cells.
28.  B cells produce antibodies.
29.  Lymphocytes account for about 25%-33% of the circulating white blood cells.
J.  Functions of White Blood Cells
1.  Diapedesis is the movement of a WBC out of the blood stream into surrounding tissues.
2.  Amoeboid motion is a form of self-propulsion used by WBCs outside the blood stream to move.
3.  The most mobile and active phagocytic leukocytes are neutrophils and monocytes.
4.  When microorganisms invade human tissues, basophils respond by chemicals that dilate local blood vessels.
5.  Positive chemotaxis is the attraction leukocytes have toward areas of damaged tissues.
6.  Pus is an accumulation of bacteria, WBCs, and damaged cells.
K.  White Blood Cell Counts
1.  A white blood cell count is normally between 5,000-10,000 cells per mm3 of blood.
2.  Leukocytosis is an increased WBC count and is often caused by acute infections.
3.  Leukopenia is a decreased WBC count and is often caused by influenza, mumps, measles, chicken pox, or AIDS.
4.  A differential white blood cell count lists percentages of the types of leukocytes in a blood sample.
5.  The number of neutrophils increases during bacterial infections, and eosinophils increase during parasitic worm infections.
L.  Blood Platelets
1.  Platelets are also called thrombocytes.
2.  Platelets arise from cells called megakaryocytes.
3.  A normal platelet count is normally between 130,000-360,000 platelets per mm3 of blood.
4.  Platelets help repair damaged blood vessels by sticking to broken surfaces.
5.  Platelets release serotonin that contracts smooth muscles in the vessels walls, reducing blood flow.

II.  Blood Plasma

A.  Introduction
1.  Plasma is the clear, straw-colored, liquid portion of the blood in which the cells and platelets are suspended.
2.  About 92% of plasma is water.
3.  Functions of plasma include transporting nutrients, gases and vitamins; helping to regulate fluid and electrolyte balance; and maintaining a favorable pH.
B.  Plasma Proteins
1.  The three main plasma protein groups are albumins, globulins, and fibrinogen.
2.  Albumins are the smallest of the plasma proteins and are synthesized in the liver.  
3.  Albumins function to help maintain the colloid osmotic pressure of blood. 
4.  Colloid pressure is the osmotic pressure produced by plasma proteins.
5.  Globulins can be divided into the following three groups:  alpha, beta, and gamma globulins.
6.  Alpha and beta globulins are synthesized in the liver.
7.  Alpha and beta globulins function to transport lipids and fat-soluble vitamins in the blood.
8.  Gamma globulins are synthesized lymphatic tissues and function as constituents of antibodies.  
9.  Fibrinogen is synthesized in the liver.
10.  The function of fibrinogen is to promote blood clotting. 
C.  Gases and Nutrients
1.  The most important blood gases are oxygen and carbon dioxide.
2.  The plasma nutrients are amino acids, simple sugars, nucleotides, and lipids.
3.  Lipoproteins are complexes of phospholipids, cholesterol, and proteins surrounding a core of triglycerides.
4.  Four types of plasma lipoproteins are chylomicrons, VLDLs, LDLs, and HDLs.
5.  Chylomicrons contain a high concentration of triglycerides and function to transport dietary fats to muscle and adipose cells. 
6.  Very low-density lipoproteins contain a relatively high concentration of triglycerides and function to transport triglycerides from the liver to adipose cells.
7.  Low-density lipoproteins contain a relatively high concentration of cholesterol and function to deliver cholesterol to various cells.
8.  High-density lipoproteins contain a relatively high concentration of protein and a low concentration of lipids.
9.  High-density lipoproteins function to transport remnants of chylomicrons to the liver.
D.  Nonprotein Nitrogenous Substances
1.  Types of nonprotein nitrogenous substances in plasma are urea, uric acid, creatinine, and creatine.
2.  Urea is produced when proteins are metabolized.
3.  Uric acid is produced when nucleic acids are metabolized.  
4.  Creatinine is produced from metabolism of creatine.
5.  Creatine phosphate is a protein that stores phosphate molecules for the production of ATP.  
6.  About half of the NPN substances in blood is urea.
E.  Plasma Electrolytes
1.  Plasma electrolytes include sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, and sulfate.
2.  Sodium and chloride ions are the most abundant plasma electrolytes.

III.  Hemostasis

A.  Introduction
1.  Hemostasis refers to the stoppage of bleeding.
2.  Three actions that may prevent blood loss are blood vessel spasm, platelet plug formation, and blood coagulation.
B.  Blood Vessel Spasm
1.  Vasospasm is smooth muscle contraction in the wall of a blood vessel.
2.  Following vasospasm, blood loss lessens and the ends of the severed vessel may close completely.
C.  Platelet Plug Formation
1.  Platelets adhere to exposed ends of injured blood vessels.
2.  A platelet plug is formed when platelets contact collagen.
3.  The function of the platelet plug is to prevent blood loss.
D.  Blood Coagulation
1.  Introduction
a.  Coagulation causes the formation of a blood clot.
b.  The extrinsic clotting mechanism is triggered by chemicals from broken blood vessels or damaged tissues.
c.  The intrinsic clotting mechanism is triggered by the contact of blood with foreign surfaces in the absence of tissue damage.
d.  Clotting factors are chemicals that control blood clotting.
e.  Vitamin K is necessary for some clotting factors to function.
f.  Procoagulants promote blood clotting and anticoagulants inhibit blood clotting.
g.  Normally, anticoagulants prevail and the blood does not clot.
h.  The major event in blood clot formation is conversion of fibrinogen into fibrin.
2.  Extrinsic Clotting Mechanism
a.  The extrinsic clotting mechanism is triggered when blood contacts damaged blood vessel walls or tissue outside blood vessels.
b.  Tissue thromboplastin is a substance released from damaged tissue and activated clotting factor VII.
c.  The series of reactions in the extrinsic clotting mechanism are dependent on calcium ions.
d.  Prothrombin activator converts prothrombin to thrombin.  
e.  The function of thrombin is to convert fibrinogen to fibrin.
f.  Once fibrin threads form, they stick to exposed surfaces of damaged blood vessels, creating a blood clot.
g.  A blood clot is composed of fibrin threads that have trapped blood cells and platelets.
h.  Blood clotting is enhanced by a positive feedback system.
i.  Normally blood clot formation is prevented by blood flow.
3.  Intrinsic Clotting Mechanism
a.  The Hageman factor initiates clotting in the intrinsic clotting mechanism.
b.  The intrinsic clotting mechanism occurs when blood is exposed to a foreign surface such as collagen in connective tissue.
c.  The reactions of the intrinsic clotting mechanism depend on calcium ions.
d.  Most of the steps of blood clot formation in the intrinsic clotting mechanism are the same as those of the extrinsic clotting mechanism.
4.  Fate of Blood Clots
a.  After a blood clot forms, it soon begins to retract.
b.  Serum is plasma minus clotting factors.
c.  Platelet-derived growth factor stimulates smooth muscle cells and fibroblasts to repair damaged blood vessel walls.
d.  Fibroblasts produce fibers that help strengthen and seal vascular breaks.
e.  Plasmin is released from blood clots and functions to break down blood clots.
f.  A thrombus is an abnormal blood clot. 
g.  An embolus is a thrombus or portion of a thrombus that is moving in the blood stream.
h.  Atherosclerosis is the accumulation of fatty deposits on the endothelium of blood vessels.
i.  Thrombosis in veins is usually caused by atherosclerosis.
E.  Prevention of Coagulation
1.  The smooth lining of blood vessels discourages blood clot formation.
2.  Prostacyclin inhibits the adherence of platelets to the inner surface of healthy blood vessel walls.
3.  Antithrombin inactivates thrombin.
4.  Heparin is an anticoagulant.

IV.  Blood Groups and Transfusions

A.  Antigens and Antibodies
1.  Agglutination is the clumping of RBCs and is due to a reaction between RBC surface molecules called antigens and proteins called antibodies.
2.  Avoiding the mixture of certain kinds of certain kinds of antibodies and antigens prevents adverse transfusion reactions.
B. ABO Blood Group
1.  The ABO blood group is based on the presence or absence of antigen A and antigen B on RBC membranes.
2.  A person with only antigen A has type A blood.
3.  A person with only antigen B has type B blood.
4.  A person with both antigen A and antigen B has type AB blood.
5.  A person with neither antigen A nor antigen B has type O blood.
6.  A person with type A blood has antibody anti-B in their plasma.
7.  A person with type B blood has antibody anti-A in their plasma.
8.  A person with type AB blood has neither anti-A nor anti-B antibodies in their plasma.
9.  A person with type O blood has both anti-A and anti-B antibodies in their plasma.
10.  Antibodies anti-A and anti-B do not cross the placenta.
11.  The major concern in blood transfusion procedures is that the cells in the donated blood not clump due to antibodies present in the recipient’s plasma.
12.  A person with type AB blood is called a universal recipient because type AB lacks both anti-A and anti-B antibodies, so a person with this blood type can receive blood from any other blood type.
13.  Type O blood is the universal donor because it lacks antigens A and B, so this blood type can be given to persons of all other blood types.
14.  A person with Type A blood cannot receive Type B blood because antibodies in the recipient’s plasma would destroy the RBCs of the donor blood.
C.  Rh Blood Group
1.  The Rh blood group was named after the Rhesus monkey.
2.  Blood is said to be Rh positive when Rh antigens are present on RBCs.
3.  Blood is said to be Rh negative when Rh antigens are not present on RBCs.
4.  Anti-Rh antibodies form only in Rh-negative persons when the Rh negative person is exposed to Rh positive blood.
5.  When an Rh-negative woman is pregnant with an Rh positive fetus, she will produce anti-Rh antibodies.
6.  Erythroblastosis fetalis occurs when a woman has already developed anti-Rh antibodies and they cause hemolysis of the RBCs of the fetus.