Chapter 19: The Blood

BIO 211 LectureInstructor: Dr. Gollwitzer

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• Today in class we will discuss:– The primary functions of the blood– List the physical characteristics and major components

of the blood

– Plasma• Describe the composition and functions of plasma• Describe the roles of various plasma proteins

– Red Blood Cells (RBCs)• List the characteristics and functions of RBCs• Describe the structure and function of hemoglobin• Explain the basis for ABO and Rh blood types and the cause of

incompatibilities

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2 Major Fluid (Circulatory) Systems

• Cardiovascular system (CVS)– Circulating fluid = blood (Chapter 19)– Pump = heart (Chapter 20)– Conducting “pipes” = blood vessels (Chapter 21)

• Lymphatic system (Chapter 22)– Interconnected and interdependent with CVS

• CVS (bloodstream) fluid tissues fluid lymphatic vessels CVS

• CVS assists lymphatic system (defense system) – blood carries lymphatic cells, antibodies, cytokines, etc.

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Blood

• Specialized fluid connective tissue• Contains– Cells in fluid matrix– Proteins

• Functions– Transport of dissolved substances– Regulation of pH and ion composition– Restriction of fluid loss at injury sites– Defense against toxins and pathogens– Stabilization of body temperature

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Functions: Transportation• Dissolved gases– Oxygen (O2) from lungs to tissues

– Carbon dioxide (CO2) from tissues to lungs

• Nutrients– Absorbed from digestive tract, adipose tissue, liver

• Hormones– From endocrine glands to target cells

• Metabolic wastes– Absorbs and carries from tissue cells to liver

• Immune system cells– Defend tissues from infection and disease

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Functions: Regulation of pH and Ion Composition of Interstitial Fluids

• Occurs via diffusion between blood and interstitial fluids

• Eliminates local deficiencies or excesses of ions– e.g., increases/decreases calcium or potassium

• Absorbs and neutralizes acids– e.g., lactic acid produced by skeletal muscles

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Functions: Restriction of Fluid Loss at Injury Sites

• Via blood clotting– Enzymes and other substances in blood respond

to breaks in vessel walls by initiating clotting process

• Blood clot– Temporary patch which prevents further blood

loss

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Functions: Defense Against Toxins and Pathogens

• Transports white blood cells (WBCs)– Fight infections– Remove debris from peripheral tissues

• Delivers antibodies– Special attack proteins against invading organisms

or foreign compounds

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Functions: Stabilization of Body Temperature

• Absorbs heat generated by active skeletal muscles (heat reservoir)

• Redistributes heat to other tissues• If body temp high– Heat lost through skin

• If body temp low– Warm blood directed to brain and other temp-

sensitive organs

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Physical Characteristics of Blood• Temperature = 100.4 F• High viscosity – 5 times thicker than water– Cells are stickier (more cohesive), more resistant

to flow than water• pH = 7.4 (slightly basic/alkaline)• Volume– 4 (female) - 6(male) quarts– 7% of BW in kg

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Composition of Whole Blood• Whole blood = plasma + formed elements• Plasma = matrix (fluid part of blood)– Plasma proteins in solution (vs. insoluble

fibers like other CT)–Makes blood more dense than water

• Formed elements = suspended blood cells/cell fragments

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Composition of Whole Blood• Formed elements (formed through hematopoiesis)– RBCs (erythrocytes)• Most abundant• Transport O2 and CO2

–WBCs (leukocytes)• Part of immune system/defense mechanisms

– Platelets• Small, non-cellular, membrane-bound packets of cytoplasm• Contain enzymes, substances important in clotting

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Plasma• = H20 (> 90%) + plasma proteins + other solutes– Watery characteristic allows plasma to function as

transportation medium for materials needed and no longer needed by body’s cells

• Slightly more than half the blood volume• Plasma + interstitial fluid (IF) = most of the fluid

outside cells (ECF, extracellular fluid)• Primary differences b/w plasma and IF– More dissolved protein in plasma (large size and

globular shapes can’t cross capillary walls)– Higher levels of respiratory gases (O2, CO2) in IF due to

activities of tissue cells13

Classes of Plasma Proteins

• Albumins (60%)• Globulins (35%)• Fibrinogen (4%)• Other (1%)

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Albumins

• Most abundant• Contribute to osmotic pressure• Transport– Fatty acids– Thyroid hormones– Steroid hormones

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Globulins

• Antibodies (immunoglobulins, IGs)–Attack foreign proteins and pathogens

• Transport– Small metal ions (Fe)– Thyroid hormones–Other compounds that otherwise might be

lost at the kidneys or have low solubility in water

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Fibrinogen• Produces fibrin (long, insoluble, protein

strands)• Forms blood clots• In a blood sample, if remove clot (with

clotting proteins), remainder = serum– To prevent clot: use anticoagulant, e.g.,

EDTA, citrate– KNOW if sample is plasma or serum (for

blood tests)

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Other Plasma Proteins• Enzymes• Prohormones (proteins)• Hormones

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Plasma Protein Synthesis• >90% by liver– Liver disease can lead to excess bleeding

(inadequate fibrinogen and other clotting proteins) and other blood disorder

• Plasma cells make antibodies• Endocrine organs make peptide hormones

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Formed Elements• RBCs, WBCs, platelets• Formed in red bone marrow in adult (hematopoiesis)• Differentiation– Hemocytoblasts (stem cells)

• Lymphoid stem cells lymphocytes (WBCs)• Myeloid stem cells RBCs, some WBCs, platelets

– Erythropoiesis• RBC formation• Stimulated by erythropoietin (EPO)

– Platelets formed from fragmentation of megakaryocytes

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RBCs• Most abundant– 99.9% of formed elements and 1/3 of ALL body cells– Several million produced/sec

• Most specialized blood cell• Contains hemoglobin that binds and transports O2

and CO2 (primary function of both hemoglobin and RBCs)

• Normal RBC count– Males: 4-6 million/uL Females: 4-5 million/uL– Androgens stimulate RBC production, estrogens do not

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RBCs• Biconcave disc (thin in middle, thick at edge;

like breath mint)• Large surface area to volume– Quickly absorbs and releases oxygen

• Can form stacks (like breath mints)– Smooths flow through small blood vessels

• Can bend and flex– To fit through small capillaries

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RBCs

• No nucleus, ribosomes, mitochondria– Cannot divide– Cannot synthesize enzymes or other proteins• Cannot perform repairs (lifespan = 120 days/3 mo)

– Low energy demand• Gets energy from anaerobic metabolism of glucose

absorbed from plasma• Transported O2 is NOT stolen by RBC for energy

needs

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Fig. 19-2, p. 644 24

RBCs

• Hematocrit (packed cell volume, PCV)– % of formed elements in whole blood (most of

which are RBCs)• Male = 46%• Female = 42%

– Increases with dehydration, EPO– Decreases with internal bleeding, anemias,

problems with RBC formation, e.g., sickle cell anemia

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Hemoglobin (Hb)• Made of 4 globular protein subunits– 2 alpha chains; 2 beta chains

• Each subunit contains 1 heme molecule– Organic ring structure around single Fe ion

• Makes up most of RBC• Function– Allows cells to reversibly bind and transport O2 and

CO2 on Fe• When tissue O2 low: O2 released from Hb, CO2 binds• When tissue O2 high: O2 binds to Hb, CO2 released

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Fig. 19-3, p. 64527

Diseases Involving Hemoglobin• Anemia– Inadequate tissue O2 levels O2 starvation– HCT too low– Hb content of RBCs reduced– Symptoms• Weakness, lethargy, mental confusion

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Potentially Lethal Inherited Blood Disorders

• From mutations that alter DNA sequence for hemoglobin– Thalassemia

• Can’t produce enough alpha or beta chains of Hb• RBC production slowed, mature RBCs fragile and short-lived• Produces anemia

– Sickle cell anemia• Change in amino acids of beta chain abnormal RBCs, lower O2

concentrations (because of abnormally shaped/defective Hb)• Cells can become stuck in capillaries circulatory block, cell

death

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Blood Types• Determined by antigens on surface of RBCs– Antigen = anything that can trigger an immune response;

defense mechanism– >50 surface antigens on RBC, but A, B, and Rh are most

important• 4 basic blood types– Blood type A = surface antigen A– Blood type B = surface antigen B– Blood type AB = surface antigens A and B (universal

recipient)– Blood type O = neither A or B surface antigens (universal

donor)

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Fig. 19-7, p. 651

Blood Types• Plasma always contains

antibodies that will react with foreign surface antigens, but not with “normal”– Type A blood: surface

antigen A on RBCs and anti-B antibodies in plasma

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Blood Types• Rh positive = surface

antigen Rh• Rh negative = no Rh

surface antigen• Plasma anti-Rh

antibodies present in Rh- ONLY if sensitized by previous exposure to Rh+ RBCs– Rh- mom has from first

Rh+ baby

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Fig. 19-9, p. 654-655

Fig. 19-7b, p. 651

Cross-reaction (Transfusion Reaction)• Same surface antigen and Ab agglutination (clumping) and

hemolysis (cell death)• Plugs small vessels in vital organs: kidneys, lungs, heart, brain =

fatal• Blood for transfusions must be carefully analyzed

– Determine blood type: expose recipients blood to antibodies A and B– Cross-match: expose recipients blood to donor blood; reveals all cross-

reactions

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• Today in class we will discuss:–White Blood Cells (WBCs)• Categories of WBCs based on their structure and function• The significance of changes in a differential count

–Structure and Function of platelets

–The definition of hemostasis• The mechanisms that control blood loss

–The definition of hemopoiesis • The role of hemocytoblasts, lymphoid stem cells, myeloid stem

cells, megakaryocytes, and reticulocytes– Locations of body sites used for blood collection and the

basic physical characteristics of blood samples drawn from those sites

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WBCs• WBCs vs. RBCs– Have nuclei and other organelles– Lack hemoglobin– 100s – 1000s of WBCs/uL vs. millions of RBCs/uL– Small fraction of WBCs circulate in blood– Lifespan = hrs (3 mo. for RBCs)

• General functions– Defend body against invasion by pathogens and foreign

proteins (lymphocytes)– Remove toxins, wastes– Attack abnormal or damaged cells (all other WBCs)

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WBCs• Types of WBCs distinguished by staining techniques– Granulocytes – abundant (usually stained) granules

(secretory vesicles and lysosomes)• Neutrophils - granules difficult to stain• Eosinophils - stain red-pink with acidic, red dye eosin• Basophils - stain deep purple-blue with basic dyes

– Agranulocytes - have smaller stained granules; nuclei darkly stained• Monocytes• Lymphocytes

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WBCs: Circulation• Small fraction of WBCs circulate in blood– Circulate for only small portion of life span (hrs)– Most in CT or lymphatic organs

• Migrate through loose and dense connective tissue• Use blood stream:– To travel from one organ to another– For rapid transportation to areas of injury or invasion

• When traveling through capillaries, can detect chemical signs of damage to surrounding tissues– Leave bloodstream to enter damaged area

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WBCs: Movement• 4 characteristics of circulating WBCs– Amoeboid movements (like “the blob”) allows movement

along walls of blood vessels and through tissues– Can move out of blood vessels (diapedesis)– Attracted to specific chemical stimuli (positive chemotaxis)

• Guides WBCs to invading pathogens, damaged tissues, and active WBCs

– Neutrophils, eosinophils, and monocytes capable of phagocytosis• Engulf pathogens, cell debris, and other materials• Neutrophils and eosinophils = microphages• Monocytes = macrophages

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Hierarchy of WBCs

• Lymphocytes (T cells, B cells, NKCs)• Phagocytes– Microphages• Eosinophils• Neutrophils

– Macrophages• Monocytes

• Basophils mast cells

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WBCs• Neutrophils – 50-70%• Lymphocytes – 20-30%• Monocytes – 2-8%• Eosinophils – 2-4%• Basophils - < 1%• Mnemonic:

Never Let Monkeys Eat BananasNeutrophils Lymphocytes Monocytes Eosinophils Basophils

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Neutrophils• Most abundant WBC in healthy individual (50-70% of

circulating WBCs)• Nucleus has 2-5 lobes = polymorphonuclear leukocytes

(PMNs)• Cytoplasm has pale granules

– Contain lysosomal enzymes and bactericidal compounds• Highly mobile = FIRST WBC to arrive at injury site• Release hormones

– Prostaglandins (coordinate local cellular activities)– Leukotrienes (coordinate tissue responses to injury or disease)

• Phagocytic cells (microphages); specialize in attacking/digesting bacteria

• 10-hr life span, only 30 min if actively engulfing

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Figure 19-10a White Blood Cells

Neutrophil LM 1500

RBC

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Lymphocytes• 20-30% of circulating WBCs• Smallest WBCs• Large nucleus with thin halo of cytoplasm• Most in CT and organs of lymphatic system– Part of the body’s specific defense system– e.g., T cells, B cells, natural killer cells (NKCs)

• NKCs important in preventing cancer– Detect and destruct abnormal tissue cells

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Figure 19-10e White Blood Cells

LM 1500Lymphocyte

RBC

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Monocytes• 2-8% of WBCs• Large cells with large nucleus• Become macrophages– Very phagocytic– Engulf large particles and pathogens

• Secrete substances that attract immune system cells and fibroblasts to injured area

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Figure 19-10d White Blood Cells

LM 1500Monocyte

RBC

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Eosinophils• 2-4% of WBCs• Red/acid-staining granules• Two-lobed nucleus• Phagocytic cells (microphages)– Engulf bacteria, protozoa, cellular debris

• Exocytose toxic compounds• Defend against large multicellular parasites

(flukes, parasitic worms)• Also involved in allergic reactions

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Figure 19-10b White Blood Cells

LM 1500Eosinophil

RBC

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Basophils• <1% of circulating WBCs• Numerous granules; dark/stained with

basic (blue-purple) dyes• Migrate to injury sites, release– Histamine• Dilates blood vessels

– Heparin• Prevents blood clotting and promotes inflammation

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Figure 19-10c White Blood Cells

LM 1500Basophil

RBC

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51Table 19-3, p 658

Table 19-3 Formed Elements of the Blood

Table 19-3 Formed Elements of the Blood

52Table 19-3, p 658

WBC Count (Differential)

• Done with blood smear, manually counted in field of 100 WBC

• Changes in circulating counts of WBCs caused by:– Pathogenic infections– Inflammation– Allergic reactions

• Abnormal conditions– Leukopenia: low, inadequate numbers of WBCs– Leukocytosis: high, excessive numbers of WBCs

• Modest increase = infection, inflammation, allergic reactions• Extreme case = leukemia

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Platelets• Cell fragments involved in clotting system• Flattened discs: appear round when viewed

from above and spindle-shaped in section or blood smear

• 350,000/uL of circulating blood (accounts for 2/3 of platelets)– Other 1/3 in spleen and other vascular organs

• Produced in bone marrow• Continuously replaced– Life cycle = 9-12 days, then phagocytosed in

spleen

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Platelet Function in Hemostasis• Transport chemicals/

enzymes important to clotting process

• Form temporary patch in walls of damaged vessel

• Cause contraction after clot formation

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Figure 19-12 The Vascular, Platelet, and Coagulation Phases of Hemostasis and Clot Retraction (Step 3)

Hemostasis• = process of stopping blood loss from the

vessels, or the cessation of bleeding

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Figure 19-12 The Vascular, Platelet, and Coagulation Phases of Hemostasis and Clot Retraction

Hemostasis• 3 Phases of Hemostasis:

1. Vascular Phase• Vascular spasm – smooth muscle contraction to decrease the vessel

diameter• Blood flow stops or slows as a result

2. Platelet Phase• Platelet adhesion occurs – platelets adhere to any exposed surface• Platelet plug forms & continues to add to it

3. Coagulation Phase• Fibrinogen produces fibrin & the fibers add to platelets along with

other chemicals• Covers the platelet plug forming a clot

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Platelets• Abnormal conditions– Thrombocytopenia• Low platelet count• Due to decreased production or increased destruction• Symptoms include: bleeding in GI tract, skin, inside CNS

– Thrombocytosis• High platelet count• Accelerated formation of infection, inflammation, cancer

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Figure 19-11 The Origins and Differentiation of Formed Elements

Blast Cells

Progenitor Cells

Lymphoid Stem CellsMyeloid Stem Cells

HemocytoblastsRed bone marrow

Proerythroblast

Erythroblast stages

Ejection ofnucleus

Reticulocyte

Erythrocyte

Red Blood Cells(RBCs)

Megakaryocyte

Platelets

Myelocytes

Band Cells

Agranulocytes

Monoblast

Promonocyte

Monocyte

Lymphoblast

Prolymphocyte

Lymphocyte

Myeloblast

Basophil Eosinophil Neutrophil

Granulocytes

White Blood Cells (WBCs)

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Hemopoiesis• = blood cell formation and differentiation• Hemocytoblasts = Stem cells in myeloid tissue that

divide to produce:1. Myeloid stem cells become RBCs, some WBCs 2. Lymphoid stem cells become lymphocytes

• Megakaryocytes =• Giant cells in bone marrow• Manufacture platelets from cytoplasm

• Reticulocyte = immature red blood cell that has shed its nucleus• is released into circulation where it will complete its maturation

process to form a mature RBC. • last stage of development before RBC completes erythropoiesis

(= RBC formation)60

Collection Methods• Venipuncture– From median cubital vein– Superficial veins easy to locate– Walls of veins thinner than arteries– Venous BP lower, so wound seals quickly

• Peripheral capillaries– From finger, ear lobe, toe, heel puncture (“stick”)– Drop of blood to prepare blood smear

• Arterial puncture– From radial artery (wrist) or brachial artery (elbow)– Check efficiency of gas exchange at lungs

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