Transcript Chapter 21: Blood Vessels and Circulation

Chapter 19: The Blood
BIO 211 Lecture
Instructor: 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 tempsensitive 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 cells
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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
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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. 645
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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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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
Fig. 19-7, p. 651
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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
Fig. 19-9, p. 654-655
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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 crossreactions
Fig. 19-7b, p. 651
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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
Neutrophils Lymphocytes
Monkeys Eat
Monocytes
Eosinophils
Bananas
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
RBC
Neutrophil
LM  1500
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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
RBC
Lymphocyte
LM  1500
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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
RBC
Monocyte
LM  1500
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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
RBC
Eosinophil
LM  1500
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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
RBC
Basophil
LM  1500
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Table 19-3 Formed Elements of the Blood
Table 19-3, p 658
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Table 19-3 Formed Elements of the Blood
Table 19-3, p 658
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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
Figure 19-12 The Vascular, Platelet, and Coagulation Phases of Hemostasis
and Clot Retraction (Step 3)
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Hemostasis
• = process of stopping blood loss from the
vessels, or the cessation of bleeding
Figure 19-12 The Vascular, Platelet, and Coagulation Phases of
Hemostasis and Clot Retraction
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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
Hemocytoblasts
Red bone marrow
Lymphoid Stem Cells
Myeloid Stem Cells
Progenitor Cells
Blast Cells
Myeloblast
Proerythroblast
Monoblast
Lymphoblast
Promonocyte
Prolymphocyte
Myelocytes
Erythroblast stages
Band Cells
Ejection of
nucleus
Megakaryocyte
Reticulocyte
Erythrocyte
Red Blood Cells
(RBCs)
Platelets
Basophil
Eosinophil
Neutrophil
Monocyte
Lymphocyte
Agranulocytes
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)
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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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