Transcript Slides - Websupport1

Anatomy & Physiology
SIXTH EDITION
Lecture 19, Blood
Lecturer: Dr. Ebadi
Room P313
Phone: (718) 260-5285
E-Mail: [email protected]
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
Learning Objectives
• List the components of the cardiovascular system
and explain the major functions of this system.
• Describe the important components and major
functions of the blood
• List the characteristics and functions of red blood
cells.
• Describe the structure of hemoglobin and indicate
its functions.
• Discuss red blood cell production and maturation.
Learning Objectives
• Explain the importance of blood typing and the
basis for ABO and Rh incompatibilities.
• Categorize the various white blood cells on the
basis of structure and function.
• Describe the structure, function and
production of platelets.
• Describe the reaction sequences responsible
for blood clotting.
The cardiovascular system
• Provides a mechanism for rapid transport of
nutrients, waste products, respiratory gases
and cells
Functions and Composition of Blood
• Fluid connective tissue
• Functions include
• Transporting dissolved gases, nutrients,
hormones, and metabolic wastes
• Regulating pH and ion composition of
interstitial fluids
• Restricting fluid loss at injury sites
• Defending the body against toxins and
pathogens
• Regulating body temperature by absorbing
and redistributing heat
Blood Composition
Blood
Plasma 46-63%
Plasma Protein 7%
Water 92%
Formed Elements 37-54%
Other Solutes 1%
Albumin
Globulin
Fibrinogen
Regulatory Proteins
Platelets
WBC
RBC 99.9%
Monocytes
Eg. Electrolytes
Neatrophils
Basophils
Lymphocytes
Eosinophils
The composition of blood
• Plasma and formed elements comprise whole
blood.
• Plasma elements include blood cells:
• Red blood cells (RBC)
• White blood cells (WBC)
• Platelets
• Can fractionate whole blood for analytical or
clinical purposes
The Composition of Whole Blood
Fresh whole blood for testing in a lab is usually collected from
a superficial vein.
When checking the
efficiency of gas
exchange, it may be
necessary to draw a
blood sample from
an artery
The Composition of Whole Blood
The chief difference between plasma and interstitial fluid involves
the concentration of dissolved oxygen and proteins.
The Composition of Whole Blood
Hemopoiesis
• Process of blood cell formation
• Hemocytoblasts are circulating stem cells that
divide to form all types of blood cells
• Whole blood from anywhere in the body has
roughly the same temperature (38ºC), pH (7.4)
and viscosity.
• Bright red color if taken from artery
• Dull red color if taken from vein
Plasma
• Accounts for 46-63% of blood volume
• 92% of plasma is water
• Higher concentration of dissolved oxygen and
dissolved proteins than interstitial fluid
Plasma proteins
• more than 90% are synthesized in the liver
• Albumins are the most abundant plasma proteins
• 60% of plasma proteins
• Responsible for viscosity and osmotic pressure
of blood
Additional Plasma Proteins
• Globulins
• ~35% of plasma proteins
• Include immunoglobins which attack foreign
proteins and pathogens
• Include transport globulins which bind ions,
hormones and other compounds
• Fibrinogen
• Converted to fibrin during clotting
• Are necessary for blood clotting
• Removal of fibrinogen leaves serum
Red Blood Cells
Abundance of RBCs
• Erythrocytes (RBC) account for slightly less than
half the blood volume, and 99.9% of the formed
elements.
• Hematocrit measures the percentage of whole
blood occupied by formed elements
• Commonly referred to as the volume of packed
red cells
Structure of RBCs
• Biconcave disc, providing a large surface to
volume ration
• Shape allows RBCs to stack, bend and flex
• RBCs lack organelles
• Typically degenerate in about 120 days.
The Anatomy of Red Blood Cells
Hemoglobin
• Molecules of hemoglobin account for 95% of the
proteins in RBCs
• Hemoglobin is a globular protein, formed from
two pairs of polypeptide subunits
• Each subunit contains a molecule of heme
which reversibly binds an oxygen molecule
• Damaged or dead RBCs are recycled by
phagocytes
The Structure of Hemoglobin
“Sickling” in Red Blood Cells
RBC life span and circulation
• Replaced at a rate of approximately 3 million new
blood cells entering the circulation per second.
• Replaced before they hemolyze
• Components of hemoglobin individually recycled
• Heme stripped of iron and converted to
biliverdin, then bilirubin
• Iron is recycled by being stored in phagocytes, or
transported throughout the blood stream bound
to transferrin
Red Blood Cell Turnover
RBC Production
• Erythropoeisis = the formation of new red blood
cells
• Occurs in red bone marrow
• Process speeds up with in the presence of EPO
(Erythropoeisis stimulating hormone)
• RBCs pass through reticulocyte and
erythroblast stages
Stages of RBC Maturation
Blood types
• Determined by the presence or absence of surface
antigens (agglutinogens)
• Antigens A, B and Rh (D)
• Antibodies in the plasma (agglutinins)
• Cross-reactions occur when antigens meet
antibodies
Blood Typing and Cross-Reactions
Blood Type Testing
Rh Factors and Pregnancy
The White Blood Cells
Leukocytes
• Have nuclei and other organelles
• Defend the body against pathogens
• Remove toxins, wastes, and abnormal or
damaged cells
• Are capable of amoeboid movement
(margination) and positive chemotaxis
• Some are capable of phagocytosis
Types of WBC
Granular and agranular
• Granular leukocytes
• Neutrophils – 50 to 70 % total WBC
population
• Eosinophils – phagocytes attracted to
foreign compounds that have reacted with
antibodies
• Basophils – migrate to damaged tissue
and release histamine and heparin
Types of WBC
• Agranular leukocytes
• Agranular leukocytes are formed inred bone
marrow.
• Agranular leukocytes include:
• Monocytes - become macrophage
• Lymphocytes – includes T cells, B cells, and
NK cells
White Blood Cells
Differential count
• Indicates a number of disorders
• Leukemia = inordinate number of leukocytes
WBC Production
• Granulocytes and monocytes are produced by
bone marrow stem cells
• Divide to create progenitor cells
• Stem cells may originate in bone marrow and
migrate to peripheral tissues
• Several colony stimulating factors are involved in
regulation and control of production
The Origins and Differentiation of Formed
Elements
Animation: The origins and differentiation of blood cells (see tutorial)
Figure 19.12
Platelets
• Flattened discs
• Circulate for 9-12 days before being removed by
phagocytes
Platelet functions
• Transporting chemicals important to clotting
• Forming temporary patch in walls of damaged
blood vessels
• Contracting after a clot has formed
Platelet production (thrombocytopoiesis)
• Megakaryocytes release platelets into circulating
blood
• Rate of platelet formation is stimulated by
thrombopoietin, thrombocyte-stimulating factor,
interleukin-6, and Multi-CSF
Hemostasis
• Prevents the loss of blood through vessel walls
• Three phases –
• Vascular phase
• Platelet phase
• Coagulation phase
Hemostasis
• Vascular phase
• Local blood vessel constriction (vascular
spasm)
• Platelet phase
• Platelets are activated, aggregate at the site,
adhere to the damaged surfaces
The Vascular and Platelet Phases of Hemostasis
Coagulation phase
• Factors released by platelets and endothelial cells
interact with clotting factors to form a clot
• Extrinsic pathway
• Intrinsic pathway
• Common pathway
• Suspended fibrinogen is converted to large
insoluble fibrin fibers
The Coagulation Phase of Hemostasis
The Coagulation Phase of Hemostasis
Clot retraction
• Final phase of healing
• Platelets contract and pull the edges of the vessel
together
Fibrinolysis
• Clot gradually dissolves through action of
plasmin
• Activated form of plasminogen
• Clotting can be prevented through the use of
drugs that depress the clotting response or
dissolve existing clots
• Anticoagulants include heparin,
coumadin, aspirin, dicumarol, t- PA,
streptokinase, and urokinase
You should now be familiar with:
• The components of the cardiovascular system and
its major functions.
• The important components and major functions
of the blood.
• The characteristics and functions of red blood
cells.
• The structure of hemoglobin and its functions.
• Red blood cell production and maturation.
You should now be familiar with:
• The importance of blood typing and the basis for
ABO and Rh incompatibilities.
• The various white blood cells.
• The structure, function and production of
platelets.
• The reaction sequences responsible for blood
clotting.