THE BLOOD: key words and concepts
 Plasma
 Formed elements
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Erythrocytes (RBC)
Leukocytes (WBC)
Lymphocytes
Monocytes
Granulocytes
neutrophils
eosinophils
basophils
Platelets
 Hemoglobin
o2
CO2
 Hematocrit
 Anemia
 Carbonic anhydrase
 Bicarbonate
H CO3Hematopoietic stem cells
HEMATOCYTOBLAST
Proerythroblast, Myeloblast,
Lymphoblast, Monoblast,
Megakaryoblast
Erythropoiesis, Erythropoietin
Blood
- more key words
 Hemostasis Coagulation
 Plasma:
 Antibodies
H2O, solutes, Proteins:
Albumins,
Globulins,
Clotting factors:
Fibrinogen fibrin
Prothrombin thrombin
 Extrinsic, intrinsic clotting
pathways
 ‘Clotting cascade’
Fibrinolysis: clot dissolution
Plasminogen Plasmin
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Antigens
ABO, RH blood types
Agglutination
Type and cross-match
Transfusion
Hemolysis
COMPOSITION OF BLOOD
 Blood
 Composed of plasma and formed elements

(55%)
(45%)
 Complex transport medium --performs vital pickup
and delivery services for the body
 WORKING WITH THE MUSCLES AND SKIN -Blood is the
key to the
heat-regulating mechanism of the body
 Blood volume
 Young adult male has approximately 5-6 L of blood,

female 4-5 Liters
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occupying the CARDIOVASCULAR SYSTEM
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(IN THE INTRAVASCULAR
SPACE)
A UNIT of donated whole blood = .5 liter
Composition of Whole Blood
FORMED ELEMENTS OF BLOOD
 Red blood cells (RBCs), also called
ERYTHROCYTES
 Most numerous of the formed elements
 no nucleus -- shaped like tiny biconcave
disks

also do not contain ribosomes,
mitochondria, et al.
PRIMARY COMPONENT
 IS HEMOGLOBIN
Function of RBCs
TRANSPORT OF OXYGEN AND CARBON
DIOXIDE
depends on hemoglobin
Carbonic anhydrase: enzyme in RBCs
that catalyzes a reaction that joins carbon
dioxide and water to form carbonic acid
Carbonic acid: dissociates and
GENERATES BICARBONATE IONS,
which diffuse out of the RBC and
TRANSPORT CARBON DIOXIDE
IN THE BLOOD PLASMA (as H2CO3-)
Hemoglobin
 Within each RBC are approximately 200 to 300 million
molecules of hemoglobin
 HEMOGLOBIN IS COMPOSED OF FOUR GLOBIN
CHAINS, EACH ATTACHED TO A HEME (iron)
GROUP
 Hemoglobin is able to unite with four oxygen molecules to
form oxyhemoglobin to allow RBCs to
transport oxygen
where it is needed
 ANEMIA: a decrease in the number or volume of
functional RBCs in a given unit of whole blood,
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(which means there is a decreased level of HEMOGLOBIN)
Formation of RBCs,
cells
& other blood
 ERYTHROPOIESIS: the process of RBC
formation
 Formation begins in the red bone marrow as
HEMATOPOIETIC STEM CELLS
 and goes through several stages of development to
become erythrocytes; entire maturation process
requires approximately 4 days.

Once in the bloodstream, RBC lifespan is around

120 days
(4 months)
Anemia,
Erythropoietin,
 AN-EMIA literally, ‘no blood’ --
actually means
‘too little blood’ either decreased numbers of RBC’s,
or RBC’s with decreased levels of HGB in them
nml male: Hgb is 14-16 gm/dl
nml female Hgb is 12-14 gm/dl
there are many possible causes for anemia
 If Erythropoiesis is the formation of Blood,
then what does the Hormone Erythropoietin do?
Stimulates RBC production
 ERYTHROPOIETIN (EPO) is a hormone that is produced
in the kidneys.
 Produced by the kidneys when specialized cells in the
kidneys sense oxygen level in the body's tissues is low.
 THIS HORMONE STIMULATES THE PRODUCTION
OF RED BLOOD CELLS IN THE BONE MARROW.
 When introduced synthetically by injection,
erythropoietin can help treat anemia by boosting the
number of red blood cells in the body. Injections might be
required because the kidneys are not producing enough
erythropoietin on their own or when a patient is
experiencing severe anemia.
The hematopoietic STEM cell,
the Hemocytoblast
White blood cells (WBCs), also called leukocytes
 Granulocytes:
 NEUTROPHILS: approx. 65% of total WBC count in a
normal blood sample;
highly mobile and active
PHAGOCYTIC CELLS; capable of diapedesis
;cytoplasmic granules contain lysosomes. ELEVATED #’s
during ACUTE MICROBIAL INFECTIONS
 EOSINOPHILS: 2% to 5% of circulating WBCs;
 numerous in lining of respiratory and digestive tracts;;
provide protection against infections caused by parasitic
worms and are increased in ALLERGIC REACTIONS
 Basophils: only 0.5% to 1% of circulating WBCs; motile and
capable of diapedesis; cytoplasmic granules contain histamine
and heparin (mediators of INFLAMMATION)
Neutrophil,
(PMN)
Eosinophil
Basophil)
Agranulocytes –Lymphocytes, Monocytes
 LYMPHOCYTES: the smallest leukocytes
 T lymphocytes and B lymphocytes have
an important role in immunity:
 T LYMPHOCYTES directly attack an infected or cancerous cell,
B LYMPHOCYTES produce antibodies against specific
antigens
 MONOCYTES: largest leukocytes; mobile and highly
phagocytic cells
 WBC numbers: 1 mm3 of normal blood usually contains
5000 to 9000 leukocytes, with diffnt % for each type;
 WBC numbers have clinical significance because they
change with certain abnormal conditions.
 *** In general, WBC goes up in : INFECTION and
INFLAMMATION ***
White Blood Cell Count:
WBC numbers:
1 mm3 of normal blood usually contains
5,000 to 9,000 leukocytes,
with diffnt % for each type;
WBC numbers have clinical significance because
they change with certain abnormal conditions.
***
In general, WBC goes up in :
INFECTION and INFLAMMATION ***
FORMED ELEMENTS OF BLOOD (cont.)
 Formation of WBCs
 Granular and agranular leukocytes mature from the
undifferentiated hematopoietic stem cell
 Neutrophils, eosinophils, basophils, and a few
lymphocytes and monocytes originate in red bone
marrow; most lymphocytes and monocytes develop
from hematopoietic stem cells in lymphatic tissue
FORMED ELEMENTS OF BLOOD (cont.)
 Structure
 In circulating blood, platelets are small, pale bodies that
appear as irregular spindles or oval disks
 Three important properties are agglutination,
adhesiveness, and aggregation
 Platelet counts in adults average 250,000/mm3 of blood;
normal range is 150,000 to 400,000/mm3
FORMED ELEMENTS OF BLOOD (cont.)
 Functions of platelets
 Important role in hemostasis and blood coagulation;
secondary role in defending against bacterial attacks
 Hemostasis: refers to stoppage of blood flow; however,
if injury is extensive, the blood-clotting mechanism is
activated to assist
FORMED ELEMENTS OF BLOOD (cont.)
 Platelet plug formation
 One to five seconds after injury to vessel wall, platelets
adhere to damaged endothelial lining and to each other,
forming a platelet plug
 Temporary platelet plug is an important step in
hemostasis
 Normal platelets (positive charge) adhere to damaged
capillary wall and underlying collagen fibers, both of
which have a negative charge
 “Sticky platelets” form physical plug and secrete several
chemicals involved in the coagulation process
 Formation and life span of platelets (7 to 10 days):
formed in red bone marrow, lungs, and spleen by
fragmentation of megakaryocytes
BLOOD TYPES: BLOOD GROUPS
 The ABO system
 Every person’s blood belongs to one of four ABO
blood groups
 Named for antigens on RBC membranes
 Type A: antigen A on RBCs
 Type B: antigen B on RBCs
 Type AB: both antigens A and B on RBCs; known as
universal recipient
 Type O: neither antigen A nor B on RBCs; known as
universal donor
BLOOD TYPES: BLOOD GROUPS (cont.)
 The Rh system
 Rh-positive: Rh antigen is present on the RBCs
 Rh-negative: RBCs have no Rh antigen present
 Anti-Rh antibodies are not normally present in blood;
anti-Rh antibodies can appear in Rh-negative blood if
it has come in contact with Rh-positive RBCs
BLOOD PLASMA
 Plasma: liquid part of blood; clear, straw-colored fluid;
composed of 90% water and 10% solutes (Figure 17-20)
 Solutes: 6% to 8% of plasma solutes are proteins, consisting
of three main compounds
 Albumins: help maintain osmotic balance of the blood
 Globulins: essential component of the immunity mechanism
 Fibrinogen: key role in blood clotting
 Plasma proteins have an essential role in maintaining normal
blood circulation
BLOOD CLOTTING: COAGULATION
 Mechanism of blood clotting: goal of
coagulation is to stop bleeding and prevent loss
of vital body fluid in a swift and sure method
 Classic theory of coagulation advanced in 1905
 Identified four components critical to coagulation
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Prothrombin
Thrombin
Fibrinogen
Fibrin
BLOOD CLOTTING: COAGULATION
(cont.)
 Current explanation of coagulation involves three
stages
 Stage 1: production of thromboplastin activator by
either of the following:
 Chemicals released from damaged tissues (extrinsic
pathway)
 Chemicals present in the blood (intrinsic pathway)
 Stage 2: conversion of prothrombin to thrombin
 Stage 3: conversion of fibrinogen to fibrin and
production of fibrin clot
BLOOD CLOTTING: COAGULATION
(cont.)
 Conditions that oppose clotting
 Clot formation in intact vessels is opposed
 Several factors oppose clotting
 Perfectly smooth surface of the normal endothelial
lining of blood vessels does not allow platelets to
adhere
 Antithrombins: substances in the blood that oppose or
inactivate thrombin; prevent thrombin from converting
fibrinogen to fibrin (e.g., heparin)
BLOOD CLOTTING: COAGULATION
(cont.)
 Conditions that hasten clotting
 Rough spot in the endothelium
 Abnormally slow blood flow
 Clot dissolution Fibrinolysis: physiological
mechanism that dissolves
 Fibrinolysin: enzyme in the blood that catalyzes the
hydrolysis of fibrin, causing it to dissolve
 Additional factors are presumed to aid clot
dissolution (e.g., substances that activate
profibrinolysin)
THE BIG PICTURE: BLOOD AND THE
WHOLE BODY
 Blood plasma transports substances, including heat, around the
body, linking all body tissues together
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Substances can be transported between almost any two points in the
body
 Blood tissue contains formed elements—blood cells and platelets
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RBCs assist in the transport of oxygen and carbon dioxide
WBCs assist in the defense mechanisms of the whole body
Platelets prevent loss of the fluid that constitutes the internal
environment
 No organ or system of the body can maintain proper levels of
nutrients, gases, or water without direct or indirect help from
blood

Other systems assist the blood
 Blood is useless unless it continues to transport, defend, and
maintain balance