Lecture Outline
Blood
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
The Composition and Functions of Blood
o
Functions of Blood
•
Transport



•
Carries oxygen to tissues
Carries carbon dioxide and other wastes away
from tissues
Hormones
Defense


•
Defends body against pathogens
Removes dead and dying cells
Regulation



Body temperature
Water-salt balance
Body pH
Components of Blood
o
Plasma
•
•
•
Liquid portion of blood
About 92% is water
About 8% is composed various salts
and organic molecules
Plasma proteins
•
Albumins
Globulins






Alpha and beta – produced by the liver
Gamma - antibodies
Fibrinogen – functions in blood clotting
Help maintain homeostasis
Formed Elements
o
Produced continuously in the red
bone marrow of the:
•
•
•
•
•
Skull
Ribs
Vertebrae
Iliac crests
Ends of long bones
Formed Elements
o
Hematopoiesis
•
Multipotent stem cells – red bone
marrow cells
Multipotent cells replicate
Each daughter cell then differentiates
•
•
Myeloid stem cells further differentiates






Red blood cells
Granular leukocytes
Monocytes
Megakaryocytes
Lymphatic stem cells differentiate to
produce the lymphocytes
Formed Elements
o
Red Blood Cells (erythrocytes)
•
•
•
•
•
Small, biconcave disks
Anucleate
4 to 6 million per mm3
Transport oxygen
Contain hemoglobin



Respiratory pigment
Oxyhemoglobin is formed when oxygen
binds with hemoglobin
Hemoglobin that is not combined with
oxygen is called deoxyhemoglobin
Formed Elements
•
Production of red blood cells






Myeloid stem cells give rise to
erythroblasts
Erythroblasts divide many times
As they mature, erythroblasts gain many
molecules of hemoglobin and lose their
nucleus and most of their organelles
Mature RBCs live about 120 days
About 2 million RBCs are produced per
second to keep RBC count in balance
Erythropoietin stimulates production and
maturation of RBCs
Formed Elements
•
Destruction of red blood cells
Destroyed in the liver and spleen
Hemoglobin is released





Globin portion is broken down into amino acids
that are recycled by the body
Iron is recovered and returned to the bone
marrow for reuse
Heme portion is degraded and is excreted as
bile pigments by the liver
Bilirubin
Biliverdin
Formed Elements
•
Anemia



Illness characterized by tiredness
Cells are not getting enough oxygen due
to decreased hemoglobin or decreased
number of red blood cells
Hemolysis can also cause anemia
Formed Elements
o
White Blood Cells (leukocytes)
•
•
•
•
•
Usually larger than RBCs
Nucleated
Do not contain hemoglobin
About 5,000-11,000 per mm3
Functions include



•
•
Fighting infection
Destroying dead or dying body cells
Recognizing and killing cancerous cells
Derived from stem cells in the red bone
marrow
Able to leave the blood stream
Formed Elements
•
Types of White Blood Cells
Granular leukocytes




Neutrophils
Most abundant of the WBCs
First type of WBC to respond to an infection
Engulf pathogens during phagocytosis
Eosinophils
Increase in number during parasitic worm
infections
Lessen an allergic reaction during an allergic
attack
Basophils
Release histamines – dilates blood vessels and
causes contraction of smooth muscle
Release heparin – prevents clotting and
promotes blood flow
Formed Elements
Agranular leukocytes



Lymphocytes
Specific immunity
Recognize and destroy cancer cells
B lymphocytes produce antibodies
T lymphocytes attack and destroy any cell
with a foreign antigen
Monocytes
Largest of the WBCs
Differentiate into macrophages that
phagocytize pathogens, old cells, and
cellular debris
Stimulate other WBCs to defend the body
Platelets and Hemostasis
o
Platelets
•
•
•
o
Fragments of megakaryocytes
150,000-300,000 per mm3 of blood
Lifespan about 10 days
Hemostasis
•
•
Cessation of bleeding
3 events:
Vascular spasm – constriction of a broken blood
vessel
Platelet plug formation




In a broken blood vessel, collagen fibers are exposed
Platelets adhere to collagen and aggregation of
platelets result in a platelet plug
Platelets and Hemostasis
Coagulation – blood clotting




Requires many protein clotting factors
Two mechanisms for activation of clotting
Intrinsic mechanism – clotting factors
intrinsic to the blood – exposed collagen
Extrinsic mechanism – clotting factors
extrinsic to the blood - thromboplastin
Clotting process is self-limiting and confined to
the area of injury
Platelets and Hemostasis
 Four steps:
- Prothrombin activator is
formed
- Prothrombin activator
converts prothrombin to
thrombin
- Thrombin converts
fibrinogen to fibrin
- Fibrin threads wind
around platelet plug and
trap RBCs
Platelets and Hemostasis
•
Disorders of hemostasis
Thrombocytopenia – low platelet count
Hemophelias – inherited clotting disorders
caused by deficiencies of clotting factors
Thrombus – stationary blood clot
Embolus – dislodged blood clot
Thromboembolism – dislodged clot blocks
a blood vessel







Pulmonary thromboembolism
Cerebrovascular accident or stroke
Capillary Exchange
•
Lymph has the same composition as
tissue fluid
Edema
•
Localized swelling
Accumulation of tissue fluid
Caused by:








Increase in capillary permeability
Decrease in the uptake of water at the venous
end of blood capillaries
Increase in venous pressure
Insufficient uptake of tissue fluid by the
lymphatic capillaries
Blocked lymphatic vessels
Blood Typing and Transfusions
o
Blood transfusion
•
•
Transfer of blood from one individual
into the blood of another
Blood must be typed so that
agglutination does not occur
Blood Typing and Transfusions
o
ABO Blood Groups
•
•
•
•
•
Based on the presence or absence of
inherited antigens
Type A blood has type A antigen and
anti-B antibodies
Type B blood has type B antigen and
anti-A antibodies
Type AB blood has both antigens and
neither antibodies
Type O blood has no AB antigens and
both antibodies
Blood Typing and Transfusions
•
•
•
•
Agglutination occurs if
antibodies in the
plasma combine with
the antigens on the
surface of the RBC
Type O blood is the
universal donor
Type AB blood is the
universal recipient
Autotransfusion
technology and blood
substitutes are
alternatives to
matching blood types
Blood Typing and Transfusions
o
•
Rh Blood Groups
Rh- individuals do not have antibodies to the Rh factor until
they are exposed to it
Hemolytic disease of the newborn
•



May occur in subsequent pregnancies with an Rh+ baby and an
Rh- mother
Bilirubin in the blood of the newborn can lead to brain damage
or death
Prevented by giving Rh- women an Rh immunoglobulin
injection
Effects of Aging
o
Anemia
•
•
o
o
Iron deficiency anemia
Pernicious anemia
Leukemia
Clotting disorders, such as
thromboembolism
•
•
Associated with arteriosclerosis
May be controlled by diet and
exercise