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Blood Summary Essay

Blood is composed of
formed elements and plasma
Hematocrit is a measure of
one formed element, erythrocytes, as a % of total blood volume.
Blood’s physical characteristics and volume
viscous, slightly alkaline fluid representative about 8% of total body weight

normal adult blood volume is about 5 L

Distribution functions of blood include
1.) delivery of oxygen and nutrients to body tissues
2.) removal of metabolic wastes
3.) transport of hormones
Regulation functions of blood are
maintenence of:
1.) body temperature
2.) constant blood of pH
3.) adequate fluid volume
Protective functions of blood are
1.) hemostasis
2.) prevention of infection
Blood plasma is what color and
stra-colored, viscous fluid
90% water
the remaining 10% of blood plasma is
solutes such as nutrients, respiratory gases, salts, hormones, proteins
plasma makes up what percent of whole blood?
55%
Plasma proteins are made by what organ
liver
plasma proteins include
albumin
globulins
fibrinogen
albumin is an important
blood buffer and contributes to the osmotic pressure of blood.
formed elements account for what percent of whole blood? and what are they?
45%
– erythrocytes
– leukocytes
– platelets
all formed elements in the blood arise from
hemocytoblasts in the bone marrow
Erythrocytes (RBCs) are
small,
biconcave
cells containing large amounts of hemoglobin
have no nucleus
few organelles
what allows RBCs to change shape as they pass through capillaries?
spectrin
what’s the major function of RBCs?
oxygen support
in the lungs, oxygen binds to what and what does it produce?
hemoglobin molecules, oxyhemoglobin
in body tissues, oxygen disassociates from what and what does it produce?
iron, deoxyhemoglobin
what do RBCs begin as?
hemocytoblasts
erythropoiesis stages
1.) hemocytoblasts
2.) proerythroblast (committed cell)
3.) erythroblast (early and late stages)
4.) normoblast
5.) reticulocyte
during the erythropoiesis process, what happens?
hemoglobin accumulates and the organelles and nucleus are extruded

differentiation of reticulocytes is completed in the bloodstream

what 2 things enhance erythropoiesis?
erythropoietin (EPO) and testosterone
erythropoiesis
the process of producing red blood cells by the stem cells in the bone marrow
erythropoietin EPO
A hormone produced and released by the kidney that stimulates the production of red blood cells by the bone marrow.
what 3 things are essential for production of hemoglobin?
1.) Iron
2.) vitamin B12
3.) folic acid
How many days make up the RBCs life span?
120 days
How are old and damaged erythrocytes removed from circulation?
by macrophages of the liver and spleen
what is released iron from hemglobin stored as?
ferritin or hemodestrin to be reused
the balance of the heme group is degraded to and secreted in what?
billirubin and secreted in bile
amino acids of globin are…
metabolized or recycled
Erythrocyte disorders include
anemia and polycythemia
leukocytes are
WBCs, all are nucleated and have crucial roles in defending against disease.
two main leukocyte categories:
1.) granulocyte
2.) agranulocytes
Granulocytes include
Neutrophils
Eosinophils
Basophils
Basophils contain what?
contain histamine
histamine does 2 things
enhances migration of leukocytes to inflammatory sites and promotes vasodilation
Neutrophils
are active phagocytes
against bacteria
Eosinophils
attack parasitic worms and their numbers increase during allergic reactions
Agranulocytes
have crucial roles in immunity

– lymphocyts = immune cells
– monocytes = differentiate into macrophages

Leukopoiesis
is directed by colony-stimulating factors ad interleukins released by supporting cells of the bone marrow and mature WBCs
Leukopoiesis
the formation of white blood cells, begins in the marrow.
Leukocyte disorders
include leukemias and infectious mononucleosis
Platelets
fragments of large, megakaryocytes formed in red marrow.
role of platelets when a blood cell is damaged
form a plug to help prevent blood loss and play a central role in the clotting cascade
Hemostasis
prevention of blood loss
the 3 major phases of hemostasis
1.) vascular spasm
2.) platelet plug formation
3.) coagulation
What do spasms of smooth muscle in blood vessel walls and accumulation of platelets (platelet plug) at the site of vessel injury provide?
a temporary means of stopping blood loss until coagulation occurs
coagulation of blood may be initiated by either the
intrinsic or extrinsic pathways
Platelet phospholipid PF3
is crucial to both intrinsic or extrinsic pathways.
Tissue Factor TF (Factor III)
exposed by tissue injury allows the extrinsic pathway to bypass many steps of the intrinsic patway
a series of activated procoagulants oversees the
intermediate steps of each coagulation cascade
the pathways converse as
prothrombin is converted to thrombin
what happens after a clot is formed?
clot retraction occurs
what happens during clot retraction?
serum is squeeze out and the ruptured vessel edges are drawn together
how is the vessel repaired?
by smooth muscle, connective tissue, and endothelial cell proliferation and migration
fibrinolysis
clot digestion that occurs when healing is complete
abnormal expansion of clots is prevented by
removal of coagulation factors in contact with rapidly flowing blood by inhibition of activated blood factors.
Prostacyclin PGI2 & NO
secreted by endothelial cells help prevent undesirable clotting
Thromboembolic disorders
involved undesirable clot formation which can blood vessels
DIC
is a condition of body wide clotting in undamaged blood vessels and subsequent hemorrhages,

disseminated intravascular coagulation

Thrombocytopenia
a deficit of platelets, causes spontaneous bleeding from small blood vessels
Thrombocytopenia
a bleeding disorder characterized by an abnormal decrease in the number of platelets in the blood, which impairs the clotting process
petechiae
Small, pinpoint hemorrhages
Hemophilia
sex-linked recessive disorder defined by the absence of one or more proteins required for blood clotting

is caused by a genetic deficiency of certain coagulation factors.

liver disease can cause
bleeding disorders because many coagulation proteins are formed by this organ
whole blood transfusions
are given to replace severe and rapid blood loss.
packed RBCs are given to
replace lost O2 carrying capacity
blood group is based on
agglutinogens (antigens) present on red blood cell membranes
when mismatched blood is transfused,
the recipients agglutinins (plasma antibodies) clump the foreign RBCs
the clumped cells
are lysed
blood vessels may be blocked by
clumped RBCs
released hemoglobin may precipitate in
the kidney tubules, causing renal shutdown
before whole blood can be transfused,
it must be typed and cross matched so that transfusion reactions are avoided.
the most important blood groups for which blood must be typed are
ABO and Rh types
plasma volume can be replaced with
balanced electrolyte solutions

and these are generally preferred over plasma expanders

diagnostic blood tests
can provide large amounts of information about the current status of the blood and of the body as a whole
erythropoietin
the hormonal stimulus that prompts RBC formation
the WBC that can become an antibody secreting cell is the
lymphocyte
factor XI does not
promote multiple steps in the clotting pathway
the normal pH of blood is about
7.4
suppose your blood was AB positive,
– agglutinogens A and B are present on your RBCs

– there are not anti-A or anti-B antibodies in your plasma

– your blood is Rh+

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