CH. 21 Blood

Question 1

What are the three components of blood that can be separated through centrifuguation?

Answer 1

1. Erythrocytes: also known as red blood cells and form the lower layer of the centrifuged blood
2. Buffy coat: makes up middle layer; composed of leukocytes (white blood cells) and cell fragments called platelets
3. Plasma: a straw colored liquid that lies above the buffy coat in the centrifuge tube; generally makes up about 55% of blood

Question 2

What make up the formed elements of blood?

Answer 2

Erythrocytes and the components of the buffy coat (leukocytes and platelets)

Question 3

What are the functions of blood?

Answer 3

1. Transportation: transports numerous elements and compounds throughout the body
2. Regulation: regulates body functions including body temperature, regulates the pH levels in the body’s tissues, maintains normal fluid levels in the cardiovascular system
3. Protection: leukocytes help guard against infection by mounting an immune response if a pathogen or an antigen is found
   - antibodies, which are molecules that can bind to antigens until a leukocyte can completely kill or remove the antigen, are transported in plasma

Question 4

What is blood plasma composed of?

Answer 4

1. Water: makes up about 92% of plasma’s total volume; faciltates the transport of materials in plasma
2. Proteins: plasma proteins make up about 7% of the plasma; inlcude albumins, globulins, fibrinogen, and regulatory proteins
3. Other solutes

Question 5

What about the erythrocytes’ structure allows it to efficiently perform its function?

Answer 5

erythrocytes transport oxygen and carbon dioxide between the tissues and the lungs; a normal, mature erythrocyte is very small, and its unique biconcave disc structure allows respiratory gases to be loaded and unloaded rapidly and efficiently

Question 6

Why do erythrocites have a finite life span of about 120 days?

Answer 6

The absence of both a nucleus and cellular organelles comes at a
cost to the erythrocyte by reducing its life span. A mature erythrocyte
cannot synthesize proteins to repair itself or replace damaged
membrane regions. Aging and the wear-and-tear of circulation
through blood vessels cause erythrocytes to become more fragile
and less flexible

Question 7

What determines a person’s blood type?

Answer 7

The most commonly identified group of antigens in an erythrocyte is the ABO blood group; this group has two surface antigens called A and B and presence or absense of A and/or B surface antigen determines ABO blood type

■ Type A blood has erythrocytes with surface antigen A only.
■ Type B blood has erythrocytes with surface antigen B only.
■ Type AB blood has erythrocytes with both surface antigens
A and B.
■ Type O blood has erythrocytes with neither surface antigen
A nor B.

Question 8

Within ABO blood group, what blood types and antibodies are normally associated?

Answer 8

■ Type A blood has anti-B antibodies within its blood plasma.
■ Type B blood has anti-A antibodies within its blood plasma.
■ Type AB blood has neither anti-A nor anti-B antibodies within
its blood plasma.
■ Type O blood has both anti-A and anti-B antibodies within its
blood plasma.

Question 9

What can occur if a blood transfusion is distributed but with an incompatible donor?

Answer 9

antibodies in the plasma bind to surface antigens
of the transfused erythrocytes, and clumps of erythrocytes bind
together in a process termed agglutination (ă-glū-ti-nā′shŭn; ad =
to, gluten = glue). Clumped erythrocytes can block blood vessels
and prevent the normal circulation of blood. Eventually,
some or all of the clumped erythrocytes may rupture, a process
called hemolysis (hē-mol′i-sis; lysis = destruction). The release
of erythrocyte contents and fragments into the blood often causes
further reactions and ultimately may damage organs

Question 10

What are the five types of leukocytes and what are their distinguishable classes?

Answer 10

1. Granulocytes: have granules in their cytoplasm
   - Neutrophil: exhibit a multilobed nucleus with as many as five lobes interconnected by thin strands; remain in circulation until they enter tissue spaces to phagocytize infectious pathogens
   - Eosinophil: nucleus is bilobed, with two lobes connected by a thin strand; release chemical mediators that attack react to antigen-antibody complexes or allergens
   - Basophils: exhibit a bilobed nucleus and abundant blue-violet granules in the cytoplasm that often obscure the nucleus; released during anti inflammatory or allergic reactions
2. Agranulocytes: leukocytes that have such small granules in their cytoplasm that they are frequently overlooked
   - Lymphyocytes: dark staining nucleus is usually rounded or slightly indented; three categories - T-lymphocytes, B-lymphocytes, and Natural killer cells
   - Monocytes: pale staining nucleus of monocyte is kidney shaped or C shaped; change into large phagocytic cells called macrophages

Question 11

Describe the process of hemopoiesis.

Answer 11

Hemopoiesis occurs
in red bone marrow (see section 6.2a). The process starts with
hemopoietic stem cells called hemocytoblasts (hē′-mō-sī′tō-blast)
(figure 21.10). Hemocytoblasts are considered multipotent cells,
meaning that they can differentiate and develop into many different
kinds of cells. Hemocytoblasts
produce two lines for blood cell
development: the myeloid (mī′ě-loyd; myelos = marrow) line forms
erythrocytes, megakaryocytes, and all leukocytes except lymphocytes;
the lymphoid (lim′foyd) line forms lymphocytes.
The maturation and division of hemopoietic stem cells is influenced
by colony-stimulating factors (CSFs), or colony-forming
units (CFUs). These molecules are all growth factors (except erythropoietin,
which is a hormone)

■ Multi-colony-stimulating factor (multi-CSF) increases
the formation of erythrocytes, as well as all classes of
granulocytes, monocytes, and platelets from myeloid stem cells.
■ Granulocyte-macrophage colony-stimulating factor
(GM-CSF) accelerates the formation of all granulocytes and
monocytes from their progenitor cells.
■ Granulocyte colony-stimulating factor (G-CSF) stimulates
the formation of granulocytes from myeloblast cells.
■ Macrophage colony-stimulating factor (M-CSF) stimulates
the production of monocytes from monoblasts.
■ Thrombopoietin stimulates both the production of
megakaryocytes in the bone marrow and the subsequent
formation of platelets.

■ Erythropoietin (EPO) is a hormone that is produced primarily
by the kidneys (small amounts are produced by the liver) to
increase the rate of production and maturation of erythrocyte
progenitor and erythroblast cells (see section 20.9a).