Transcript Blood Human Anatomy Chapter 17 I. Overview: Composition of Blood Blood is considered a connective tissue.

Blood
Human Anatomy
Chapter 17
I. Overview: Composition of Blood
Blood is considered a connective
tissue. It carries all substances
that must travel throughout the
body. These include nutrients,
waste, hormones, electrolytes,
antibodies, etc. Clinical
examiners study blood of
patients, more often than other
tissues, to help in making a
diagnosis. Blood looks red when
it is oxygenated and blue when it
is not (although it is not truly ever
blue). It travels from the heart in
arteries, arterioles, and
capillaries, and returns to the
heart through venuoles, and
veins.
Blood is composed of cells called formed elements and liquid called
plasma. The formed elements are erythrocytes (red blood cells),
leukocytes (white blood cells), and platelets. The plasma is
composed of a high amount of water and all components that would
be dissolved in blood. The components are separated when spun in
a centrifuge. The heavier more dense red blood cells accumulate at
the bottom and the yellowish liquid (plasma) float at the top. In
between these two layers lie the white blood cells.
II. Blood Plasma
This fluid is about 90% water and contains over 100 different
chemicals. Aside from nutrients, waste, and electrolytes, plasma also holds
three important proteins:
Albumin- prevents water from diffusing out into the tissue
Globulin- antibodies and proteins that carry lipids, iron, and copper
Fibrinogen- this is involved in forming blood clots.
II. Formed elements
• Two of these
components are not
considered true cells:
erythrocytes and
platelets. These
components do not
undergo mitosis.
• ***White blood cells are
true cells because they
have all organelles and
they can multiply in the
blood stream
A. Erythrocytes- The specialty of these cells is
to transport oxygen and carbon dioxide. Red
blood cells originate in bone marrow and as
they mature they expel their organelles before
entering the blood stream. They are shaped like
a disc with a depressed center. They are the
most numerous component of formed
elements. These cells contain no nucleus or
organelles, instead they are packed with
hemoglobin. Hemoglobin is a combination of
proteins and iron molecules. Erythrocytes
collect oxygen at the lungs and deliver it to the
tissues then carry carbon dioxide back to the
lungs. There are three important characteristics
of red blood cells:
1. Their concave shape allows for 30%
more surface area for carrying oxygen.
2. 97% of their content is hemoglobin. It is
used for binding both oxygen and CO2
3. They depend on anaerobic respiration
thus they do not consume any oxygen
B. Leukocytes- The specialty of
these cells is to fight disease.
These are true cells containing
organelles and have the ability to
divide. The have the ability to
travel through the blood to a body
region that is infected, exit the
blood stream, and enter the site of
infection. Site of the body that are
infected release certain chemicals
to attract white-blood cells. These
cells also originate in the bone
marrow and once matured entered
the blood stream. During times of
infections the amount WBC
increases, thus a higher WBC
count indicates infection. Some
groups of WBC may contain large
amount of granules that hold
hydrolytic enzymes and some do
not.
1. Granulocytes- These are called neurtophils, eosinophils, and
basophils. Larger than RBCs they are short lived. All granulocytes are
phagocytic.
Neutrophil
Eosinophil
Basophil
Lymphocyte
Monocyte
a. Neutrophil- Most common,
makes up 60% of WBC
count. These cells have 2-6
lobed nucleus, they contain
vesicles filled with digestive
enzymes specifically
designed to destroy the cell
walls of bacteria. They are in
the first line of defense of an
inflammatory response.
They can destroy the
bacteria by phagocytosis or
by releases chemical
substances. These
chemicals can even cause
damage to the surrounding
tissues. Pus is a collection of
dead neutrophils, WBCs, and
bacterial debri.
b. Eosinophils- Account for
1-4% of WBC is blood. It
has a bi- lobed nucleus.
Contain large vesicles
that stain red. They are
involved in ending
allergic reactions by
degrading histamine
and parasitic
infections by exposing the
parasite to digestive
enzymes.
• c. BasophilsMost rare of all
types, makes
up 0.5% of
WBC count.
Has a bi-lobed
nucleus. They
release
histamine and
other chemicals
that signal
inflammation.
They are
present in the
later stages of
infection
2. Agranulocytes- These include
lymphocytes and monocytes, cells
that do not contain granules of
digestive enzymes.
•
a. Lymphocytes- Most important
types, makes up about 20-45% of
WBC count. When viewed under
the microscope they appear to
have a large purple nucleus.
Most are embedded in lymphatic
tissue. They specialized in
attacking specific foreign
molecules recognized as an
antigen. The two main types of
lymphocytes are B-cells and Tcells. They produce antibodies or
attack a foreign cell directly by
destroying it.
Lymphocyte
Monocyte
B-lymphocytes produce antibodies and
respond to bacterial cells.
T lymphocytes respond to antigens
presented by the membranes of eukaryotic
cells. These are the ones responsible for
rejection of transplanted tissue. They also
destroy self cells that are infected.
Natural killer cells spontaneously attack
tumor cells and infected cells.
b. Monocytes- Contain a
large nucleus that
resembles a kidney. Its
cytoplasm may have
some granules. These
cells travel through the
blood stream and
transform into
macrophages once
they enter the tissues
Lymphocyte
Monocyte
Part of a blood clot
C. Platelets- These small
cell fragments that broke off
larger cells called
megakaryocytes, are also
called thrombocytes. Their
specialty is to release
chemicals that cause blood
clots. They plug tears in the
walls of blood vessels to
reduce bleeding. Their
secretions may induce more
platelets to accumulation, or
an inflammatory response,
or constriction of blood
vessels.
• Platelets contract pulling
the edges of a blood clot
closer together in order to
assist in healing of torn
tissue. If a healthy tissue
is roughened by scaring,
inflammation, or
atherosclerosis, platelets
will attach and form a blood
clot called a thrombus
IV. Blood Cell Formation
Hematopoiesis is the process by
which blood cells form. After birth,
about 1000 billion blood cells are
created in the bone marrow per day.
A. Bone marrow as the site of
hematopoiesis- Red bone marrow
generates blood cells. In adults it is
located in bones of the axial skeleton
and in the epiphysis of the humerus
and femur. Newborns have only red
bone marrow that is replaced by
yellow bone marrow during the ages
of 8-18. Bone marrow contains
reticular fibers and macrophages.
• B. Cell lines in blood cell formation- blood cells arise
from blood stem cells or pluripotential hematopoietic
stem cell. They divide consistently and produces lines of
progenitor cells called lymphoid stem cells and myeloid
stem cells. These cells will divided until they become
committed cells and thus differentiate into a specific type
of blood cell.
– 1. Genesis of erythrocytes- See diagram on page 493. Blood
stem cell becomes a myeloid stem cell, these give rise to
proerythroblast that eventually becomes a Nomoblast, then a
Reticulocyte, then an Erythrocyte.
– 2. Formation of leukocytes and platelets- See diagram on page
493. Blood stem cell becomes a myeloid stem cell or lymphoid
stem cell. The Lymphoid stem cell directly becomes a B or T
lymphocytes. The Myeloid stem cell becomes a Myeloblast,
Monoblast, or Megakaryoblast, then specialize to for the granular
leukocytes, macrophates, or platelets.
V. Blood Types
Every person has a certain blood type. It is determined by the markers on the
surface of the red blood cells. Immune system cells learn to identify those
markers as “self” and if they encounter any RBCs with different marker they will
attack them. Thus it is important to know one’s blood type and to be aware of
which type one can receive if a blood transfusion is needed. Complete the chart
below
Blood Type
Surface Marker
Genotype
Plasma antibodies
(fights against)
Can receive blood from
Can donate blood to
• www.nlm.nih.gov
gslc.genetics.utah.edu/.../ABObloodsystem.gif
V. Blood DisordersA. Erythrocytes• Polycythemia- abnormal excess of RBCs that
can be caused by bone marrow cancer. This
increase blood viscosity slowing or blocking
blood flow. It can be treated by diluting or
removing blood.
• Anemia- abnormally low RBCs or low
hemoglobin. May be caused by excessive
bleeding, iron deficiency, deficiencies in folic
acid or B12 vitamin, excessive destruction of
RBCs, or abnormal structure of hemoglobin.
•Sickle cell disease- it is an inherited abnormality of the
hemoglobin. The RBC are shaped like a crescent and are fragile.
They may block blood vessels and causing pain, strokes, or
infections. There are several forms of treatment so the person
lives into adult hood. 1 in 400 African Americans have sickle cell
disease.
Normal RBC
Sickle Cell RBC
B. Leukocytes
• Leukemia- this is a form of cancer that causes an
increase production of WBCs. There are several forms
of leukemia but in all forms immature WBCs enter the
blood stream and also take over the bone marrow
crowding out the normal WBCs. Infections and
hemorrhaging are the causes of death in patients with
leukemia.
C. Platelets
• Thrombocytopenia- abnormally low platelet
concentration. Diminished clot formation and internal
bleeding.