Transcript Blood - Mount Carmel Academy

Chapter 10
 Blood
• Is the “river of life” that
surges within us.
• It transports everything
that must be carried
from one place to
another within the body
– nutrients, wastes, and
body heat – through
blood vessels.
• Is the only fluid tissue.
 Blood
contains both
solid and liquid
components.
1. Formed Elements –
Cellular portion of
blood.
 Contains living blood cells.
2. Plasma – The fluid
portion of the blood.
 Nonliving fluid matrix.
 If
blood is spun in a
centrifuge, 3 layers are
formed:
1.
Bottom Layer - The heavier
formed elements are packed
down by centrifugal force.
 Most of the reddish mass at the bottom is erythrocytes
(RBC that function in O2 transport).
2. Top Layer - The lighter plasma rises to the top.
3. Buffy Coat - Thin, whitish layer between the
formed elements layer and the plasma layer.
 Contains leukocytes (WBC that act in various ways to
protect the body) and platelets (cell fragments that
function in blood clotting).
 Percent
of the total
volume of blood:
• Erythrocytes: 45%
 Percentage known as
hematocrit
• WBC and Platelets:
<1%
• Plasma: 55%
 Texture: Sticky
opaque
fluid; Heavier than
water and about 5 times
thicker (more viscous)
than water
 Taste: Metallic and salty
 Color: Varies from
scarlet (oxygen-rich) to
dull red (oxygen-poor)
 pH: Slightly
alkaline (pH between 7.35
and 7.45)
 Temperature – Always slightly higher
than body temperature (100.4°F)
 Body Weight and Volume: Accounts for
approximately 8% of body weight;
Volume in healthy males is about 5-6 L
 Plasma
– The liquid part of the blood.
• Is ~90% water.
• Over 100 different substances are dissolved in
this straw-colored fluid.
 Examples include: nutrients, salts, respiratory gases,
hormones, plasma proteins, and various wastes
• Functions:
1. Transports various substances around the body.
2. Helps to distribute body heat evenly throughout
the body.
 Plasma
Proteins – The most abundant
solutes in plasma.
• Serve a variety of functions:
1. Albumin – Contributes to the osmotic pressure of
blood, which acts to keep water in the bloodstream.
2. Clotting Proteins help stop blood loss when a blood
vessel is injured.
3. Antibodies help protect the body from pathogens.
4. Plasma proteins are NOT taken up by the cells to be
used as food fuels or metabolic nutrients.
 The
composition of blood
plasma varies continuously as
cells remove or add
substances to the blood.
• The composition of plasma is kept
relatively constant by various
homeostatic mechanisms.
 When blood proteins drop to
undesirable levels: Liver is stimulated
to make more proteins.
 When the blood starts to become too
acidic or too basis: The respiratory
system and the kidneys are called into
action to restore it
 Make
up about 45% of whole blood.
 Contains erythrocytes or red blood cells
(RBCs).
• Function: To ferry O2 to all of the cells of the body.
• Contain no organelles.
 Lacks both a nucleus and a mitochondria
 Make ATP by anaerobic mechanisms, they do not use up
any of the O2 they are transporting.
• Are literally sacs of hemoglobin (Hb).
 Hemoglobin - An iron-containing protein that
transports the bulk of the oxygen that is carried
by the blood.
 Are
small cells shaped
like biconcave disks.
• Flattened discs with
depressed centers.
• They look like doughnuts
when viewed through a
microscope.
• Their small size and peculiar
shape provide a large
surface area relative to their
volume, making them ideally
suited for gas exchange.
 RBCs
outnumber
WBCs by about 1000
to 1.
 Are the major factor
contributing to blood
viscosity.
• When the number of
RBCs increase, blood
viscosity increases.
• As the number of RBCs
decrease, the blood thins
and flows more rapidly.
 The
more hemoglobin molecules the
RBCs contain, the more O2 they will be
able to carry.
• Each hemoglobin molecule can bind 4
molecules of O2
 The
most accurate way of
measuring the oxygencarrying capacity of the blood
is to determine how much Hb it
contains.
• A single RBC contains ~250 million
Hb molecules.
 Each Hb molecule can bind 4 molecules
of O2. Therefore, each of these tiny RBCs
can carry about 1 billion O2 molecules!
 The
Hb content is slightly
higher in men than women.
 Anemia
– A decrease
in the oxygen-carrying
ability of the blood.
• May be the result of:
1. Lower-than-normal
number of RBCs
2. Abnormal or deficient
hemoglobin content in
the RBCs
 Sickle-Cell
Anemia – Genetic
defect that leads to abnormal
Hb, which becomes sharp
and sickle-shaped under
conditions of increased O2
use by the body.
• The deformed (crescent-shaped)
RBCs rupture easily and dam up
in small blood vessels.
 These events interfere with oxygen
delivery and cause severe pain.
 Occurs
chiefly in black people, who live in
the malaria belt of Africa and among their
decendants.
• Individuals with the sickle-cell gene have a better
chance of surviving where malaria is prevalent.
 The same gene that causes sickle cell anemia, also makes
RBCs infected by the malaria-causing parasite stick to the
capillary walls and then lose potassium (an essential
nutrient for the survival of the parasite).
 The malaria causing parasite is prevented from
multiplying.
 Polycythemia
– An excessive
or abnormal increase in the
number of erythrocytes.
• May result from:
1. Bone marrow cancer
2. Normal physiological response to living at high
altitudes, where the air is thinner and less oxygen
is available.
• Major problem that results from high numbers of
RBCs is increased blood viscosity.
 Increased blood viscosity causes RBCs to flow
sluggishly in the body and impairs circulation.
 Leukocytes
– White blood cells (WBCs);
crucial to the bodies defense against
disease.
• Far less numerous than RBCs; Account for >1% of
total blood volume.
• Form a protective,
moveable army that
helps defend the
body against damage
by bacteria, viruses,
parasites, and tumor
cells.
1.
Are able to slip into and out of the blood
vessels – a process called diapedesis.
• The circulatory system is simply their means of
transportation to areas of the body where their
services are needed for inflammatory or
immune responses.
 Can
locate areas of
tissue damage and
infection in the body by
responding to certain
chemicals that diffuse
from the damaged cells.
• Called positive chemotaxis.

Once they have “caught the
scent,” the WBCs move
through the tissue spaces by
ameboid movement .
• Ameboid Movement - Flowing
cytoplasmic extensions that help
them move.

By following the diffusion
gradient, they pinpoint the
areas of damage and rally
round in large numbers to
destroy foreign substances
or dead cells.
 Whenever WBCs
mobilize for action,
the body speeds up
their production.
• As many as twice the
normal number may
appear in the blood
within a few hours.
 Leukocytosis
– A total
WBC count above
11,000 cells/mm3
• Generally indicates that a
bacterial or viral infection is
stewing in the body.
 Leukopenia
–
Abnormally low WBC
count.
• Commonly caused by
certain drugs, such as
corticosteroids and
anticancer agents.
 Leukemia
– “White blood”; Bone marrow
becomes cancerous; Excessive
production of abnormal WBCs.
• The “newborn” WBCs are immature and
incapable of carrying out their normal protective
functions.
• Consequently, the body
becomes easy prey of
disease-causing bacteria
and viruses.