Transcript The Transport System

The Transport System
Topic 6.2 and H5
Circulatory System- Overview
System of internal transport that transport
oxygen and carbon dioxide, distributes
nutrients to body cells, and conveys the
waste products of metabolism to specific
sites for disposal.
Necessary in any animal whose body is too
large or too complex for vital chemicals to
reach all its parts by diffusion alone.
Provides an efficient long-distance internal
transport system that brings resources
close enough to cells for diffusion to occur.
Circulatory System- Overview
Circulatory system must have an
intimate connection with body tissues
For example—
capillaries form a system of microscopic
blood vessels that the heart pumps blood
through once it has been oxygenated in the
lungs.
Capillaries form an intricate network among
the cells of a tissue, such that no substance
has to diffuse far to enter or leave a cell.
Figure 23.1 A
Circulatory System- Overview
Materials do no exchange directly
between blood and body cells
Each body cell is immersed in a water
interstitial fluid
Molecules such as oxygen and nutrients
diffuse first out of a capillary into the
interstitial fluid and then from the
interstitial fluid into a tissue cell.
Figure 23.1 B
Circulatory System- Overview
Circulatory System is also responsible
for conveying metabolic wastes to
waste disposal organs:
Carbon Dioxide to lungs
variety of metabolic wastes to the
kidneys.
Circulatory System- Overview
Circulatory System plays a key role in
maintaining homeostasis (a constant
internal environment)
By exchanging molecules with the
interstitial fluid, the circulatory system
helps control the makeup of the blood by
continuously moving it through organs,
such as the liver and kidneys, that
regulate the blood’s contents.
Circulatory System-Overview
Animals with thick, multiple layers of
cells require a true circulatory system
containing a specialized circulatory
fluid, blood.
Closed circulatory system
Also called the cardiovascular system
Blood is confined to the vessels, which
keep it distinct from the interstitial fluid.
Circulatory System-Overview
Three kinds of vessels in a closed circulatory system:
Arteries
Carry blood away from the heart to organs and tissues throughout the
body
Most arteries convey oxygen-rich blood, although there are some
exceptions:
– Two arteries called the pulmonary arteries carry oxygen-poor blood
from our heart to our lungs.
Veins
Return blood to the heart
Most veins transport blood depleted of oxygen, with a few
exceptions:
– Four pulmonary veins that carry freshly oxygenated blood from the
lungs to the heart.
Capillaries
Convey blood between arteries and veins within each tissue.
Circulatory System-Overview
Other vessels:
Arterioles
Branch from large arteries
small vessels that give rise to capillaries
Capillary beds
Network of capillaries that infiltrate every organ and
tissue in the body.
Thin wall allow chemical exchange between the blood
and interstitial fluid
Venules
Form from capillaries
Converge into veins that return blood to the heart.
Circulatory System-Overview
Structure of blood vessels fits their functions:
Capillaries
Form fine branching networks where materials are
exchanged between the blood and the intersitital fluid
that bathes the cells.
Have very thin walls formed of a single layer of
epithelial cells, which is wrapped in a basement
membrane.
The inner surface of the capillary is smooth and keeps
the blood ells from being abraded as they tumble along.
Arteries, arterioles, veins, and venules have
thicker walls than those of capillaries
Circulatory System-Overview
Structure of blood vessels fits their function, contd….
All blood vessels have same epithelium as
capillaries, but they are reinforced by two other
tissue layers:
An outer layer of connective tissue with elastic fibers enables
the vessels to stretch and recoil
The middle layer consists mainly of smooth muscle.
Both layers are thick and sturdier in arteries, providing the
strength and elasticity to accommodate the rapid flow and
high pressure of blood pumped by the heart.
– Arteries can also regulate blood flow by constricting or relaxing their
smooth muscle layer.
Thinner-walled veins convey blood back to the heart at low
velocity and pressure.
– Within large veins, flaps of tissues act as one-way valves.
Arteries, Arterioles, Capillaries
Veins
Circulatory System-Overview
Double circulation
Blood is pumped a second time after it
slows down in the capillary beds of the
lungs
Pulmonary circuit
Carries blood between the heart and the gas
exchange tissues in the lungs
System circuit
Carries blood between the heart and the rest
of the body
http://www.icyou.com/topics/diseasesconditions/systemic-and-pulmonarycirculation+
Circulatory System-Overview
Four chambers to the heart:
Two atria (on top)
Two ventricles (on bottom)
Right side
Handles only oxygen-poor blood
Left side
Receives and pumps only oxygen-rich blood
***evolution of a powerful four-chambered heart was an
essential adaptation to support the high metabolic
rate characteristic of birds and mammals, which are
endothermic and require lots of energy….need to
deliver lots of fuel and oxygen to body tissues***
Circulatory System-Overview
Human Heart- General
Characteristics
About the size of a clenched fist
Enclose in a sac just under the breastbone
Thin-walled atria collect blood returning to
the heart, most of which then flows into the
thicker-walled ventricles.
Ventricles pump blood to the lungs and to
all other body tissues.
Flap-like valves regulate the direction of
blood flow
Circulatory System- Blood Flow
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Beginning with the pulmonary (lung) circuit, the right ventricle pumps
blood to the lungs via two pulmonary arteries.
As blood flows through capillaries in the lungs, it takes up oxygen and
unloads carbon dioxide.
Oxygen-rich blood then flows back through the pulmonary veins to the left
atrium.
The oxygen-blood flows from the left atrium into the left ventricle.
Powerful muscles in the left ventricle pump blood to all body tissues
through the systemic circuit.
Oxygen-rich blood leaves the left ventricle through the aorta. The aorta is
the largest blood vessel, with a diameter of roughly 2.5 cm, about the
same diameter as a quarter.
First branches from the aorta are the coronary arteries, which supply
blood to the heart muscle itself.
Several large arteries branch from the aorta, leading to the head, chests,
and arms, and to the abdominal region and legs.
Within each organ, arteries lead to arterioles that branch to capillaries.
Capillaries rejoin as venules, which convey the blood back to veins.
Oxygen-poor blood from the upper body is channeled into a large vein
called the superior vena cava, and the inferior vena cava drains blood
from the lower body.
Both vena cavas empty their blood into the right atrium.
Circulatory System- Blood Flow
Summary
The path of any single blood cell is always
heart to lung capillaries to heart to body
tissue capillaries and back to heart.
In one systemic circuit, a blood cell may
travel to the brain; in the next (after a
pulmonary circuit) it may travel to the legs.
It never travels from the brain to the legs
without first returning to the heart and
being pumped to the lungs to be recharged
with oxygen.
http://www.smm.org/heart/heart/pumping.ht
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Cardiac Cycle
Cardiac Cycle
The heart is the “hub” of the circulatory
system
In a continuous cycle, it passively fills
with blood and then actively contracts
The complete sequence of filling and
pumping is called the cardiac cycle.
Cardiac Cycle
Cardiac Cycle, Figure 23.6
Shows a cardiac cycle that takes about
0.8 seconds, corresponding to a heart
rate of 75 beats per minute.
3 phases:
1.
Diastole:
When the entire heart is relaxed, in the phase
called diastole, blood flows into all four of its
chambers. Blood enters the right atrium from
the venae cavae and the left atrium from the
pulmonary veins. The AV valves are open.
Diastole lasts about 0.4 seconds, during which
the ventricles nearly fill with blood
Cardiac Cycle
Cardiac Cycle, Figure 23.6
2. Systole
Systole begins with a very brief (0.1-second)
contraction of the atria that completely fills the
ventricles with blood (atrial systole).
Then the ventricles contract for about 0.3
seconds (ventricular systole)
The force of their contraction closes the AV
valves, opens the semilunar valves located at
the exit from each ventricle, and pumps blood
into the large arteries.
Cardiac Cycle
Cardiac output
The volume of blood per minute that the
left ventricle pumps into the systemic
circuit.
This volume is equal to the amount of
blood pumped by the left ventricle each
time it contracts (about 75mL per beat
for the average person) times the heart
rate (about 70 beats per minute). =
5,250mL/min
Influenced by many factors: age, fitness,
etc. Increases during heavy exercise.
Cardiac Cycle
Heart valves
Made of flaps of connective tissue, prevent backflow
and keep moving in the correct direction.
Closing of the AV valves when the ventricles contract
keeps blood from flowing back into the atria.
When the ventricles relax in diastole, blood in the
arteries starts to flow back toward the heart, causing the
flaps of the semilunar valves to close and preventing
blood from flowing back into the ventricles.
The heart sound we can hear “lub-dup” “lub-dup” are
caused by the closing of the heart valves.
“Lub” comes from the recoil of blood against the closed AV valves
“Dup” comes as the semilunar valves snap shut.
Cardiac Cycle
Heart valves
Murmurs
Causes a hissing sound, caused by a defect
in one or more of the heart valves
Occurs when a stream of blood squirts
backward through a valve
May be born with it, or can be caused by
infection (rheumatic fever)
Usually do not reduce efficiency of blood flow
enough to warrant surgery, however, can be
corrected by replacing damaged valves with
artificial valves or by a donor.
Pacemaker
PaCeMaKeR!!!, or SA (sinoatrial)
node
Specialized region of cardiac muscle
Maintains the heart’s pumping rhythm by
setting the rate at which all the muscle
cells of the heart contract.
Located in the wall of the right atrium
Pacemaker
Function of pacemaker (figure 23.7):
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The pacemaker (SA node) generates electrical signals
a. Cardiac muscle cells are electrically connected by
specialized junctions between cells, allowing signals to
spread quickly through both atria, making them contract
in unison.
b. Signals pass to a relay point called the AV node, in
the wall between the right atrium and right ventricle.
Here the signals are delayed about 0.1 second. The
delay ensures that the atria contract and empty before
the ventricles contract.
Specialized cardiac muscle fibers then relay the signals
to the apex of the heart and
Up through the walls of the ventricles, triggering the
strong contractions that drive the blood out of the heart.
Pacemaker
Although the AV node sets the basic rhythm of the
heart, the rate and strength of heart beat is
modified by two centers within the medulla
oblongata in the brain:
One sends nerve impulses down accelerans nerves.
Associated with noradrenaline; speeds up heart rate and
strength
Increase in blood pressure
The other sends nerve impulses down a pair of vagus
nerves
Slows the heart beat
Decrease in blood pressure
Pacemaker
Physiological and emotional cues can
influence heart rate.
Hormones also influence heart rate:
Epinephrine (also known as adrenaline)
“fight or flight” hormone released at times of
stress
Pacemaker
Certain heart diseases prevent the
heart’s self-pacing system from
functioning properly to maintain a
normal heart rhythm:
Artificial pacemaker
Tiny electronic device surgically implanted
near the AV node.
Emit electrical signals that trigger normal
heart beats
Pacemaker
Electrocardiogram
ECG or EKG
Electrical signals in the heart generate
electrical changes in the skin, which can
be detected by electrodes and recorded
as an EKG.
Electrocardiogram
Heart Attack
If one or more coronary arteries become blocked,
heart muscle cells will die quickly causing the heart
to not function properly is a heart attack
(myocardial infarction).
Approximately 1/3 of heart attack victims die
almost immediately.
For those who survive, the ability of the damaged
heart to pump blood may be seriously impaired
Heart attacks rank first in causes of death in the
US
Strokes, death of brain tissue resulting from
blockage of arteries in the head, are third.
Heart Attack
Diseases of the heart and blood
vessels are known as cardiovascular
disease.
Accounts for almost 50% of all deaths in
the US, killing over 1 million people each
year- about one every 30 seconds
Heart Attack
Atherosclerosis
Chronic cardiovascular disease
Growths called plaques develop in the inner
walls of arteries, narrowing the passages
through which blood can flow
Smooth muscle layer of an artery becomes
thickened and infiltrated with cholesterol and
fibrous connective tissue
A blood clot is more likely to become trapped in
a vessel that has been narrowed by plaques.
Therefore, plaques are common sites of blood
clot formation.
Heart Attack
Causes of cardiovascular disease:
Inheritance
Smoking doubles the risk of heart attack
and harms the circulatory system in
several other ways.
Lack of exercise
Exercise can cut the risk of heart disease in
half
Diet
Eating a healthy diet, low in cholesterol and
saturated fat, can reduce the risk of
atherosclerosis.
Heart Attack
Treatment
Heart attack victims are treated with clotdissolving drugs, which stop many heart attacks
and help prevent damage.
Cholesterol and B.P. measurements, CT and MRI
help identify risks
Drugs can lower cholesterol and blood pressure
Angioplasty
Inserting a tiny catheter with a balloon that is
inflated to compress plaques and widen
clogged arteries.
Stents
• Small wire mesh tubes that prop arteries open
Heart Attack
Treatment (continued)
Heart transplant
Severe shortage of donor hearts, various
artificial pumping devices are under
development.
Bypass surgery
Blood vessels removed from a patient’s legs
are sewn into the heart to shunt blood
around clogged arteries.
Heart Attack
Good news!
US death rates from cardiovascular disease
have been cut in half over the past 50 years
Reduction in risk factors has contributed to this.
Availability of automatic external defribillators
(AEDs) has saved thousands of lives.
Devices deliver electric shocks that can
reverse a short circuit of the heart’s
pacemaker and reestablish normal electrical
rhythms in the heart.
Designed to be used anyone
http://www.pbs.org/wgbh/takeonestep/heart/videoch_01_vid.html?tos=vid&filetype=mov&bandwidth=_hi
Blood Pressure
Blood pressure
The force that blood exerts against the
walls of our blood vessels
Created by the pumping of the heart
Drives blood from the heart through
arteries and arterioles to capillary beds.
Blood pressure
Pulse
Rhythmic stretching of arteries
When the ventricles contract, blood is forced
into the arteries faster than it can flow in the
arterioles.
This stretches the elastic walls of the
arteries.
Blood pressure
B.P. depends on cardiac output
(volume of blood pumped into the
aorta) and resistance to blood flow
imposed by the narrow openings,
controlled by smooth muscles, of
arterioles.
When muscles relax, arterioles dilate,
and blood flows through them more
readily causing a decrease in b.p.
Physical and emotional stress can
increase b.p. via nervous and hormonal
signals that constrict blood vessels
Blood Pressure
Regulatory mechanisms coordinate
cardiac output and changes in the
arteriole resistance to maintain
adequate b.p. as demands on the
circulatory system change.
Blood pressure
Aorta and arteries
High blood pressure and blood velocity
Arterioles
Abrupt decline in b.p. and b.v; mainly due to
resistance to blood flow cuased by friction
between the blood and large surface area it
contacts in the wall of numerous tiny arterioles.
Capillaries
B.p. and b.v. is slowest
Enhances the exchange of substances between
the blood and interstitial fluid.
Blood pressure
Veins
B.p. is nearly at zero due to resistance passing through
all other blood vessels
Blood is able to move up legs against gravity due to
veins sandwiched between skeletal muscles
Whenever the body moves , the muscles pinch the
veins and squeeze the blood along toward the heart
Valves allow blood to flow only toward the heart.
Breathing also helps return blood to the heart
When we inhale, the change in pressure within our
chest cavity causes the large veins near our heart to
expand and fill.
Measuring blood pressure
Figure 23.10
Typical blood pressure for a healthy
young adult is 110/70. First number is
systolic, second number is diastolic.
2. Once sphygamomanometer, or blood
pressure cuff, is wrapped around the
upper arm, where large arteries are
accessible, the cuff is inflated until the
pressure is strong enough to close the
artery and cut off blood flow to the
lower arm.
1.
Measuring blood pressure
3. A stethoscope is used to listen for
sounds of blood flow below the cuff, and
systolic blood pressure is the first
measurement taken as the cuff is gradually
deflated.
The first sound of blood spurting through the
constricted artery indicates that the blood
pressure is stronger than the pressure exerted
by the cuff.
The pressure at this point is the systolic
pressure.
Measuring blood pressure
4. The sound of blood flowing
unevenly through the artery continues
until the pressure of the cuff falls
below the pressure of the artery
during diastole.
Blood now flows continuously through
the artery, and the sound of blood flow
ceases.
The reading on the pressure gauge at
this point is the diastolic pressure.
Blood pressure
Optimal blood pressure for adults is
below 120 mm Hg for systolic
pressure and below 80 mm Hg for
diastolic pressure
Lower values are generally
considered better, except in rare
cases where low blood pressure may
indicate a serious underlying condition
(such as endocrine disorders,
malnutrition, or internal bleeding)
Hypertension
High blood pressure, or hypertension
Persistent systolic b.p. at or higher than 140 mm Hg
and/or diastolic b.p. at or higher than 90 mm Hg.
“Silent Killer”; often displays no outward symptoms for
years
Affects almost one-third of the US adult population
Elevated b.p. requires the heart to work harder to pump
blodo throughout the body, and overtime the left ventricle
may enlarge
When the coronary blood supply does not keep up with the
demands of this increase in muscle mass, the heart muscle
weakens
In addition, the increases force on arterial walls causes tiny
ruptures that promote plaque formation, aggravating
atherosclerosis, and increasing the risk of blood clot formation.
Hypertension
Prolonged hypertension is the major cause of
heart attack, heart disease, stroke, and kidney
failure.
Causes
Some predispositions cannot be avoided, such
as gender, ethnicity, age, and heredity.
Males have a greater risk up to age 55, but
females have a greater risk over 85
Blood pressure generally increases with age
Children of parents with hypertension are twice
as likely to develop the condition.
Hypertension
Prevention
Eating a heart-healthy diet
Not smoking
Avoiding excess alcohol (more than two drinks
per day)
Exercising regularly (30 minutes of moderate
activity on most days)
Maintaining a healthy weight
Antihypertensive medications
Although salt is typically associate with high b.p,
it’s only a contributing factor for a small
percentage
Blood distribution
Smooth muscles can influence b.p. by changing
the resistance to flow out of the arteries and
arterioles.
Smooth muscle also regulates blood distribution to
the capillaries of the various organs.
At any given time, only about 5-10% of the body’s
capillaries have blood flowing through them.
However, each tissue has many capillaries, so
every part of the body is supplied with blood at all
times.
Blood distribution
Capillaries in a few organs, such as
the brain, heart, kidneys, and liver,
usually carry a full load of blood, but
in many other sites, the blood supply
varies as blood is diverted from one
destination to another, depending on
need.
Blood distribution
Figure 23.11; Smooth muscle
regulates the distribution of blood
Thoroughfare channel
Capillary through which blood streams
directly from arteriole to venule
This channel is always open
Capillaries branch off from thoroughfare
channels for the bulk of the capillary bed
Precapillary sphincters,
rings of smooth muscle located at the entrance of the
capillary beds
regulate the passage of blood
Blood distribution
Figure 23.11; Smooth muscle
regulates the distribution of blood
Precapillary sphincters relaxed:
blood flows though a capillary bed
when its.
Precapillary sphincters contracted:
blood bypasses the capillary bed and
goes to venule.
Blood distribution
After a meal, p.sphincters in the wall of
digestive tract let a larger quanity of blood pass
through capillary beds than when food is not
being digested.
During strenuous exercise, many of the
capillaries in the digestive tract are closed off,
and blood is supplied more generously to
skeletal muscles.
Nerves and hormones influence the contraction
of the smooth muscles in both these
mechanisms that regulate the flow of blood to
capillary beds.
Capillaries
Capillaries are the only blood vessels
with walls thin enough for substances
to cross between the blood and the
interstitial fluid that bathes the cells.
Most important function of the
circulatory system
Capillaries
Figure 23.12A Capillary cross
section
Capillary walls consists of adjoining
epithelial cells that enclose a lumen, or
space, that is just large for red blood
cells to tumble through in single file.
Each epithelial cell contains a nucleus
Capillary is surrounded by interstitial
fluid
Capillaries
Exchange of substances between
blood and interstitial fluid:
Passive transport: Some substances,
such as oxygen and carbon dioxide,
simply diffuse through the epithelial cells
of the capillary wall.
Active transport: Some larger
molecules may be carried across an
epithelial cell in vesicles that form by
endocytosis on one side of the cell and
then release their contents by
exocytosis on the other side
Capillaries
Exchange of substances between
blood and interstitial fluid (continued):
Due to leaky structure of capillary wall,
there are narrow clefts between the
epithelial cells making up the capillary
Water and small solutes, such as sugars and salts,
move freely through these clefts
Blood cells and dissolved proteins remain inside the
capillary because they are too large to pass through
these passageways.
Much of the exchange btw blood and interstitial fluid
is the result of the pressure driven flow of fluid
(consisting of water and dissolved solutes) through
these clefts.
Capillary
Capillaries
Active forces that drive fluid into or out
of the capillary:
Blood pressure, which tends to push
fluids outward
Osmotic pressure, a force that tends to
draw fluid into the capillary because the
blood has a higher concentration of
solutes than the interstitial fluid.
Proteins dissolved in the blood account for
much of this high solute concentration.
Capillaries
Direction of fluid movement into or out
of the capillary:
Depends on the difference btw blood
pressure and osmotic pressure.
Net movement of fluid out of the capillary
Blood pressure exceeds the osmotic pressure
Upstream (arterial) end of capillary
Net movement of fluid into the capillary
Blood pressure drops, osmotic pressure
increases
Downstream (venous) end of capillary
Capillaries
Direction of fluid movement into or out
of the capillary (continued):
Most of the fluid that leaves the blood at
the arterial end of a capillary bed
reeenters the capillaries at venous end.
Remaining fluid is returned to the blood
by the vessels of the lymphatic system.
Capillary
Blood
Blood
Blood consists of several types of cells suspended
in a liquid called plasma.
When a blood sample is taken, the cells can be
separated from the plasma by spinning the sample
in a centrifuge
A chemical must be added to prevent the blood
from clotting
The cellular elements which make up about
45% of the volume of blood, settle to the bottom
of the centrifuge tube, underneath the
transparent, straw-colored plasma.
Blood
Plasma is about 90% water
Among its many solutes are inorganic salts in the form of
dissolved ions.
These ions have several functions, such as:
maintaining osmotic balance
keeping the pH of blood at about 7.4
contributing to the proper environment needed for nerve and
muscle function
Also contains proteins
Help maintain the osmotic balance between blood and
interstitial fluid
Some act as buffers
Some function in blood clotting (fibrinogen)
Immunity (immunoglobulins)
Also contains a wide variety of substances in transit from one
part of the body to another, such as nutrients, waste
products, O2, CO2, and hormones.
Blood
Blood plasma contains two classes of
cells:
Red blood cells (erythrocytes)
White blood cells (leukocytes)
*3rd cellular element: platelets, are cell
fragments involved in clotting
Blood
Red blood cells
Also called erythrocytes
About 25 trillion rbc’s in the average person’s
5K of blood
Structure of rbc suits its main function: to carry
oxygen
Small biconcave disks, thinner in the center than at
the sides
Small size and shape create a large surface area
across which oxygen can diffuse
Each tiny rbc contains about 250 million molecules of
hemoglobin and can transport about a billion oxygen
molecules
It lacks a a nucleus, which allows more room to pack
in hemoglobin
Blood
Blood
White blood cells
Also called leukocytes
Five major types:
Monocytes, neutrophils, basophils,
eosinophils, and lymphocytes
Collective function is to fight infections and
cancer.
Some are phagocytes, which engulf and digest
bacteria and debris from out own dead cells
(monocytes and neutrophills)
Wbc’s actually spend much of their time
moving through interstitial fluid, where most
infections are fought
Blood cell formation
The red marrow of bones such as the ribs,
vertebrae, breast-bone, and pelvis all contain a
spongy tissue in which stem cells differentiate into
blood cells.
One type of stem cell may give rise to lymphocytes
A second type of stem cell can produce
erythrocytes, other wbc’s, and cell that produce
platelets
After forming in the early embryo, these stem cells
continually produce all the blood cells needed
throughout life.
Red blood cell production
Adequate numbers of rbc’s are essential for body function.
After circulating in the blood for 3 or 4 months, rbc’s are
broken down and their molecules are recycled
Much of the iron removed from the hemoglobin is returned to
the bone marrow, where new rbc’s are formed at the
amazing rate of 2 million per second
Production of rbc’s is controlled by a negative-feedback
mechanism sensitive to the amount of oxygen reaching
tissues via the blood.
If tissues are not receiving enough oxygen, the kidneys
produce a hormone called erythropoietin (EPO) that
stimulates the bone marrow to produce more rbc’s
Patients on kidney dialysis do not produce enough EPO,
and therefore have low rbc counts.
Genetically engineered EPO has significantly helped
these patients
Anemia
Anemia
Caused by an abnormally low amount of
hemoglobin or a low number of rbcs
Person feels constantly tired and is often
susceptible to infections because the body cells
do not get enough oxygen.
Can result from excessive blood loss, vitamin or
mineral deficiencies, or certain cancers
Iron deficiency is the most common cause
Most common in women because of blood loss during
menstruation.
Increasing RBC’s
Individuals who live at high altitudes, where oxygen levels are
low, produce more rbc’s
Many athletes train at high altitudes to benefit from this
effect
Other athletes take more drastic and illegal measure to
increase the oxygen-carrying capacity of their blood and
improve their performance.
Injecting synthetic EPO
– Increases normal rbc volume from 45% to 65%
– Athletic commissions test for EPO-like chemicals
Blood doping
– Withdrawing and storing their rbc’s and then reinjecting them
before a competition.
– Athletic commissions test for cheaters by measuring the % of
rbc’s in the blood volume
– Can be harmful a combination of dehydration and blood
already thickened by increasing rbcs can cause stroke, heart
failure, and even death
Leukemia
Cancer of the wbcs, or leukocytes
Cause a person to have an unusually
high number of leukocytes, most of
which do not function normally
Overabundance of wbc’s can crowd
out rbc’s and platelets, causing
severe anemia and impaired clotting.
Usually fatal unless treated
Leukemia
Treatment
Not all cases respond to radiation and
chemotherapy
Alternative treatment is transplanting a healthy
bone marrow tissue from a suitable donor into a
patient whose own cancerous marrow has been
destroyed.
Such a patient requires lifelong treatment with drugs
that suppress the tendency of some of the
transplanted marrow cells to “reject” the cells of the
recipient.
To avoid the rejection problem, patients may be
treated with their own bone marrow:
– Marrow from the patient is removed, processed to remove as
many cancerous cells as possible, and then reinjected.
Leukemia
Treatment (continued)
Stem Cells
Stems cells can be obtained from a donor or from the
patient in three methods
– 1. Oldest method- whole bone marrow is harvested by
inserting a large-bore needle into the pelvic bone.
– 2. More recent method- drugs are used to draw stem
cells out of the marrow and into the blood.
» Donor is connected to a refrigerated centrifuge that
separates blood components, removes the ones
need for transplantation, and returns the rest.
– 3. newest method- gathers stem cells from umbilical
cord blood.
» Cells can be stored for possible later use by the
child or donated to a compatible recipient in need of
a stem cell transplant.
» Injection of a few as 30 stem cells can repopulate
the blood and immune system.
**We will cover blood clotting when
we discuss the Immune System 