Download Lecture #18 - Suraj @ LUMS

Lecture 18
Transport in Animals II
Blood Type
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All cells of the human body have surface proteins and
other molecules that serve as "self" markers.
The human body also has antibodies that recognize
markers on foreign cells.
In a blood transfusion, or even a pregnancy, it is
important that there is no possibility of an interaction
between antibodies and foreign markers.
ABO Blood Typing
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ABO blood typing is based on surface markers on red
blood cells.
Surface markers are glycoproteins known as
agglutinogens have corresponding antibodies.
Type A has A markers; type B has B markers; type AB
has both markers; type O has neither marker.
If bloods of incompatible donors and recipients are
mixed, agglutination (clumping) will occur.
Blood Donations
• A person with type A blood can donate blood to a person with
type A or type AB.
• A person with type B blood can donate blood to a person with
type B or type AB.
• A person with type AB blood can donate blood to a person
with type AB only.
• A person with type O blood can donate to anyone.
• A person with type A blood can receive blood from a person
with type A or type O.
• A person with type B blood can receive blood from a person
with type B or type O.
• A person with type AB blood can receive blood from anyone.
• A person with type O blood can receive blood from a person
with type O only.
Blood Groups
Blood
Group
O
A
B
AB
Antigen
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A
B
A+B
Antibody
a+b
b
a
-
Rh Blood Typing
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An Rh -- person (lacks this marker) transfused with Rh+ blood
(has this marker) will produce antibodies to the Rh marker.
Occasionally, a baby will inherit an Rh positive blood type from
its father while the mother has an Rh negative blood type. The
baby's life could be in great danger if the mother's Rh negative
blood attacks the baby's Rh positive blood. If this happens, an
exchange transfusion may save the baby's life.
There are risks in pregnancy to a second Rh+ child if an Rh -woman bore a previous child who was also Rh+ and thus left
behind some antibodies that can now seep into this second child
and cause clumping.
In erythroblastosis fetalis, too many cells may be destroyed and
the fetus dies.
Medical treatment (RhoGam) given to the mother after the birth
of the first Rh+ baby can inactivate the Rh antibodies.
Blood and Oxygen
• Hemoglobin is a protein
molecule with 4 protein subunits (2 alphas and 2 betas)
• Each of the 4 sub-units contains
a heme group which gives the
protein a red color
• Each heme has an iron atom in
the center which can bind an
oxygen molecule (O2)
• The 4 hemes in a hemoglobin
can carry a maximum of 4
oxygen molecules
• When hemoglobin is saturated
with oxygen it has a bright red
color; as it loses oxygen it
becomes bluish (cyanosis)
Hemoglobin -1
• The iron in each haem group binds an oxygen
molecule.
• Release of oxygen from hemoglobin is called
dissociation.
• The amount of oxygen that can bind hemoglobin
is determined by the concentration or partial
pressure.
• The greater the partial pressure of oxygen the
more hemoglobin becomes saturated.
Hemoglobin - 2
• At the alveolar pO2 of 105 mm
Hg at sea level the hemoglobin
will be about 97% saturated, but
the saturation will fall at high
altitudes.
• At 12,000 feet altitude alveolar
pO2 will be about 60 mm Hg
and the hemoglobin will be 90%
saturated.
• At 29,000 feet (Mt. Everest)
alveolar pO2 is about 24 mm Hg
and the hemoglobin will be only
42% saturated.
• At very high altitudes most
climbers must breath pure
oxygen from tanks.
• The developing fetus cannot
breathe and must get all of its
blood from the placenta.
• Fetal blood has a very low
pO2, about 30 mm Hg,
equivalent to living at 26,000
feet altitude.
• To extract more oxygen from
the mother's blood fetuses
make a special hemoglobin
(hemoglobin F) which has a
very high affinity for oxygen.
The Bohr Effect
• Hemoglobin must bind oxygen tightly to load up
efficiently in the lungs, but this makes it hard to release the
oxygen in the tissues
• Some unloading occurs because the tissue pO2 is low,
causing oxygen to diffuses from the blood
• Active tissues make lots of acid (carbonic and lactic) and
this also helps to unload oxygen from the hemoglobin
• At low pH hemoglobin has a lower affinity for oxygen;
this will cause more oxygen to come off in the tissuesimportant in exercise
• The increased unloading of O2 at low pH is known as the
Bohr Effect.
• Hemoglobin also has a lower affinity for oxygen at higher
temperatures.
The Bohr Effect
Blood Flow
Hypoxia
• Hypoxia is tissue oxygen deficiency.
• Brain is the most sensitive tissue to
hypoxia: complete lack of oxygen can cause
unconsciousness in 15 sec and irreversible
damage within 2 min.
Types of Hypoxia
Type of
Hypoxia
O2 Uptake
in Lungs
Hemoglobin Circulation
Tissue O2
Utilization
Hypoxic
Low
Normal
Normal
Normal
Anemic
Normal
Low
Normal
Normal
Ischemic
Normal
Normal
Low
Normal
Histotoxic
Normal
Normal
Normal
Low
Causes of Hypoxia
• Hypoxic: high altitude, pulmonary edema,
hypoventilation, emphysema, collapsed
lung
• Anemic: iron deficiency, hemoglobin
mutations, carbon monoxide poisoning
• Ischemic: shock, heart failure, embolism
• Histotoxic: cyanide poisoning (inhibits
mitochondria
Carbon monoxide (CO)
poisoning:
• CO binds to the same heme
Fe atoms that O2 binds to
• CO displaces oxygen from
hemoglobin because it has a
200X greater affinity for
hemoglobin.
• Treatment for CO poisoning:
move victim to fresh air.
Breathing pure O2 can give
faster removal of CO
Cyanide poisoning:
• Cyanide inhibits the cytochrome
oxidase enzyme of
mitochondria
• Two step treatment for cyanide
poisoning:
1) Give nitrites
Nitrites convert some
hemoglobin to methemoglobin.
Methemoglobin pulls cyanide
away from mitochondria.
2) Give thiosulfate.
Thiosulfate converts the cyanide
to less poisonous thiocyanate
Human Cardiovascular System
The Cardiovascular System
• The circulatory system functions in the delivery of
oxygen, nutrient molecules, and hormones and the
removal of carbon dioxide, ammonia and other
metabolic wastes.
• Capillaries are the points of exchange between the
blood and surrounding tissues.
• Veins carry blood from capillaries to the heart.
• Venules are smaller veins that gather blood from
capillary beds into veins. Pressure in veins is low,
so veins depend on nearby muscular contractions
to move blood along. The veins have valves that
prevent back-flow of blood.
Blood Vessels
• Arteries - designed for high pressure are elastic: must
swell to take up blood expelled by the heart. Swelling
stretches elastic tissue and keeps the blood pressure fairly
high between heart beats.
• Small arteries (arterioles) have muscles that contol their
diameters (precapillary sphincters): used to control blood
flow through an organ.
• Veins – designed for low pressure, expand to take up blood
when animal is not active.
• Capillaries - This is where materials are delivered from
blood to cells, and vice versa, thin: one layer of flattened
(squamous) cells, not elastic .
ARTERY
VEIN
Structure of the Human Heart
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The heart has four
chambers through which
blood is pumped.
The upper two are the right
and left atria.
The lower two are the right
and left ventricles.
Left side deoxygenated
blood.
Right side oxygenated
blood.
Heart Valves
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Four types of valves
1.
2.
3.
4.
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The tricuspid valve is located between the right atrium and right
ventricle.
The pulmonary or pulmonic valve is between the right ventricle
and the pulmonary artery.
The mitral valve is between the left atrium and left ventricle.
The aortic valve is between the left ventricle and the aorta.
Under normal conditions, the valves let blood flow
in just one direction.
Blood flow occurs only when there's a difference in
pressure across the valves that causes them to
open.
The Cardiac Cycle
• The sequence of events during a complete heart beat.
• Systole – contraction and Diastole - relaxation.
• Stage 1 – Atrial diastole, both atria and ventricles are relaxed.
Blood enterr the atria under low pressure. As the atria fill with
blood pressure rises and eventually forces the tricuspid and
bicuspid valves to open.
• Stage 2 – Atrial systole, two atria contract at the same time and
blood pumped into the ventricles.
• Stage 3 – Ventricular systole, 0.2 secs later the ventricles
contract this causes the cuspid valves close, closing makes a
sound, “lub”. The semi lunar valves of aorta and pulmonary
artery open and blood enters.
• Stage 4 – Ventricular diastole, high pressure in aorta and
pulmonary closes the semi-lunar valves, closing makes a second
sound, “dub.”
Heartbeat
• One complete heartbeat consists of one systole and one
diastole.
• Human heartbeats originate from the sinoatrial node (SA
node) near the right atrium.
• A discharge from this natural "pacemaker" causes the heart
to beat. This pacemaker generates electrical impulses at a
given rate, but emotional reactions and hormonal factors
can affect its rate of discharge. This lets the heart rate
respond to varying demands.
• Modified muscle cells contract, sending a signal to other
muscle cells in the heart to contract.
• The signal spreads to the atrioventricular node (AV node).
• Signals carried from the AV node, through bundle of His
fibers and Purkinjie fibers cause the ventricles to contract
simultaneously.
Heat Beat
Regulation of Heart Rate
• Blood flow can be increased by increasing the
blood pressure (higher cardiac output, constriction
of many arterioles)
• It can also be increased by opening up (dilating)
arterioles in the tissue which needs more blood
• Both cardiac output and blood vessel diameter are
controlled by hormones and nerves
Heart Disease
• 40% of all premature deaths caused by
cardiovascular disease.
• Athersclerosis – development of a clot in
arteries.
• Once artery is blocked the tissue it supplies
will suffer oxygen starvation will become
damaged or die.
Assignment 5
Read Chapter 14
Q1.How is heart rate controlled during
exercise?
Q2. If exercise is a good way to keep your
heart healthy, why is there a chance of
having a heart attack during vigorous
exercise?
Q3.How do electrocardiograms(ECGs) use
the cycle to detect abnormalities in the
heart?