Transcript Blood Transport System

HAEMOGLOBIN, MYOGLOBIN
& THE BOHR SHIFT
AS PE
Learning objectives

1.
2.
By the end of this lesson you will be able to:
Explain the role of haemoglobin and myoglobin
Explain how exercise can have an effect on the
dissociation of oxygen from haemoglobin at the
tissue (Bohr shift)
The transport of oxygen
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1.
2.
When oxygen from the alveoli diffuses across the
alveolar capillary membrane, it enters the
bloodstream. It is the function of the blood to
transport oxygen, and it does this in two ways:
97% is carried in chemical combinations with
haemoglobin (a red iron-based pigment found in red
blood cells)
3% is dissolved in blood plasma (oxygen is not very
soluble in water, hence why this percentage is low)
Key terminology
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Haemoglobin - Red-iron based pigment found in red blood cells.
Myoglobin – a respiratory iron-based protein that is found in
skeletal muscles and acts as a store of oxygen within the muscle cell
Affinity - affinity means likes. If something has a high affinity for
oxygen then it wants to bind to oxygen and vice versa for low
affinity
Oxygen Saturation - a measure of how much oxygen the blood is
carrying as a percentage of the maximum it could carry
Oxy-haemoglobin – haemoglobin combined with oxygen
Partial pressure (p) - the pressure exerted by an individual gas
when it exists within a mixture of gases
Haemoglobin & partial pressure
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The most important factor that determines how much oxygen
combines with haemoglobin is the partial pressure of
oxygen (pO2):
High pO2 (alveolar capillaries of the lungs) – haemoglobin
readily combines with large amounts of oxygen until it
becomes almost fully saturated (96%)
Low pO2 (capillaries of contracting muscles) – oxygen is
released by the haemoglobin
This oxygen can be used by the respiring tissues and muscles
Oxy-haemoglobin dissociation curve
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An oxy-haemoglobin dissociation curve
represents the amount of haemoglobin
saturated with oxygen as it passes through
areas of the body that have different partial
pressures of oxygen.
Q: Where in the body will oxygen
dissociation from haemoglobin be the
highest?
Answer: At the muscle tissue (where it is
needed readily)
At the lungs on the other hand saturation of
haemoglobin with oxygen is very high due to
a high partial pressure of oxygen in the lungs
PO2 at the muscle
tissue
PO2 at the
lungs/alveoli
The bohr effect
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During exercise the
require more oxygen
muscles
Therefore oxygen dissociates
from haemoglobin more readily
This causes a shift in the oxyhaemoglobin dissociation in
which direction?
Answer: To the right
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This is known as the Bohr effect
and frees up more oxygen to be
used by the working muscles
Task
In pairs brainstorm what factors may cause the body to respond
in this way to release more oxygen?
FACTORS:
1.
More carbon dioxide
2.
More lactic acid production-increase in acidity of the blood
3.
Increase in blood and muscle temperature due to energy
released as heat during muscular contraction
quiz
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1.
2.
3.
4.
In pairs, design 4 questions (one from each of the
topics we have covered so far):
Health, Exercise & Fitness
Nutrition
Pulmonary Function
Blood Transport System
Use your workbooks to help you design your questions
THE BLOOD TRANSPORT
SYSTEM
AS Physical Education
Learning objectives

1.
2.
3.
By the end of this lesson you will:
Identify the role of the pulmonary and systemic
circulatory systems
Identify structure of the major blood vessels
Receive individual feedback from Progress Test 2
and complete monitoring forms
starter
haemoglobin
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Red-iron based pigment found in red
blood cells.
The iron atom attached to each chain in a
haemoglobin molecule acts like a magnet
for oxygen – transports it around the body
High affinity for oxygen – binds with it!
Each molecule of haemoglobin combines
with four oxygen molecules
Hb4+4O2 =Hb408
Men have more haemoglobin in the blood
than women (this partially determines why
men have a higher aerobic capacity)
myoglobin
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Iron-based protein found only in
skeletal muscles
Provides intramuscular oxygen storage
Only contains one iron atom
(haemoglobin contains four)
Mb + 02 = Mb02
Higher affinity for oxygen than
haemoglobin and acts as an oxygen
store – saturates itself with oxygen that
has dissociated from haemoglobin
Bohr shift recap
1. Draw the oxy-haemoglobin
dissociation curve
2. Draw the Bohr shift due to
exercise
3. Why does this happen?
Bohr shift – key points
1.
2.
3.
4.
Exercise increases temperature;
Exercise causes increased CO2 and the acidity in
blood increases (lower pH)
More oxygen disassociates from haemoglobin, there
is a reduced affinity for oxygen – muscles receive
more oxygen!
Curve shifts to right
Transport of carbon dioxide
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1.
2.
3.
Like oxygen, carbon dioxide is transported around the body
by the blood. It is carried in several forms:
70% is transported in the blood as hydrogen carbonate
(bicarbonate) ions. When CO2 is produced by the muscles it
diffuses into tissue capillaries and enter the blood stream
where it combines with water to form carbonic acid –
carbonic acid is weak and quickly dissociates into hydrogen
ions – in this form majority of CO2 is transported back to
the lungs and expired
23% combines with haemoglobin in red blood cells to form
carbaminohaemoglobin
7% is dissolved in the plasma of the blood
circulation
http://www.youtube.com/watch?v=0jznS5psypI
Recap quiz
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Using the questions you designed last week,
we will now have a class quiz from all topics
covered so far
homework
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Complete the exam questions provided
Going forward…. After Christmas, homework will be specific
to each individual and the areas that they need to improve
This means exam questions on a weekly basis to maintain
strengths and improve areas for development
If you have any special requests please mention them!!
Vessels of circulation
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1.
2.
3.
4.
5.
There are several types of blood vessel, and each
have a specific purpose. They include:
Arteries
In allocated groups, you are to
Veins
research and produce a poster on the
allocated blood vessel
Capillaries
You will then present your work to the
rest of the group
Arterioles
You have 20 minutes to complete this
1. Main rolestask
/
Venules
responsibilities
2. Structure of the vessel
(valves/walls/pressure/el
asticity/lumen size)
Blood vessels
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In your groups you are to present the key
characteristics / roles of the blood vessel that you
were allocated
Purpose & Function
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Vibrant structures that constrict and relax to
transport blood around the body
Vasodilation – blood vessels swell or dilate –
widen – allows blood flow
Vasoconstriction – narrowing (constriction) of
blood vessels – blood slowed / blocked
Arteries & veins
Arteries
Veins
High Pressure – carry blood away
from the heart for delivery around the
body
Low Pressure – blood returning back to
the heart from the body
Thick Walls
Thinner Walls – thick tunica externa –
wider inner diameter that can hold
more blood
Highly Elastic – deal with surges of
blood from the heart – stretch and
recoil - pulse
Low elasticity – less smooth muscle
No Valves
Pocket valves to aid venous return –
ensure blood flows back to the heart in
the right direction and prevents a
backflow
Carry oxygenated blood, except
pulmonary artery (deoxygenated)
Move stored blood into general
circulation during exercise – at rest up
to 70% of blood is stored in veins
Smooth muscle layer
Carry deoxygenated blood back to
Arterioles
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Smaller version of arteries
Connect arteries to capillaries
Smooth muscle controls the shape of the
lumen via vasodilation and
vasoconstriction
They are responsible for the
redistribution of blood flow and blood
pressure
Capillaries
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Arterioles subdivide into capillaries
Smallest blood vessel in the body – microscopic
(one cell thick)
This allows for capillary exchange – where
oxygen, carbon dioxide, nutrients and metabolic
waste pass between blood and interstitial fluid by
diffusion
Has a venous end which connects to a vein
Arterial end – connects to an artery
They serve to distribute oxygenated blood from
arteries to the tissues of the body and to feed
deoxygenated blood from the tissues back into the
veins
Venules
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Small veins, have connective tissue in
their walls
Connect capillary bed to veins –
allowing deoxygenated blood to
return to them
Collect the outflow of blood from
the capillary bed at low pressure
Exam question
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Complete the exam question
provided
Mark scheme
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(i) C
Accept first answer only
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(1)
(ii) (Thick) Elastic walls.
(Small) lumen.
(Smooth) muscle layer.
Required terms
Carrying blood away from the heart / to tissues / muscles.
Cushion and smooth out / recoil / pulse / withstand pumping action
/ pressure
/ velocity from heart.
 (3)
recap
Explain the difference between the pulmonary
circuit system and the systemic circuit system
(2 marks)
Pulmonary – deoxygenated blood is transported from the heart
to the lungs to pick up oxygen, and back to the heart
Systemic – oxygenated blood is transported from the heart to the
body tissues, and deoxygenated blood is returned back to the
heart
Venous return
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The volume of blood that returns to the right side of
the heart via venules and veins
Up to 70% of the blood sits in the veins at rest
providing a large reservoir of blood that can be
called upon quickly when needed.
The heart can only pump out as much blood as it
receives so stroke volume (and therefore cardiac
output) is dependant on venous return.
Mechanisms to improve blood flow
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1.
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4.
When we exercise we need more oxygen and thus cardiac output needs to increase.
However due to the low pressure of the blood in the veins, stroke volume cannot be
maintained during exercise without calling upon a number of mechanisms to aid blood
flow back to the heart and enhance stroke volume:
SKELETAL MUSCLE PUMP -When the skeletal muscles contract it creates a massage
effect on the nearby blood vessels helping push blood back to the heart
POCKET VALVES -Control the direction of the blood flow by snapping shut to prevent
any backflow of blood
SMOOTH MUSCLE WITHIN THE VEINS- wall of each vein contains a very thin layer
of smooth muscle which contracts to help push the blood back towards the heart
RESPIRATORY PUMP - As the muscles involved in respiration and the lungs expand
extra pressure is placed up on the nearby blood vessels helping push the blood back
to the heart.
Venous return during exercise (running)
1
2
3
4
• Action of muscles contracting compresses
veins
• Veins have one way valves / to prevent
backflow
• Pressure increases/changes due to greater
inspiration / size of chest cavity
• Blood is pushed towards the heart and
draws it up
task
Complete the exam questions provided
 Use the mark scheme to mark your work
 Revise for Mock Exam – ALL topics
covered so far may be tested!
 1-to-1’s with those I have not yet spoken
with!
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