Download Lung Capacities and Volumes

Answer the following questions…
• During a practice session, blood flow is
redirected to the active muscles. Explain how
this is achieved.
(3 marks)
Answers
1. Increased metabolic activity / increased carbon
dioxide / increased lactic acid / drop in pH;
2. Detected by chemoreceptors
3. Message to medulla / vasomotor control centre
4. Sympathetic nerve impulse to blood vessels
5. Adrenaline / Noradrenaline is produced
6. Pre-capillary sphincters at capillaries
7. Vasoconstriction (in blood vessels)/ preventing
blood flow to muscles / organs not required
8. Vasodilatation (in blood vessels) / blood vessels
open to allow increased blood flow to the muscle
(3 marks)
Lung Capacities and Volumes
Volumes at Rest
• The tidal volume (TV), about 500 mL, is the amount of
air inspired during normal, relaxed breathing.
• The inspiratory reserve volume (IRV), about 3,100 mL,
is the additional air that can be forcibly inhaled after
the inspiration of a normal tidal volume.
• The expiratory reserve volume (ERV), about 1,200 mL,
is the additional air that can be forcibly exhaled after
the expiration of a normal tidal volume.
• Residual volume (RV), about 1,200 mL, is the volume
of air still remaining in the lungs after the expiratory
reserve volume is exhaled.
Volumes at Rest
• Vital Capacity (VC), about 4800mL, is the
maximal amount of air exhaled after a
maximal inspiration.
– Which 3 lung volumes combine to create VC?
• Total Lung Capacity (TLC), about 6000mL is
vital capacity plus residual volume.
Minute ventilation
• The amount of air taken into or out of the
lungs in one minute.
• Frequency x tidal volume
Volumes During Exercise
• Using page 32 of your text book, complete the
table to show what happens to lung capacities
during exercise.
Long Term Effects of Exercise
• Aerobic exercise has little impact on Lung
capacity.
Partial Pressure
• Pressure of O2 is high in the lungs compared
to the pressure of O2 of the blood in the
pulmonary artery (that flows into the alveoli).
• The difference in pressure is called a
concentration gradient.
• The concentration gradient allows diffusion
(movement of gases) to occur.
Partial Pressure
• Diffusion only occurs from areas of high
pressure to areas of low pressure (its moving
down the gradient).
• Oxygen diffuses from the alveoli into the
capillaries (down the concentration gradient).
• The oxygen combines with haemoglobin (in
the RBCs) in the blood to form
oxyhaemoglobin.
Gaseous Exchange
• When blood arrives to the muscle cell via the
capillaries, there is another concentration
gradient.
• During exercise, this concentration gradient is
steeper than at rest due to the higher levels of
O2 being used by the cell (and thus more CO2).
• The steeper the gradient, the faster O2
diffuses into the muscle cell.
Gaseous Exchange
• In order for O2 to be given to the muscle cells,
it must dissociate with the haemoglobin.
• As body temperature rises, dissociation occurs
more readily.
• A drop in pH (due to increase in lactic acid)
also causes dissociation to occur more readily.
Gaseous Exchange
• Haemoglobin has a higher affinity for CO2 than
O2.
• So the increase of CO2 during exercise causes
O2 to dissociate rapidly.
• The same process of gaseous exchange occurs
with CO2 due to the difference in pressures of
CO2 between the muscle cells and capillaries,
creating a concentration gradient.
Partial Pressure at Altitude
• At altitude there is lower pressure of O2 in the
alveoli.
• This means there is a reduction in the
concentration gradient.
• Therefore, less oxygen is diffused into the
blood and there is less O2 picked up by the
haemoglobin.
• This results in less O2 being transported in the
body.
Partial Pressure at Altitude
• When we are exposed to high altitude, our body
responds by increasing our breathing rate (and
heart rate) in an attempt to get more O2 into the
body.
• This is not efficient, so our body needs to adapt
to our environment.
• The body begins to increase RBC production,
which means more haemoglobin molecules
available to associate with O2.
• Therefore, more O2 is transported around the
body.
Altitude Training
• Is the deliberate attempt to increase RBC
production to gain an advantage in aerobic
based sports.
• It is widely used by many athletes but
particularly by long and middle-distance event
athletes.
• Athletes will train at altitude for a number of
weeks to increase RBC production before
returning to sea level and competing, where
an increased no. of RBCs will improve their
VO2max.
Altitude Training
• It is important to be at altitude for a number of
weeks prior to competition as initially, exercising
at altitude is very difficult.
• This is due to the lower pressure of O2 and less
O2 being pumped around the body.
• Therefore, the body must work a lot harder to get
the same results experienced during training at
sea level.
• In the first few weeks of being at altitude the
body is more reliant on the anaerobic system and
therefore fatigue sets in quickly due to the
production of lactic acid.