learning objectives learning objectives
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The respiratory systemTRANSCRIPT
Learning objectives Learning objectives
What we will learn in this presentation: The structures of the
respiratory system and their functions The mechanisms of breathing
How gases are exchanged during breathing The composition of inhaled
and exhaled air The different measurements of lung capacity and
breathing The effects of exercise on the respiratory system What is
meant by aerobic and anaerobic respiration The oxygen debt.
Learning objectives 1 of 28 Boardworks Ltd 2006 The respiratory
system The nasal passages and lungs
Air is drawn into the body via the nose or mouth.There are
advantages to breathing through your nose: the air is warmed so
that it is closer to body temperature tiny hairs and mucus in the
nose filter the air, preventing larger dust and pollen particles
reaching the alveoli mucus moistens the air, making it easier for
the alveoli to absorb. Air then travels through the larynx, trachea
(windpipe), bronchi (one bronchus to each lung) and bronchioles to
the alveoli, where oxygen passes into the bloodstream. Mechanisms
of breathing inspiration
When you breathe in: Intercostal muscles pull ribs up and out
intercostal muscles between the ribs contract, pulling the chest
walls up and out the diaphragm musclebelow the lungs contracts and
flattens, increasing the size of the chest the lungs increase in
size, so the pressure inside them falls. This causes air to rush in
through the nose or mouth. Diaphragm contracts and moves down
Mechanisms of breathing inspiration Mechanisms of breathing
expiration
When you breathe out: Ribs move in and down Intercostal muscles
between the ribs relax so that the chest walls move in and down.
The diaphragm muscle below the lungs relaxes and bulges up,
reducing the size of the chest. The lungs decrease in size, so the
pressure inside increases and air is pushed up the trachea and out
through the nose or mouth. Diaphragm relaxes and bulges up
Mechanisms of breathing expiration Gas exchange at the
alveoli
The alveoli are bunches of tiny air sacks inside the lungs. Each
individual sack is called an alveolus. When you breathe in, they
fill with air. The alveoli are covered in tiny capillaries (blood
vessels). Gases can pass through the thin walls of each alveolus
and capillary, and into the blood stream. Gases can also pass from
the blood stream, into the alveolus. Gas exchange at the alveoli
Composition of inhaled and exhaled air
Gas Amount in inhaled air Amount in exhaled air Oxygen Carbon
dioxide Nitrogen Water vapour 21% Very small amount 79% Small
amount 17% 3% 79% Large amount What are the main differences
between inhaled and exhaled air? Ask the students to compare the
relative amounts. Point out that: The amount of oxygen inhaled is
greater than the amount of oxygen exhaled. Consider the efficiency
of respiration at the cells. The amount of carbon dioxide is
greater in exhaled air. The amount of nitrogen is the same. Mouth
to mouth resuscitation works because there is still a lot oxygen
left in exhaled air. Why does mouth-to-mouth resuscitation work?
Respiratory rate is how many breaths you take per minute.
Measuring breathing Tidal volume is the amount you breathe in and
out in one normal breath. Respiratory rate is how many breaths you
take per minute. Minute volume is the volume of air you breathe in
one minute. Vital capacity is the maximum volume of air you can
breathe out after breathing in as much as you can. Clarify and
expand on the definitions with the students Residual volume is the
amount of air left in your lungs after you have breathed out as
hard as you can. Measuring breathing Calculating minute
volume
Remember: Minute volume is the volume of air you breathe in one
minute. You can calculate a persons minute volume by multiplying
the volume of air they breathe in one breath, by their respiratory
(breathing) rate. Question If you breathe 14 times in one minute
(respiratory rate) and you breathe 0.5 litres in each breath, what
is your minute volume? Get students to calculate the answer before
revealing it. Point out that at rest, the volume of air breathed in
each breath will be the persons tidal volume. During extreme
exercise, it may be closer to their vital capacity. Answer: Minute
volume = 14 0.5 litres = 7.0 litres Breathing during exercise
Muscle cell respiration increases more oxygen is used up and levels
of CO2 rise. The brain detects increasing levels of CO2 a signal is
sent to the lungs to increase breathing. Breathing rate and the
volume of air in each breath increase. This means thatmore gaseous
exchange takes place. The brain also tells the heart to beat faster
so that more blood is pumpedto the lungs for gaseous exchange. More
oxygenated blood gets to themuscles and more CO2 is removed. The
effects of exercise on lung structures
In the long-term, regular exercise strengthens the respiratory
system. The respiratory muscles (the diaphragm and intercostals)
get stronger, so they can make the chest cavity larger. This larger
chest cavity means more air can be inspired, therefore increasing
your vital capacity. More capillaries form around the alveoli,so
more gaseous exchange can take place. Relate these facts to
improvements in performance. Emphasise that lungs are NOT muscles
and therefore do not increase in size they function more
efficiently. Gas exchange can now take place more quickly meaning
exercise can be maintained at a higher intensity for longer.
respiration Respiration energy glucose oxygen
Respiration is the process that takes place in living cells which
releases energy from food molecules. Glucose from food is used to
fuel exercise. Oxygen is required to break down the glucose to
produce energy.This energy is used to make muscles contract.
respiration glucose energy oxygen Waste products,including carbon
dioxide,are produced as a result ofthe chemical reactions.
Thesemust be removed and excreted. Aerobic respiration There are
two different types of respiration.
When you exercise at a steady, comfortable rate, the cardiovascular
system is able to supply the muscles with all the oxygen they need.
Under these conditions, aerobic respiration takes place. carbon
dioxide glucose +oxygen energy + +water Aerobic exercise can be
maintained for long periods without the performer getting
breathless or suffering muscle cramps. Moderate activities like
walking, jogging, cycling and swimming use aerobic respiration.
Anaerobic respiration
When you exercise at a high intensity, the cardiovascular system
cannot supply enough oxygen to the muscles. Under these conditions,
anaerobic respiration takes place. glucose energy +lactic acid With
no oxygen available, glucose is burned to produce energy and lactic
acid. Lactic acid is a mild poison. As it builds up, it causes
muscle pain and eventually cramp. Short, intense activities like
sprinting, weightlifting, jumping and throwing use anaerobic
respiration. Oxygen debt After anaerobic activity, oxygen is needed
to neutralize the lactic acid. This is called an oxygen debt. It is
repaid after exercise. The oxygen reacts with the lactic acid to
form CO2 and water. Rapid and deep breathing is needed for a short
period after high intensity exercise in order to repay the debt.
This also helps to remove the carbon dioxide which accumulates in
the blood during intense exercise. Image 2006 Jupiterimages
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