1. RESPIRATION 3 Main Processes Function:
1. Delivery of sufficient oxygen to our muscles to produce the energy which fuels muscle contraction.
2. Carbon Dioxide produced by the muscles must be cleared and removed from the body
3 Main Processes
Pulmonary Ventilation – the breathing of air into and out of the lungs.
External Respiration – exchange of oxygen and carbon dioxide between the lungs and blood.
Internal Respiration – the exchange of oxygen and carbon dioxide between the blood and the muscle tissues.

2. Link between Cardiovascular and Respiratory Systems
The Vascular System
Includes the blood and the blood vessels.
Transports oxygen around the body’s tissues and carbon dioxide to the lungs
The Respiratory System
Ensures an adequate supply of oxygen is available to meet demands
Removes carbon dioxide
The Heart
Acts as a dual pump
Left side pumps oxygen-rich blood around to the body’s tissues so they can function properly
The right side pumps blood low in oxygen but high in carbon dioxide around to the lungs – carbon dioxide can be expired and blood re-oxygenated

3. Task
Draw Fig Page 39
Put the following structures in order to show the route of atmospheric air to the site where gaseous exchange takes place:
nose/trachea, alveolus, larynx, pharynx, oral cavity, alveoli sacs, left and right bronchi, nasal cavity, lungs, bronchioles, mouth.

5. Respiration at Rest
Mechanics of
Breathing

7. Inspiration Lung Ribcage moves upwards and outwards Diaphragm is
Atmospheric pressure outside forces air into the lungs
Air in lungs is at lower pressure than air in atmosphere
Lung
Ribcage moves
upwards and
outwards
Diaphragm is
pulled down flat
DURING EXERCISE
the scalenes, sternocleidomastoid, pectoralis minor muscles contract
lungs have even bigger volume - more air forced in

9. Expiration Ribcage moves inwards and down – falls in The diaphragm
relaxes and returns
to its resting
dome shape
DURING EXERCISE
internal intercostal and abdominal muscles contract, air forced out more rapidly

10. Inspiration Expiration
External Intercostals contract
Ribcage moves upwards and outwards
Diaphragm contracts downwards and flattens
Increases the size of the thoracic cavity
Decreases air pressure in lungs
Air drawn into lungs
Expiration
External Intercostals relax
Ribcage moves downwards and inwards
Diaphragm relaxes back to its dome shape
Decreases the size of the thoracic cavity
Increases air pressure in lungs
Air forced out of lungs

12. 5 Easy Steps to learn the mechanics of respiration:
Muscles – actively contract or passively relax to cause:
Movement – of the ribs and sternum and abdomen which causes:
Thoracic cavity volume – to either increase or decrease which in turn causes:
Lung air pressure – to either increase or decrease which causes:
Inspiration or expiration – air breathed in or out.

13. Exam Question
June 10
Explain the mechanics of breathing which allow a performer to fill the lungs with air during exercise.

14. Mark Scheme
June 10
A. Diaphragm/intercostal muscles contract/ flattens;
B. Lungs/ribs also pulled upwards and outwards;
C. Lungs attached to pleural membranes;
D. Volume/size of chest/thoracic cavity/lungs increases;
E. Reducing pressure within lungs;
F. Air sucked in;
G. During exercise other muscles – strernocleidomastoid / scalenes and pectoralis minor increase action;

16. Figure 1 shows the spirometer reading of an athlete.
Which ‘lung volume’ is represented by the letter B.
(1 mark)
B = Inspiratory reserve (volume)
(ii) What would be the effect on the spirometer trace for lung volume A of a period of continuous running? (2 marks)
A. Increase in tidal volume/larger/higher proportion
B. More frequent peaks/closer together

17. LUNG VOLUMES Lung volumes are defined as :
TLC = total lung capacity = total volume of air in the lungs following maximum inspiration
VC = vital capacity = maximum volume of air that can be forcibly expired following maximum inspiration
TV = tidal volume = volume of air inspired or expired per breath
IRV = inspiratory reserve volume = volume of air that can be forcibly inspired above resting tidal volume
ERV = expiratory reserve volume = volume of air that can be forcibly expired above resting tidal volume
RV = residual volume = volume of air remaining in the lungs after maximal expiration

18. Lung Capacities
Lung capacities result from adding two or more lung volumes together.
Vital capacity is the sum of Inspiratory reserve volume, tidal volume and expiratory reserve volume (VC=IRV+TV+ERV)
This is typically 5000ml of air
Lung volumes can be measured using a Spirometer, which identifies lung function.
- Use show me boards for Spirometer trace

20. Lung Volume Question
While running, a performer will experience changes in lung volumes.
Complete Table 3 below to show how the tidal volume, inspiratory reserve volume and expiratory reserve volume change during exercise.

21. Mark Scheme A. Tidal volume – increases
B. Inspiratory reserve volume – decreases
C. Expiratory reserve volume – decreases

22. Minute Ventilation
Minute ventilation is the volume of air breathed in or out per minute. It is calculated by multiplying a persons Tidal Volume (TV) by the number of times they breathe per minute (breathing rate, f)
VE =TV x Breathing rate (f)
Calculate numbers on show-me board

23. Pulmonary Ventilation
Lung volume or capacity
Definition
Average value at rest (litres)
Average value during exercise
Change during exercise
Tidal Volume
Volume of air breathed in or out per breath
0.5 / 500ml
2.8L
Increase
Inspiratory Reserve Volume (IRV)
Volume of air that can be forcibly inspired after a normal breath
3.1 L 2L
Decrease
Expiratory Reserve Volume (ERV)
Volume of air that can be forcibly expired after a normal breath
1.0 L
1.2L
Slight decrease

24. Minute Ventilation = number of breaths per minute x tidal volume
Lung volume or capacity
Definition
Average value at rest (litres)
Average value during exercise
Change during exercise
Residual Volume
Volume of air that remains in the lungs after maximum expiration
1.2 L
1.2
Remains the same
Vital Capacity
Volume of air forcibly expired after maximum inspiration in one breath
4.8 L
4.8
Minute Ventilation
Volume of air breathed in and out per minute
6 L
110
Increase
Total Lung Capacity
Vital capacity + residual volume. 6
Frequency
Amounts of breaths per minute
Increases
Minute Ventilation = number of breaths per minute x tidal volume
= 12 x 0.5 OR 15 x 0.5
= BETWEEN 6 litres and 7.5 litres

25. Ventilation during exercise
What will happen to breathing during exercise? Why?
During exercise, both the rate (frequency) and depth (tidal volume) of breathing Increases in direct proportion to the intensity of the activity.
This is to satisfy the demand by the working muscles for oxygen and to remove the carbon dioxide and lactic acid that is produced.

26. Minute Ventilation during exercise
Sub-Maximal exercise – low intensity
Sporting examples…
Maximal exercise – high intensity

27. Maximal Exercise Anaerobic Submaximal Exercise Aerobicd e e f f
a = anticipatory rise – due to emotional excitement & release of adrenaline.
b = sharp rise – increase in CO2 & lactic acid. Muscle movement detected by proprioceptors. Send messages to respiratory centre in medulla of brain to increase the rate and depth of breathing.
c & d = slower increase/steady state – plateau due to O2 demand being equal to the O2 supply.
e = rapid decline– O2 demand drops suddenly.
f = slower recovery as body returns to resting levels.

28. CHANGES IN MINUTE VENTILATION WITH EXERCISE

29. Exam tips
In the exam, you may be required to explain the patterns of the two graphs, so make sure you understand them.

30. Prep Task Gaseous exchange: Read pages 46-49
Name four factors that influence the rate of gaseous diffusion across the respiratory membrane in the alveoli.

31. Explain how carbon dioxide and oxygen are exchanged
Gaseous Exchange
Learning Outcomes
Explain how carbon dioxide and oxygen are exchanged
Explain / describe how oxygen and carbon dioxide is transported around the body

32. Partial Pressure Oxygen Alveoli Blood Muscle
Partial pressure is a term often used when describing the gaseous exchange process.
All gasses exert a pressure.
Oxygen makes up only a small part of air (21%) so it therefore exerts a partial pressure.
Gases flow from an area of high pressure to an area of low pressure.
As Oxygen moves from the alveoli the partial pressure of oxygen in the blood and then the muscle needs to be successively lower.
Partial pressure of oxygen in the alveoli is higher than the partial pressure of oxygen in the blood because oxygen has been removed from the working muscles, so its concentration in the blood is lower.

33. External Respiration Internal Respiration Where? Movement Why? – O2
Alveolar-capillary membrane between alveoli air and blood in alveolar capillaries.
Tissue-capillary membrane, between the blood in the capillaries and the tissue (muscle) cell walls.
Movement
O2 in alveoli diffuses to blood;
CO2 in blood diffuses to alveoli.
O2 in blood diffuses into tissue;
CO2 in tissues diffuses into blood.
Why? – O2
PP of O2 in alveoli higher than PP of O2 in the blood so the O2 diffuses to the blood.
PP of O2 in blood is higher than the PP of O2 in the tissue so the O2 diffuses into the Myoglobin within tissues.
Why – CO2
PP of CO2 in the blood is higher than the PP of CO2 in the alveoli so CO2 diffuses into the alveoli.
PP of CO2 in the tissue is higher than the PP of CO2 in the blood so CO2 diffuses into the capillary blood.

35. What happens when we start taking part in exercises?
Increases in Lactic Acid
Increases in CO2
Increases in blood and muscle temperature
Decreases in pH thus acidity levels increase.
These changes mean that the body needs oxygen quickly.

36. Features that Facilitate Diffusion at the Alveolar
1. Alveolar membrane is very thin = short diffusion distance between the air in alveoli and the blood
2. Numerous (millions) of alveoli creates a VERY LARGE surface area for diffusion to take place
3. Alveoli are surrounded by a vast (large) network of capillaries = huge surface area for diffusion
4. The diameter of the capillaries is slightly narrower than the area of a red blood cell. This forces the blood flow slowly in single file.

37. The reaction between 02 and Hb is easily reversible and is represented by the oxy-haemoglobin dissociation curve
Rest
The oxy-haemoglobin dissociation curve represents the amount of Hb saturated with 02 as it passes through areas of the body that have very different partial pressures of 02 (P02)

38. The Bohr Effect
During exercise muscles need more oxygen so the dissociation (release) of oxygen from Hb happens more readily
This is known as the Bohr effect and frees up more oxygen = used by working muscles
This happens because:
CO2 and lactic acid production
=acidity of blood (pH)
blood & muscle temp (energy released as heat from muscle contraction)
Dissociation curve shifts to the RIGHT

39. Factors shifting the dissociation curve to the right are:
1. Increase in blood and muscle temperature
2. Decreases in PP oxygen within muscle increasing the oxygen diffusion gradient.
3. Increase in PP of carbon dioxide increasing carbon dioxide gradient.
4. Bohr effect – increase in acidity (lower pH)
These factors increase during exercise. The effect is that the working muscles:
Generate more heat when working
Use more oxygen to provide energy, lowering the PP oxygen
Produce greater carbon dioxide as a by-product
Increase lactic acid levels which increase muscle/blood acidity
Collectively all four factors increases the dissociation of oxygen from haemoglobin that increases the supply of oxygen to the working muscles.

40. Direction of diffusion (high to low pp)
Effects of Exercise
on the dissociation of oxygen
Difference between any two pressures = concentration/diffusion gradient.
The steeper the gradient the faster diffusion is.
Oxygen diffuses from the alveoli into the blood until the pressure is equal in both.
Movement of carbon dioxide occurs in the same way but in the reverse order, from the muscle to the blood to the alveoli.
Partial pressure
Capillary blood
Direction of diffusion (high to low pp)
Muscle tissue
Diffusion gradient
O2 resting
100 40 60
O2 during exercise
<5 95
CO2 resting 45 6
CO2 during exercise 80

41. Nervous/Neural Control
AT REST
Inspiratory centre is responsible for rhythmic cycle of inspiration and expiration to produce a respiratory rate of breaths a minute.
Impulses are sent via:
Phrenic nerves to the diaphram
Intercostal nerves to the external intercostals.
When stimulated these muscles contract, increasing the volume of the thoracic cavity, causing inspiration (active)
When their stimulation stops, the muscles relax, decreasing the volume of thoracic cavity, causing expiration (passive)
The expiratory centre is inactive during quiet/resting breathing. It is passive as a result of the relaxation of the diaphragm and external intercostals.

42. Nervous/Neural Control
DURING EXERCISE
Pulmonary ventilation increases during exercise, which increases both the depth and rate of breathing. This is regulated by:
The Inspiratory Centre which:
(a) increases the stimulation of the diaphragm and external intercostals
(b) stimulates additional inspiratory muscles for inspiration, the sternocleidmastoids, scalens and pectoralis minor, which increase the force of contraction and therefore the depth of inspiration.
The expiratory Centre which:
(a) stimulates the expiratory muscles, internal intercostals, rectus abdominus and obliques, causing a forced expiration which reduces the duration of inspiration.
(b) the inspiratory centre immediately stimulates the inspiratory muscles to inspire, which results in an increase in the rate of breathing.

43. Hering-Breuer Reflex
Expiratory centre acts as a safety mechanism in the lungs to ensure they are never over inflated.
Stretch receptors in the lungs detect when the depth of breathing increases and stimulate the RCC to inhibit the inspiratory centre and stimulate the expiratory muscles.

44. Control of Ventilation
Chemoreceptors (detect changes in blood acidity)
Stretch receptors (prevent over inflation of the lungs; if these start to get excessively stretched they send impulses to the expiratory centre to induce expiration (Hering Breur reflex))
Thermoreceptors
Baroreceptors (detect changes in blood pressure)
Proprireceptors (detect movement)
Expiratory Centre
Respiratory Centre
(Medulla Oblongata)
Inspiratory Centre
Phrenic nerve
Phrenic nerve
Intercostal nerve
Diaphram and external intercostals
Abdominals and internal intercostals
Increase breathing rate
Increase expiration

45. Effects of Altitude on the Respiratory System
At high altitude (above 1500m) the PP of oxygen in the atmospheric air is significantly reduced.
Decreases pO2 in alveoli – Hypoxia which causes a reduction in the diffusion gradient thus a decrease in O2 and Hb association.
This results in a decreases O2 transport in the blood causing a reduction in the O2 available to working muscles.
It thus decreases VO2 max or aerobic capacity also can increase breathing which leads to hyperventilation. Can also lead to dehydration quicker.
Long term affect – increases in Hb and RBC production which increases external respiration and O2 transport.

46. Myoglobin Iron based protein Similar to Hb
In the muscle oxygen is transported by myoglobin.
Myoglobin has a high affinity for oxygen.
It stores oxygen and transports it from the capillaries to
the mitochondria.
Mitochondria are the centres in the muscle where aerobic respiration takes place.
Much
higher
affinity
For 02 than Hb

47. Arterial-venous oxygen difference
(a-vo2 diff)
This represents how much oxygen is actually extracted and used by the muscles
Measured by:
Analysing the difference in oxygen content of the blood in the arteries leaving the lungs and that in the mixed venous blood returning to the lungs