The ventilatory and cardiovascular systems work together to increase oxygen delivery during exercise in order to maintain homeostasis. The ventilatory system increases breathing rate and volume through actions of the diaphragm and intercostal muscles. The cardiovascular system increases cardiac output through higher heart rate and stroke volume to distribute more blood to working muscles. Both systems must precisely coordinate their responses to exercise in order to meet increased demand for oxygen while removing carbon dioxide.

1. Exercise Physiology
The Ventilatory and
Cardiovascular Systems

2. INTRO
• HOMEOSTASIS
• Maintenance of a constant internal environment
• Example: temperature, O2 levels
• Exercise challenges this
• GAS EXCHANGE
– Transfer of oxygen & carbon dioxide between
2 systems

3. IMPORTANT POINT
• The ventilatory & cardiovascular systems
work together in a highly coordinated way
to increase O2 delivery during exercise.
• This is the body trying to maintain
homeostatis

4. VENTILATORY SYSTEM
• Movement of air in & out of the lungs is
due to repeated contraction & relaxation of
muscles by the diaphragm & chest wall to
increase & decrease the volume
(pressure) in the lungs.

6. I. Structure of the Ventilatory System
A. Conducting Airways:
*offers a low resistance
pathway for air flow
*warms and moistens
air
*mucus and ciliated
cells filter air

7. II. Pulmonary Ventilation: the exchange of
air between the atmosphere and lungs
(breathing).
A. Mechanics of Breathing:
1. Inhalation:
*diaphragm contracts
and lowers
*chest cavity
expands increasing
volume and
decreasing internal
air pressure
Why can our ribs
expand?

8. 2. Exhalation:
*Diaphragm relaxes and
moves up.
*chest cavity volume
decreases and
internal air pressure
increases.
*during exercise the
intercostal and
abdominal muscles
act on the ribs to
produce greater
exhalation

9. III. Total Lung Capacity: (TLC) maximum
volume of lungs after maximum inhalation
(vital capacity + residual vol.).
A. Tidal Vol.: (TV)
Volume of air
breathed in and out
in any one breath.
B. Inspiratory Reserve
Vol.: additional
inspired air over and
above tidal volume.

10. C. Expiratory Reserve Volume: volume of air in
excess of tidal volume that can be exhaled
forcibly
D. Residual Vol.: (RV) volume of air still in lungs
after maximum expiration.
E. Vital Capacity: max volume of air exhaled after
max inhalation

11. GAS EXCHANGE
• DIFFUSION: Gas will move along a
gradient from an area of higher pressure
to lower pressure
– (or concentration)

12. GAS EXCHANGE
• Challenge during exercise is to ensure
homeostasis of gases.
• The ventilation and cardiovascular system
must therefore make changes.

13. Explain the Mechanism of
Ventilation
• Include the actions of the diaphragm and
the intercostal muscles, and the
relationship between volume and
pressure.

14. When inhalation occurs the external
intercostal muscles contract, making the
ribcage move up and out. The diaphragm
contracts, becoming flat. These contractions
increase the volume of the thorax, which
drops the pressure inside it bellow
atmospheric pressure. Air from outside the
body flows to the lungs via mouth or nose.
This continues until the pressure in the lungs
rises to atmospheric pressure.

15. • Then during exhalation, the external
intercostal muscles contract, moving the
ribcage down and in. The abdominal
muscles contract, pushing the diaphragm
up. These contractions decrease the
volume of the thorax, which increases the
pressure inside it above atmospheric
pressure. Air from the lungs flows out of
the body through the mouth or nose. This
continues until the pressure in the lungs
falls back to atmospheric pressure.

16. VENTILATION
• Minute ventilation = volume of air being
exhaled per minute
VE (L.min) = VT(L.breath) x Bf(breaths.min)
• Complete green box on page 35 text.
• What happens to VE during exercise? Why?
• What happens when you exercise at altitude
versus sea level?
• How do ‘freedivers’ hold their breath for so
long?

17. VO2 Max
• VO2 Max
– the maximum or optimum
rate at which the heart,
lungs, and muscles can
effectively use oxygen
during exercise, used as
a way of measuring a
person's individual
aerobic capacity.

18. IV. CO2 transport in the blood:
• CO2 is transported
in the blood in the
form of bicarbonate
• O2 is less soluble in
plasma, but easily
attaches to
hemoglobin – an
iron-rich pigment

19. Increased Carbon
dioxide content in
blood
Detected by
respiratory center
Ventilation
increases because
of direct result of
blood acidity levels
(low pH)
D. What’s the role of CO2 in the control of
pulmonary ventilation during exercise?

20. V.Oxygen Transport in the Blood:
A. Hemoglobin: (Hb)
iron containing
pigment that binds
with oxygen to form
oxyhemoglobin.
Hb + 4 O2 Hb4O8

21. VI. Gas Exchange in the lungs:
A. Alveoli: thin
membrane sacs
at the end of the
bronchioles.
*serve as the site of
gas exchange
by diffusion.

22. Gas Exchange
• In the lungs and other body tissues gas
exchange takes place in a passive
process known as diffusion.
• High pressure to lower partial pressure

23. BLOOD
• Total blood volume for a 70kg male is
~5litres
• 55% blood fluid is plasma, 45% is blood
cells and platelets

24. VII. Blood: transport vehicle for nutrients,
hormones, waste products and electrolytes.
1. Blood Composition:
A. Cellular:
i. erythrocytes: (RBC’s)
Contain hemoglobin
that binds to oxygen
for transport to
tissues.

25. Electrolytes
• Electrolytes are important because they
are what your cells (especially nerve,
heart, muscle) use to maintain voltages
across their cell membranes and to carry
electrical impulses (nerve impulses,
muscle contractions) across themselves
and to other cells. Your kidneys work to
keep the electrolyte concentrations in your
blood constant despite changes in your
body.

26. Example
• When you exercise heavily, you lose
electrolytes in your sweat, particularly
sodium and potassium. These electrolytes
must be replaced to keep the electrolyte
concentrations of your body fluids
constant. So, many sports drinks have
sodium chloride or potassium chloride
added to them.

27. ii. Leukocytes: (WBC’s) defend the body
against disease.
*produce antibodies
*destroy bacteria and
viruses
*produce marker
proteins

28. iii. Platelets: (thrombocytes) play a role in
the clotting of blood.

29. B. Liquid Component:
i. Plasma: 60% total
volume of blood.
90% water and 10%
solutes
• Metabolites and
wastes (gases,
hormones, vitamins)
• Salts (ions)
• Plasma proteins

30. BLOOD
• Q&A
– What is EPO? And what does it do?
– Why is it advantageous for an endurance
athlete to have a higher concentration of
RBC’s?
– How can an athlete naturally increase their
RBC stores?
– What are some ways athletes are illegally to
increase their RBC’s?

31. Ventilation and Blood Review
• During exercise what is the primary
function of blood?
• Transport from various tissues- gases, nutrients, waste
products, hormones, or even heat.
• During exercise what is the relationship
between the ventilation system and blood?
• Ventilation increases as a direct result of
increases in blood acidity levels due to
increased carbon dioxide content of the blood.

32. What is the role of the following:
• Platelets
– Repair after injury
• Leucocytes (WBC)
– Protecting the body from infection
• Erythrocytes (RBC)
– Contain hemoglobin and O2 attaches to
hemoglobin

33. VII. Anatomy of the Heart
Superior
vena cava
Tricuspid
valve
Right atrium
Aortic Arch
Pulmonary Valve
Left atrium
Left pulmonary artery
Mitral
valve or
bicuspid
valve
Septum
Left pulmonary
veins
Left ventricle
Right ventricle
Inferior vena
cava
Aortic
valve

34. HEART
• PULMONARY
CIRCULATION
– Delivers deoxygenated
blood from right side of
the heart to the lungs
• SYSTEMIC
CIRCULATION
– Delivers oxygenated
blood from left side of the
heart to the body

35. CIRCULATION PATHWAY
Arteries
Arterioles
Capillaries
Venules
Veins

36. CIRCULATION
• Arteries: thick muscular walls; O2 rich;
transport blood away from the heart
• Veins: deoxygenated blood; less
muscular; valves to prevent back flow
• Capillaries: narrow vessels with thin
walls; site of exchange between blood &
tissue

37. THE CARDIAC CYCLE
• Atrium: receives blood from a vein
• Ventricle: thicker walled, pushes blood out
of the heart into arteries
• Valves: between chambers; ensures
blood travels in 1 direction only
• Look at figure 2.3 the Cardiac Cycle

38. THE CARDIAC CYCLE
• Contraction of the heart is initiated by an
impulse in the pacemaker (SA and AV
node)
• The impulse travels through the heart
muscle causing contractions in the correct
sequence
• Contraction rate
is affected by hormones
& the nervous system

39. • Use the following website to help you
practice your heart anatomy:
• http://www.wisc-
online.com/Objects/ViewObject.aspx?ID=
AP12504
• Do activity: The anatomy of the Heart.

40. 4
5
6
3
2
1

42. Explain the path of blood
from the body to the heart
and back out to the body.
(8 marks)

43. • Deoxygenated blood comes from the body
to the inferior and superior vena cava.
• Blood enters right atrium, pressure
increases and tricuspid valve opens
• Deoxygenated blood enters right ventricle
pressure increases and pulmonary valve
opens
• Deoxygenated blood goes to the lungs via
pulmonary artery where diffusion occurs in
the capillary beds- CO2 and O2 exchange
occurs

44. • Oxygenated blood returns via pulmonary
veins
• Blood enters left atrium pressure
increases and bicuspid valve opens
• Blood flows into left ventricle pressure
increases aortic valve opens
• Oxygenated blood flows to the body via
aortic arch

45. By the end of today’s class:
• How the heart is stimulated by electrical
impulse
• Describe the intrinsic and extrinsic
regulation of heart rate
• Relationship between pulmonary and
systemic circulation
• Blood and response to exercise

46. A. Heart Rate: is regulated by both intrinsic
and extrinsic factors.
i. Intrinsic regulation:
a. Sinoatrial (S-A)
node: a mass of
specialized cardiac
muscle located on
the exterior wall of
the right atrium.
Initiates the
electrical impulse.

47. b. Atrioventricular (A-V) node: receives impulse
from the S-A node and delays it about .10 sec. for
atrial contraction.
c. A-V Bundle of His:
speeds the impulse
over the ventricles to
the Purkinje system
causing simultaneous
contraction of the
ventricles.
Video

48. ii. Extrinsic Regulation: the autonomic nervous
system can override the myocardial rhythm.
a. Sympathetic
Influence:
epinephrine is
released when
stimulated causing
heart rate to
increase.
b. Parasympathetic Inf:
releases
acetylcholine to slow
heart rate.

49. Adrenaline
• Influences heart rate
• Plays a larger role in metabolic action, i.e.
increasing glycogen and lipid breakdown

50. B. Circulation of Blood:
i. Pulmonary
Circulation:
deoxygenated blood
is pumped from the
right side of the heart
through the
pulmonary arteries to
the lungs.
Oxygenated blood is
returned by the
pulmonary veins.

51. ii. Systemic Circulation: oxygen rich blood is
pumped from the left side of the heart through the
aorta to the rest of the body.

52. iii. Cardiac Output: the volume of blood pumped by
the heart in one minute. Equal to stroke vol. x
heart rate.
a. Stroke Vol.: the
volume of blood
pumped by one
ventricle with each
beat. Approx. 70 ml.
Stroke vol.=EDV-ESV

53. iv. Cardiovascular Drift: an increase in heart rate
during steady exercise due to a reduction in stroke
volume.
Caused by:
*exercising in heat
*rise in core temp.
*decrease in plasma
vol.

54. C. Blood Pressure: the pressure exerted on
the walls of the arterial system.
i. Systolic pressure:
– The force exerted by
blood on arterial walls
during ventricular
contraction
ii. Diastolic pressure:
– The force exerted by
blood on arterial walls
during ventriuclar
relatation

55. Cardiac Cycle
• The cardiac cycle is the order of events
making up one heartbeat. Cycle lasts for
approx. 0.8 seconds and occurs approx.
72 times a minute
• Cardiac cycle includes a period of
relaxation, known as diastole (0.5 secs),
followed by a period of contraction, known
as systole (0.3 secs)

57. BLOOD PRESSURE
• Healthy blood pressure =
120mmHg (systolic)
80mmHg (diastolic)
• Low blood pressure = 90-100/50-60
• High blood pressure = 140/100

58. iii. Blood Pressure Response to Exercise:
a. Dynamic Exercise:
systolic pressure
increases with
intensity with
relatively little
change in diastolic
pressure.
Ex. Walking, jogging,
swimming, cycling.

59. b. Static Exercise: heavy resistance training
increases blood pressure due to muscular
contractions compressing peripheral arteries.
Ex. Weightlifting,
isometrics

60. iv. Distribution of Blood
Rest (cardiac output
5,000 ml)
*liver = 1350 ml
*kidneys = 1100 ml
*muscle = 1000 ml
*brain = 700 ml
*skin = 300 ml
*heart = 200 ml
Exercise (cardiac output
25,000 ml)
*liver = 500 ml
*kidneys = 250 ml
*muscle = 21,000 ml
*brain = 900 ml
*skin = 600 ml
*heart = 1000 ml

61. v. Cardiovascular Adaptations to Exercise:
a. Lower resting heart
rate.
b. Increased left
ventricular volume.
c. Increased stroke vol.
and cardiac output.
d. Capillarization:
increase in capillary
surface area in
muscles.
e. Greater
arteriovenous
oxygen diff. (a-vO2)

62. D. Maximal Oxygen Consumption: (VO2) refers to
the maximum amt. of O2 that an individual can
utilize during maximal training.
*measured as ml of O2
used in one minute
per Kg of body
weight.
(ml Kg-1 min-1)

63. BP Q&A
• What is your blood pressure?
• TO DO: green box p.41
• Explain what happens to blood flow
distribution during exercise
• Draw Figure 2.7 (page 42)
• What is cardiac output and how is it
measured?
• What happens to cardiac output during
exercise and why?
• TO DO: green box p.43
• READ ‘To think about’ p. 43

64. VO2max
• There are limits to how far the body can be
pushed
• Each person has different tolerance levels
• VO2max is commonly used to measure
aerobic capacity
– It is the maximum rate an individual can take
in and use oxygen

65. VO2max
• Amount of air going in and
out is measured as
exercise intensity
progressively increases
• VO2max is reached when
the person can no longer
continue
“aerobic capacity”

66. VO2max
• VO2max quantifies the maximum rate that
an individual can take in and use O2
• This value is of great interest for elite
endurance athletes = aerobic capacity

67. FICK EQUATION
Relationship bw max
cardiac output, arterio-
venous O2 difference &
VO2max
VO2max = max cardiac
output X max arterio-
venous O2 difference
*Complete ‘To do’ p. 44

68. VO2max
• ABSOLUTE VO2max = L.min -1
• RELATIVE VO2max = ml.kg-1.min-1
– (takes body mass into account; used for
weight bearing activities)
*Read p.45 text
1. Explain how gender, age and type of
exercise affect VO2max
2. How does training increase VO2max?

69. SUMMARY
• Read Theory of Knowledge box on p.48
– Can you think of at least 2 factors
(geographical, physiological, training,
psychosocial, economic or cultural) that East
Africans have to their advantage when
producing endurance athletes?
• Review self-study questions p. 48-49

73. Cardiac SystoleAtrial Systole
– SA node sends electrical impulse to the atrium walls
causing the atrium to contract
– Contractions force all remaining blood into the
ventricles and the antrioventricular valves close
Ventricular Systole
– Pressure inside the ventricles pushes open the
semilunar valves (Pulmonary and aortic)
– Electric signal travels down the Purkinje Fibers
stimulating contraction of the ventricular
myocardium
– Blood flows into the pulmonary (lungs) and systemic
(around the body) systems.

74. Cardiac Diastole
• During relaxation the atria fill with blood
while the tricuspid and bicuspid vales are
closed
• Valves then are pushed open due to
increase in atrial pressure and ventricles
begin to fill with blood