AREA OF STUDY 2 –
PHYSIOLOGICAL
RESPONSES TO PHYSICAL
ACTIVITY
Mechanisms responsible
responses to exercise in
cardiovascular system.
 Mechanisms responsible
responses to exercise in
system.
 Mechanisms responsible
responses to exercise in
system.

Key knowledge 1
for the acute
the
for the acute
the respiratory
for the acute
the muscular

Participate in physical activities to collect
and analyse data relating to the range of
acute effects that physical activity has on
the cardiovascular, respiratory and
muscular system of the body.
Key skills 1
Copy down the chart of page 98
 Write it big enough to fill the page, and
leave space to write around it

What is an acute response?

The body’s immediate, short term
responses that last only for the duration
of the training or exercise session and for
a short time afterwards during the
recovery period.
What does
“mechanism” mean?
It is what has made the change occur.
 For example:

◦ What has made your heart rate increase?
◦ What has made your respiratory rate increase?
Acute responses
of the respiratory
system
Comprehensive and detailed analysis of
collected data, thorough and insightful
understanding of the mechanisms responsible
for acute effects of the cardiovascular,
respiratory and muscular systems of the body.
Respiratory system
Respiratory rate or respiratory frequency,
also known as breathing rate
 Respiratory rate = the number of breaths
taken per minute
 RR at rest = 12 breaths/min
 RR during exercise can increase to 30-48
breaths/min

Respiratory rate

What causes RR to increase?
◦ An increase in CO2 concentration in the blood
◦ This increases stimulates the respiratory
control centre in the brain which increases RR
Respiratory rate
Lets time you Respiratory Rate for
1minute
 Record this number

Respiratory rate
Tidal Volume (TV) is the amount of air
breathed in and out in one breath
 At rest TV is approx 0.5Litres
 During exercise TV can reach 2.5-4L per
breath

Tidal Volume

Ventilation is the amount of air inspired or
expired by the lungs per minute



Ventilation = respiratory rate x tidal volume
V = RR x TV
This varies between each individual depending on
gender and size
At rest ventilation is approx 4-15L/min
During max exercise it can increase beyond
190L/min
It can increase to approx 25 to 35 times resting
levels



Ventilation

At the beginning of exercise, receptors in
the working muscles stimulate ventilation
by sending a message to the respiratory
centre in the brain to increase the
respiratory rate (RR) and tidal volume
(TV)
Ventilation
Conditions
Rest
12
0.5
6
Moderate
exercise
30
2.5
75
Maximal
exercise
48
4.0
192
Ventilation – Fill in the
gaps
Conditions
Respiratory
rate (breaths
per minute)
Tidal volume
(litres)
Ventilation
(litres per
minute)
RR (breaths
per minute)
X TV (litres)
=V
Rest
12
0.5
6
Moderate
exercise
30
2.5
75
Maximal
exercise
48
4.0
192
Ventilation

Do you breathe faster or bigger breathes
when you exercise?

What does breathing faster mean?

What does breathing deeper mean?
Question
Ventilation
Respiratory
responses
Tidal
volume
Respiratory
rate
At high intensities, tidal volume plateaus
and any further increase in ventilation is
due to further increases in respiratory
rate
 The point where ventilation is no longer
increasing linearly with the increase in
exercise intensity is called Ventilation
threshold

The gas exchange occurring in the lungs
at the alveolar-capillary interface and in
the muscles at the tissue-capillary
interface
 Diffusion of gas always occurs from high
pressure to an area of low pressure

Diffusion
Oxygen is high in the lungs, so it diffuses
from the alveoli into the blood stream
 Carbon dioxide is high in the blood, so it
diffuses from the blood stream into the
alveoli

Diffusion in the lungs
Oxygen is high in the blood, so it diffuses
from the blood stream into the muscles
 Carbon dioxide is high in the muscles,
so it diffuses from the muscles into the
blood stream

Diffusion in the muscles

During exercise the diffusion capacity is
increased (due to increase surface area of
the alveoli and muscle tissue)so that
greater amounts of oxygen and carbon
dioxide can be exchanged at the alveoli
and muscles
Diffusion