AREA OF STUDY 2 – PHYSIOLOGICAL RESPONSES TO PHYSICAL ACTIVITY

Key knowledge 1

Mechanisms responsible for the acute responses to exercise in the cardiovascular system.

Mechanisms responsible for the acute responses to exercise in the respiratory system.

Mechanisms responsible for the acute responses to exercise in the muscular system.

Key skills 1

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.

Copy down the chart of page 98Write 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

Respiratory rate or respiratory frequency, also known as breathing rate

Respiratory rate = the number of breaths taken per minute

RR at rest = 12 breaths/minRR 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

Tidal Volume

Tidal Volume (TV) is the amount of air breathed in and out in one breath

At rest TV is approx 0.5LitresDuring exercise TV can reach 2.5-4L per

breath

Ventilation

Ventilation is the amount of air inspired or expired by the lungs per minute

Ventilation = respiratory rate x tidal volumeV = RR x TVThis varies between each individual depending on

gender and sizeAt rest ventilation is approx 4-15L/minDuring 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 – Fill in the gaps

Conditions

Rest 12 0.5 6

Moderate exercise

30 2.5 75

Maximal exercise

48 4.0 192

Ventilation

Conditions Respiratory rate (breaths per minute)

RR (breaths per minute)

Tidal volume (litres)

X TV (litres)

Ventilation (litres per minute)

= V

Rest 12 0.5 6

Moderate exercise

30 2.5 75

Maximal exercise

48 4.0 192

Question

Do you breathe faster or bigger breathes when you exercise?

What does breathing faster mean?

What does breathing deeper mean?

Respiratory responses

Ventilation

Respiratory rateTidal volume

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

Diffusion

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 in the lungs

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 muscles

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

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