Functions of the Respiratory system P6 M3. responsible The respiratory system is responsible for: – getting oxygen in to our body – Getting carbon dioxide.

Functions of the

Respiratory system

P6 M3

• The respiratory system is responsible for: – getting oxygen in to our body– Getting carbon dioxide and other waste products out of our body

• All living creatures need Oxygen in combination with food to produce energy and movement.

• Every cell of the body needs Oxygen to function

• Respiration is the process by which cells receive a constant supply of oxygen and carbon dioxide is removed.

General description

• The aim of the respiratory system is to get:– Oxygen to the bloodstream

• so that the CV system can deliver it to the muscles.

– Carbon dioxide out of the bloodstream

• All endurance performance relies on– Delivery of Oxygen into the

blood stream– Removal of Carbon Dioxide out

of the blood• Give a couple of specific

examples in your worksheet

General description…

When we exercise: CO2 dissolves within the bloodstream and increases acidity levels. So the respiratory centre in the brain speeds up the rate

of breathing to get rid of excess CO2.

So rate of breathing increases due to CO2 levels

rising. Not the cells demanding more O2.

• Gases move through a process called diffusion– Gas moves from a high concentration to a low

concentration• Eg: someone wearing perfume.

• In the respiratory system

–Two different types of diffusion:• Diffusion of Oxygen into the blood

stream, attracted by haemoglobin• Diffusion of Carbon Dioxide out of the

blood stream to be excreted by the lungs

Gaseous Exchange: Diffusion

Diffusion of Oxygen into the blood stream

• The alveoli are in constant contact with the capillaries

• The air we breath in arrives in the alveoli, rich in Oxygen

• The blood arrives from the pulmonary artery very low in oxygen

• Following the principle of diffusion, the Oxygen moves across the capillary wall and into the blood stream– It is attracted by the haemoglobin into the red

blood cells

• The blood returns to the heart to be pumped to the rest of the body

Diffusion of Carbon Dioxide out of the blood stream

• The blood arrives in capillaries of the lungs with a high concentration of Carbon Dioxide

• The air in the alveoli has a low concentration of Carbon Dioxide

According to the principles of diffusion, the Carbon dioxide moves across the wall of the capillaries and into the alveoli, so that it can be expired.

• Breathing is regulated by:• the respiratory centre,

located in the brain. • Receptors in the air

passages and lungs• Breathing in = Inspiration• Breathing out =

Expiration• To breathe the thorax must

increase and then decrease in size

The mechanics of breathing

Overview

Inspiration• In order to breathe in the volume of the

chest cavity needs to increase. • This increase in size of the chest cavity,

causes a decrease in pressure within the lungs• Boyle’s Law states that a volume of gas is

inversely proportional to its pressure. • This means that the increase in volume in

the lungs causes a decrease in pressure. • Gases flow from a high pressure area to a

low pressure area• In this situation the ambient air is the high

pressure area and the lungs are the low pressure area, so the air flows into the lungs

Inspiration

• Inspiration – Breathing in• Diaphragm contracts

• It flattens and pulls down• This is an active process

• External intercostal muscles contract• The sternum moves up and out, with the

lungs following• The lungs are attached to the pleural sac

(containing pleural fluid), which in turn is attached to the thoracic cage

• As the chest expands, the surface tension, created by the film of pleural fluid causes the lungs to be pulled outwards, with the chest

• These two actions cause the volume of the thoracic cavity to increase• According to Boyles Law

this increase in volume causes a decrease in pressure

• Air flows into the lungs• As gas flows from high

pressure to low pressure.

Expiration• To breathe out – Expiration:• Diaphragm relaxes

• It moves back up and into the thoracic cavity• This is a passive process

• The external intercostal muscles relax• The ribs/sternum moves down. • The lungs, sternum and rib cage are elastic structures that naturally 'spring'

back to their resting positions once the forces of the inspiratory muscles are removed. So expiration is a passive process.

• The volume of the thoracic cavity decreases causing the air to move out of the lungs. • This is because air pressure in the lungs is now higher than atmospheric

pressure, according to Boyles Law, so the air is forced out of the lungs to equate the pressure in and out of the body.

The muscles of breathing

Respiratory volumes

Lung Volumes

• Lung volumes: refers to physical differences in lung volume, while lung capacities represent different combinations of lung volumes, usually in relation to inhalation and exhalation.

• The average pair of human lungs can hold about 6 litres of air, but only a small amount of this capacity is used during normal breathing.

Spirometer trace

Respiratory volumes

• Tidal Volume– The volume of air inspired

or expired per breath (Approx 500ml at rest)

• Expiratory Reserve Volume– The amount of space that is available to breathe out, once you have exhaled

normally

• Eg: Breathe out normally, then force out more air. This is your ERV.

• Inspiratory Reserve Volume– The amount of space that is

available to draw in more air• Eg; Breathe in normally, then

breathe in more. This extra capacity is your IRV

Respiratory volumes

• Total Lung Capacity– Take in as

much breath as possible

– This is your total lung capacity

– ERV+IRV+TV+RV (Approx 6000ml)

• Vital Capacity– Breathe in as much as you can,

and then force as much air out of your lungs as possible. • This is your IRV+ERV+TV, and

is your Vital Capacity

• Residual Volume– Breathe out as much as

possible• There is always

some air left in your lungs

• This is your RV (Approx 1200ml)

Describe the (1) Structure with

all the parts named BELOW and (2) Function (1-4 BELOW) of the respiratory system.

2. Function: 1. Gaseous exchange2. Mechanisms of breathing (inspiration and expiration)3. Lung volumes: e.g. tidalvolume, vital capacity, residual volume 4. Control of breathing (neural and chemical)

1. Structure of the respiratory system: • Nasal cavity • Epiglottis• Pharynx• Larynx• Trachea• Bronchus• Bronchioles• Lungs (lobes, pleural membrane, thoracic cavity,

visceral pleura, pleural fluid, alveoli)• Diaphragm• Intercostal muscles (external and internal)

Examine the respiratory system

and explain how it works and how each part of the system is

designed to meet its function