P6 M3 Functions of the Respiratory system

•

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.

When we exercise: CO 2 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 CO 2. • •

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 So rate of breathing increases due to CO 2 levels rising. Not the cells demanding more O 2.

•

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

• • • • • 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

• • 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.

The mechanics of breathing

Overview

• • • •

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

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

•

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 •

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.

Respiratory volumes

•

Residual Volume

– Breathe out as much as possible • • • There is always some air left in your lungs This is your RV (Approx 1200ml)

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 •

Total Lung Capacity

– Take in as much breath as possible – – This is your total lung capacity ERV+IRV+TV +RV (Approx 6000ml)

Describe

the

(1) Structure

with all the parts named BELOW and

(2) Function

(1-4 BELOW) of the respiratory system.

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 how each part of the system is and designed to meet its function

2. Function:

1. Gaseous exchange 2. Mechanisms of breathing (inspiration and expiration) 3. Lung volumes: e.g. tidal

volume, vital capacity, residual volume

4. Control of breathing (neural and chemical)