AS Biology

Mammalian Respiratory System

Name _________________________

1

Learning Objectives

Can I...? Done?a. Describe the basic functions of the mammalian respiratory

system?

b. Discuss the advantages and implications of an active gas exchange system?

c. Identify the structures of the mammalian respiratory system?

d. Describe the function of structures in the respiratory system?

e. Describe the passage of air from the mouth to the alveolus?

f. Explain how the lungs and alveolus are adapted to gas exchange

g. Describe the role of diaphragm and intercostal muscles in inspiration?

h. Describe the role of diaphragm and intercostal muscles in expiration?

i. Explain how volume and pressure changes lead to air movement in the thorax?

j. Use a spirometer to measure lung volumes?

k. Describe the terms:- Tidal volume?- Inspiratory reserve volume?- Expiratory reserve volume?- Vital capacity?- Residual volume?- Peak flow?

2

Introduction

How aware are you of your breathing?

Most of us only become aware of our breathing if we stop to consider this question. Before reading this you were probably breathing without any conscious thought or control.

The lungs are a major organ you would associate with breathing and are highly specialised in extracting oxygen from the air around us. This gas is a vital requirement for respiration (the breakdown of glucose), therefore providing us with the energy to work, grow and thrive.

This unit will look at the basic structure of the entire system, the mechanism by which we are able to breathe, adaptations required to obtain enough oxygen and how we are able to measure the function of the respiratory system.

a. Describe the basic functions of the mammalian respiratory system? (there are more than one…)

Mammals, birds and reptiles have all evolved with specialised active respiratory systems. This means that air is physically moved in a process called ventilation.

b. How does this differ to a single cellular organism such as a bacteria or amoeba?

c. Discuss the advantages and implications of having an active respiratory system.

3

Structure

Label the major organs of the respiratory system:

LabelsNasal cavity

Epiglottis

Base of left lung

Intercostal muscles

Trachea

Left bronchus

Right bronchus

Ribs

Heart space

4

Function

Describe the function of the following organs:

Organ Function

Ribs

Diaphragm

Trachea

Lungs (including alveoli)

Additional organs:

5

Passage of air

Label and annotate the diagram to describe the passage of air from the mouth to the alveolar ducts.

6

Gaseous exchange

Once air reaches the alveolar duct vital gases can be exchanged.

Below is some data representing the content of air before and after breathing:

1. What does this information tell you about what happens to the air once inside the lung?

2. Name the process by which gases move into the blood from air in the lungs.

3. Evaluate the benefits and implications of moving air in this way.

4. Describe how the lung is adapted to deal with any of the implications discussed above.

7

5. In the space below, draw a diagram of a single alveolus with associated blood vessels. Label the diagram and annotate to discuss how gases are exchange.

An example image can be found by Google Image searching ‘gas exchange in the alveoli’

8

Epithelium

One of the key adaptations of the lung and alveoli is that every surface is cover by a single layer of epithelial tissue that comes into direct contact with the air inhaled into the thorax.

Epithelial tissue is often only a single cell thick.

Above is a light micrograph of epithelial tissue surround each alveolus.

1. Describe the main advantages of single cell epithelia.

2. What are the implications of single cell epithelia in the lung?

9

Breathing and Ventilation

Another key adaptation that you should have included is the way that the respiratory system is able to continuously cycle air from the internal to external environment.

This process is known as ventilation and can be broken down into 2 key stages:

- Inspiration- Expiration

1. Name the main organs responsible for the mechanism of ventilation.

2. Label and annotate the diagrams below to describe the key stages of ventilation. (Include reference to the intercostal muscles, diaphragm and rib cage).

10

Inspiration

3. How will the air volume of the lung change during inspiration?

4. How will this affect the air pressure inside the lung cavity?

5. How does this lead the movement of air into the lungs? (You may draw an image to aid your explanation)

Expiration

6. How will the air volume of the lung change during expiration?

7. How will this affect the air pressure inside the lung cavity?

8. How does this lead the movement of air into the lungs? (You may draw an image to aid your explanation)

11

9. Complete the flow diagram to explain the stages of inspiration to include: intercostal muscles, diaphragm, thorax volume, thorax pressure and why the air moves.

12

10.Complete the flow diagram to explain the stages of expiration to include: intercostal muscles, diaphragm, thorax volume, thorax pressure and why the air moves.

13

Spirometry

The lungs and respiratory system play a vital role in maintaining basic life functions; providing the oxygen for cellular respiration whilst remove the waste carbon dioxide. Problems with this system can lead to serious implications.

Above is an image of a wet spirometer that can be used to measure and assess lung function.

Below is a typical spirometer trace that can be obtained using the above equipment.

1. What do ‘up’ and ‘down’ movements represent on the spirometer trace?

14

15