Gaseous Exchange

Question 1

What is breathing?

Answer 1

A mechanical process of taking oxygen into the lungs

Question 2

What is cellular respiration?

Answer 2

Cellular respiration refers to a chemical process which takes place within cells in order to release energy

Question 3

What is gaseous exchange?

Answer 3

Gaseous exchange is a physical process which involves the exchange of gases between the air and the blood in the lungs. Organs are structurally suited to ensure this process is optimised, mammals have a breathing mechanism that ensures the entry of gases in their bodies, this allows gaseous exchange and cellular respiration to occur efficiently

Question 4

List the important aspects of gaseous exchange.

Answer 4

• Structure to function: how the organism is designed to carry out gaseous exchange
• Regulation and control of breathing in humans
• How the amount of gases are kept at manageable levels in the blood
• Disease and certain life choices can impact negatively on gaseous exchange. Breathing can be impaired which affects the general health of an individual

Question 5

Define diffusion

Answer 5

The movement of molecules from a region of high concentration to a region of low concentration until equilibrium is reached

Question 6

Define catabolism

Answer 6

The breaking down of complex molecules into simple molecules to release energy

Question 7

Define aerobic

Answer 7

Occurring in the presence of oxygen

Question 8

Define anaerobic

Answer 8

Occurring in the absence of oxygen

Question 9

Define cellular respiration

Answer 9

The breakdown of organic compounds (glucose/sugar) in the mitochondria of cells into inorganic products (CO2 & H2O) with the release of cellular energy (ATP) ; either aerobic or anaerobic

Question 10

Requirement: large

Answer 10

Reason: a large surface area to volume ratio allows enough oxygen and carbon dioxide to defuse

Question 11

Requirement: thin and permeable

Answer 11

Reason: diffusion can occur more rapidly and efficiently if the surface is thin and permeable

Question 12

Requirement: moist

Answer 12

Reason: oxygen and carbon dioxide diffuse when in dissolved water

Question 13

Requirement: protected

Answer 13

Reason: all gaseous exchange surfaces need to be protected from mechanical injury as well as from dying out (desiccation)

Question 14

Requirement: well-ventilated

Answer 14

Reason: ensuring that oxygen rich air for terrestrial organisms and oxygen rich water for aquatic organisms are continually brought into contact with the gaseous exchange surface

Question 15

Requirement: vascular

Answer 15

Reason: an efficient method of transporting gases to and from the gaseous exchange surfaces is required

Question 16

The amount of oxygen taken up and carbon dioxide released depends on the ratio of surface area to volume of the organism.
What does this mean?

Answer 16

• Surface area is the combination of all exposed surfaces of the organism
• The volume is the space taken up by the same organism
• Therefore, the surface area to volume ratio would be the amount of surface an organism has relative to its size

Question 17

Define terrestrial

Answer 17

Organisms that live on land

Question 18

Define aquatic

Answer 18

Organisms that live in water

Question 19

Define gaseous exchange

Answer 19

The exchange of oxygen and carbon dioxide at a respiratory surface occurs at two places in mammals:

• at a gaseous exchange surface (lungs) and the blood
• between the blood and the body cells at the tissue level

Question 20

Define breathing/ventilation

Answer 20

Mechanical process of inhalation and exhalation through which air moves in and out of the respiratory organs enabling the uptake of oxygen and the removal of carbon dioxide

Question 21

The human gaseous exchange system consists of the following distinct sections:

Answer 21

• air passages
• lungs
• muscles involved in the mechanism of breathing (ventilation)

Question 22

Structure: 2 nostrils

Answer 22

Function: air inhaled through nostrils

Question 23

Structure: 2 nasal cavities

Answer 23

Function:

• cavities are lined with epithelial and goblet cells
• mucous from the goblet cells together with the cilia trap dirt and sweep it out of the nose; keeps cavity moist
• blood capillaries warm the incoming air

Question 24

Structure: trachea

Answer 24

Function:

• windpipe is situated in front of the oesophagus
• c shaped cartilage rings protect the trachea and keep it open for easy movement of air

Question 25

Structure: bronchus/bronchi

Answer 25

Function:

• trachea branches into the left and right bronchi that enter the upper lobes of the left and right lungs
• held open by O shaped cartilage rings; lined with mucous membranes

Question 26

Structure: bronchiolus/bronchioli

Answer 26

Function:

• each bronchus divides into many branches, the bronchioli
• these passages are smaller and narrower and do not have cartilage for reinforcement

Question 27

Structure: alveoli

Answer 27

Function:

• bronchioli end in a collection of alveoli (air sacs) that are sites for gaseous exchange
• many alveoli increase the surface area to maximise the gas exchange
• have thin wallah of squamous epithelial cells allowing for easy diffusion of gases
• tissue fluid keeps the walls of the alveoli moist
• a large blood capillary network surrounds the alveoli

Question 28

Structure: pharynx

Answer 28

Function:

• connects the nasal cavity with the larynx
• lined with mucous membranes
• leads into the trachea and the oesophagus

Question 29

Structure: larynx

Answer 29

Function:

• larynx contains the vocal cords
• air passes over the chords and sound is protected

Question 30

Structure: epiglottis

Answer 30

Function:

• a cartilage structure on top of the larynx (voice box)
• closes when food is swallowed preventing food from entering the trachea

Question 31

Structure: lungs

Answer 31

Function:

• each of the two spongy, elastic lungs are surrounded by the double pleural membrane
• pleural fluid acts as lubricant and helps prevent friction during inhalation and exhalation

Question 32

Structure: ribs

Answer 32

Function:

-on either side of the sternum, protect the lungs from injury

Question 33

Structure: intercostal muscles

Answer 33

Function:

• found between the ribs
• contract and relax during inhalation and exhalation altering the volume of air in the chest (thoracic cavity)

Question 34

Structure: diaphragm

Answer 34

Function:

• a sheet of muscle below the lungs
• contracts and flattens altering the volume of the chest cavity and is important in breathing