6 Lungs and Digestion

Question 1

Why is the volume of oxygen absorbed and volume of carbon dioxide removed large in mammals?

Answer 1

• Relatively large organisms with a large volume of living cells
• Maintain a high body temperature which is related to them having high metabolic and respiratory rates

Question 2

Why are the lungs inside the body?

Answer 2

• Air is not dense enough to support and protect these delicate structures
• The body as a whole would otherwise lose a great deal of water and dry out

Question 3

What are the lungs in and what is its function?

Answer 3

Ribcage
Supports and protects lungs

Question 4

What are the main parts of the human gas-exchange system?

Answer 4

Lungs
Trachea
Bronchi
Bronchioles
Alveoli

Question 5

What is the structure and function of the lungs?

Answer 5

Pair of lobed structures made up of a series of highly branched tubules, called bronchioles, which end in tiny air sacs called alveoli

Question 6

What is the structure and function of the trachea?

Answer 6

Flexible air supported by rings of cartilage
Tracheal walls made of muscle, lined with ciliated epithelium and goblet cells

Question 7

What is the structure and function of the bronchi?

Answer 7

• Two divisions of the trachea, each leading to one lung
• Similar in structure to the trachea and similarly produce mucus to trap dirt particles and cilia move mucus towards throat
• Larger bronchi supported by cartilage, amount of cartilage is reduced as the bronchi get smaller

Question 8

What is the structure and function of the bronchioles?

Answer 8

• Branching subdivisions of the bronchi
• Walls made of muscle lined with epithelial cells
• Muscle allows them to constrict so that they can control the flow of air in and out of the alveoli

Question 9

What is the structure and function of the alveoli?

Answer 9

Minute air-sacs at end of bronchioles
Between alveoli are collagen and elastic fibres
Alveoli are lined with epithelium
Elastic fibres
Alveolar membrane is the gas-exchange surface

Question 10

What is the location and function of cartilage in the gas-exchange system?

Answer 10

Trachea and larger bronchi
Larger bronchi supported by cartilage, amount of cartilage is reduced as the bronchi get smaller
Cartilage prevents the trachea collapsing as the air pressure inside falls when breathing in

Question 11

What is the location and function of goblet cells in the gas-exchange system?

Answer 11

Line trachea and bronchi
Secrete mucus which traps dust and microorganisms

Question 12

What is the location and function of cilia in the gas-exchange system?

Answer 12

Bronchi, bronchioles, trachea
Cilia move the dirt-laden mucus towards the throat

Question 13

What is the location and function of muscle tissue in the gas-exchange system?

Answer 13

Tracheal walls, bronchioles
Bronchioles have walls made of muscle which allows them to constrict so that they can control the flow of air in and out of the alveoli

Question 14

What is the location and function of elastic tissue in the gas-exchange system?

Answer 14

Alveoli
Elastic fibres allow the alveoli to stretch as they fills with air when breathing in
Spring back during breathing out in order to expel the CO2-rich air

Question 15

Describe the state the structures of the ventilation system are in during inspiration

Answer 15

Internal intercostal muscles - relaxing
External intercostal muscles - contract
Ribcage - up and out
Diaphragm - contracts, flattens
Thorax volume - increases
Pressure inside lungs - decreases
Movement of air - air is drawn in

Question 16

Describe the state the structures of the ventilation system are in during expiration

Answer 16

Internal intercostal muscles - contracting
External intercostal muscles - relaxing
Ribcage - down and in
Diaphragm - relaxes, returns to dome shape
Thorax volume - decreases
Pressure inside lungs - increases
Movement of air - air is forced in

Question 17

Why is diffusion of gases between the alveoli and blood quick?

Answer 17

• RBCs slowed passing through pulmonary capillaries, allowing more time for diffusion
• Distance between the alveolar air and RBCs is reduced as the RBCs are flattened against the capillary walls
• Walls of alveoli and capillaries are very thin - short diffusion pathway
• Alveoli and pulmonary capillaries have a very large total SA
• Breathing movements constantly ventilate the lungs, and the action of the heart constantly circulates blood around alveoli - steep conc gradient
• Blood flow through pulmonary capillaries maintains a concentration gradient
• Layer of moisture

Question 18

What walls does oxygen have to pass through to reach the blood flow from the alveoli?

Answer 18

Endothelium of capillary (capillary walls) and epithelial cells

Question 19

How are the 5 features of a gas exchange surface achieved in the lungs?

Answer 19

Large SA - Many alveoli
Thin - oxygen only needs to diffuse through 2 cells before it reaches the blood, these cells are all thin
Selectively permeable - phospholipid bilayer with proteins which O2 and CO2 can diffuse through but not pathogens
Movement of external medium - ventilation
Movement of internal medium - blood flow in capillaries

Question 20

What are risk factors for lung disease?

Answer 20

Smoking
Air pollution
Genetics
Infections
Occupation