3.1.1 Exchange Surfaces

Question 1

why do larger organisms require more specialised gas exchange?

Answer 1

• smaller SA:V ratio
• oxygen cannot diffuse in quick enough due to large diffusion distance
• higher metabolic activity

Question 2

what are adaptations of root hair cells?

Answer 2

large surface area —> increases rate of diffusion

Question 3

what are the adaptations of alveoli?

Answer 3

squamous epithelial cells —> thin diffusion distance

Question 4

what are the features of gills?

Answer 4

good blood supply/ventilation —> maintains concentration gradient

Question 5

what’s the role of goblet cells?

Answer 5

• secret mucus which traps dust/bacteria which enters the lungs
• has cilia attached to it

Question 6

what’s the role of the cilia?

Answer 6

wafts the mucus to the back of the mouth where it is swallowed or coughed up

Question 7

what’s the role of elastic fibres?

Answer 7

• recoil to their original shape
• expel air
• prevents lungs from bursting
• return lungs to original size

Question 8

what’s the role of a smooth muscle?

Answer 8

• constricts the airways
• prevents harmful chemicals entering lungs

Question 9

what’s the role of cartilage?

Answer 9

• provides strength and support for trachea and bronchi
• helps prevent collapse during breathing in
• as chest volume increases there will be a lower pressure in trachea

Question 10

what structures does the trachea have?

Answer 10

• cartilage
• ciliated epithelial cells
• smooth muscle

Question 11

what structures do bronchi have?

Answer 11

• pieces of cartilage
• smooth muscle
• elastic fibres
• ciliated epithelial

Question 12

what structures does the bronchiole have?

Answer 12

• smooth muscle
• elastic fibres
• squamous epithelial

Question 13

what structures do the alveoli have?

Answer 13

• elastic fibres
• squamous epithelial

Question 14

what happens during inspiration?

Answer 14

1. diaphragm contracts and flattens
2. ribs move up and out
3. external intercostal muscles contract
4. internal intercostal muscles relax
5. volume in thorax increases
6. pressure in thorax decreases
7. air moves into thorax along pressure gradient

Question 15

what happens during expiration?

Answer 15

1. diaphragm relaxes and rises
2. ribs move down and in
3. external intercostal muscles relaxes
4. internal intercostal muscles contracts
5. **volume* in thorax decreases
6. pressure in thorax increases
7. air moves out along pressure gradient

Question 16

how do you calculate pulmonary ventilation?

Answer 16

tidal volume ✖️ breathing rate

Question 17

what’s the tidal volume?

Answer 17

volume of air breathed in and out at rest

Question 18

what’s the breathing rate?

Answer 18

number of breaths per minute

Question 19

what’s the oxygen uptake?

Answer 19

• air breathed into the spirometer once the carbon dioxide has been removed by the soda lime
• oxygen is used for aerobic respiration