Mammalian gas exchange and ventilation Flashcards Preview

OCR A level biology > Mammalian gas exchange and ventilation > Flashcards

Flashcards in Mammalian gas exchange and ventilation Deck (24)
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1
Q

Why is it not possible to expel all air from the lungs?

A
  • thorax cannot be completely flattened

- trachea/bronchi held open by cartilage

2
Q

Why are specialised exchange surfaces are needed by some organisms?

A
  • they have a low SA:V so exchange surfaces increase that
  • maximise efficiency of diffusion
  • ensure the demand for oxygen and glucose is met
3
Q

What are the 4 features of efficient exchange surfaces?

A
  • Increased surface area
  • Thin layers
  • Good blood supply
  • Ventilation to maintain a diffusion gradient
4
Q

Why does an increased surface area make an exchange surface efficient?

A

Provides the area needed for exchange overcomes limitations of low SA:V ratio

5
Q

Why do thin layers make an exchange surface efficient?

A

the distances that substances have to diffuse across is short making it fast and efficient

6
Q

Why does a good supply make an exchange surface efficient?

A

the greater the difference in concentration the greater the rate of diffusion. A good supply means substances are constantly being delivered and removed, maintaining the steep concentration gradient

7
Q

Why does ventilation make an exchange surface efficient?

A

For gases ventilation helps to maintain concentration gradients

8
Q

How is the nasal cavity adapted for the gas exchange system?

A
  • good blood supply warms air to body temperature
  • cells secrete muscus to trap dust and bacteria to protect lung tissue
  • moist surfaces reduce evaporation from the exchange surfaces which increase humidity
9
Q

How is the trachea adapted for the gas exchange system?

A
  • supported by incomplete rings of strong, flexible cartilage to allow for movement and prevent the trachea from collapsing
  • lined with ciliated epithelium and goblet cells
10
Q

What is the function of goblet cells?

A

Secrete mucus which traps dust and microogranisms

11
Q

What is the function of ciliated epithelial cells?

A

Cilia beat and move mucus away from the lungs, protecting them

12
Q

How are the bronchi adapted for the gas exchange system?

A

-supported by small rings of cartilage

13
Q

How are bronchioles adapted for the gas exchange system?

A
  • contain no cartilage
  • contain smooth muscle
  • smooth muscle contracts when bronchioles constrict and relaxes when they dilate
14
Q

How are the alveoli adapted for the gas exchange system?

A
  • very thin walls
  • contain elastic fibres which allow alveoli to stretch as air is drawn n and when they return to size help squeeze air out
  • good capillary blood supply
  • coated in surfactant
15
Q

What is breathing?

A

The movement of air in and out of the lungs

16
Q

What is gas exchange?

A

the delivery of oxygen from the lungs to the bloodstream and the elimination of carbon dioxide from the blood stream

17
Q

Outline the steps in inspiration

A
  • diaphragm flattens and contracts
  • external intercostal muscles contract making the ribs move up and out
  • this increases the volume of the thorax so reduces pressure
  • pressure is more negative than the atmosphere air
  • air is drawn into the lungs to equalise the pressures inside and outside the chest
18
Q

Outline the steps in normal expiration

A
  • diaphragm relaxes and curves upwards
  • external intercostal muscles relax so ribs move in
  • decreases volume of the thorax
  • pressure in the lungs is less negative than atmospheric air
  • air moves out of the lungs until pressure inside and out is equal
19
Q

Outline the steps in forced expiration

A
  • abdominal muscles contract, pushing diaphragm upward quickly making lung pressure less negative
  • internal intercostal muscles contract pulling ribs down hard and fast
20
Q

What is inspiration?

A

the movement of air into the lungs

21
Q

What is expiration?

A

the movement of air out of the lungs

22
Q

Does inspiration require energy?

A

Yes

23
Q

Does expiration require energy?

A

No, it is a passive process

24
Q

What are the 3 ways lung capacity can be measured?

A
  • peak flow metre
  • vitalographs
  • spirometer