3.1.1 - exchange surfaces Flashcards

1
Q

why do multicellular organisms require specialised gas exchange surfaces?

A

their smaller surface area to volume ratio means the distance that needs to be crossed is larger and substances cannot easily enter the cells as in a singe-celled organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how is surface area to volume ratio calculated?

A

ratio = surface area ÷ volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

name 3 features of an efficient gas exchange surface

A
  1. large surface area (e.g. root hair cells)
  2. thin/short distance (e.g. alveoli)
  3. steep concentration gradient, maintained by blood supply or ventilation (e.g. gills)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe the trachea and its function in the mammalian gaseous exchange system

A
  • wide tube supported by C-shaped cartilage to keep the air passage open during pressure changes
  • lined by ciliated epithelium cells which move mucus, produced by goblet cells, towards the throat to be swallowed, preventing lung infections
  • carries air to the bronchi
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe the bronchi and their function in the mammalian gaseous exchange system

A
  • like the trachea, they are supported by rings of cartilage and are lined by ciliated epithelium cells and goblet cells
  • however, they are narrower and there are two of them, one for each lung
  • allow passage of air into the bronchioles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe the bronchioles and their function in the mammalian gaseous exchange system

A
  • narrower than the bronchi
  • do not need to be kept open by cartilage, therefore mostly have only smooth muscle and elastic fibres so that they can contract and relax easily during ventilation
  • allow passage of air into the alveoli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe the alveoli and their function in the mammalian gaseous exchange system

A
  • mini air sacs, lined with epithelium cells, site of gas exchange
  • walls only one cell thick, covered with a network of capillaries, 300 million in each lung, all of which facilitates gas diffusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

explain the process of inspiration and the changes that occur throughout the thorax

A
  • external intercostal muscles contract while internal intercostal muscles relax, pulling the ribs up and out
  • diaphragm contracts and flattens
  • volume of the thorax increases
  • air pressure outside the lungs is therefore higher than the pressure inside, so air moves in to rebalance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

explain the process of expiration and the changes that occur throughout the thorax

A
  • external intercostal muscles relax while internal intercostal muscles contract, bringing the ribs down and in
  • diaphragm relaxes and domes upwards
  • volume of the thorax decreases
  • air pressure inside the lungs is therefore higher than the air pressure outside, so air moves out to rebalance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

explain how a spirometer works

A
  • it is used to measure lung volume
  • a person breathes into an airtight chamber which leaves a trace on a graph which shows the volume of the breaths
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

define vital capacity

A
  • the maximum volume of air that can be expelled from the lungs after taking the deepest possible breath
  • can be calculated from the spirometer graph by finding the maximum amplitude
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

define tidal volume

A
  • the volume of air we breath in and out during each breath at rest
  • can be calculated from the spirometer graph by finding the amplitude at rest
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define breathing rate

A
  • the number of breaths we take per minute
  • can be calculated from the spirometer graph by counting the number of peaks in one minute
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

name and describe the two main features of a fish’s gas transport system

A
  • gills = located within the body, supported by arches along which are multiple projections of gill filaments, which are stacked up in piles
  • lamellae = at right angles to the gill filaments, give an increased surface area, blood and water flow across them in opposite directions (countercurrent exchange system)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

explain the process of gas exchange in fish

A
  • buccal cavity volume increased to enable water to flow in, reduced to increase pressure
  • water is pumped over the lamellae by the operculum, oxygen diffuses into the bloodstream
  • waste carbon dioxide diffuses into the water and flows back out of the gills
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does the countercurrent exchange system maximise oxygen absorbed by the fish?

A
  • maintains a steep concentration gradient, as water is always next to blood of a lower oxygen concentration
  • keeps rate of diffusion constant and enables 80% of available oxygen to be absorbed
17
Q

name and describe the 3 main features of an insect’s gas transport system

A
  • spiracles = holes on the body’s surface which may be opened or closed by a valve for gas or water exchange
  • tracheae = large tubes extending through all body tissues, supported by rings to prevent collapse
  • tracheoles = smaller branches dividing off the tracheae
18
Q

explain the process of gas exchange in insects

A
  • gases move in and out of the tracheae through the spiracles
  • a diffusion gradient allows oxygen to diffuse into the body tissue while waste CO2 diffuses out
  • contraction of muscles in the tracheae allows mass movement of air in and out