7.1-4 Exchange and transport Flashcards
1
Q
What is the need for specialised exchange surfaces?
A
- size of the organisms
- surface area to volume ratio decreases
2
Q
Why can substances easily enter cells of single celled organisms?
A
- distance that needs to be crossed over is short
3
Q
Why is the distance for substances to cross larger in larger organisms?
A
- a lower surface area to
volume ratio
4
Q
What do multicellular organisms require?
A
- specialised exchange
surfaces for efficient gas exchange of carbon dioxide and oxygen
5
Q
What is a feature of efficient exchange surfaces?
A
- large surface area
-for instance the root
hair cells or folded membranes, such as those of the mitochondria
6
Q
What does an efficient exchange surface require?
A
- should be thin to ensure that the distance that needs to be crossed by the substance is short
- a good blood supply/ventilation to
maintain a steep gradient, for example that of the alveoli
7
Q
What are the lungs?
A
- a pair of structures with a larger surface area located in the chest cavity with the ability to inflate
- surrounded by the rib cage as a form of protection
8
Q
What is released between the rib cage and what does it help with?
A
- a lubricating substance is secreted to reduce friction during inflation and deflation
9
Q
What are placed between the ribs?
A
- external and internal intercostal muscles
10
Q
What do the intercostal muscles do?
A
- contract to raise and lower the ribcage
11
Q
What does the diaphragm do?
A
- separates the lungs and from abdomen area
12
Q
How does air enter the first half of the respiratory system and what are they adapted for?
A
- nose
- along the trachea
- bronchi
- bronchioles
- to their role in enabling passage of air into the lungs
13
Q
Where does gaseous exchange take place?
A
- in the walls of the alveoli which are tiny air sacs filled with air
14
Q
Which three structures allow air in and out of the lungs?
A
- trachea
- bronchi
- bronchioles
15
Q
How are the airways held open and how is this different in the trachea?
A
- with the help of rings of cartilage
- incomplete in the trachea to allow passage of food down the oesophagus behind the trachea
16
Q
Which two structures are similar yet different and what reasons?
A
- trachea and bronchi
- similar in structure
- different in size (bronchi smaller)
17
Q
What is the structure of trachea and bronchi like?
A
- composed of several layers which together make up a thick wall
- the wall is mostly composed of cartilage in the form of C rings
18
Q
What is the inside surface of cartilage like?
A
- a layer of glandular and connective tissue, elastic fibres, smooth muscle and blood vessels
- referred to as ‘loose tissue’
19
Q
What is the inner lining of an epithelial layer made out of?
A
- ciliated epithelium and goblet cells
20
Q
How are bronchioles different to bronchi?
A
- narrower
- larger bronchioles contain cartilage
- wall is made out of smooth muscle and elastic fibres
- smallest bronchioles have alveoli clusters at the ends
21
Q
What does cartilage do?
A
- involved in supporting the trachea and bronchi, plays an important role in preventing the lungs from collapsing in the event of pressure drop during exhalation
22
Q
Ciliated epithelium is …
A
- present in bronchi, bronchioles and trachea, involved in
moving mucus along to prevent lung infection by moving it towards the throat
23
Q
Goblet cells are …
A
- cells present in the trachea, bronchi and bronchioles involved in mucus
secretion to trap bacteria and dust to reduce the risk of infection with the help of
lysozyme which digests bacteria
24
Q
Smooth muscle is …
A
- their ability to contract enables them to play a role in constricting
the airway, thus controlling its diameter as a result and thus controlling the flow of
air to and from alveoli
25
Elastic fibres are ...
- stretch when we inhale and recoil when we exhale thus controlling
the flow of air
26
What is ventilation?
- the flow of air in and out of the alveoli is referred to as ventilation
27
What are the two stages of ventilation?
- inspiration
- expiration
28
What does the process of ventilation have help from two muscles?
- intercostal muscles
- diaphragm
29
What do the intercostal muscles do at inspiration?
- external contract
- internal relax
- causing the ribs to move upwards
30
What does the diaphragm do at inspiration?
- contracts and flattens
31
What do the diaphragm and intercostal muscles cause in inspiration?
- volume inside the thorax increased
- lowering partial pressure
32
What is the role of pressure in inspiration?
- pressure inside the lungs and the atmospheric pressure create a gradient
- causing air to enter the lungs
33
What do the intercostal muscles do at expiration?
- internal contract
- external relax
- lowering the rib cage
34
What does the diaphragm at expiration?
- relaxes and rises upwards
35
What to the intercostal muscles and diaphragm cause in expiration?
- decrease the volume of the thorax
- increasing partial pressure
- forcing air out of the lungs
36
What is a spirometer?
- a device used to measure lung volume
37
How do you use a spirometer?
- a person using a spirometer
breathes in and out of the airtight chamber
-thus causing it to move up and down
-leaving a
trace on a graph which can then be interpreted
38
Vital capacity is ...
- the maximum volume of air that can be inhaled or exhaled in a single
breath
- varies depending on gender, age, size as well as height
39
Tidal volume is ...
- the volume of air we breathe in and out at each breath at rest
40
Breathing rate is ...
and what equipment is used?
- the number of breaths per minute can be calculated from the spirometer
trace by counting the number of peaks or troughs in a minute
41
Residual volume is ...
- the volume of air which is always present in the lungs
42
Expiratory reserve volume is ...
- the additional volume of air that can be exhaled on top of the tidal volume
43
Can tidal volume exceed itself?
- yes
- in cases such as during exercise where the inspiratory reserve volume is reached in an attempt to increase amount of air breathed in
44
Which animal have a small surface area to volume ratio and why?
- fish
- for gaseous exchange
-
45
What do fish have to be specialised exchange surfaces?
- an impermeable membrane so gases can't diffuse through their skin
46
What is bony fish's adaptation for gas exchange?
- four pairs of gills all containing an arch
- along each arch there are gill filaments with lamellae on them
- blood and water flow across the lamellae in a counter current direction meaning they flow in opposite directions
47
Why can fish not survive very long out of water?
- the projections are held apart by water flow
- so in the absence of water they stick together
48
What does ventilation maintain?
- continuous unidirectional flow
49
When does ventilation begin for fish?
- it begins with the fish opening its mouth
- followed by lowering the floor of buccal cavity
-thus enabling water to flow into it
- then the fish closes its mouth, causing the buccal cavity
floor to raise
-thus increasing the pressure
50
How does the water leave the gill filaments?
- water is forced over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity
- the operculum acts as a valve and pump and lets water out and pumps it in
51
As insects do not have a transport system, how do they undergo respiration?
- oxygen needs to be transported directly to tissues undergoing respiration
- this is achieved with the help of spiracles, small openings of tubes, either bigger trachea or smaller tracheoles, which run into the body of an insect and supply it with the required gases
- at the end of each tracheole is a small amount of tracheal fluid which allows gasses to dissolve and then diffuse into the cells
- spiracles can be opened and closed to avoid excessive water loss
