3.1.1 Exchange surfaces and breathing Flashcards
1
Q
define exchange surface
A
specialised area that is adapted to make it easier for molecules to cross from one side of the surface to another
2
Q
what factors affect the need for an exchange surface?
A
-increasing size
-level of activity
-SA:V ratio
3
Q
what are the properties of exchange surfaces?
A
-large surface area
-thin layers
-diffusion gradient
-moist cells
-good blood supply
-ventilation for diffusion gradient
4
Q
how does a large surface area allow efficient diffusion to occur in exchange surfaces?
A
provides area needed for exchange and overcomes limitations of SA:V ratio
5
Q
how does thin layers allow efficient diffusion to occur in exchange surfaces?
A
shortens diffusion distance making it more efficient
6
Q
how does a diffusion gradient allow efficient diffusion to occur in exchange surfaces?
A
areas of high concentrations and areas of low concentration cause diffusion to occur
7
Q
how do moist cells allow efficient diffusion to occur in exchange surfaces?
A
prevents evaporation from lungs and substances need to be dissolved in water to be transported
8
Q
how does a good blood supply allow efficient diffusion to occur in exchange surfaces?
A
ensures substances are constantly delivered which maintains a steep concentration gradient
9
Q
how does ventilation for diffusion gradient allow efficient diffusion to occur in exchange surfaces?
A
helps maintain diffusion gradient
10
Q
what are some examples of a large surface area in exchange surfaces?
A
root hair cells and villi in small intestine
11
Q
what are some examples of thin layers in exchange surfaces?
A
alveoli and villi
12
Q
what are some examples of a diffusion gradient in exchange surfaces?
A
alveoli, gills and villi
13
Q
what are some examples of moist cells in exchange surfaces?
A
alveoli
14
Q
what are some examples of good blood supply in exchange surfaces?
A
alveoli, gills and villi
15
Q
what are some examples of ventilation for diffusion gradient in exchange surfaces?
A
alveoli in lungs and continuous water flow over gills
16
Q
what is the trachea lined with?
A
columnar epithelial ciliated cells covered in mucus which is produced by goblet cells
17
Q
what are pleural membranes?
A
they surround the lungs
18
Q
what is the pleural cavity filled with?
A
pleural fluid
19
Q
what does pleural fluid do?
A
acts as a lubricant and protects the lungs from the ribs
20
Q
describe the process of inhalation in the lungs
A
-the external intercostal muscles in the ribs and sternum contract causing ribs to move up and out
-the diaphragm contracts and moves it down (creating a bigger chest cavity)
-the volume of the thorax increases
-the air pressure inside the thorax decreases
-the air moves into the lungs
21
Q
describe the process of exhalation in the lungs
A
-the external intercostal muscles in the ribs and sternum relax causing ribs to move down and in
-the diaphragm relaxes and moves it up (creating a smaller chest cavity)
-the volume of the thorax decreases
-the air pressure inside the thorax increases
-the air moves out of the lungs
22
Q
how does forced breathing occur?
A
internal intercostal muscles contract which pulls ribs down hard and fast
23
Q
label a diagram of the lungs
A
on paper flashcard
24
Q
list the order in which air passes from the nose to the lungs
A
mouth/nose, trachea, bronchi, bronchioles, alveoli
25
what are bronchioles?
smallest respiratory passageways
26
what is another name for the windpipe?
trachea
27
where does gas exchange take place?
alveoli
28
what is the epiglottis?
stops food "going the wrong way" ie choking during swallowing
29
what is the pharynx?
both air and food pass through this
30
what is expiration?
the movement of air out of the lungs
31
what is the main muscle involved in inspiration?
diaphragm
32
what are the pleural membranes?
membranes that cover the lungs and line the pleural cavity
33
how does ventilation maintain the steep concentration gradient in the alveoli?
inhalation brings in lots of O2 creating a high concentration and exhalation removes CO2 keeping concentration low inside alveoli
34
alveoli secrete a fluid called surfactant- why is this important?
1. prevents them from drying out
2. allows gases to dissolve so that they can diffuse across the membrane
35
there are millions of alveoli in the lungs- why is this important?
this creates a larger area of exchange so gas exchange into the blood is quicker
36
why is it important the alveolar wall is one cell thick?
short diffusion distance so quicker diffusion of gases
37
why is it important the capillary wall is one cell thick?
short diffusion distance so quicker diffusion of gases
38
how does a good blood supply maintain a steep concentration gradient in the alveoli?
brings high concentration of CO2 to lungs and has a low concentration of O2, also carries the O2 away straight away maintaining the low concentration of oxygen in the lungs
39
alveoli are very small- why is this important?
this creates a larger SA:V ratio so diffusion distance is shorter so CO2 and O2 can be exchanged into the blood much faster
40
what different tissues do the trachea contain?
-ciliated epithelium
-cartilage
-elastic fibres
-muscle
41
what different tissues do the bronchus contain?
-ciliated epithelium
-cartilage
-elastic fibres
-muscle
42
what different tissues do the bronchioles contain?
-elastic fibres
-muscle
43
what different tissues do the alveoli contain?
-squamous epithelium
-elastic fibres
44
what does the ciliated epithelium tissue do in the trachea and bronchus?
the cilia waft rhythmically and goblet cells produce mucus which is moved upwards
45
what does the squamous epithelium tissue do in the alveoli?
one cell thick for short diffusion distance
46
what does the cartilage tissue do in the trachea?
c-shaped cartilage holds it open and allows for expansion
47
what does the cartilage tissue do in the bronchus?
irregular distributions of cartilage holds tube open
48
what do elastic fibres do in the trachea, bronchus and bronchioles?
elastic fibres are for stretch and recoil
49
what do elastic fibres do in the alveoli?
elastic fibres provide strength and flexibility, they stretch and recoil to push air out
50
what does muscle tissue do in the trachea and bronchus?
involuntary muscles
51
what does muscle tissue do in the bronchioles?
involuntary muscles contract to make them narrower
52
what are insects exoskeletons made of?
chitin
53
what are the characteristics of chitin?
-little or no gas exchange occurs over this
-tough, light and allows movement
-has a waxy cuticle
54
what does the waxy cuticle on an insects exoskeleton do?
reduces water loss to reduce dehydration risk on land
55
describe what gas exchange is like in insects
-open circulatory system and a high oxygen requirement
-oxygen is delivered directly to cells
56
what do spiracles do in insects?
-open and close depending on oxygen demands
-help reduce water loss
57
what does tracheal fluid do in insects?
-it limits the surface area through which gases can diffuse into cells
-if oxygen demand increases, lactic acid will build up (this lowers water potential of cells) causing water to move out of the tracheoles by osmosis
-this exposes more surface area for diffusion
58
why do insects need ventilation?
large beetles, locusts, grasshoppers and bees have very high energy demands so they need to be able to supply respiring cells with additional oxygen
59
how do insects ensure they have enough oxygen for their high energy demands?
through mechanical ventilation and collapsible enlarged tracheae
60
describe mechanical ventilation in insects
-rhythmical flattening and expanding of the thorax and abdomen
-creates differences in volume and therefore pressure
-air is drawn into and out of the tracheae and tracheoles as the pressure changes
61
describe the collapsible enlarged tracheae
-act as air reservoirs
-inflated and deflated by mechanical ventilation
62
what are the problems for fish?
water is a problematic exchange medium
63
why is water a problematic exchange medium?
-water has around 20 times less oxygen per cm³ than air
-water is much denser than air
64
how do fish overcome the problem of water being a problematic exchange medium?
fish have an exchange surface to obtain oxygen and a mechanisms to maximise water movement over the surface
65
what are the different types of fish?
cartilaginous and bony
66
what is the ventilation system in cartilaginous fish?
parallel flow
67
what does it mean by a parallel flow system?
blood travels through the gills in the same direction as water
68
what is the ventilation system in bony fish?
counter-current flow
69
what does it mean by counter-current flow system
blood travels through gill capillaries in the opposite direction to the water
70
describe the ventilation in bony fish
TO TAKE IN WATER:
pressure in mouth is decreased by:
-opening mouth, lowering the floor of the buccal cavity
-increases volume of mouth
-water rushes into mouth
TO PUSH WATER OUT THROUGH GILLS:
increasing pressure in mouth by:
-closing mouth and raising floor of buccal cavity
-this decreases volume of mouth
-the operculer valve closes the opening at the back of the thorax
-so, water moves out over the gills
71
what does counter current exchange ensure?
it ensures that a steep concentration gradient is maintained
72
what does counter current exchange successfully do?
it successfully removes up to 80% of oxygen from the water
73
what happens if the current flows in the same direction as the blood in fish?
-initially there is a steep concentration gradient from water to blood
-equilibrium is then reached
-no more net movement of oxygen from water to blood
74
what happens if the current flows in opposite directions to the blood?
-a steep concentration gradient is maintained along the gill
-so oxygen can continuously diffuse into the blood
-equilibrium is not being reached
-the blood carries the oxygen away further maintaining the diffusion gradient
-carbon dioxide also removed from the blood in a parallel system
75
what does the graph of a parallel flow system look like?
*see paper flashcard*
76
what does the graph of a counter current system look like?
*see paper flashcard*
77
what is the organ involved in gaseous exchange in fish?
gills
78
what are the key features of gills that allow them to be successful in gas exchange?
-thin layers
-good blood supply
-large surface area
79
where are the gills found?
gill cavity
80
what is the role of the operculum?
to protect the gills and it's active in maintaining water flow
81
what are lamellae?
thin plate like structures that are distributed across all of the gill filaments
82
why are the lamellae the main site of gas exchange in fish?
because they have:
-good blood supply
-large surface area
-thin layers
83
what is the gill arches function?
to support the structure of the gills
84
what is the main adaptation of the gill filaments?
large surface area
85
how are the gill filaments kept apart to ensure their adaptation of a large surface area is utilised?
flow of water around them and the fact they are four separate stacks so water can flow through them
86
how do cartilaginous fish maintain water flow?
by continuously moving
87
what structures do bony fish rely on to maintain the movement of water across the gills?
the operculum and the buccal cavity (its mouth)
88
why can diffusion not occur through the exoskeleton of an insect?
it is impermeable to gases
89
when do spiracles open in an insect?
-oxygen demand is raised
-when carbon dioxide levels build up
90
when do spiracles close in an insect?
-when an insect is inactive
-when oxygen demand is very low
91
what is the purpose of spiracles?
to allow air to enter and leave
92
what do the spiracle sphincters do?
they open and close the spiracles
93
what is a tracheole?
a minute tube made of elongated cells
94
why are tracheoles freely permeable to gases?
there is no chitin
95
where does most gas exchange occur within an insects body?
tracheoles
96
what is the purpose of chitin?
hold tracheae open and make it impermeable
97
what is the diameter of the tracheae?
1mm
98
does gas exchange occur through the tracheae and why?
no, they are impermeable to gases because it's made of chitin
99
what do the tracheae branch into?
tracheoles
100
what are the ways to measure the volume of air in the lungs?
-using a peak flow meter
-using a lung capacity bang
-using a spirometer
101
describe a peak flow meter
-sterile mouthpieces
-use 3 times and take highest reading
102
describe a lung capacity bag
-gives an air volume using a scale on the bag
-take a deep breath and exhale into the bag
103
define tidal volume
the volume of air that moves into and out of the lungs with each resting breath
104
define vital capacity
the volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath
105
define inspiratory capacity
the maximum volume of air that can be inhaled at the end of a normal expiration
106
define residual volume
the volume of air that is left in your lungs when you have exhaled as hard as possible
107
define inspiratory reserve volume
the maximum volume of air you can breathe in over and above a normal inhalation
108
define expiratory reserve volume
the extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breathe out
109
label a typical spirometer trace
*on paper flashcard*
110
what are the different things you can calculate from a spirometer?
-breathing rate
-tidal volume
-vital capacity
-oxygen consumption
-ventilation rate
-maximum inspiratory reserve
-minimum expiratory reserve
111
how do you calculate ventilation rate?
breathing rate x tidal volume
112
what is the reason for calibrating the spirometer?
this allows us to calculate the actual volumes breathed
113
what is the reason for filling the drum with fresh air in the spirometer?
to ensure normal levels of oxygen in the air to be breathed by the subject
114
what is the reason for needing the subject to be in good health when using the spirometer?
to avoid any medical problems
115
what is the reason for the subject wearing a nose clip when using the spirometer?
to prevent them from breathing through their nose instead of their mouth which allows valid measurements
116
what is the reason for the subject breathing normally into the spirometer using the mouthpiece?
to record volume of air being breathed
117
what is the reason for using a sterile mouthpiece in the spirometer?
to avoid infection
118
what is the reason for the subjects exhaled air passing through a can of soda lime in the spirometer?
to absorb the CO2
119
what is the reason for turning on the kymograph in the spirometer?
to start the recording of the trace
120
what is the reason for the subject breathing normally for at least three full breaths into the spirometer?
to record resting breathing rate
121
what is the reason for the drum moving up and down in the spirometer?
it moves up as the subject breathes out and down as they breathe in
122
what are the steps for using a spirometer?
1. calibrate the spirometer, the details vary from machine to machine but you need to know how to measure a litre and a minute on the trace
2. fill the drum with fresh air
3. subject should be in good health
4. subject wears a nose clip
5. subject breathes normally into the machine through the mouthpiece
6. use a sterile mouthpiece
7. the subjects exhaled air passes through a canister of soda lime
8. turn on the kymograph
9. subject breathes normally for at least three full breaths
10. the drum will move up and down
