Exchange and Transport Flashcards
1
Q
Factors affecting
exchange system
A
Size
SA: V ratio
Metabolic activity
2
Q
How does size affect
the need for an
exchange system
A
In single-celled organisms, the cytoplasm is very close to its environment. Diffusion will supply enough 02 and nutrients to keep the cells alive and active In multicellular organisms have several layers of cells, so there's a longer diffusion pathway. Diffusion is too slow to enable a sufficient supply to the innermost cells
3
Q
How does SA:V affect
the need for an
exchange system
A
When organisms have a large SA:V their SA is large enough to supply all the cells with sufficient 02 Volume increases more quickly than SA so the SA:V is smaller in larger organisms so a specialised exchange surface is needed
4
Q
How does metabolic
activity affect the
need for an exchange
system
A
Metabolically active organisms need good supplies of 02 and nutrients to supply energy for movement and warmth so the exchange of substances need to be efficient
5
Q
Features of a good
exchange surface
A
Large surface area achieved by folding walls and membranes Thin, permeable barrier - shorter diffusion distance Good blood supply maintain steep concentration gradient (brings molecules to supply side and removes from demand side)
6
Q
How are lungs
adapted
A
Many alveoli - large SA:V Thin barrier - short diffusion pathway Good blood supply capillaries to carry dissolved gases to and from alveoli Ventilation refreshes air in alveoli Elastic tissue to stretch/ recoil to help expel air
7
Q
Function of
goblet cells
A
Produce mucus
8
Q
Function of cartilage
A
Prevent collapse
of airways
9
Q
Why do the walls of
alveoli contain elastic
fibres
A
Expand (inhalation) to increase lung volume
Prevent alveoli bursting
Elastic fibres recoil
10
Q
Inspiration
A
Diaphragm contracts to move down and become flat. Displaces digestive organs downwards External intercostal muscles contract moving the ribs outward and upward Volume of thorax increases Pressure in thorax < atmospheric pressure Air is drawn in through the nasal passages, trachea, bronchi and bronchioles into lungs
11
Q
Thorax
A
Chest cavity Lined with pleural membranes - space between these membranes is the pleural cavity - usually filled with lubricating fluid
12
Q
Expiration
A
Diaphragm relaxes and is pushed up by displaced organs underneath External intercostal muscles relax and ribs fall Volume of thorax decreases Pressure in thorax > atmospheric pressure Air is moved out of the lungs
13
Q
What does the alveoli
consist of
A
Thin, flattened
epithelial cells alone
with some collagen
and elastic fibres
14
Q
Elastic recoil
A
When the elastic fibres in the alveoli return to their resting size, they help squeeze the air out
15
Q
What is the inner
surface of the alveoli
covered in
A
A thin layer of solution of water, salts and lung surfactant When 02 diffuses out of the alveoli, it first dissolves in the water before diffusing into the blood. Water can also evaporate into the air in the alveoli
16
Q
Lung surfactant
A
Phospholipid that coats the surfaces of the lungs Without it, watery lining of alveoli would have surface tension ->collapse
17
Q
Collagen in alveoli
A
Ensures alveoli aren’t
deformed as they
stretch (support)
18
Q
Distribution and function of capillaries
A
Over surface of alveoli
To provide a large
surface area for
exchange
19
Q
Distribution and function of cartilage
A
In walls of bronchi and trachea To hold the airways open and provide structural support
20
Q
Distribution and
function of goblet
cells
A
In ciliated epithelium
To produce and
release mucus
21
Q
Distribution and
function of smooth
muscle
A
In walls of airways
Contracts to constrict
or narrow the airways
22
Q
Loose tissue
A
Contains elastic
fibres, glands and
blood vessels
23
Q
Peak flow meter
A
Simple device that measures how much air can move out of (and therefore into) the lungs
24
Q
Spirometer
A
Device that measures the movement of air in and out of the lungs as the person breathes Also measures oxygen consumption as the chamber of soda lime absorbs carbon dioxide
25
Vital capacity
```
Maximum volume of
air that can be moved
by the lungs in one
breath
Measured by taking a
deep breath and
expiring all the air
possible from the
lungs
Usually in the region
or 2.5-5.0 dm^3
```
26
What does vital
| capacity depend on
```
The size of the person
(particularly their
height)
Their age and gender
Their level of
regular exercise
```
27
Tidal volume
```
Volume of air moved
in and out with each
breath
Usually measured at
rest (0.5 dm^3)
sufficient to supply all
the oxygen
Increases when
exercising
```
28
Residual volume
```
Volume of air that
remains in the lungs
even after forced
expiration
Air remains in airways
and alveoli
Approx. 1.5 dm^3
```
29
Total lung capacity
Sum of vital capacity
| and residual volume
30
Precautions to take
when using a
spirometer
```
Subject should be
healthy and free from
asthma
Wear a nose clip
Sterilise mouthpiece
No air leaks in
apparatus - invalid/
inaccurate results
Don't overfill water
chamber - water may
enter air tubes
```
31
How do we know the
volume of oxygen
absorbed by the
blood
```
We can assume that
the volume of carbon
dioxide released and
absorbed by the soda
lime is equal to the
volume of 02
```
32
How is breathing rate
| calculated
Counting the number
of peaks in one
minute
33
Calculating
| oxygen uptake
Divide the difference
between the first peak
and last peak by the
time (s)
34
What will increases
oxygen uptake result
from
Exercise (more 02
and less CO2)
Deeper breaths
35
Why do insects
require a gas
exchange system
```
Very active in
life cycle
Tough exoskeleton
through which little/
no gas exchange
takes place
```
36
Spiracles
Air opening in each
segment of the insect
Allows air to enter
inside the insect
37
Why do insects
frequently close their
spiracles
To minimise
| water losS
38
Insect tracheae
```
Leads away from
the spiracles
Run both along and
into the body of the
insect
Carry air into the body
```
39
What are insect
| tracheae lined with
Spirals of chitin which
keeps them open if
they are bent or
pressed
40
Why does little gas
exchange take place
in insect tracheae
Chitin is mostly
| impermeable to gases
41
Tracheoles
```
Further branches of
the tracheae
Vast number gives a
large surface area
Some oxygen
dissolves in moisture
in the walls of the
tube and diffuses into
the surrounding cells
```
42
Where is tracheole fluid found
In the ends of
| tracheoles
43
Why do insects
frequently close
spiracles
To reduce water loss
44
How do larger insects
ventilate their tracheal
system
```
Sections of the
tracheal system can
be expanded and
contacted by flight
muscles
Movement of wings
can alter volume of
the thorax
Abdomen volume can
also be expanded
then reduced
```
45
Oxygen conc. in
| water is
Typically lower than
| that in air
46
Operculum
Covers and protects
the gills and is active
in maintaining a flow
of water over the gills
47
Gill arch
Bony structure with
two rows of gill
filaments (primary lamellae) coming off it
48
Gill filaments
Very thin and their
surface is folded into
many secondary
lamellae
49
Where does gas
exchange take place
in bony fish
Secondary lamellae
blood capillaries carry
deoxygenated blood
close to the surface
50
Advantages of
| counter current flow
```
Absorbs maximum
amount of oxygen
from the water
Ensures steeper conc.
gradients are
maintained vs a
parallel system
Bony fish can remove
approx. 80% of 02
from the water
```
51
Ram-ventilation
```
Only occurs when fish
are moving
Fish open their
mouths and
operculums to keep a
current of water
flowing over their gills
```
52
Buccal - opercular
| pump
Used when fish
| aren't moving
53
How does the buccal-
| opercular pump work
```
Base of mouth moves
downward, lowering
pressure in buccal
cavity - water is
drawn in
Mouth then closes,
pressure of buccal
cavity increases
pushing water
through gills
At the same time,
operculum opens
reducing pressure in
opercular cavity
helping water flow
over gills
```
54
Inspiratory capacity
The maximum volume
of air that can be
breathed in
55
Function of ciliated
| epithelial
Move mucus
56
Function of squamous
| epthelial
Provide a short
| dffusion distance
57
Features of
| nasal cavity
```
Large SAw/ good
blood supply - warms
air to body temp
Hairy lining - secretes
mucus to protect lung
tissue from infection
Moist surfaces
Increase humidity of
incoming air, reducing
evaporation
```
58
Bronchus
```
Division of trachea
Also has supporting
rings of cartilage but
much smaller
Ciliated cells but v.
little goblet cells
```
59
Bronchiole
```
No cartilage
Walls contain smooth
muscle, contracts to
constrict bronchioles,
changes amount of air
reaching lungs
Lined w/ thin layer of
flattened epithelium
```
60
Adaptations of gills
```
Large SA for diffusion
Rich blood supply to
maintain conc
gradient
Thin layers - short
diffusion distance
Tips of adjacent gill
filaments overlap
increases resistance
to flow of water over
gill surfaces and
slows down
movement of water
more time for gas
exchange
```
61
How is the steep conc
gradient maintained in
the lungs
```
Blood is constantly
flowing through and
out of lungs, bringing
a fresh supply of RBC
Blood arrives in the
lungs w a lower [02]
and a higher [CO2]
than air in alveoli
```
