Exchange and Transport Flashcards
Name one type of epithelial tissue found in the lungs.(1)
squamous / ciliated;
Explain why the lungs can be considered to be an organ. (2)
(organ is) a collection of tissues / named tissues;(working together) to enable gas exchange / AW;
Outline the mechanism of inspiration. (3)
diaphragm / intercostal muscles, contract:
diaphragm moves down / ribs move upwards and outwards;
volume of thorax increased;
pressure inside thorax falls;
to below atmospheric pressure (so air enters lungs);
A person breathes through the mouthpiece of a spirometer. State what happens to the air chamber during inspiration. (1)
it falls/ goes down;
Suggest a chemical that could be used in a spirometer to absorb carbon dioxide. (1)
soda lime/ sodium hydroxide / potassium hydroxide /
calcium hydroxide;
Explain why a person using the spirometer to measure their vital capacity should wear a nose clip. (2)
to ensure all air breathed comes from chamber
OR
to prevent, escape of air / entry of air, through nose;
make results invalid;
State three precautions that should be taken when using a spirometer to measure vital capacity.
- wear nose clip
- use (medical grade) oxygen / fresh air;
- disinfect mouthpiece;
- ref. to health of subject;
e.g. asthmatics - ref to correct functioning of equipment;
e.g. maintain constant temperature (so that volume of gases is not affected)
ensure, valve / hinge, is working
level of water correct
no leaks / airtight / lips sealed around mouthpiece
what are the four things in common in all effective gas exchange surfaces?
- increased SA
- thin layers
- good blood supply
- good ventilation
why is it important to maintain a good blood supply in an exchange surface?
in order to maintain a steep concentration gradient for diffusion of substances
what is the journey that air takes through the mammalian gaseous exchange system?
nasal cavity trachea bronchus bronchioles alveoli
features of the nasal cavity
- large SA with good blood supply
- –> warms the air to body temp
- hairy lining
- –> secretes mucus to drap dust and bateria, protecting delicate lung tissue
- moist surfaces
- –> increase humidity of incoming air, reducing evaporation from exchange surfaces
structure of mammalian trachea
- wide tube supported by incomplete rings of strong, flexible cartilage —- stops the trachea from collapsing,
- ciliated epithelium
- goblet cells
why are the cartilage rings of trachea incomplete?
so as not to break the oesophagus when food moves down
what does mucus do in the trachea?
beats rhythmically and moves the mucus (along with trapped dust and pathogens) away from the lungs towards the mouth where it is swallowed and digested
structure of bronchus
- cartilage rings
- smaller than trachea
structure of bronchioles
- no cartilage
- smooth muscle —-> allows bronchioles to constrict when it contracts and dilate when it relaxes, so controls the amount of air reaching the lungs
- flattened epithelium
structure of alveoli
- thin, flattened epithelial cells
- a little collagen and elastic fibres —–> allow alveoli to stretch as air is drawn in and squeeze air out as they return to their resting size ELASTIC RECOIL
- lined with lung surfactant —–> ensures alveoli remain inflated by coating
adaptations of alveoli for effective gaseous exchange
- large SA
- thin layers
- good blood supply (capillaries)
- good ventilation
inspiration
- uses energy
- diaphragm contracts, flattening and lowering
- external intercostal muscles contract
- ribs move upwards and outwards
- volume of thorax increases so pressure in thorax reduces, drawing air in
expiration
- passive (mostly)
- diaphragm muscles relax, moving it upwards into resting domed shape
- external intercostal muscles relax
- ribs move down and inwards
- elastic fibres of alveoli return to normal length
- volume of thorax decreases so pressure increases and air is forced out
what happens when you exhale forcibly (using energy)?
- internal intercostal muscles contract, pulling ribs down hard and fast
- abdominal muscles contract, forcing the diaphragm up to rapidly increase pressure in the lungs
what happens during an asthma attack?
cells lining bronchioles release histamines
- —> make epithelial cells inflamed and swollen
- —> stimulate goblet cells to secrete excess mucus
- —> smooth muscle in bronchiole wall contracts
airways narrow and fill with mucus, making it hard to breath
what are the two main ways of treating asthma?
Relievers - chemicals similar to adrenaline attach to active sites on surface membranes of smooth muscle cells in bronchioles, making them relax and dilating the airways
Preventers - steroids, reduce sensitivity of the lining of the airways
what are the three ways of measuring the capacity of your lungs?
- peak flow meter
- spirometer
- vitalograph
tidal volume
volume of air that moves into and out of lungs with each resting breath
- 500cm^3
vital capacity
volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath
inspiratory reserve volume
maximum volume of air you can breath above a normal inhalation
expiratory reserve volume
extra air you can force out of your lungs above the normal tidal volume of air you breath out
residual volume
volume of air left in your lungs when you have exhaled as hard as possible
total lung capacity =
vital capacity + residual volume
vital capacity =
inspiratory reserve volume + tidal volume + expiratory reserve volume
ventilation rate =
tidal volume x breathing rate (per min)
breathing rate
breaths / min
ventilation rate
total volume of air inhaled in one min
what is the journey that air takes through the insect gaseous exchange system?
spiracle
trachea
tracheoles
in many insects spiracles can be opened or closed by……
these are kept closed as long as possible to ………………
sphincters
minimise water loss
structure of insect trachea
- lined by CHITIN spirals —> keep the trachea open if they are bent or pressed. relatively impermeable to gases so little gaseous exchange
structure of tracheoles
- no chitin —> freely permeable to gases
- single greatly elongated cell
- very tiny —> spread throughout tissues of cells
how does air travel in the trachea?
diffusion alone
- O2 dissolves in moisture on the walls of the tracheoles and diffuses into the surrounding cells
tracheal fluid
end of the tracheoles
- limits the penetration of air for diff.
HoWever…….. when O2 demand increases, lactic acid build up in tissues results in water moving out of the tracheoles by osmosis, exposing more SA for gas exchange
how do some insects with higher energy demands use alternative methods of increasing the level of gaseous exchange?
- mechanical ventilation of the tracheal system
- -> causes changes in pressure of tracheoles, drawing air in or forcing out
- collapsible enlarged trachea or air sacs, act as air reservoirs
- –> inflated/ deflated by ventilating movements of thorax and abdomen
gills are contained in the …………… and covered by a protective layer called the ……………………
gill cavity
operculum
operculum
protective layer covering the gills
‘bony flap’
- maintains a flow of water over the gills
how do fish maintain a large SA for gas exchange?
- ## gill filaments occur in large stacks (gill plates) and are kept apart by a flow of water with exposes large SA on gill lamellae
Suggest why it is not possible to expel all the air from the lungs (2)
throax/ rib cage/ lungs cannot be completely flattened/compressed;
trachea/bronchi held open by cartilage;
bronchioles/alveoli held open by elastic fibres;
Describe how a spirometer can be used to measure tidal volume (4)
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