3.1)Exchange Surfaces & Breathing Flashcards
Why do single celled organisms not need a specialized transport system?
Cytoplasm of the cells are close to the environment in which they live = diffusion pathway is short = diffusion alone is enough
Why do large organisms need a transport system?
Multicellular = many layers of cells = longer diffusion pathway = diffusion would take too long
What are the 4 factors that affect the need for an exchange system?
Size
SA:vol ratio
Level of activity
Ventilation
How does the SA:Vol ratio affect the need for an exchange system?
small organism = large sa:vol ratio = sa is large enough to supply all cells w sufficient oxygen
Large organism = small sa:vol ratio = sa is too small to supply cells w sufficient oxygen THEREFORE require a exchange system
How does level of activity affect the need for an exchange system?
High metabolic activity = require more oxygen for aerobic respiration to release more energy
Low activity = require less oxygen THEREFORE do not need exchange system
What are the 4 features of a good exchange surface?
Large SA
Thin wall/membrane
Good blood supply
Ventilation
How is a large sa efficient for gas exchange?
Large sa = more space for molecules to pass through
How is a thin wall efficient for gas exchange?
Thin wall = reduce diffusion pathway = gas exchange occurs quickly
How is a good blood supply efficient for gas exchange?
Good blood supply = fresh supply of molecules = maintain steep conc grad = diffusion can occur rapidly
Why is ventilation useful in a gas exchange system?
Maintains diffusion gradient=faster and more efficient
What are the main structures of a gas exchange system?
Nasal cavity
Trachea
Bronchus
Bronchioles
Alveoli
How is the nasal cavity adapted for gas exchange?
1.large SA & good blood supply=warms the air as it passes
2.hairy lining=trap dust and bacteria=prevent from reaching lungs (infection)
3.moist= ⬆️humidity=prevent drying of lungs=prevent irritation
How is the trachea adapted to G.E?
Layer of cartilage=prevent collapsing of lungs when P drops during inspiration
Incomplete rings=bend when food is swallowed down the oesophagus
Lined with ciliated epithelial & goblet cells=prevent dust and bacteria entering
How is the bronchus adapted to G.E?
Similar structure to trachea
Complete cartilage rings=hold pipe open
How are the bronchioles adapted to G.E?
1mm diameter
No cartilage
Held open by smooth muscle
Smooth muscle contract=bronchiole contract
Lined with epithelial tissue=some gas exchange
How is the alveoli adapted to G.E?
Gas exchange occurs
Thin layer of flattened epithelial cell
Collagen
Elastic fibres
what happens during inspiration?
ribs + intercostal muscle (im) contract
diaphragm moves up + out
=
lung volume increases
thoracic P decreases
=
air inhaled
what happens during exhalation?
ribs + im relax
diaphragm moves down + in
=
lung vol decreases
thoracic P increases
=
air exhaled
what is a spirometer?
device that measures movement of air in/out of the lungs
why should the subject be healthy during spirometer reading?
if unhealthy, lung volume will be changed
what is the purpose of soda lime in the spirometer?
absorbs the CO2 (that has been exhaled) to prevent it from being breathed in again by the subject
how is the total lung volume calculated?
vital capacity + residual vol
what is vital capacity?
the max vol of air moved (inhaled + exhaled) by lungs in 1 breath
what is residual vol?
the vol of air left in the lungs after exhalation
what happens to the overall vol of gas in the spirometer tank over time and WHY?
DECREASES
inhaling = uses O2 in the tank
exhaling = CO2 released is absorbed by soda lime in the tank to prevent it from being inhaled again
what is tidal vol?
the max vol of air that can be inhaled/exhaled
what is expiratory capacity?
the max vol of air exhaled after a normal inhalation
what is inspiratory capacity?
the max vol of air inhaled after a normal exhalation
what is the inspiratory reserve vol?
the max vol of air that you can breathe in at NORMAL INHALATION
what is the expiratory reserve vol?
the max vol of air you can breathe out at NORMAL EXHALATION
what happens to the graph of a spirometer reading when inspiring?
trace goes down
what happens to the graph of a spirometer reading when expiring?
trace climbs up
what does the peak to trough of inspiration indicate?
vol of a single breath
what precautions should be taken using a spirometer?
-subject should be healthy
-soda lime should be fresh
-no air leaks in apparatus
-mouthpiece sterilised
-water chamber NOT overfilled
what is a peak flow meter and its limitations?
ONLY measures expiration so is less accurate, compared to spirometer which measures BOTH exhalation + inspiration
where do the tracheal tubes run from in insects?
body surface –> tissue
what do the tracheal tubes in insects allow?
transport gases directly between environment + body cells
what are spiracles?
each segment of the insect has lip like openings, which the tracheal tubes connect to
what is formed when the tracheal tubes connect to the spiracle branch?
tracheoles
what do tracheoles do?
-repeatedly divide
-ends penetrate into individual body cells
what are the 2 ways in which gas exchange takes place?
-diffusion gradient
-ventilation by rhythmic abdominal movements
how does the diffusion gradient allow gas exchange to take place?
-O2 move down the conc. gradient= air –> body cells
-CO2 move down conc. gradient = body cell –> air
how does ventilation by rhythmic abdominal movements allow gas exchange to take place?
-speed up
-generate mass movement of air in + out
what are the gas exchange surfaces in fish?
gills
what are gills composed of?
gill filaments
(stacked like pages in a book)
what is the structure of the gill lamellae?
-few cells thick
-contain blood capillaries
what are the gill lamellae for?
-project at right angle from filaments
-increase S.A
what is countercurrent flow?
-blood always comes in contact with water with a higher O2 conc.
what does the countercurrent flow allow?
-O2 diffusion gradient maintained
-max possible gas exchange
what happens to the conc. gradient during parallel flow?
-conc. gradient level out
-when blood + water have 50% O2 conc.
what happens to the conc. gradient during countercurrent flow?
-conc. gradient does not level out
-blood continuously absorbs O2
