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