Module 3 - Exchange and transport
Describe why a single-celled organism - Low metabolic activity
doesn’t require a specialised exchange - Small diffusion distance
surface - Large SA:V ratio
Explain why a multicellular organism - High metabolic activity
requires a specialised exchange surface - Diffusion distance is too far for
effective diffusion
- Small SA:V ratio
Name the features of an efficient exchange - Increased SA
surface - Thin layers
- Good blood supply/ventilation to
maintain diffusion gradient
Goblet cells Lines the airways secreting mucus which
traps microorganisms and dust particles in
the inhaled air, stopping them from reaching
the alveoli
Ciliated epithelium On the surface of cells lining the airways,
beats mucus upwards away from the alveoli
towards the throat where it’s swallowed
Prevents lung infections
Rings of cartilage - In the walls of the trachea and
bronchi providing support
- Strong but flexible as it stops the
trachea and bronchi collapsing when
you breathe in and the pressure
drops
Smooth muscle - In the walls of the trachea, bronchi
and bronchioles allowing their
diameter to be controlled
- During exercise smooth muscle
relaxes making the tubes wider so
there is less resistance to airflow
and air can move in and out easier
, Elastic fibres - In the walls of the trachea, bronchi,
bronchioles and alveoli
- On breathing in, the lungs inflate
and the elastic fibres are stretched
- The fibres recoil to help push air out
when exhaling
Trachea Cartilage - large c-shaped pieces
Smooth muscle - yes
Elastic fibres - yes
Goblet cells - yes
Epithelium - ciliated
Bronchi Cartilage - smaller pieces
Smooth muscle - yes
Elastic fibres - yes
Goblet cells - yes
Epithelium - ciliated
Bronchioles Cartilage - none
Smooth muscle - yes
Elastic fibres - yes (no in sb)
Goblet cells - yes (no in sb, smb)
Epithelium - ciliated (no cilia in smb)
sb - smaller bronchiole
smb - smallest bronchiole
Alveoli Cartilage - none
Smooth muscle - no
Elastic fibres - yes
Goblet cells - no
Epithelium - no cilia
Label the micrograph of the lining of the
trachea using a light microscope
Describe why a single-celled organism - Low metabolic activity
doesn’t require a specialised exchange - Small diffusion distance
surface - Large SA:V ratio
Explain why a multicellular organism - High metabolic activity
requires a specialised exchange surface - Diffusion distance is too far for
effective diffusion
- Small SA:V ratio
Name the features of an efficient exchange - Increased SA
surface - Thin layers
- Good blood supply/ventilation to
maintain diffusion gradient
Goblet cells Lines the airways secreting mucus which
traps microorganisms and dust particles in
the inhaled air, stopping them from reaching
the alveoli
Ciliated epithelium On the surface of cells lining the airways,
beats mucus upwards away from the alveoli
towards the throat where it’s swallowed
Prevents lung infections
Rings of cartilage - In the walls of the trachea and
bronchi providing support
- Strong but flexible as it stops the
trachea and bronchi collapsing when
you breathe in and the pressure
drops
Smooth muscle - In the walls of the trachea, bronchi
and bronchioles allowing their
diameter to be controlled
- During exercise smooth muscle
relaxes making the tubes wider so
there is less resistance to airflow
and air can move in and out easier
, Elastic fibres - In the walls of the trachea, bronchi,
bronchioles and alveoli
- On breathing in, the lungs inflate
and the elastic fibres are stretched
- The fibres recoil to help push air out
when exhaling
Trachea Cartilage - large c-shaped pieces
Smooth muscle - yes
Elastic fibres - yes
Goblet cells - yes
Epithelium - ciliated
Bronchi Cartilage - smaller pieces
Smooth muscle - yes
Elastic fibres - yes
Goblet cells - yes
Epithelium - ciliated
Bronchioles Cartilage - none
Smooth muscle - yes
Elastic fibres - yes (no in sb)
Goblet cells - yes (no in sb, smb)
Epithelium - ciliated (no cilia in smb)
sb - smaller bronchiole
smb - smallest bronchiole
Alveoli Cartilage - none
Smooth muscle - no
Elastic fibres - yes
Goblet cells - no
Epithelium - no cilia
Label the micrograph of the lining of the
trachea using a light microscope
