Exchange Surfaces Flashcards
Why do organisms with a small SA:V need specialised exchange surfaces
surface area small and the distance too large, so diffusion takes too long to supply their needs.
Why do organisms with high metabolic activity need specialised exchange surfaces
increased oxygen demands for muscle cells which diffusion can’t supply fast enough
Why do multicellular rather than single cellular organisms need specialised exchange surfaces.Refer to both SA:V and metabolic activity
multicellular org are larger than single celled organisms.
large / active, organisms have high(er), demand for oxygen / need
to remove CO2
multicellular have small(er), surface area to volume ratio than single celled, so
diffusion distance too large (to supply needs)
How do you work out SA:V ratio
ratio= surface area/volume
State features of an efficient exchange surface
Increased surface area
thin layers
good blood supply
good ventilation to maintain conc gradient
Explain how increased S.A is advantageous for exchange surfaces.Use example
provides area needed for gas exchange. Eg; root hair cell has long extensions called root hairs.This gives it a larger S.A increasing rate of osmosis/diffusion
Explain how a thin layer is advantageous for exchange surfaces.Use example
Alveoli walls are single epithelial cell thick provides a short diffusion distance.
Explain how good blood supply can be advantageous for exchange surfaces.Use example
good blood supplies means that O2 is constantly being delivered to alveoli and CO2 is is removed from the capillaries.
This maintains good conc. gradient resulting in faster diffusion
Explain how good ventilation can be advantageous for exchange surfaces.Use example
breathing in and out of alveoli helps maintain the steep conc. gradient
Draw structure of mammalian gas exchange system
trachea–>bronchus->bronchioles–>alveoli
lungs–>ribs–>in between ribs,intercostal muscle.diaphragm below lungs
Draw structure of ciliated epithelium cell and state its function
function-beat and move mucus along with any trapped microorganisms away from lungs
Draw structure of goblet cell and state its function
function- produces mucus onto lining of trachea trapping dust and microorganism.
Describe the structure of the trachea and how it relates to its function.
draw cross-section
function- carry clean air from nose to chest
structure:
-wide tube supported by c-shaped cartilage rings, cartilage stops it from collapsing
Describe the structure of the bronchus and how it relates to its function
draw cross-section
function- carry clean air to lungs
structure:
-alternating pieces of smooth muscle and cartilage pieces—-> elastic fibres–>ciliated epithelium containing goblet cells–>lumen
cartilage-stops it from collapsing,smaller pieces because vessel is also smaller thus ↓volume air.
Describe the structure of bronchioles and how it relates to its function
draw cross-section
structure:
smooth muscle elastic fibres—> ciliated epithelium cell.
Describe the structure of alveoli and how it relates to its function
draw cross-section
structure:
elastic fibres–> flattened epithelial cells.
function:
gaseous exchange
elastic fibres allow alveoli to stretch and recoil during inspiration and expiration.
epithelial cells 1 cell thick-short diffusion distance for gases
Why are elastic fibres useful in the gas exchange system.State which structures its present in
- alveoli
- bronchioles
- bronchus
- trachea
- prevent alveoli bursting
- recoil / aiding ventilation
Why smooth muscle is useful in the gas exchange system.State which structures its present in
- bronchioles
- bronchus
- trachea
- constrict / control diameter of , airway
Why is cartilage useful in the gas exchange system.State which structures its present in
- trachea
- bronchus
hold airway open
provides support
