Specialised Gas Exchange Surfaces Flashcards
Why do all orgaisms need to exchange substances with their environment?
- Oxygen + Glucose is needed for aereobic respiration to generate ATP
- Oxygen diffuses into cell through cell membrane
- CO2 diffuses out of the cell through cell membrane
Why do microscopic organisms exchanges all the substances they need through cell membrane?
- They have low rate of respiration - not active organisms
- SA is large compared to volume of cell
How do calculate SA:V ratio?
Ratio = SA ÷ V
Describe the trend in SA:V ration in terms of cell size?
The SA:V ratio decreses as cells get larger
Single-celled organisms
- Large SA:V ratio
- Transfer all substances diffuse directly across cell membrane
- Quick diffusion rate due to short diffusion distance
Multicellular organisms
- Small SA:V ratio
- difficult to exchange substances to supply large volume through small SA
- Slow diffusion rate due to large diffusion distance between cells and outside environment
- Higher metabolic rate so use Oxygen and glucose faster
Speciialised exchange surface in plants
- Large Surface Area
- hair cells on plant roots in soil
- increases rate of absorbing water by osmosis
- increase rate of absorbing mineral ions by active transport
Speciialised exchange surface in alveoli 1
- Alveoli are made from thin layer of flst cells - alveolar epithilium (AE)
- decreases diffusion distance for O2 in and CO2 out of the blood
- increses diffusion rate
Specialised exchange surface in alveoli 2
- large capillary network so good blood supply
- increased exchange of O2 and CO2
- lungs are ventilated so air in alveoli constantly replaced
- maintain concentrtion gardients of O2 and CO2
Speciialised exchange surface in Fish
- Gills have large capilary network so good blood supply
- Gills exchanges gas between fish’s blood and water
- Gills are ventilated due tp fresh water
- maintain concentration gradient of O2 so increased diffusion rate
Describe the structure of the lungs for gas exchange
- Air enters trachea
- Trachea splits into to bronchi - one bronchus for each lung
- Bronchus branches into bronchioles
- Gases exchange in alveoli at the end of bronchioles
- Ribcage, intercostal muscle, diaphragm move air in and out of
Structure 1 for efficient gas exchange
- Goblet Cells line the airways (nasal cavity)
- secrete mucus to trap dust and pathogen when air is inhaled
- stops them from reaching alveoli
Structure 2 for efficient gas exchange
- Cilia on surface of epithelial cells
- Beat the mucus trapped with pathogens and dust
- Moves mucus upwards away from alveoli towards the throat to be swallowed & digested by stomach enzymes
- Prevents lung infections
Structure 3 for efficient gas exchange
- Elastic Fibres in walls of trachea, bronchi, bronchioles and alveoli
- Inhalation: lungs inflate & elastic fibres are stretched
- Exhalation: fibres recoil to push air out
- Help the process of breathing out
Structure 4 for efficient gas exchange
- Smooth Muscle in walls of trachea, bronchi and bronchioles
- Allows diameter to be controlled
- During exercise smooth muscle relaxes, makes tubes wider
- Less resistance to airflow, air moves in & out of lungs easily
Structure 5 for efficient gas exchange
- Cartilage in walls of trachea and bronchi
- provides support
- Strong and flexible
- stops trachea & bronchi from collapsing when inhaling and pressure drops
How is the Trachea adapted for efficient gas exchange?
- cartilage - C-shaped: no cartilage near oesophagus to allow food to pass down easily
- smooth muscle
- Ciliated epithelium
- Goblet cells
Which Adaptation do all parts of the lumg have?
- Elastic fibres
- Help the process of breathing out
How is the Bronchi adapted for efficient gas exchange?
- Cartilage - small pieces
- smooth muscle
- ciliated epithelium
- Goblet cells
One structure all sizes of bronchioles don’t have?
- NO Cartilage
- to allow for flexibility and efficient airflow
- cartilage would restrict ability to expand and contract
How is the Large Bronchiole adapted for efficient gas exchange?
- smooth muscle
- ciliated epithelium
- goblet cells
How is the Smaller Bronchiole adapted for efficient gas exchange?
- Smooth muscle
- Ciliated epithelium
How are the Smallest Bronchioles adapted for efficient gas exchange?
- Elastic fibres
- NO smooth muscle - maximise air flow efficiency in narrow airways, muscle contraction could restrict air passage.
- NO ciliated epithelium - prevent clogging, very small diameter of airways remains open for gas exchange.
Why do smaller bronchioles, smallest bronchioles not have goblet cells?
- maximize airflow efficiency
- mucus production could obstruct air flow.
How are the Alveoli adapted for efficient gas exchange?
- Elastic fibres
- Large SA - lots of alveoli
- Short diffusion distance - very thin walls, made squamous epithelial cells.
- Maintains a concentration gradient - large capillary network to remove exchanged gases
- NO smooth muscle - flexibility to expand and contract freely for efficient gas exchange
- NO ciliated epithelium - primary function is gas exchange, not removing mucus & pathogens
