Gas Exchange Flashcards
What is diffusion?
The net movement of particles down a concentration gradient from an area of high concentration to low concentration
2 substances an organism needs to take in from the environment ?
Glucose
Oxygen
2 substances that an animal needs to release?
CO2
Urea
How do single cell organism diffuse substances ?
-directly in or out the cell across the cell surface membrane.
Why is diffusion rate quick in single cell organisms
Short diffusion distance
Relatively high SA:V ratio
How do multi-cellular organisms diffuse substances?
Require specialised exchange surfaces such as alveoli
What are the 3 reasons multicellular organisms need specialised exchange surfaces?
1) some cells are too deep within the body
2)larger animals have low SA:V
3)higher metabolic rate so use more oxygen and glucose
What are the 3 special features of exchange surfaces?
1)a large surface area
2) they’re thin
3) a good blood supply or ventilation
Why are root hair cells good exchange surfaces?
Each hair branched of a root and is covered in millions of microscopic hairs
-gives root hair cell a large SA:V ratio increases water absorption by osmosis and mineral ions by active transport
Why are alveoli good exchange surfaces?
-made of alveolar epithelium-> decreases the distances O2 and CO2 takes place increasing rate of diffusion
Why are the alveoli surrounded by a large capillary network?
-gives each alveolus its own blood supply
-helps maintain concentration gradient
-lungs are ventilated so air in each alveoli is constantly replaced
Why are fish gills good exchange surfaces?
-contain large network of capillaries-> well supplied with blood
-well ventilated -> fresh water constantly flows over them
What is the structure of the gaseous exchange system?
1) trachea
2) splits into 2 bronchi-> 1 to each lung
3)each bronchi branches into bronchioles
4)the bronchioles end in alveoli
Ribcage, inter coastal muscles and diaphragm work to move air in and out
Where are goblet cells found?
Line the airways
Function of goblet cells?
-secrete mucus
-traps microorganisms and dust particles inhaled by air stopping them getting to alveoli
Where are cilia found?
On epithelial cells lining airways
Role of cilia?
-hair like structures
-beat mucus secreted by goblets cells
-moving mucus toward throat away from alveolus
-prevent lung infections
Where are elastic fibres found?
-trachea
-bronchi
-bronchioles
-alveoli
Role of elastic fibres
-when inhaling lungs inflate stretching elastic fibres
-fibres then recoil to push air out when exhaling
Where is smooth muscle found
Walls of
-trachea
-bronchi
-bronchioles (except the smallest ones)
Role of smooth muscle
-allows diameter to be controlled
-during exercise smooth muscle relaxes making the tubes wider
-less resistance so air can move in and out lungs easier
-supplying muscles with more oxygen
Where are rings of cartilage found?
-walls of
Trachea
Bronchi
Role of rings of cartilage?
-provide support
-strong and flexible
-stops trachea and bronchi collapsing when breathe in and pressure drops
What happens to pressure during inhalation ?
Pressure drops below atmospheric pressure as volume of thorax increases