Exchange Surfaces Flashcards
(65 cards)
Define tissue
A collection of similar cells that are specialised to work together for a particular function
Why must large active organisms have a specialised has exchange surface
Higher demand for oxygen Greater need to remove CO2 Smaller SA:Vol Diffusion distance too great to just use surface area as diffusion would take too long => need for specialised exchange surface
Explain why small inactive organisms do not need a specialised has exchange surface
Lower demand for O2 and CO2 to be removed
Have a large SA:Vol
Diffusion distance short enough to use only SA- diffusion happens quickly
Name 6 factor which affect the rate of diffusion
Temperature Concentration gradient Stirring movement Surface area Diffusion distance Size of molecule
What is the formula for rate of diffusion
Rate of diffusion= (area of diffusion surface x difference in concentration)/ thickness of membrane
Describe the structure of the alveoli and how it helps it to carry out its function
- squamous epithelium- one cell thick- short diffusion distance for CO2 and O2
- good blood supply as capillary runs close to alveoli- maintaining high concentration gradient
- elastic fibres so can stretch and recoil, this helps prevent bursting
- small size of alveoli: large SA:vol
Describe the movement of oxygen from trachea to the blood
1)Oxygen moves through the trachea> bronchi> bronchioles> alveoli
2) dissolves in thin liquid layer into solution
3)
What is the function of elastic fibres
Can stretch and recoil
This prevents bursting
Recoiling helps expel air and maintain a conc gradient
What type of specialised cell is the capillary made up of
Squamous endothelium
What is the function of c shaped cartilage in the trachea
Prevent the airway from closing
In the trachea there are elastic fibres and what other type of fibres
Smooth muscle fibres
What is the job of smooth muscle fibres
Contract to reduce diameter of trachea
Explain the job of goblet cells in the trachea
Goblet cells release mucus, this traps particles (pollen/bacteria), then the ciliates epithelium cells waft (using atp) the mucus to the top of the trachea
Describe the structure of ciliates epithelial tissue
Columnar cells, they have cilia which can beat rhythmically to prevent unwanted particles from entering lungs
What does the smooth muscles fibres in the bronchiole do
Contract to reduce diameter of bronchiole
Is there ciliates epithelial cells in the bronchiole
Yes and goblet cells
Explain what happens during an asthma attack
Mast cells in the lungs bind to pathogen
They then release histamines into the area
These histamines bind to receptors
Triggering the muscle to contract and capillary walls to be more leaky - more tissue fluid
What is the diaphragm
A broad, domed sheet of muscle which forms the floor of the thorax
What do the internal intercostal muscle do
When u exhale forcibly using energy they contract pulling the ribs down hard and fast
What is the job of the rib cage
Provides a semi-rigid case within which pressure can be lowered with respect to the air outside
What do the external intercostal muscle do
When they contract, it moves the rib cage up and out, when relax it moves rib cage down and in
Describe the process of inhalation
External intercostal muscle contract Rib cage moves up and out Diaphragm contracts and moves down Thorax volume increased Pressure in thorax decreases Air moves in
What happens during exhalation
External IC muscles relax Rib cage moves down and in Diaphragm relaxes and moves up Thorax volume decreases Thorax pressure increases Air moves out
What is surfactant
A lipoprotein that stabilises the alveoli preventing collapse
