Exchange Surfaces Flashcards
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
What is ventilation rate
The number of breaths per minute
What’s the formula for tidal volume
The volume of air inhaled or exhaled in one breath during steady regular breathing
Formula for pulmonary ventilation
Ventilation rate x tidal volume
What is vital capacity
The maximum volume of air inhaled or exhaled in one breath
What is a spirometer used to measure
Tidal volume
How do u use a spirometer
A nose clip is fitted so that all air comes from the chamber
They breathe normally through mouth
The trace is measured for height and amplitude
In a spirometer what removed CO2
Soda lime / sodium hydroxide
Name the system insects use to exchange gas
The tracheal system
Where are spiracles found
Along the thorax and abdomen
How does air enter and leave the system
Via spiracles
What opens and closes these spiracles
Sphincters
What do tracheae do
Carry air into the insect body
How are tracheae kept open
By circular bands of chitin which is impermeable to gases
What to tracheae go into
Tracheoles (these are so small that they run between individual cells)
There are vast numbers of tracheoles, what does this mean
A very large surface area for exchanging gases
How does oxygen diffuse into cells of insects
It dissolved into the moisture on the walls of tracheoles and into surrounding cells
What is there towards the end of the tracheoles
Tracheal fluid
What does tracheal fluid do
Limit the penetration of air for diffusion
What happens when oxygen builds up when flying for example
Lactic acidosis builds up in the tissue
Water then moves by osmosis from tracheoles into tissues
Exposing more surface for gaseous exchange
How is the tracheal system ventilated
Mechanically, aid is actively pumped into the system by muscular pumping movements of the thorax/ abdomen this changes the volume and pressure in the tracheae and tracheoles
Air is drawn in and forced out when pressure changes
What is the purpose of collapsible enlarged tracheae (air sacs)
They act as reservoirs to increase the amount of air that is moved through the system
Can inflate and deflate
What are the three states of a discontinuous gaseous exchange cycle
Spiracles are:
Open
Closed
Fluttering
Explain what happens when spiracles in DCG are:
Closed
Fluttering
Open
Closed- no gas moves in or out, oxygen diffuses into cells, CO2 is held in body fluids
Fluttering- spiracles open and close rapidly, moving fresh air into traceable, minimises water lost
Open- CO2 builds up in body fluids
Describe the SA:Vol in fish
Small sa:volume
Name three features of gills that make them good at their job
Very thin= short diffusion distance
Large SA= increase rate of diffusion
Good blood supply= maintain steep conc gradient
Describe the movement of water through the mouth
Enters the mouth (buccal cavity)
Passes over gills
Leaves via opercular opening
What covers the gills
Operculum
How does the fish ventilate the gills
By alternatively opening and closing buccal cavity
Explain what happens when the mouth is open in a fish
-mouth opened/ floor of buccal cavity drops decreasing pressure
Volume of buccal cavity increases
-water moves in (opercular valve is shut)
-opercular cavity (where gills is) expands which lowers pressure
-floor of buccal cavity rises, increasing pressure
-water moves from buccal cavity over the gills due to pressure difference
What happens when mouth is closed in a fish
- Mouth closed and operculum opens
- sides of opercular cavity move inwards
- increase of pressure in opercular cavity forces water over the gills and out the operculum
- floor of buccal cavity moves up maintaining the flow of water over gills
Describe the structure of gills
Each Gill is made of four bony gill arches
These are lined with hundreds of gill filaments that are very thin and flat
The gill filaments occur in large stacks called gill plates
What is a gill plate
A large stack of gill filaments
How many bony gill arches in a gill
Four
What are lamellae
These are on the filament and increase SA more
The bony gill arch contains two vessels
Describe
Efferent vessel/ takes blood out of the system
Afferent vessel/ brings blood into the system
The gill filaments overlap with the neighbouring gill arch filaments providing resistance to water, why is this important
passage of water slows
Means there is more time for gaseous exchange
What occurs in a counter current system
Water moves over the gills and blood in the gill filament flows in the opposite direction
What are the advantages of a counter current system
Constant diffusion of O2 as it does not reach a dynamic equilibrium as there is a constant concentration gradient
What is a concurrent system
What is a disadvantage of this
Where the blood and water moving over gills flows in the same direction
Equilibrium is quickly reached and there is no further diffusion
What type of system does a bony fish have
Counter current
What type of system does a cartilage fish have
Concurrent/ parallel system
