Exchange Surfaces Flashcards
(32 cards)
How does the SA:V ratio change as an organism increases in size?
The SA:V ratio decreases because there is less surface area for the exchange of material compared to the number of cells within that organism
How are eukaryotic cells adapted to deal with the smaller SA:V ratio?
They contain mitochondria, specialist cells for respiration, which have a large surface area.
What is the SA:V like for prokaryotic organisms?
What does this result in?
Very large
It allows them to meet the cells energy requirements through respiration that occurs across the plasma membrane only
What are some features of a good exchange surface?
-Large surface area
-A small distance to travel across/thin barrier
-A good blood supply
All maintain a steep conc gradient
Why do some organisms require a faster metabolism than others?
If they are more active
Eg. Hibernating animals don’t move
What muscles help to produce breathing movements/ventilation?
The intercostal muscles that hold the ribs together and the diaphragm.
What molecules are able to cross the alveolus wall and the wall of the blood capillary? Why is this?
Oxygen and carbon-dioxide
Because the molecules are small and non-polar
How many cells thick is the capillary wall and the alveoli wall?
1 cell thick
1 cell thick
What happens during inspiration?
- The diaphragm contracts to move down and become flatter
- the external intercostal muscles contract to raise the ribs
- volume of chest cavity increases
- pressure within chest cavity drops below atmospheric pressure
- air moved into the lungs
What happens during expiration?
- The diaphragm relaxes and is pushed up
- external intercostal muscles relax and ribs fall
- internal intercostal muscles can contract to help push air out during sneezing, coughing or exercise
- volume of chest cavity decreases
- pressure rises above the atmospheric pressure
- air is moved out of the lungs
What are alveoli walls comprised of?
- Squamous epithelium which are flattened/thin cells
- elastic fibres that stretch during inspiration and recoil during expiration
What are the airways lined by?
Ciliated epithelium
- goblet cells in the epithelium produce mucus to trap pathogens
- the cilia then waft mucus to the top of the airway where it’s swallowed
How are the trachea and bronchi adapted to carry out their function?
- They are supported by rings of c-shaped cartilage to withstand high pressures and to allow movement (rather than being a full ring)
- They are large enough to allow sufficient airflow
What are bronchioles comprised of?
Smooth muscle and elastic fibres
Why is it necessary for smooth muscle to contract within the airways?
This will constrict the lumen and restrict harmful substances in the air from entering the alveoli
What is an operculum?
A bony plate that covers gills
What does a gill consist of?
- Two rows of gill filaments (primary lamellae) attached to a bony arch.
- the surface of the gill filaments is folded into many secondary lamellae where blood capillaries carry deoxygenated blood to the surface of
How does countercurrent flow work within fish?
Blood flows along the gill arch and out along the filaments to the secondary lamellae, the blood then flows through the capillaries in the opposite direction of the flow of water over the lamellae.
How can bony fish maintain water flow over their gills?
By using a buccal-opercular pump. The buccal cavity(mouth) can change volume. The floor of the mouth moves down drawing water into the buccal cavity. The mouth is closed and the floor is raised again pushing water from the buccal cavity, as this happens the operculum moves outwards reducing pressure in the operculum cavity galling water to flow through the gills.
What type of circulatory system to insects have?
Open circulatory system
Explain the tracheal-system that insects possess?
Air enters the system via a spiracle (a pore in each segment). The air is transported via tracheae which divide into smaller and smaller tubes called tracheoles. The ends of the tracheoles are filled with tracheal fluid. Exchange occurs between the air in the tracheoles and the tracheal fluid and some across the thin walls of the tracheoles.
What happens when insect tissues are active?
Tracheal fluid can be withdrawn into the body fluid to increase surface are in the tracheoles for exchange to take place.
How can insects ventilate their tracheal system?
- Sections of the tracheal system can be expanded due to flexible walls. These act as air sacs and can expand and contract through repetitive action of flight muscles.
- movement of the wings can alter the volume of the thorax. Higher volume in the thorax means that pressure drops and air is pushed in from the outside and visa versa
What is a spirometer?
A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake
