Exchange & Transport Pt2 Flashcards
(26 cards)
What are the adaptations of the locust respiratory system?
- there are many small tracheoles that increase the surface area in contact between the muscle cells and air
- oxygen diffuses in from a higher concentration in the air to a lower concentration in the muscle cells
What’s the role of spiracles in locusts?
- air enters the anterior spiracles and exits the posterior spiracles
- when open to take in oxygen, the spiracles can lose water
How is water lost prevented on the spiracles of locusts?
- they’re closed for as long as possible, which limits the exposure of the respiratory surface
- they are sunken into small pits, with hair round them. Which traps water vapour, reducing the concentration gradient, lowering the evaporation of water from the spiracles
- the trachea is lined with a cuticle, water is only lost through the tracheoles
How can locusts increase the oxygen uptake into cells from the tracheoles?
- when the rate of respiration is high, eg. Intense flying, the rate of anaerobic respiration is high
- this produces lactic acid
- lactic acid reduces the water potential inside muscle cells
- water enters the cells from the fluid collected in the end of the tracheoles
- by osmosis
- this increases the SA of the tracheole in contact with the muscle cells
- this increases the rate of diffusion of oxygen into the muscle cells from the air
- increasing the rate of aerobic respiration
How do single celles organisms exchange substances?
- substances can diffuse directly into the cell across the cell surface membrane
- diffusion rate is quick because of the short distances the substances have to travel
- & single celled organisms have a high SA: volume ratio
Why do multicellular organising need specialised exchange surfaces?
- Some cells are deep in the body- a big distance between them and the outside environment
- Large animals have a low SA: volume ratio - it’s hard to exchange enough substances to supply a large volume of animal through a small outer surface
- Multicellular organism have metabolic rate so use up oxygen & glucose faster
Give an example of an exchange surface that has a large surface area?
- root hair cells
- each branch of root is covered in million of root hair cells
- this gives a large SA helping increase the rate of absorption of water (osmosis) & mineral ions (by active transport)from the soil
What’s an example of a thin exchange surface?
- alveoli
- each alveolus is made from a single layer of thin, flat cells called the alveolar epithelium
- O2 diffuses out of the alveolar space into the blood, CO2 diffuses in the opposite direction
- the thin alveolar epithelium helps decrease the distance, increasing the rate of diffusion
Give an example of a mammal exchange surface that has a good blood supply & ventilation?
- alveoli
- it’s surrounded by a large capillary supply which constantly takes oxygen away and brings CO2
- the lungs also ventilate so the air in each alveolus is replaced
- maintain a steep concentration gradient of CO2 & O2
Give an example of a fish exchange surface that has a good blood supply & ventilation?
- gills
- fish gills have a large network of capillaries- keeping them well supplied with blood
- fresh water constantly passes over the gills keeping them well ventilated
- maintaining a steep concentration gradient of O2
What’s ventilation?
It consists of inspiration (breathing in) & expiration (breathing out). It’s controlled by the movements of the diaphragm, intercostal muscles and rib cage
What’s oxygen uptake?
The rate at which a person uses up oxygen
What do spirometers read?
Tidal volume
Vital capacity
Breathing rate
Oxygen uptake
Explain the structure of gills?
- each gill is made of gill filaments/primary lamellae giving it a big surface area
- gill filaments are converted in lots of gill plates/secondary lamellae
- each gill is supported by a gill arch
What’s meant by the counter-current system?
In the gills blood flows through the gill plates in 1 direction and water flows over in the opposite
Explain how the water leaves the fish during ventilation?
- when the fish closes its mouth the floor of the buccal cavity is raised
- the volume inside the Cauvery decreases & pressure increases, water is forced out of the cavity across the gill filaments
- each gill is covered by the operculum, the increase in pressure forces them to open allowing water to leave the gills
Explain the structure of the gas exchange system in insects?
- the tracheae branch into smaller tracheoles which have thin, permeable walls & go into individual cells
- tracheoles contain a fluid which dissolves oxygen
- O2 then diffuses from the guild into the body cells & CO2 diffuses the other way
How do insects move air in & out if spiracles?
-they use rhythmic abdominal movements to change the volume of their bodies and move air in & out of spiracles
What are 4 dissection tools? What are they useful for and risks?
- Scalpels- have a detachable blade & used to made fine cuts
- Dissecting scissors- also used for precise cutting & are safer (they’re blades are less likely to snap under pressure) & easier to avoid damaging tissue underneath
- Dissecting pins- used with wax-filled dissection tray
- tweezers- are for holding & manipulating the smaller parts of the specimen
What should you ensure about your dissecting tools before you use them?
- all should be clean, sharpe and free from rust
- blunt tools don’t cut as well & can be dangerous
How would you dissect fish gills?
- Place fish on a dissection tray
- Push back operculum & use scissors to carefully remove gills. Cut each gill arch through the bone at the top & bottom
- Should be able to see gill filaments
- Draw the gill & label it
How Would you dissect an insect (grasshopper or cockroaches)?
- Fix it to the dissecting board, by putting dissecting pins throug it’s legs
- To examine the tracheae you need to cut & remove a part of the exoskeleton (hard outer shell) from along the length of the insect’s abdomen
- Use a syringe to fil the abdomen with saline solution. You should be able to see a network of thin, grey tubes - these are the tracheae
- Mount the trachea on a wet mouth microscopic slide & examine under a light microscope
How do you find the volume of a sphere?
V = 4/3 x pi x r*3
How do you find the surface area of a sphere?
SA = 4 x pi x r*2
