3A Exchange and Transport Systems Flashcards
What are the 5 common traits of exchange surfaces?
- A large SA to volume ratio of the organism
- Very thin so that diffusion can occur across a short distance
- Selectively permeable to control which substances exchange
- Movement of the environmental medium
- A transport system to move the internal medium
Name two animal exchange surfaces
Alveoli, Villi
Name one plant exchange surface
Root hair cell
How many cells do O2 and CO2 diffuse across between the air and the blood. What tissues are they part of?
2 cells
Must travel through the alveoli which is one cell and capillaries which is also one cell
What structure is partially permeable. Suggest how movement of substances is controlled.
Cell surface membrane
It is selectively permeable
Give 4 examples of mechanisms by which environmental media are moved by animals across exchange substances.
Active transport
Diffusion
Facilitated diffusion
Cotransport
What is the primary transport system of vertebrates
Cardiovascular system
What is the transport system of vascular plants
Xylem and Phloem
State how unicellular organisms such as bacteria obtain vital substances from their environment.
They use active transport, diffusion, cotransport and facilitated diffusion through their cell membrane
Why do unicellular organisms not require a transport system?
They have a high SA to volume ratio
Therefore they can just use diffusion
State two ways in which insect ventilate their exchange systems
- Insects flex their muscles which expands and compresses their system
- Valves on the spiracles - valves at the front of the body bring air in, at the back they draw air out forming a ventilation system
How do gases enter an insect’s body?
Through spiracles which are small holes in the side of their bodies - They don’t have lungs
How is gas exchanged in an insect?
Through spiracles which run along the side of their bodies
Name the 4 parts of an insect that help in gas exchange?
- Spiracles
- Tracheae
- Some have air sacs
- Tracholes
What are the tracheae?
It runs through an insects body and is a part of their respiratory system
What are the Tracheoles?
At the ends of the tracheae in an insect, they go right to the tissues that need the gases
How many cells make up a singular tracheole?
One
How is the flow of gases controlled in an insect?
There are valves in the spiracles which determine which direction the gases can flow, this stops the insect inhaling too much
How do insects prevent dust particles etc entering their respiratory system?
There are protective lattices in the spiracles which prevent small particles from entering the system
List the order of the parts of the gas exchange system of an insect
Spiracles –> Tracheae –> Tracheoles
How do insects react to oxygen debt during intense exercise?
There is water in the Tracheae which is released into cells, this breaks down the lactic acid and prevents too much lactic acid building up
Explain how the tracheal system limits the size of insects
The conc. of oxygen in our atmosphere means conc. gradient isn’t high enough for the oxygen to reach tissues in the insect with this respiratory system
If the insect was scaled up too much, they would become dehydrated
Give 3 examples of exchange surfaces in humans
- Alveoli
- Villi
- Capillaries
Give 4 examples of things that are exchanged at exchange surfaces in humans
- Oxygen
- CO2
- Heat
- Minerals/vitamins
Life is ….
Cellular (like a box of chocolates)
What do all substances enter or leave a living organism through?
A cell plasma membrane
What is any surface which substrates are transferred across called?
Exchange surface
What does every exchange surface always include?
A cellular membrane - this is true even for multicellular organisms
How do exchange surfaces pose a problem to multicellular organisms?
Distance between exterior and interior environments is too great for substances to simply diffuse
How do multicellular organisms overcome the problems with exchange surfaces?
- Have had to evolve
- More intricate systems for exchange
Name an issue with surface area
Smaller molecules don’t have the same amount of difficulty as larger molecules do
What is the role of the waxy outer layer of a cactus?
Prevents water loss (due to the hydrophobic lipids)
Why do cactuses have spines?
They are leaves which have curled up –> This reduces the SA and therefore the water loss
Name 5 ways cactuses prevent water loss
- Waxy outer layer
- Small plants
- Smooth skin
- Long thin layer of roots
- Reduced area of leaf to spines
What is the formula for SA of a cylinder?
2πr^2 + 2πrh
What is the formula for the volume of a cylinder?
πr^2h
What occurs along the length of the tracheal system in an insect?
Diffusion gradients
What is the conc. of O2 and CO2 at the tracheole ends?
- The lowest conc. of O2
- Highest conc. of CO2
How do insects circulate gases around their body?
Insects flex their bodies by muscle contraction
How do muscle contractions help insects to circulate gases?
–> It expands and compresses their system - including the air sacs
–> Fluctuating pressure moves air in and out of body
Why is the tracheole ends being filled with water helpful?
During intense activity, lactate builds up around the muscles - dissolves this
Why is lactate being soluble useful for the breaking down of lactate in tracheoles?
It reduces the water potential - water then moves into the cells
This reduces the water in the tracheole ends + so extends the reach of air into the tissues
Fish’s skin must be…
Watertight –> consequently makes them oxygen tight
Fish are relatively large animals compares to insects, what does this mean for their SA to volume ratio?
They have a relatively low SA to volume ratio
Fish are aquatic, do they still require oxygen?
Yes!
Their cells still need oxygen for respiration
Where do fish obtain oxygen from?
From water
Why don’t fish breathe with lungs?
It would be mechanically difficult to breathe water with lungs
What is the concentration of oxygen in water like compared to the concentration in air?
Water contains far less (dissolved) oxygen than air
What do fish use to breathe instead of lungs?
They have to have a different system, therefore they use gills
What are fishes gills like?
They are highly evolved
How are fish gills high evolved?
They use several structure to maximise the area of the exchange surfaces
What sort of flow is in fish gills?
They have a counter current flow
How do fish take in air?
Through their mouths
Why is fish taking in air through their mouths good?
It keeps a constant flow of water, helping the gills
What are gill filaments like?
They are long and flat
What do gill filaments have running along them?
Lamella
What is the role of Lamella on gills?
To increase the SA of the gill to allow more oxygen to flow through
What is running along the gill arch?
The gill filaments
Name the structure of a gillin size order
Gill arch –> Gill filaments –> Lamella
What is a counter current flow in a fish?
The blood and water flow in opposite directions
What would happen if there was a concurrent flow in a fish?
The conc. would become the same at one point and there would no longer be a conc. gradient
Why is there a counter current flow in a fish?
So there is a large conc. gradient at all stages
The conc. gradient in the lamelle allow what?
Oxygent to move from the water into the blood
Large SA to volume ratio allows what
Speed up the rate of exchange
Very thin exchange surface allows what?
Short diffusion pathway
Partially permeable exchange surface allows what?
Allows selected/materials to diffuse easliy
Gills are made up of stacks of what?
Gill filaments
At right angles to the filaments in gills are what?
Lamellae
What is the lamellaes role in gills?
Increase the SA
In order for efficient gas exchange in fish the flow of __1__ and __2__ must be in opposite directions
1 -Blood
2- Water
What is blood and water flowing in opposite directions in a fish known as?
Countercurrent flow
Give an example of movement of an external medium
Oxygen
What does movement of external medium allow for exchange surfaces?
To maintain diffusion grad
What does movement of internal medium allow for exchange surfaces?
To maintain diffusion grad
What are 5 features that would create an effective exchange surface?
- Large SA to volume ratio
- Very thin
- Movement of external medium
- Movement of internal medium
- Partially permeable
Why do we need exchange surfaces?
To allow substances to be transported/exchanged
To allow cells to perform their essential functions
What substances need to be exchanged in humans?
- O2
- CO2
- Glucose
- All minerals and nutrients needed
Name 4 essential functions cells need to perform involving exchange surfaces
- Take in O2
- Take in nutrients
- Maintaining temp/heat loss
- Get rid of CO2
What is the diffusion pathway of larger organisms like?
Larger organisms have much longer diffusion pathways
Why are large active organisms unable to rely on their body surface for diffusion?
- SA to volume is insufficient for exchange
- The distance is too great
What is the main transport method for single-celled organisms?
Diffusion
What is the main transport method for multicellular organisms?
Mass transportation
What does the rate of heat loss from an organism depend on?
Its surface area
Give an example of an animal with a small SA
A hippo
If an animal has a larger SA, what does this mean for the rate of heat loss?
It makes it harder for them to lose heat
Give an example of an animal with a large SA
A mouse
If an animal has a smaller SA, what does this mean for the rate of heat loss?
They have a high SA to volume ratio, therefore they lose heat a lot more easily
As smaller animals lose heat more easily what does this require them to have?
A relatively high metabolic rate, in order to generate enough heat to stay warm
Why is a gaseous exchange surface being thin helpful?
It provides a short diffusion pathway
Give 3 features which increase the rate of diffusion
1 - Large SA
2 - Thin
3 - Steep conc. gradient
Where do single celled organisms absorb and release gases?
Via diffusion through their outer surface
Why is diffusion an effective method of transport in single celled organisms?
They have a large SA + a thin surface and a short diffusion pathway
What is the structure of the trachea?
It is flexible and is surrounded by cartilage rings
What is the role of the cartilage rings that surround the trachea?
Allow the trachea to stay open, even when inhalation causes the air pressure in the tube is decreased
What would happen if you didn’t have the cartilage around the trachea?
When exhaling the trachea would collapse due to the decrease in pressure
What is the structure of the Bronchi?
Two divisions of he trachea - have cartilaginous rings
What is the structure of the bronchioles?
Wall is made of muscle - heavily branched to carry air to all parts of the plants
What does the muscular walls of the bronchioles allow them to do?
To regulate the flow of air into and out of the alveoli by contraction of pipes
What is the role of goblet cells?
Produce mucus
What is the role of ciliated cells?
Waft the mucus out of the trachea and away from the lungs
What is the structure of the alveoli?
Minute air sacs
How big are the alveoli?
100-300um
How can alveoli stretch to pull air in?
The collagen and elastic fibres allow them to be flexible
What lines the inside of both the trachea and bronchi?
Ciliated cells and goblet cells
How does the structure of the trachea compare to the structure of the bronchi?
They are exactly the same, the bronchi are just smaller
Why do mammals need lungs?
- Mammals are large animals they need a larger SA to get sufficient oxygen
- Increasing SA increases efficiency of exchange
- Ventilation increases efficiency with internal/external mediums
Why do sharks need to keep moving?
Sharks are cartilaginous fish, so they can’t circulte and make the external medium and their bloody oxygen levels would lower
Why are mammalian lungs inside the body?
- The lungs need the ribs to stop them collapsing
- Exchange surface in inside the body - if it was on outside the system would get damaged lots
- Exchange surface outside body = lots of water loss
How thick are alveoli?
0.05um - 0.3um
How thick are capillaries?
0.04um-0.2um
How many red blood cells can pass through a capillary at once?
1 red blood cell, the cell is forced against the wall of the capillary - they therefore slow down and this allows more time for gases to diffuse
Why is the red blood cells being flattened against the capillary walls a positive adaptation?
Reduces the diffusion pathway
Why is the constant flow of blood around the alveoli a useful adaptation?
Maintains the constant concentration gradient
How are the lungs kept ventillated?
Breathing movements keep the lungs ventilated, replacing the external medium
