Gas Exchange Flashcards
What is the ideal surface area to volume ratio?
Large
What is the surface area to volume ratio of large organisms?
Small
How do single celled organisms exchange gas and why?
- Direct oxygen diffusion- They have a very high SA:V- They absorb oxygen across their membrane
How do flat worms exchange gas and why?
- Direct oxygen diffusion- Flat so they have a short diffusion pathway to all cells- High SA:V
How do small mammals exchange gas and why?
- Highly specialised organ systems- Higher SA:V than big mammals- Lose more heat per gram- Faster rate of respiration- More oxygen needed - Need to maintain a concentration gradient
How do large mammals exchange gas and why?
- Highly specialised organ systems- Lower SA:V than small mammals- Lose less heat per gram- Slower rate of respiration- Less oxygen needed
What does the efficiency of gas exchange depend on?
- Small diffusion pathway
- High concentration gradient
- High surface area
What is the structure of an insects gas exchange system?
- Waxy cuticle- Spiracles- Trachea lined with cells
How do insects exchange gas?
- Air enters through the spiracles- Oxygen diffuses down a concentration gradient along the trachea- Oxygen diffuses out of trachea and into cells- Ventilation maintains the concentration gradient
How do insects prevent water loss?
- Open and close spiracles (prevent evaporation)- Covered in a waxy cuticle
How do the stomata help prevent water loss?
When cells have a lot of water they are turgid and when cells don’t they are flaccid. Flaccid guard cells close the stomata
How do dicotyledonous plants carry out gas exchange?
- Takes place in the spongey mesophyll (large SA)- Gaseous diffusion in and out of the mesophyll- Stomata is the gap between 2 guard cells- Stomata can open/close to increase/decrease water loss
How do xenophytic plants prevent water loss?
- Curled leaf, sunken stomata and epidermis hairs allow water vapour to build up, decreasing the water vapour gradient- Waxy cuticle and fever stomata reduce evaporation
Where does photosynthesis take place?
Palisade cells
What is the structure of the gas exchange site in a fish?
- Gill filaments- Lamellae- Counter current flow
How do fish exchange gas?
-Gill filaments (lamellae) have a large surface area which increases the efficiency of diffusion.-Thin epithelial cells line the filaments (short diffusion pathway)-Countercurrent flow maintains a high concentration gradient -Circulation of blood and the ventilation of water maintain the concentration gradient so that low oxygen blood is always next to high oxygen water
What is the structure of the human gas exchange system?
- Trachea branch into bronchi which further branch into bronchioles inside the lungs which have alveoli at the bottom. - Lungs are surrounded by ribs with intercostal muscles between them.- Diaphragm sits bellow the lungs- Alveoli are surrounded by capillaries
How do the lungs increase surface are?
Many airsacs called alveoli are found at the end of bronchioles, they have a highly folded membrane with a high surface area
How do the lungs maintain the concentration gradient?
- Ventilation brings in highly oxygenated air and removes unoxygenated air. - Circulation brings in unoxygenated blood (Pulmonary artery) and removes oxygenated blood- Maintaining the high concentration gradient
How do the lungs maintain a small diffusion pathway?
- Alveoli and capillaries have a thin epithelial lining- Gives a short diffusion pathway
What is tidal volume?
The volume of air breathed in or out per breath
What is ventilation rate?
Breaths per minute
What is pulmonary ventilation?
Total volume of air breathed in per minute
How is pulmonary ventilation calculated?
Tidal volume x breathing rate
What effect does exercise have on tidal volume?
It increases because breaths are deeper
What effect does exercise have on ventilation rate?
It increases because breaths are quicker
What effect does exercise have on pulmonary ventilation?
It is increased
What effect does exercise have on oxygen consumption?
It is increased
What is oxygen consumption?
Volume of oxygen used per minute
What is inspiration?
Breathing in
What is expiration?
Breathing oout
How does inspiration happen?
- Diaphragm contracts and flattens- External intercostal muscles contract- Ribcage moves up and out- Pressure decreases - Thorax volume increases - Air rushes in from high to low pressure
How does expiration happen?
- Diaphragm relaxes and domes- External intercostal musclesrelax- Ribcage moves down and in- Pressure increases - Thorax volume decreases - Air rushes out from high to low pressure
What is forced expiration?
Internal intercostal muscles contractRibcage is pulled down faster and more frequently
What are the internal and external intercostal muscles?
An antagonistic pair
How is an animal’s ability to lose heat affected by having large ears?
- Greater SA:V- Loses more heat per gram
What is a by-product released from respiration?
Heat
What system within the body carries the waste around?
Circulatory
What are reasons for diffusion being slow in multicellular organisms?
- Large diffusion pathway to cells deep inside the body- Very thick out membranes compared to single celled organisms- Smaller surface area to volume ratio
What adaptation do elephants have in order to to lose heat more quickly?
Large, thin ears
How do single celled organisms get rid of their waste?
They diffuse across their membrane
How are gas exchange surfaces adapted for efficient gas exchange?
- Short diffusion pathway- High concentration gradient- High surface area
Gases diffuse into leaves via which structure?
Stomata
What organ do insects use for gas exchange?
Trachea
What surrounds alveoli?
Capillaries
Within a leaf, what is it’s main exchange surface called?
Mesophyll layer
How does air enter the insects?
Spiracles
In photosynthesis in plants, what gas is needed?
Carbon dioxide
The diaphragm is made from which type of tissue?
Muscle
There are muscles which are in between each rib. What are these called?
Intercostal
What are the ways that insects control water loss?
- Waxy outer cuticle- They can close their spiracles- Water is trapped around the spiracles by hairs
