Adaptations For Gas Exchange💨 Flashcards
What increases the rate of gas exchange?
- Increasing the surface area
- Reducing the length of the diffusion pathway
- Increasing the steepness of the concentration gradient
What properties do gas exchange surfaces need for efficient gas exchange?
- Permeable to gases
- Moist
- A large surface area
- Thin - short diffusion pathway
- Able to maintain a concentration gradient
Why must gas exchange surfaces be moist?
Because gases must dissolve before they can diffuse across membranes
What is the equation for aerobic respiration?🗣
Oxygen + glucose ->
Carbon dioxide + water
Surface area to volume ratio
The quantity of oxygen required by an organism is proportional to its volume.
The rate of uptake of oxygen from the environment is proportional to its surface area.
What happens to the surface area to volume ratio as an organism increases in size?
It decreases
Adaptations of an amoeba🔍
- Large surface area to volume ratio
- Short diffusion pathways
- Moist
Flatworm adaptations🥓
- Short diffusion pathway
* Large surface area to volume ratio - flat and elongated shape
What is respiration?🗣
A series of oxidation reactions taking place in all living cells.
It results in the release of energy from organic compounds such as glucose.
What is gas exchange?
The diffusion of gases into and out of cells so that respiration can take place
Earthworm adaptations🐛
- Use body surface for gas exchange
- Secrete mucus to maintain moisture
- Elongated shape provides a large surface area to volume ratio
- Closed circulatory system with a well developed capillary network
- Short diffusion pathway
- Haemoglobin in the blood
How do insects reduce water loss?🐞
- Exoskeleton has a waxy cuticle over surface
* Spiracles have valves or hairs
Gas exchange in insects🐞
•They have spiracles which lead to tracheae
•These lead to tracheoles which come into contact with every tissue
The tracheoles have fluid in the ends which dissolve the gases, allowing them to diffuse
Why do tracheae have rings of chitin?🐞
To stop the tubes collapsing and prevent gas exchange of the body
What is the gas exchange surface for insects?🐞
The tracheoles
Advantages of tracheal system🐞
- Every tissue is supplied directly with oxygen
- No circulation or haemoglobin is needed
- Reduced water loss
Ventilation in insects🐞
Contract and relax muscles in thorax and abdomen.
This creates rhythmical movements that ventilate the tracheoles.
How is the tracheal system efficient?🐞
- High surface area - many tracheoles
- Short diffusion pathway - direct
- Moist - fluid in tracheoles
- Permeable - no chitin at ends of tracheoles
- Maintained concentration gradient - ventilation
Gas exchange in amphibians such as a frog🐸
- The larval form uses gills
* The adult uses lungs when active and skin when inactive
How is gas exchange in amphibians efficient?🐸
- Moist skin
- Thin tissues in lungs are thin
- Vascular tissues
Gas exchange in reptiles🐍
•More efficient lungs than amphibians
How is gas exchange in reptiles efficient?🐍
- Large surface area - highly folded lungs
* Able to maintain a concentration gradient -ribcage allows them to ventilate
Gas exchange in birds🦆
•Lungs with air sacs
How is gas exchange in birds efficient?🦆
Able to maintain a concentration gradient - ventilation. This is more effective because the air sacs act as bellows
Gas exchange in mammals🐯
- Trachea
- Bronchi
- Bronchioles
- Lungs
- Alveoli
Why do the trachea, bronchi and bronchioles contain rings of cartilage?🐯
To stop the airways from collapsing under the negative pressure produced in the lungs during inspiration
How is gas exchange in mammals efficient?🐯
- Alveoli and extensive capillary network provide a large surface area
- Moist surface - tissue fluid lining the alveolus
- Walls of alveoli and capillaries are one cell thick - short diffusion pathway
- Ventilation and dense capillary network maintains a concentration gradient
What is the importance of goblet cells in the trachea?🐯
They secrete mucus which traps and removes dust and microorganisms that may be present in inspired air
What is the importance of the cilia?🐯
They beat in a wave like manner, moving the mucus upwards and out of the lungs
Is inspiration active or passive?
Active process
Is expiration active or passive?
Passive process
Inspiration of mammals🐯
- Intercostal muscle contract
- Rib cage moves upwards and outwards
- Diaphragm contracts and flattens
- Volume of thoracic cavity increases
- Pressure in thoracic cavity and lungs decreases
- Air moves into the lungs
Expiration of mammals🐯
- Intercostal muscles relax
- Rib cage moves downwards and inwards
- Diaphragm relaxes and domes
- Volume of thoracic cavity decreases
- Pressure in thoracic cavity and lungs increases
- Air moves out of the lungs
Why must warm blooded animals have a well developed gas exchange system?
Because they need lots of energy from respiration to maintain a constant internal environment
What is the respiratory medium used by fish?🐟
Water - it’s a dense medium and passes over the gills in a undirectional flow
Alveoli🐯
- Mammalian gas exchange surface
- Exist in groups at the end of alveolar ducts
- Covered in fine capillaries
- Squamous epithelium
What is surfactant?🐯
It prevents the alveoli sticking inside and keeps them moist
How is gas exchange in fish efficient?🐟
- High surface area from gill lamellae
- Short diffusion pathway - lamellae are thin
- Ventilation, dense capillary network and haemoglobin maintains a steep concentration gradient
- Moist - aquatic
Inspiration of fish🐟
- The fish opens its mouth and lowers the floor of the buccal cavity
- The volume increases and the pressure decreases
- Water enters the mouth
- The volume of the opercular cavity increases and the pressure decreases below that of the buccal cavity
- Water is drawn across the gills down a pressure gradient
Expiration in fish🐟
- The mouth closes and the floor of the buccal cavity is raised
- The volume decreases and the pressure increases
- Water is forced back over the gills
- As water enters the opercular cavity, the increase in pressure cause the valve to open
- Water exits the fish
What is the counter current system?🐟
•Water flows over the gills in the opposite direction to that if the blood flow in the lamellae
Why is the counter current mechanism efficient?🐟
- The concentration of oxygen in the water is always higher than that if the blood
- This means equilibrium is never reached
- This enables oxygen to diffuse into the blood along the whole length of the gill lamellae
- Allows bony fish to extract about 80% of oxygen in water
What is parallel flow?🐟
Where water flows over the gills in the same direction as that of the blood in the lamellae
Why is parallel flow less efficient?🐟
The concentration of oxygen in the water and the blood reaches equilibrium part way across the lamellae.
The cartilaginous fish can only extract 50% of oxygen in the water
How are the leaves adapted for light absorption?🌱
- Plants can orientate leaves towards their light and expose a greater surface area
- Leaves are flat - large S.A
- Leaves are thin - light can penetrate lower tissue layers
How are the cuticle and epidermis adapted for light absorption?🌱
Transparent to allow light to penetrate mesophyll tissue
How are palisade cells adapted for light absorption?🌱
- Elongated to reduce number of cell walls that would absorb light
- Contain chloroplasts to maximise light absorption
How are chloroplasts adapted for light absorption?🌱
They move inside cells to gain the best position for absorbing light
How are leaves adapted for gas exchange?🌱
They are thin to reduce diffusion distance
How is the spongy mesophyll adapted for gas exchange?🌱
- Large S.A
- Air spaces which allow the circulation of gases and reduce the diffusion pathway
- Moist for absorption of carbon dioxide
Plant adaptations to reducing water loss🌱
- Waxy cuticle on upper epidermis prevents evaporation
- Stomatal pores on lower epidermis reduce water loss via evaporation
- Guard cells can change shape to open or close the stomatal pores
Mechanism of stomatal opening🌱
- ATP is used to actively transport potassium into the guard cells
- The lower carbon dioxide concentration triggers the conversion of insoluble starch to soluble malate
- The potassium and malate lower the water potential in the guard cells
- Water moves into the guard cells by osmosis
- The guard cells swell and become turgid
- The outer wall is more elastic so the cells curve, opening the stomatal pore
The pleural cavity🐯
- Each of the lungs is enclosed in the pleural membrane
- The pleural cavity is filled with fluid which lubricates the lungs
- The ribs pull on the outer pleural membrane
- The inner membrane pulls on the lungs
What is meant by a ventilating mechanism?
Moving a respiratory medium over a respiratory surface
