Bio paper 1 only (book 1 - chapters 7/8/9) Flashcards
How have plant roots adapted to become a good exchange surface?
They have root hair cells to increase the SA for absorption of water
How have the cells in the endothelium layer (that line the gut) become a good exchange surface?
They have microvilli on the surface to increase SA for absorption of digestive food products
What is the difference between breathing and ventilation?
Breathing is a bodily action carried out by animals, whereas ventilation is regarding a specific process involving gas exchange e.g. plants and humans ventilate, only humans breathe
Why is it more important for mammals to rid of the waste CO2 rather than plants?
Plants can make sure of some of the CO2 in photosynthesis, mammals only want O2 in their body
How does gas exchange occur in unicellular/small organisms?
As oxygen is used up in respiration, conc of O2 within organism is lower than that outside it - so O2 diffuses in
CO2 is produced in respiration so its conc gradient is favourable for movement out of the cell
What does gas exchange in small organisms depend on?
The exchange surface must be permeable to both gases and moist - they can only dissolve through in a solution
What happens to the SA:VOLUME as an organism gets larger?
The SA increases, but the volume increases proportionally more so the SA:VOLUME decreases
What does it mean in terms of amount of gases, when SA:VOLUME is decreasing?
The organism is getting bigger - SA is increasing and Volume is increasing more, so the demand for oxygen is is getting bigger than the supply
What is the gas exchange surface in mammals?
The alveoli (air sacs) within the lungs
What is the sequence of body parts which are involved in taking in the air?
Mouth and nose, trachea, two bronchi, bronchioles, alveoli
What is the thoracic cavity?
The area inside the rib cage where the lungs are situated
What do the interior and exterior intercostal muscles do?
Move the rib cage in and out during deep breathing
What is the pleural cavity?
The area between the pleural membranes (the lungs double membrane), filled with fluid
What does the fluid between the lungs double membrane do?
Provides lubrication between the lungs and the rib cage
What is at the base of the thoracic cavity?
The diaphragm - a sheet of muscle
Adaptations for gas exchange?
SA is large Gas exchange surface is thin Good blood supply Ventilation mechanism Exchange surface is moist
Feature of alveoli cell walls?
Walls are one-cell thick , therefore short diffusion pathway
Why and how is a good blood supply maintained in the alveoli?
They are well supplied with capillaries which absorb O2 and deliver CO2
Cartilage - role and function?
A form of connective tissue - provides strength and support (keep tubes open)
What is cartilage resistant to?
Tension and compression
What is epithelium?
A layer of cells that form a covering or a lining
What is the purpose of the ciliated epithelium?
The airways are coated in mucus which traps dust/bacteria - this needs removing and is done so by moving the mucus to the top of the trachea - The cilia of the CE pumps to move the mucus
What do goblet cells do?
Produce the mucus which lines the trachea/bronchioles
Where are goblet cells found?
Between ciliated cells in the epithelium
Where is smooth muscle found?
In the trachea, bronchi, bronchioles
What is the function of smooth muscle?
Maintains the tone in the airways and allows expansion In areas where extra O2 is needed
Where are elastic fibres found?
In all lung tissue - even alveoli
What is the trachea?
The widest tube in the gas exchange system - a simple channel which allows air to flow through and reach the lungs
What special feature does the trachea have?
C shaped cartilage rings which provide a scaffolding so that the walls don’t collapse
Why are the cartilage rings c shaped?
So the oesophagus wall does not rub against the semi-rigid rings of cartilage and cause friction
What lies below the epithelium?
Mucous glands
How does the structure of bronchi differ from that of the trachea?
They have a smaller diameter and thinner walls
The bronchi have complete rings of cartilage
Bronchioles differing structure to the bronchi?
They get smaller the nearer they get to the alveoli - walls are thin and diameter smaller