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
Are there mucous glands in the bronchioles?
No, only in trachea and bronchi
Are there goblet cells in the bronchioles?
Only in the larger bronchioles - goblet cells are present wherever the ciliated epithelium is
Alveoli structure and arrangement?
Arranged in groups at the end of the smallest bronchioles - its wall consists of a single endothelium layer and some elastic fibres are present in the extracellular matrix
What conc gradients must be present to allow gas exchange?
A conc gradient of O2 - higher in alveoli than in blood
A conc gradient of CO2 - lower inside the alveoli than in the blood
What is inspiration?
Drawing air IN
What is expiration?
Moving air OUT (exported)
What does the ribcage do when inhaling?
Moves up and out
What does the ribcage do when exhaling?
Moves in and down
What does the diaphragm do when inhaling?
Move down - maximise air space inside lungs
What does the diaphragm do when exhaling?
Move up - minimise air space inside lungs
What is the relationship between the pressure inside the thoracic cavity and the volume of it?
Inverse relation, one increases the other decreases
In terms of pressure changes, why does air move into the body?
When the volume of the thoracic cavity increases, pressure decreases - when it decreases to a pressure below that of the atmospheric pressure, air will begin to move in
When are the internal and external intercostal-muscles needed mainly?
When blowing hard or undergoing strenuous exercise
What is the first thing to start inspiration?
The inspiratory centre (in the medulla oblongata of the brain) sends out a nerve impulse
What muscles contract in inspiration - causing the rib cage to raise?
The external intercostal muscles contract and the internal intercostal muscles relax (external muscles contract when the rib cage is being pushed outwards)
What muscles contract in expiration - causing the rib cage to lower?
The internal intercostal muscles contract and the external intercostal muscles relax (Internal muscles contract when rib cage is moving inwards and down)
What is a spirometer?
An instrument used to take measurements related to breathing
Vital capacity?
The max volume of air which can be breathed in or out in a single breath
Tidal volume?
The volume of air which is normally breathed in or out at rest
Breathing rate?
The number of breaths per minute (one in and out = one breath)
Oxygen uptake?
The amount of O2 consumed by the subject (The spirometer removes CO2 - change in volume in spirometer is the O2 uptake)
How to calc breathing rate?
Number of breaths/time taken (want it in breaths per min or second, so 5 breaths in 4 mins = 5/4)
How to calc tidal volume?
The mean of the volumes of air breathed in and out for each breath
What does total lung capacity - residual volume = ?
Vital capacity
Why when doing a spirometer experiment must it usually come to a halt at a given point?
Air is being re-breathed over and over (although CO2 is removed, the O2 conc drops slightly), the subject breaths quicker and deep in attempt to get more O2
Two types of fish?
Bony fish/the teleosts and the elasmobranchs
What skeleton do Teleosts/bony fish have?
One made of bone
What skeleton do elasmobranchs have?
One made of cartilage
What are the gas exchange organs in bony fish?
Gills
How do gills increases their SA?
Gills are divided into many gill filaments
How do gill filaments increase their SA?
Gill filaments have gill lamellae
Operculum?
A flap of tissue that covers the gills in bony fish
How does water enter and leave the buccal cavity?
With its mouth open, the fish lowers the floor of the buccal cavity (decreasing its pressure so water flows down the gradient into the buccal cavity)
How does water enter and leave the gill cavity?
The floor of the buccal cavity is raised and the mouth is shut (pressure is increased so flows down gradient into the gill cavity), pressure builds in the gill cavity which forces open the operculum - water leaves through this
What is counter-current flow?
Blood flows in opposite direction to the flow of water over the gills
Blood always encounters water with a higher O2 conc than itself (in the gill lamella), maintaining a diffusion gradient
What is con-current flow?
Blood flows with and in same direction as water over gills - an equilibrium is reached (O2 in blood and water is the same), blood doesn’t take up O2 - less efficient
How does gas exchange occur in insects?
O2 containing air is delivered straight to the tissues via trachea
What is tracheae?
A system of tubes
What is present along the sides of an insect’s abdomen?
Spiracles
What are spiracles?
The series of openings along the insects abdomen
How many spiracles does a segment have, on an insects abdomen?
Two
What does the spiracle branch into?
Spiracle, trachea, tracheoles, into the muscle/tissue
How do small/unicellular organisms get their O2/nutrients?
Diffusion through their body surface, due to favourable diffusion gradients
Why do bigger organisms need a transport system, due to distance?
The bigger the organism, the longer the diffusion distance from the surface to the innermost cells - diffusion is slow so these cells would die
Why do bigger organisms need a transport system, due to SA?
O2 diffuses through the surface of organisms (so the SA is a measure of the supply of O2), the no. of cells (the volume in theory) is an indication of the demand of O2
Larger organisms have a smaller SA:volume
Why do bigger organisms need a transport system, due to activity?
Larger animals tend to be more active
They have more cells which means more O2 is required and more waste is produced
Mass flow?
The directed movement of material - usually due to some force (e.g. the heart beat)
Features of single circulatory systems?
The blood passes through the heart once for each circuit of the body
These animals hearts have ONE atrium and ventricle
Deoxygenated blood is pumped by the heart to (the gills - in fish)
The then oxygenated blood travels to the rest of the body, returning to the heart as deoxygenated
Features of a double circulatory system?
The blood passes through the hearts twice per circuit of the body
The heart is divided into left and right (on paper - the right hand side = the left)
(Rhian is definitely oval, Lucy is oval)
What side of the heart deals with oxygenated blood?
The left side of the heart deals with oxygenated blood, the right side deals with deoxygenated blood (rob (right) is dead)
Simple overview of one circuit of the double circulatory system?
The deoxygenated blood leaves the right side of the heart and travels to the lungs, the lungs
