exchange systems Flashcards
How to calculate SA:V
SA / V
what organisms have a large SA:V?
Smaller organisms/ single cell organisms given that their cell membranes are relatively thin
How are larger organisms exchange systems specialised for high activity demands?
xylem and phloem transport water and solutes and the blood and circulatory system transports glucose, oxygen and carbon dioxide
Why is heat exchange required in organisms?
So that enzymes don’t denature causing the 3D tertiary protein structure to be damaged
What is a suitable medium to transport substances in organisms?
Blood
What are blood vessels?
Closed systems to transport the medium with branches to reach all parts of the organisms body
What is the role of the heart in transport systems?
Mechanism to provide a pressure difference between parts of the system to keep things moving
What is the role of the valves?
A mechanism to maintain the movement of the medium
How is the alveoli adapted for efficient exchange?
Thin walls for a short diffusion pathway
Alveolus with a low CO2 conc and high O2 conc to maintain a concentration gradient
How does a partially permeable membrane benefit exchange rates?
Allows selected materials to diffuse easily
How does a moist and warm environment benefit exchange rates?
Warmth increases the kinetic energy of particles, moisture allows gasses to diffuse
How does movement of internal and external mediums allow exchange of gasses?
Maintains a diffusion gradient
Why do terrestrial insects suffer with dehydration?
They have a waterproof covering and a small SA:V, minimising gas exchange
What are tracheae and what do they do?
Tubes that penetrate in the body carrying air to each tissue- maintaining a diffusion gradient
What are tracheoles?
Branched tissues
What are spiracles?
Openings in the body surface leading to the tracheae- can be closed to prevent water loss
What is abdominal pumping?
Body contractions that speed up the gasses from the tracheae to the cells
Why must water flow continuously in fish?
To maintain a concentration gradient for the exchange of oxygen and carbon dioxide
Role of gill filaments
To provide fish with water providing them oxygen
Role of lamellae?
Stacked to increase surface area
What is a counter current flow?
Water is taken in through the mouth, and passed over the gills and out the openings in the body. Water flows in the opposite direction to blood maintaining conc gradient
What is a concurrent flow and why is in not efficient?
Blood and water flow across the body in the same direction and will eventually reach an equilibrium meaning fish will not gain oxygen and die
How are leaves thin a benefit for photosynthesis?
Short diffusion pathway so gasses can reach cells easily
How do lots of chloroplasts help photosynthesis?
Located at the top of the cell to absorb light and air
How do veins help photosynthesis?
Carry water to cells and glucose carried away
Role of stomata?
Open and close through guard cells to let water and air pass in and out
What are xerophytes?
Plants adapted to live in dryer conditions
How do thick waxy cuticles benefit xerophytes?
Increase the diffusion distance so less chance of gasses leaving
How do hairs on leaves benefit xerophytes?
Traps water vapour next to the surface- water potential is reduced
How do curled leaves benefit xerophytes?
stomata’s are trapped so transpiration is reduced
How do sunken stomata’s benefit xerophytes?
Traps water vapour on the underside of the leaf
How to work out Frick’s law of diffusion?
Diffusion = (surface area x difference in concentration) / length of diffusion pathway
What is each alveoli lined with?
Flattened layer of epithelial cells
Why is it beneficial that capillaries are narrow?
So that travelling RBC’s are flattened and can squeeze through. It also helps to slow down the pace of RBC’s increasing surface area for diffusion
Describe the squamous epithelia and where it is found
they are found in the tissues and are the only cells which are; Flat, smooth, thin, packed closely together and found in the linings of cheeks, blood vessels and heart chambers
Why is it important that the surface of the epithelial cells are low friction?
Decreases the chance of clots forming
How does slow passing RBC’s increase diffusion rate?
More time for gas exchange
How do flattened RBC’s help diffusion rate?
reduces the distance between alveoli and capillaries creating a short diffusion pathway
How do thin wall help diffusion rate?
Decrease diffusion pathway
How do alveoli folds help diffusion rate?
increases the surface area
How does ventilation and circulation help diffusion rate?
Maintains a concentration gradient
Describe the process of inspiration
The internal intercostal muscles and the diaphragm contract whilst internal muscles remain relaxed
Volume of thorax increases as diaphragm flattens
Pressure of the thorax decreases as volume increases
The pressure of the air is higher pressure than in the thorax
Active process and requires energy
Describe the process of expiration
external intercostal muscles and diaphragm relax
Volume of the thorax decreases as diaphragm becomes domed
Pressure in the thorax increases as volume decreases
Pressure in air is lower than in the thorax
Air is forced out the lungs
What is pulmonary ventilation?
The measure of the amount of air moved into the lungs in a minute
Calculation of pulmonary ventilation
tidal volume x ventilation rate
