Topic 3.4.1 Mass Transport in animals Flashcards
What are the benefits of a mass transport system?
Large organisms have a small SA:VR so a mass flow transport system is needed to transport substances fast and efficiently between exchange surfaces
Why can’t complex multi cellular organisms rely on diffusion to transport substances around the body?
Diffusion is selective due to permeability and concentration gradients. It is a slower process and needs a large SA to be effective
Define a closed circulatory system
The blood stays contained within vessels throughout the whole body
Define a double circulatory system
The blood travels through the heart twice for each complete circuit of the body: once to the lungs, once to the rest of the body
Why is a closed circulatory system more efficient?
• makes it possible for the organism to control where the blood is flowing with more precision and more efficiency.
• also creates a larger amount of pressure, which allows the blood to travel farther distances.
Describe three disadvantages of single circulatory systems as seen in fish
•Lower blood pressure > lower blood circulation
• Limited stamina
• Impairs temperature regulation
What is the inner tissue lining of a blood vessel called?
endothelium
Describe the three structural layers of an artery
•Inner layer - endothelium resting on elastic fibres
•Middle layer - elastic fibres/smooth muscle/ collagen fibres
•Outer layer - mostly collagen fibres, some elastic fibres
Describe the stretch and recoil in arteries
The elastic tissue allows walls to stretch and recoil to maintain pressure
What is the role of arterioles?
Carry blood from arteries to capillaries, control the flow of blood between the two
Describe how veins are adapted to carry blood back to the heart
Wide lumen to aid blood flow
Contain semilunar valves to prevent backflow
Describe how blood flows in veins
Blood flows at a low pressure back to the heart in veins
What is the function of the capillaries?
Provide a short distance for exchange by diffusion
Describe the structure of capillaries
Walls consist of a single layer of epithelium
Narrow lumen (same diameter as red blood cell)
Numerous and highly branched
Describe how capillaries are adapted for exchange
Walls consist of a single layer of epithelium with flattened cells
Narrow lumen (same diameter as red blood cell)
Numerous and highly branched
