3.3.4.1 - mass transport in animals Flashcards
(12 cards)
what is a mass transport system?
a system which moves materials from exchange surfaces to cells (may be over large distances)
what are key features of mass transport systems?
- suitable medium for transport
- substances moved around in bulk
- transport occurs through closed system of tubular vessels
- mechanism of moving the transport medium
- mechanism to maintain flow in one direction
- mechanism to control the flow to suit changing needs
what is the role of arteries?
carry blood away from the heart
how does the structure of arteries relate to their function?
- have a narrow lumen
- have thick walls with muscle and elastic fibres - strengthens them to withstand high pressure of blood and allow walls to expand when blood flows through at high pressure and recoil when heart relaxes, maintaining the high pressure
what is the role of arterioles?
arteries branch into them and they transport blood to capillaries
how does the structure of arterioles relate to their function?
- have fewer elastic fibres in their walls as blood is at a lower pressure than in the arteries
- have large number of muscle cells so they can contract and close lumen to stop blood flow to specific organ
what is the role of veins?
carry blood towards the heart
how does the structure of veins relate to their function?
- their walls are relatively thin and their lumen is larger than arteries because the blood flowing through them is at a lower pressure
- they contain valves to prevent backflow of blood
what are the haemoglobins?
a group of chemically similar molecules found in many different organisms
what is haemoglobin?
a protein with a quarternary structure found in red blood cells
what is the role of haemoglobin?
to transport oxygen from lungs to tissues
what are the details of the structure of haemoglobin?
- 4 polypeptide chains
- 2 alpha chains, 2 beta chains
- 4 haem groups, each containing an Fe^2+ ion
