circulation + blood vessels (8) Flashcards
what are the 3 factors that affect the need for a transport system
size - several cell layers, there’s an increased distance from the nutrients and o2 and the cells requiring them
SA:V ratio - surface area of large animals isn’t big enough to supply all nutrients needed to inner cells
active animals require more…
oxygen for respiration
why do jellyfish not require transport system
they have a highly branched gastro vascular cavity which serves deeper cells. they are energy efficient swimmers.
why do sponges not require transport systems
water enters thru tiny pores and leaves from opening in top. they don’t move much. fundamentally sessile.
why do small animals not need a circulatory system
no cell in their bodies is very far away from their gas exchange surface and each cell gets enough oxygen by diffusion with the atmosphere.
how do insects do gas exchange
they use their spirales
what is mass transport
everything - water + dissolved substances all moving tg in 1 direction (the cells, plasma, dissolved sbstances all move tg in the blood)
what is the driving force in mass transport
pressure
why is mass transport better than just diffusion
mass transport is much fater way of getting materials from one place to another when there are distances greater than a few mm.
what are the 2 types of circulatory system
open and closed circulatory system
what are the 3 basic components of an opem/closed circulatory system
- a circulatory fluid (blood or haemolymph)
- a set of tubes (blood vessels)
- a muscular pump (the heart)
describe the open circulatory system
in this system, there is not a separate blood sytsem and lymph system. the circulatory fluid is called haemolymph. only 1 vessel is present in the insect circulatory system: the dorsal vessel. in the abdominal region the dorsal vessel acts as the heart, pumping haemolymph forward into the head and thorax where it acts as the aorta and delivers the haemolymph into the head, from here it flows back through the body. its returned to the heart via ostia, the ostia have valves that close during heart contraction.
what is haemolymph
it fulfills similar combined functions of blood + lymph. the haemolymph does not carry co2 or o2, it transports food and nitrogenous waste products and has a role to play in immunity. o
what is the dorsal vessel
the only vessel present in the insect circulatory system.
what is the ostia
they are smaller slits in the heart region of the dorsal vessel designed for haemolymph uptake. the ostia have valves during heart contraction
