transport in humans

why do multicellular animals need transport systems?

• long diffusion distance, cells that need oxygen x get it easily,

• larger organisms are more active, therefore cells are respiring quicker

• higher metabolic rate

• low surface area to vol ratio

what are the different types of circulatory systems?

• open - blood flows freely through the body cavity

• closed - blood enclosed inside blood vessels

• double - blood only passes through the heart once for each complete circuit e.g. mammals

• single - blood only passes through the heart twice for each complete circuit of the body e.g. fish

what are the pulmonary and seismic systems?

pulmonary - blood to the heart

seismic - rest of the body

advantage of double circulatory system

heart can give the blood an extra push, travelling faster and is delivered to the tissues quicker

how does an insects circulatory system work?

1. heart is segmented - contracts in a wave starting from the back

2. pumps the haemolymph (insect blood) into a single main artery (the dorsal vessel)

3. the artery opens up into the body cavity

4. the blood bathes the organs

5. fluid returns to the heart via valves

transports hormones and nutrients,

no oxygen supplied through circulation

• delivered directly via tracheae

structure and function of arteries + arterioles

arteries -

• carry blood away from the heart

• small lumen - to allow for a high pressure

• folded inner wall - lumen to expand with increased blood blow

wall layers

1. thin layer of elastic tissue

2. thick layer of smooth muscle

3. thick layer of elastic tissue and collagen

arterioles

• branch into narrower blood vessels - arterioles, transporting blood into capilliaries

elastic tissue purpose

• allows walls to stretch and recoil

• help maintain blood pressure

structure of capilliaries .

structure of venules and veins