With this topic, it is difficult to know where to stop. There is so much, yet the syllabus does not refer to everything which might be studied. The resources below are quite complete but there could still be a whole lot more.
Here is the syllabus content for D.4
Here is the probable SAT content:
Reading (as always, from Biology in Context for Cambridge International A Level, by Glenn and Susan Toole)
First: The need for transport systems in animals and plants:
Blood vessels: Arteries, veins and capillaries
A useful powerpoint: Arteries, Arterioles, Veins, Venules, Capillaries
The HEART (and much more!): HEART and much more PPT
The electrical heart!
A useful powerpoint: BLOOD PPT (2)
IB Past Paper questions – a sample: