A circulatory system typically consists of blood, a heart, and a system of blood vessels or
spaces through which blood circulates
a molecule can diffuse 1um in less than 1 msec – so diffusion is adequate over
microscopic distances; occurs in small, simple invertebrates (sponges, cnidarians,
Specialized circulatory systems are required
where transport is necessary over
many cell thickness in larger animals
Requires blood, heart, blood vessels or spaces
No Circulatory System (Fig 43-1)
In all animals what is the role of the interstitial fluid? is a circulatory system
necessary for the efficient distribution of materials in all animals?
If not how do these animals carry their oxygen, nutrients and excretory products
without blood, a heart or blood vessels?
Open Circulatory System (Fig 43-2)
Found in arthropods, most mollusks
Blood and interstitial fluid is indistinguishable; it spills out of blood vessels into
the sinuses - what is this fluid called ? Where does it flow to? What is the body
This fluid bathes the tissues directly, reentering the circulatory system through
openings in heart (arthropods) – what are these openings called? Is there
something similar in the molluscks?
Closed Circulatory Systems (Fig 43-3)
Found in some invertebrates: annelids, cephalopods and echinoderms and all
Proboscis worms have no heart, but have large blood vessels in a continuous
circuit, so how does their blood circulate?
What about earthworms? Do they have hemoglobin? Is it contained in red blood
cells like vertebrates?
What is different about the fast-moving cephalopods?
Vertebrate Circulatory System (Fig 43-4, table 43-1):
muscular heart that
pumps blood into arteries, capillaries, veins, transports
nutrients, oxygen, metabolic
fluid balance, pH, body temperature
and defends the
body against disease
what is plasma, what is it role in the circulation and
describe the proteins that it
contains as well as their roles in blood homeostasis.