Circulatory systems Flashcards
What kind of organisms don’t need a circulatory systems?
Small organisms
Why do small organisms not need a circulatory system?
The diffusion distance is so small
What is the effect of the small diffusion distance?
Diffusion alone is fast enough to get oxygen and nutrients into the centre of the cell and get carbon dioxide and water products out of
What do larger animals need?
A variety of of different tissues to support them
Why do lager animals need circulatory systems?
Their bigger size means substances take longer to diffuse and to form their internal tissues
What is affected by animal size?
SA:V ratio and diffusion pathway
Why do single celled organisms not need circulatory systems?
The diffusion pathway is short and SA:V ratio is high
What do larger multicellular organisms need circulatory systems?
Diffusion pathway is long so SA:V ratio is smaller
What is the purpose of a circulatory system?
To deliver oxygen and nutrients to each cell then take away waste products of metabolism
What are the 4 types of circulatory systems?
Open, closed, single and double
Where is an open circulatory system found?
In molluscs and arthropods (insects)
What are the components of an open circulatory system?
Hemocoel and haemolymph
What is haemocoel?
The body cavity where the tissues are surrounded
How does blood move in an open circulatory system?
Blood diffuses back into the circulatory systems between cells
What is the blood in open circulatory systems?
Haemolymph
What is haemolymph?
It is. fluid that circulates in the interior of the arthropod body remaining in direct contact with animal’s tissue
How is blood transported in an open circulatory system?
It can be pumped by peristalsis and is not always in vessels
Where is blood located in an open circulatory system?
It is not always in vessels but lies in the body cavity and carries nutrients and waste
What is the function of the blood?
It directly bathes tissues and cells but moves slowly at lower pressure
How are open circulatory systems structured?
They have separate systems to transport oxygen and carbon dioxide and some have tubes attached to heart to take blood to active areas.
What is haemolymph composed?
Fluid plasma which haemocytes are suspended in
Where are closed circulatory systems present?
In vertebrates and a few invertebrates
Where is the blood in closed circulatory system?
It is enclosed at all times within vessels of different sizes and wall thickness
How is blood transported?
It is pumped by a heart through vessels and doesn’t fill body cavities
