A8- Circulation and The Heart Flashcards
Function of circulatory system
It transports many essential materials around the body including…
Oxygen from the respiratory system
Nutrients from the digestive system
Hormones from the endocrine system
Chemicals and cells from the immune
system (e.g. T-cells, B-cells, macrophages)
Metabolic wastes from the cells to the
lungs and kidneys
Thermal energy
A circulatory system allows for… (2 answers)
oxygen and nutrients to be delivered to every cell in the body
also allowed for wastes in the these cells to be removed from the body
a true circulatory system has 3 key features:
A fluid that transports or circulates materials throughout the body
A network of tubes in which the fluid circulates
A pump that pushes the fluid through the tubes
3 types of circulatory systems:
none, opened, closed
No circulatory system
Not all living things have a circulatory system, just like not all living things have a digestive or respiratory system
Unicellular organisms, like some bacteria, algae and fungi, can function without a circulatory system because they directly exchange gases with the environment
Some simple multicellular organisms do not either, but instead depend on an internal body cavity lining covered in flagella to circulate fluid through the body (recall: flagella are microscopic hair like structures that help with locomotion)
Open circulatory system
In an open circulatory system, the circulating fluid is pumped into a connected system of body cavities, often called sinuses
These openings bathe the cells directly in the hemolymph, a mixture of blood and tissue fluid
The contraction of one or more hearts forces the hemolymph around the body
Most invertebrates, like snails and insects, have this type of system
hemolymph
a mixture of blood and tissue
fl uid that is the circulating fl uid in an open
circulatory system
Why are open circulatory systems ineffective?
relatively inefficient method of circulation because the hemolymph is under low pressure and circulates slowly
- however, is practical for many animals with low metabolic rates which therefore have lower oxygen and energy demands
In a closed circulatory system, the fluid, often blood, is contained within…
a network of tubes called blood vessels
The blood and tissue fluid (recall- the interstitial fluid) are always ____ in closed circulatory systems
The blood and tissue fluid (recall- the interstitial fluid) are always separate
All vertebrates and some complex invertebrates have a
closed system
Closed circulatory systems may include one of…
5 versions of an increasingly complex “heart” structure depending on their evolution
Aortic Arch:
which are enlarged blood vessels that work like hearts to pump blood through the system (found in earthworms)
Two Chambered Heart:
this structure is commonly found in fish
atrium
a chamber of the heart that
receives blood from the body
ventricle
a chamber of the heart that
pumps blood to the body
septum
a wall of tissue that divides a
body cavity or structure into smaller parts;
for example, the ventricle of a mammal’s
heart is divided into two cavities by
a septum
pulmonary circuit
the part of the
circulatory system that delivers blood to
the lungs
