Circulatory System: Gas Exchange and Respiration Flashcards
(38 cards)
What do organisms exchange with the surrounding environment?
Molecules!
Intake of oxygen, proteins, sugars;
Removal of molecules toxic to life
How does exchange occur in organisms?
Diffusion, across a membrane (cell) or exchange surface (tissue)
How do single-celled organisms make exchange?
DIRECTLY, with the surrounding environment (fluid),
A gastrovascular cavity is sufficient for gas exchange, distribution of substances = Enough surface area available!
When does diffusion work well?
It is only efficient over small distances –> Easy, rapid movement in smaller organisms!
Time of diffusion is proportional to (distance)^2
What do simple animals lack?
A circulatory system.
Where does an exchange take place in simple organisms?
In the CAVITY (aka gastrovascular)
What is a complex animal’s circulatory system comprised of?
- A set of interconnecting VESSELS
- A muscular pump –> the HEART
- A circulatory fluid, BLOOD
What is a circulatory system’s function?
To link exchange surfaces with cells throughout the body.
Within a circulatory system, ___________ facilitate gas exchange.
Specialized organs.
For example, lungs, gills, tracheal system
What are lungs?
Infoldings of the body, that create a large surface area for gas exchange = Max contact with the environment
-Our lungs are the site of exchange of oxygen (in), carbon dioxide (out)
What are gills?
Outfoldings of the body, that create a large surface area for gas exchange
What is the tracheal system?
In insects, a network of branching tubes delivers oxygen to cells and tissues = Exchange of gas to the liver.
Air diffuses passively in/out, and the openings can be opened/closed as necessary = Holes that mediate!
*Depends on moisture levels!
What is an open circulatory system?
In which there is no distinction between blood and the interstitial fluid.
It then relies on the process of diffusion to move cells in/out.
What is hemolymph?
A circulatory fluid in insects, other arthropods, and most molluscs, that bathes organs (heart) directly in an open circulatory system.
A mixture of blood and other extracellular fluids
What is a closed circulatory system?
In which blood is confined to vessels, distinct from the interstitial fluid.
It is more efficient in transporting circulatory fluids to tissues and cells. The heart contraction moves blood in a specific direction.
Movement only WITHIN the circuit (blood).
Who possesses a cardiovascular system?
Humans and other vertebrates!
In cardiovascular systems, blood flow is _________ in the vessels, accomplished by a series of _______.
One way; valves
What is the role of skeletal and smooth muscles in the circulatory system?
Their squeezing moves the fluid through the vessels.
Where are valves located?
Throughout the blood vessels, and within organs.
What is single circulation?
In which blood leaving the heart passes through two capillary beds before returning.
The heart has a single pump that forces fluid directionally, passing through two different areas: Gill capillaries, body capillaries.
There is no separation in having dedicated blood vessels for carrying oxygenated and deoxygenated blood.
Arteries carry blood away from the heart, veins carry blood into the heart.
Which species have single circulation?
Bony fishes, rays, sharks, which have a single circulation with a two-chambered (atrium (receives blood) and the ventricle (holds blood and pumps it away)) heart.
What is double circulation?
In which oxygen-poor and oxygen-rich blood are pumped separately
= Two circuits
How is oxygen-rich blood delivered from the heart to the rest of the body, in double circulation?
Systemic circuit: Connecting the rest of the body tissues to the heart
How is oxygen-poor blood delivered from the heart to the rest of the body, in double circulation?
Pulmonary (lungs) circuit
