1.1 - What is Cardiovascular Disease? Flashcards
What is diffusion?
The movement of molecules or ions from a region of their high concentration to a region of their lower concentration by relatively slow and random movement of molecules.
In what type of organism is passive diffusion enough to meet their needs?
Unicellular organisms
Larger multi cellular organisms are too large to rely on passive diffusion. What do they use instead?
Mass transport systems to move substances efficiently over longer distances by mass flow (circulatory system). This often comes on the form of a heart and blood in animals.
Where is an open circulatory system found and what is it?
In insects and other small animals, open circulatory systems circulate blood in large open spaces or cavities surrounding the organs.
How does diffusion occur in open circulatory systems?
Substances diffuse between the blood and cells of tissues.
How does the open circulatory system work?
When the heart muscle relaxes, blood is drawn from the cavities back into the heart through small, valved openings
What is a closed circulatory system and where is it found?
Found in many animals including all vertebrates. Blood is enclosed within tubes (blood vessels).
How does the closed circulatory system work?
Higher blood pressure as blood is forced along narrow channels instead of larger cavities. The blood travels faster and is more efficient at delivering substances.
How does diffusion take place in an open circulatory system?
Large numbers of capillaries come into close contact with the cells in the body where substances are exchanged between the blood and cells across a thin wall.
What is a single circulatory system and where is it found?
Animals with closed circulation systems either have single or double circulatory systems. Fish have a single circulatory system.
How does a single circulatory system work?
The heart pumps deoxygenated blood to the gills. Gaseous exchange takes place to oxygenate the blood. The blood leaves the gills and flows round the rest of the body before returning to the heart. (The blood passes through the heart once for each circulation).
What kinds of animals have a double circulatory system?
Birds and mammals
How does a double circulatory system work?
The right ventricle pumps deoxygenated blood to the lungs where gaseous exchange takes place. The blood returns to the heart and is pumped a second time by the left ventricle to the rest of the body.
What is the benefit of a double circulatory system?
The blood is given an additional “boost”, reducing the time it takes to circulate around the body. This gives birds and mammals a high metabolic rate as oxygen and other substances are delivered more rapidly to meet demands
What is the main fluid in blood?
Plasma - mainly water and contains dissolved substances such as glucose, oxygen and CO2.
