Circulatory systems (double + single) Flashcards
(11 cards)
Why do larger organisms need a mass transport system while single celled organisms do not
-Cells in living organisms require reactants e.g glucose and oxygen, for metabolic reactions
-Single celled organisms can gain oxygen and glucose directly from their surroundings as these molecules can diffuse to all parts of the cell due to short diffusion distances
-However, larger organisms have many layers of cells which means the time taken for the metabolic reactants to diffuse to all cells would take too long
-To solve this problem, larger organisms have mass transport systems connected to exchange surfaces
Why would it take too long for reactants such as glucose and oxygen to reach all the cells in a larger organism
-Due to the greater diffusion distances involved
-Larger organisms often have larger energy requirements and so the delivery of metabolic reactants needs to happen quickly
examples of exchange surfaces connected to mass transport systems
The digestive system is connected to the circulatory system
-Lungs are connected to the circulatory system
What is mass transport+ an example of a mass transport system
-Mass transport is the bulk movement of gases and liquids in one direction, usually via a series of tubes/vessels
-The human circulatory system is an example of a mass transport system as it transports blood carrying essential gases and nutrients to all the cells in the body
What is an exchange surface + examples
-Exchange surfaces are specialised structures in the body that allow for the exchange of substances between the body and the environment
-For example alveoili in the lungs, the gut, or skin
What are the uses of mass transport system
-Brings substances quickly from one exchange surface to another
-Enables efficient cell functioning by supplying reactants and removing waste products
-Maintains concentration gradients between exchange surfaces as well as the concentration gradient between a cell and its fluid surroundings
Surface area to volume ratio comparison between smaller organisms and larger organisms
-smaller organisms have a much higher surface to volume ration, this means that substances such as glucose and oxygen can be exchanged between the environment and the organism via diffusion
-However, larger organisms with smaller surface area to volume rations must rely on mass transport systems for exchange of substances
Level of activity comparison between smaller and larger organisms
-Larger organisms are often very active, they have a high demand for oxygen for aerobic respiration
-This means that larger organisms cannot solely rely on diffusion for the exchange of substances
Single circulatory system vs double circulatory system
SINGLE CIRCULATORY SYSTEM
The single circulatory system is where blood passes through the heart once per complete circuit
-Blood pressure is low after passing through the gills
-Oxygen delivery is slower and less efficient
-There is no complete separation of oxygenated and deoxygenated blood
DOUBLE CIRCULATORY SYSTEM
The double circulatory system is where blood passes through the heart twice per complete circuit
-Blood pressure is high in the systemic circuit (the body)
-Oxygen delivery is faster and more efficient
-There is complete separation of oxygenated and deoxygenated blood
Types of circulation in double circulatory system
-Pulmonary circulation: Deoxygenated blood is pumped to the lungs
-Systemic circulation: Oxygenated blood is pumped to the body
Advantages of a double circulatory system
-Maintains high blood pressure in systemic circulation meaning oxygenated blood travels to body tissues faster, ensuring sufficient oxygen delivery for high metabolic demands
-Maintains low blood pressure in pulmonary circulation, which prevents damage to delicate alveoli and provides sufficient time for gas exchange
-Complete separation of oxygenated and deoxygenated blood maintains a high concentration gradient for diffusion in body tissues as well as improving the efficiency of aerobic respiration
