Mammalian Circulatory System Flashcards
Why do larger organism require specialised exchange surfaces?
As size increases, surface area to volume ratio decreases, meaning diffusion alone is insufficient for material exchange
What is the role of specialised exchange surfaces?
To absorb nutrients and respiratory gases ad remove excretory products efficiently
Why is a transport system necessary in larger organisms?
It moves materials between cells and exchange surfaces, as well as between different parts of the organism
What two factors determine the need for a specialised transport system with a pump?
- Surface area to volume ratio - smaller ratios require a transport system
- Activity level - more active organisms need faster material transport
How does surface are to volume ratio affect the need for a circulatory system?
The lower the ratio, the greater the need for a specialised transport system with a pump
What is a suitable transport medium in most organisms?
Usually a liquid based on water (eg. blood) because it dissolves substances easily, but in some cases, it can be a gas
Why do transport systems use mass transport instead of diffusion?
Mass transport moves substances in bulk over large distances, making it much faster than diffusion
Why do transport systems have a closed system of tubular vessels?
This is to contain the transport medium and ensure efficient distribution throughout the organism
What creates movement of the transport medium in animals?
Pressure differences which are generated by muscular concentration or body muscle movement
How do plants move their transport medium?
Plants rely on passive processes, such as evaporation of water in transpiration
How is one way flow of the transport medium maintained?
By valves, which prevent backflow and ensure unidirectional movement
What type of circulatory system do mammals have?
A closed, double circulatory system,where blood is confined to vessels and passes twice through the heart per complete circuit
Why is high - pressure circulation important for mammals?
It ensures rapid delivery of substances, which is essential due to their high metabolism and high body temperature
Why does blood pass through the heart twice in one full circuit?
Blood pressure is reduced when it passes through the lungs, so it is boosted by the heart before being circulated to the rest of the body
What are the three types of blood vessels in the mammalian circulatory system?
Arteries, veins and capillaries
How do substances reach individual cells from the circulatory system?
By diffusion from blood vessels to cells
Why is the final exchange of substances between blood and cells rapid?
This is because it occurs over a large surface area, with a short diffusion distance and a steep diffusion gradient
