CH8 transport systems in multicellular animals Flashcards
1
Q
Why are processes such as diffusion alone unable to supply everything multicellular organisms require
A
- high metabolic demands
- low surface area to volume ratio
- molecules such as enzymes are made in one place but needed in another
- food will be digested in an organ system but needs to be transported to every cell for use in respiration
- waste products need to be removed from cells and transported to excretory organs
2
Q
What are the features that most circulatory systems in multicellular organisms have
A
- liquid transport medium
- vessels that carry transport medium
- pumping mechanisms to move fluid around body
3
Q
What is an open circulatory system
A
- few blood vessels to contain transport medium
- pumped straight from heart to open body cavity called thee haemcoel
- blood comes into direct contact with tissues and cells
4
Q
Insect circulatory system
A
- open system
- blood is called haemolymph and carries food, nitrogenous waste and cells involved in defence
- body cavity split by a membrane and heart extends along length of thorax and abdomen of insect
5
Q
Problems with an insect circulatory system
A
- haemolymph circulates but steep diffusion gradients cannot be maintained for efficient diffusion
- amount of haemolymph flowing to a particular tissue cannot be varied to meet demands
6
Q
What is a closed circulatory system
A
- blood is enclosed in blood vessels
- doesn’t come into contact with cells of body
- amount of blood flowing to a particular tissue cannot be adjusted by narrowing and widening of blood vessels
7
Q
What is a single circulatory system
A
- blood flows through heart and is pumped out to travel all around body before returning to heart
- blood passes through lungs and then travels to body cells
- blood pressure drops so blood travels slow, decreasing efficiency
8
Q
What is a double circulatory system
A
- contains two separate circuits
- high pressure and speed can be maintained
