8.1 Transport Systems In Multicelluar Animals Flashcards
Why are specialised transport systems needed in multicellular organisms?
- SA:V ratio gets smaller as multicellular organisms get bigger
- high metabolic demand
- hormones and enzymes need to quickly travel
- food digestion will occur in one place but the nutrients need to be in another
- waste products need to be removed
What do most circulatory systems (transport) have in common?
- have a liquid transport medium that circulates (blood)
- have vessels to carry the transport medium
- have a pumping system to move the liquid around the body
What 2 types of circulatory systems are there?
open and closed
What’s a mass transport system
when substances are transported in a mass of fluid with a mechanism to move it around the body
What is an open circulatory system
When there are very few vessels to contain the liquid medium; it’s pumped straight into the body cavity of the animal; open body is called HAEMOCOEL (liquid is low pressure).
It comes in direct contact to the cells and tissues, where diffusion happens.
Found mainly in invertebrate animals; insect blood is called HAEMOLYMPH
What are closed circulatory systems?
Blood is enclosed in vessels and doesn’t come into direct contact with cells/tissues; blood returns to heart and is pumped around relatively quickly.
Amount of blood is limited or increased by narrowing/widening of vessels; contain a blood pigment to carry respiratory gases;
can be single or double closed systems
What are single-closed systems?
Found in fish, blood flows from heart around the body directly and back to heart; blood travels through heart ONCE.
Blood travels through 2 sets of capillaries before returning back to heart:
1. in first one it exchanges oxygen and carbon dioxide
2. in second it exchanges substances between blood and cells
Going through these 2 lowers blood pressure so limits speed of GE, therefore, activity and energy levels can be low in animals with a single closed system.
Why are fish an exception and have high energy levels despite having a single closed transport system?
Because they don’t have to maintain as many factors such as temperature and body weight, because they’re in the water.
What are double closed transport systems?
In animals that regulate their own temperature, they have 2 separate circulations:
1. blood is pumped from the heart to the lungs, then back to the heart (without CO2 and + O2)
2. blood flows through the heart and pumped to the rest of the body before returning to the heart again
Only one capillary network so it’s usually always high pressure and a fast flow of blood.
