M3- Chapter 8 - Transport in animals Flashcards
Why do animals need a transport system?
- Metabolic demands are high, so diffusion over long distances isn’t enough.
- SA: V ratio gets smaller
- Molecules such as hormones or enzymes may be made in one place but needed in another.
- Food will be digested in one organ system, but needs to be transported to every cell for use in respiration.
- Waste products of metabolism needs to be removed from the cells and transported to excretory organs.
Types of circulatory systems
Open circulatory systems
Closed circulatory systems
Single circulatory systems
Double closed circulatory systems
Features of a circulatory systems
Liquid transport medium that circulates around the system.
They have vessels that carry the transport medium
They have a pumping mechanism to move the fluid around the system
Mass transport system
When substance are transported in a mass of fluid with a mechanism for moving the fluid around the body.
Open circulatory system
Few vessels to contain the transport medium.
It is pumped straight from the heart into the body cavity of the animal. The exchange takes place between the transport medium and the cells, because the haemocoel comes into direct contact with the tissues and the cells.
Then, the transport medium returns to the heart through an open-ended vessel.
What is an open body cavity?
A haemocoel
Where can you find open circulatory systems
Mainly invertebrate animals. In insects, the gas exchange takes place in the tracheal system. Insect blood is called haemolymph. It only transports food or waste products, not oxygen.
What is haemolymph
Insect blood
Explain haemolymph
It doesn’t carry any oxygen or co2, but only food, water and waste products.
How is the heart positioned in the body cavity of an insect?
It extends along the thorax.
Explain a closed circulatory system
The blood is enclosed in blood vessels and they don’t come in contact with cells.
Blood is under high pressures and it returns directly to the heart.
Substances leave and enter the blood through diffusion.
What animals have a closed circulatory system
Sea urchins, starfish, all vertebrate groups.
Explain single circulatory system
Blood flows through the heart and is pumped out to the body and then it returns.
Blood passes through 2 sets of capillaries before returning to the heart.
By passing through the 2 narrow vessels, the pressure drops, so the speed decreases. This decreases the efficiency of exchange processes.
What are the 2 sets of capillaries in a single circulatory system?
- Exchange of oxygen and carbon dioxide
2. Substances are exchanges between blood and the cells.
What is the one exception to the single circulatory system that actually have high efficiency?
Fishes.
Because of their countercurrent flow, they actually have a higher ability to take oxygen.
Their body weight is supported by the water in which they live and they don’t have to maintain their temperature reducing their demands.
Explain a double closed circulatory system
Involves 2 separate circulations.
1. Heart -> lungs -> heart
2. body -> heart
Blood travels twice through the heart for 1 circuit.
There is a high pressure as it only passes through 1 capillary network.
What are the main components of blood vessels?
Elastic fibres
Smooth muscle
Collagen
Elastic fibres
Stretch and recoil
Provides flexibility
Smooth muscles
Changes the size of the lumen
Collagen
Provides structural support and maintains the size and volume of the lumen.