Unit 8 - Transport in Animals Flashcards
What are the components of a transport system?
Transport medium - fluid which circulates around the system
Pumping mechanism - moves the fluid around the system
Structures which carry the fluid
Where is an open circulatory system usually found?
In invertebrates, e.g. insects.
Define open circulatory system.
Where the fluid is not enclosed in vessels.
What is the transport medium in an open circulatory system?
Haemolymph.
How is haemolymph circulated in an open circulatory system?
The heart pumps haemolymph into the haemocoel, where exchange takes place. Once this has happened, the haemolymph returns to the heart through ostia.
Define closed circulatory system.
Where the blood (transport medium) is fully enclosed in blood vessels and does not come into direct contact with cells or tissues.
How is blood circulated in a closed circulatory system?
The heart pumps blood into a series of progressively smaller vessels called arteries. Exchange takes place in the smallest blood vessels, capillaries. Blood then returns to the heart through a series of progressively larger vessels called veins.
What are the two types of closed circulatory systems?
Single and double.
Where are single circulatory systems typically found?
In fish and some amphibians.
Define single circulatory system.
In one complete circuit of the body, blood passes through the heart once.
What is the relative blood pressure in a single circulatory system?
Blood has a relatively low pressure as it returns to the heart slowly, passing through two sets of capillaries - capillaries have walls which are one cell thick and therefore low pressure.
Give an advantage of a single circulatory system.
A single circulatory system is less complex than a double circulatory system and therefore doesn’t require complex organs.
Give a disadvantage of a single circulatory system.
The animal typically has a low activity level due to the slow movement of blood and low blood pressure.
How many chambers does the heart have in a single circulatory system?
Two.
Where is a double circulatory system typically found?
In reptiles, most amphibians, birds and mammals.
Define double circulatory system.
In one complete circuit of the body, blood passes through the heart twice - the pulmonary system sends blood to the lungs while the systemic system sends blood to the rest of the body.
What is the relative pressure of the blood in a double circulatory system?
Blood has a relatively high pressure as it only passes through one set of capillaries.
Give two advantages of a double circulatory system.
The heart can pump blood further around the body.
Blood moves faster and at a higher pressure.
How many chambers does the heart have in a double circulatory system?
Four - the right side sends blood to the lungs while the left side sends blood to the rest of the body.
