Chapter 8- Circulatory Systems Flashcards
Why do multicellular organisms need transport systems?
1) multicellular organisms are relatively big, so have small surface area to volume ratios and a higher metabolic rate.
2) they are also very active. This means a large number of cells are all respiring very quickly, so they need a constant, rapid supply of glucose and oxygen.
3) to make sure every cell have a good enough supply, so multicellular organisms need a transport system. In mammals, this is circulatory system
What is a single circulatory system?
Blood only passes through the heart once for each complete circuit of the body.
What is a double circulatory system?
The blood passes through the heart twice for each complete circuit of the body
What does the circulatory system in a fish look like?
In fish, the heart pumps blood to the gills (to pick up oxygen) and then on through the rest of the body (to deliver oxygen) in a single circuit.
What does the circulatory system in mammals?
In mammals, the heart is divided down the middle so it’s really like two hearts joined together.
1) the right side of the heart pumps blood to the lungs (to pick up oxygen)
2) from the lungs it travels to the left side of the heart , which pumps it to the rest of the body.
3) when blood returns to heart, it enters the right side again.
What are the two loops on the mammal circulatory system?
1) one sends blood to the lungs (the pulmonary system)
2) one sends blood to the rest of the body (the systemic system)
What is an advantage of the mammalian double circulatory system?
The heart can give the blood an extra push between the lungs and the rest of the body. This makes the blood travel faster, so oxygen is delivered to the tissues more quickly
What is a closed circulatory system?
All vertebrates (eg fish and mammals) have closed circulatory systems, the blood is enclosed inside blood vessels.
1) the heart pumps blood into arteries. These branch out into millions of capillaries.
2) substances like oxygen and glucose diffuse from the blood into the capillaries into the body cells, buht blood stays inside blood vessels as it circulates.
3) veins take it back to the heart
What animals have a open circulatory system?
Some invertebrates eg insects have an open circulatory system . Blood isn’t enclosed in the blood vessels all the time. Instead it flows freely through the body cavity.
How does the circulatory system of an insect look?
1) the heart is segmented. It contracts in a wave, starting from the back, pumping the blood into a single main artery.
2) that artery opens up into the body cavity .
3) the blood flows around the insect’s organs, gradually making its way back into the heart segments through a series of valves.
The circulatory system supplies the insect’s cells with nutrients and transports things like hormones around the body. It doesn’t supply the insect’s cells with oxygen though - this is done by a system of tubes called the tracheal system.
