Chapter 12 Lesson 2

Chapter 12 Lesson 2

By Madison Ballard

Lesson 2

Circulation and Gas Exchange

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• All cells need nutrients and oxygen to survive.

• Recall that animals obtain nutrients and oxygen from their environment.

• Organisms must take in these substances and get them to each cell.

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The Importance of Gas Exchange and Circulation

The Importance of Gas Exchange and Circulation

• Animals obtain the nutrients and oxygen their cells need to survive from their environment.

• Structures in animal bodies transport oxygen and nutrients to cells and help remove wastes such as carbon dioxide from the body.

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The Importance of Gas Exchange and Circulation

The type of system an animal uses to exchange gases and move substances throughout the body depends on the animal’s habitat.

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Gas Exchange

• All animals must take in oxygen and eliminate carbon dioxide to survive.

• Oxygen must enter an animal’s body so its cells and tissues are able to use it for life processes.

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Gas Exchange

• The basic process of gas exchange is called diffusion and requires no structures at all.

• Diffusion is the movement of substances from an area of higher concentration to an area of lower concentration.

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​Going from a high concentration to a lower concentration

Gas Exchange

In animals whose bodies are only a few cell layers thick, oxygen passes directly from the environment into cells by diffusion.

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Gas Exchange

• Some organisms exchange gas through the sides of their bodies.

• Spiracles are tiny holes on the surface of an organism where oxygen enters the body and carbon dioxide leaves the body.

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​Spiracles are tiny holes where an organism takes in oxygen and lets got of carbon dioxide.

Gas Exchange

• Beetles use structures called tracheal tubes to transport oxygen throughout the body.

• Spiders take in oxygen using stacks of folded wall-like structures called book lungs.

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Gas Exchange

• Most animals that live in the water have gills for gas exchange.

• Gills are organs that enable oxygen to diffuse into an animal’s body and carbon dioxide to diffuse out.

• Gills are surrounded by capillaries, which help transport oxygen and carbon dioxide to and from cells.

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Gas Exchange

• Many animals that live on land have lungs for gas exchange.

• Lungs are bag-like organs that can be filled with air.

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Circulation​

• You have learned how gases are exchanged between animals and the environment.

• After an animals takes in oxygen, the oxygen has to travel to all parts of the body.

• Much like the pipes in a house help transport water to the kitchen and bathrooms, an animal’s circulatory system helps materials move through the body.

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Circulation

• The oxygen an animal takes in has to travel to all parts of the body.

• An animal’s circulatory system helps materials move through the body.

• How quickly blood moves through an animal often depends on what type of circulatory system it has.

  On the image to the right: red is ​oxygen rich and blue is oxygen poor

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Circulation

• A system that transports blood and other fluids into open spaces that surround organs in the body is called a(n) open circulatory system, 

• Snails, insects, and many other invertebrates have open circulatory systems.

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Circulation

• A system that transports materials through blood using vessels is called a(n) closed circulatory system.

• Animals that have closed circulatory systems move blood and other substances through the body faster than animals that have an open circulatory system.

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​Open circulatory system: blood flows freely to both directions from the heart

Closed circulatory system: blood flows only one direction from the heart​

Multiple Choice

A worm has what type of circulatory sytem?

• open

• closed

Circulation

• Open and closed circulatory systems use muscles to help blood move.

• Small blood vessels called capillaries surround organs and help oxygen and nutrients move from the circulatory system to cells in the organ.

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Circulation

• Different animals have hearts with different numbers of compartments called chambers.

• Fish have hearts with two chambers, whereas amphibian hearts have three chambers.

• Birds and mammals have hearts with four chambers.

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​Amphibians: 3 chambered heart

Turtles: 3 chambered separate heart

Birds and Mammals: 4 chambered heart​

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Multiple Choice

What process helps oxygen move from the outside to the inside of the cell?

• absorption

• circulation

• undulation

• diffusion