The Human Circulatory System

1. The Human Circulatory System Transport and Circulation Part 1 11/21/03

2. Objectives • Explain the importance of transport in living things. • Compare open circulatory system to a closed circulatory system • Compare the structure and function of arteries, veins, and capillaries. • Describe the structure and function of the human heart.

3. Why is transport an important life process? • Transport is the life process by which substances move into or out of our body cells. • Transport also involves the distribution of materials within our cells. • Transport is important because our bodies and cells need certain materials such as nutrients and water in order to function properly.

4. In simple organisms such as this amoeba, no special system or structures are needed to move materials. The cells of simple organisms are in close contact with their outside environment. In single celled organisms transport is very simple

5. Large and complex organisms need a circulatory system for transport • Large and complex organisms are made up of millions even trillions of cells. The cells of the human body do not have direct access to the outside environment. • The circulatory system acts as a link between the cells of the organism and the outside environment. • This is very similar to a system of roads and highways that links towns to other towns and cities.

6. A circulatory system is made up of 3 parts • A fluid in which materials are transported • A network of tubes or body spaces that the fluid can flow through or into. • A way to drive the fluid through the tubes or spaces. ***Simply stated the three parts are: fluid, tubes, and pumps.

7. 2 Types of Circulatory Systems • Open Circulatory System: The blood is not always enclosed in blood vessels. Instead it flows directly into body spaces where it bathes the tissues. • This is the type of circulation found in mollusks and insects such as the grasshopper and snail.

8. 2 Types of Circulatory Systems 2. Closed Circulatory System In a closed circulatory system, the blood is always contained within tubes or vessels in the body. • This is the type of circulation found in many complex organisms such as mammals, birds, fish, reptiles, and earthworms

9. Open Circulatory System • In the open circulatory system of the grasshopper blood pumped by the tubular heart passes through the aorta and into the body spaces where it bathes the tissue.

10. Closed circulatory system • In the closed circulatory system of an earthworm, 5 pairs of contracting hearts pump blood through a system of vessels

11. Questions • What are the three main parts of a circulatory system? • What is the difference between a closed circulatory system and an open circulatory system? • Give an example of an organism with each type of circulatory system.

12. Questions 4. Why is it that single celled organisms do not require a circulatory system but larger and more complex organisms do? 5. What type of circulatory system would you expect to find in a bee?

13. The Circulatory System Part 2 Structure and Function of the Human Circulatory System 11/26/03

14. Pumps, Tubes, and Fluid • The three main components of a circulatory system are pumps, tubes, and fluids. • The pump is the heart, the tubes are blood vessels, and the fluid of course is blood. • The structure of the organs of the circulatory is what enables them to carry out their particular functions. • The primary goal of the circulatory system is transport.

15. The Human Heart • The Heart- This is the pump that drives the fluid through the human circulatory system. • It is composed almost entirely of muscle called cardiac muscle. • The heart is protected by a layer of tissue called the pericardium. • In the walls of the heart are two layers of muscular tissue called the myocardium. • The powerful contractions of the myocardium pump blood through the circulatory system.

17. Structures of the Heart • The hearts of all mammals are divided into four chambers – 2 atria and 2 ventricles • Atrium (Right and Left) – The upper chambers that receive the blood. • Ventricles (Right and Left) – The lower chambers that pump blood out of the heart

18. Structures of the Heart • Septum – This is a wall of tissue that separates the right side (oxygen poor blood) of the heart from the left side (oxygen rich blood) of the heart. Prevents oxygen rich blood from mixing with oxygen poor blood. • Valves – Flaps of connective tissue that prevent blood from flowing in the wrong direction.

19. Structures of the Heart - Veins • The heart contains a series of veins that bring blood to the heart. • Superior Vena Cava- Large vein that brings oxygen poor blood to from the upper part of the body to the right atrium. • Inferior Vena Cava – Large vein that brings oxygen poor blood from the lower part of the body to the right atrium. • Pulmonary Veins – Brings oxygen rich blood from each of the lungs to the left atrium

20. Structures of the Heart - Arteries • The heart also contains a series of arteries that move blood away from the heart. • Aorta – Moves oxygen rich blood from the left ventricle to the body. • Pulmonary arteries – Bring oxygen poor blood to the lungs *** FYI – Oxygen poor and oxygen rich blood are both shades of red – never blue. Oxygen poor blood is often shown as blue in diagrams to make the diagrams easier to interpret.

21. Three types of blood vessels • The tubes of the human circulatory system come in three different varieties • Arteries - Large thick walled blood vessels which move blood away from the heart and toward the body. All arteries carry oxygen rich blood can you think of the one exception? • Veins – Large blood vessels that move blood from the body toward the heart. It is the job of the veins to return blood to the heart once it has passed through the capillaries

22. Three types of blood vessels 3. Capillaries – These are the smallest of blood vessels. They are the side streets and alleys of the circulatory system. Their walls are often one cell thick and some are so narrow that blood cells must flow through them single file. • The real work of the circulatory system – bringing oxygen and nutrients to the tissues and absorbing carbon dioxide and wastes – is done by the capillaries.

23. Arteries, Veins, Capillaries Arteries move blood away from the heart. Capillaries bring nutrients & oxygen to body cells & tissues Veins bring blood from the capillaries to the heart.