The Circulatory System

Function of the Circulatory System

• Deliver oxygenated blood to cells– Oxygen and other chemicals diffuse out of the blood cells

and into the fluid surrounding the cells of the body tissues• Dispose of wastes– Waste products diffuse into the blood cells and are carries

away• Organs involved: heart, lungs, kidney, and liver– Kidney and Liver Remove wastes– Lungs Oxygen diffuses into cells; Carbon dioxide diffuses

out

Active vs. Passive Transport Systems

• Single-celled organisms don’t have circulatory systems at all. Their cells are close enough to the environment for oxygen, other gases, nutrients, and waste products to simply diffuse into and out of their cells. This is called passive transport.

• Organisms like humans have multiple layers of cells and many cells are too far away from the external environment for simple osmosis/diffusion to work quickly enough. As a result, these organisms need active transport systems.

Cnidaria – Passive Transport• 2 layers of cells• Materials can simply diffuse into

and out of cells

Humans – Active Transport

• The heart pumps the blood (carrying nutrients/wastes) through specialized transport tubes in the body (arteries, veins, capillaries)

• Requires energy

Open vs. Closed Circulatory Systems

• There are two main types of circulatory systems:1) Open circulatory systems• Blood is not always enclosed in blood vessels• Can flow into body spaces where it bathes tissues• Blood vessels are open-ended• E.g. Grasshopper

2) Closed circulatory systems• Blood is enclosed within tubes or vessels in the body• E.g. Earthworms/Humans

Open vs. Closed Circulatory Systems

Parts of the Circulatory SystemOrgans:• Heart/Lungs/Kidneys

Vessels:• Arteries

– Carry blood away from the heart and to body tissues

• Veins– Returns blood from

• Capillaries– Tiny vessels that allow the exchange

of dissolved nutrients, wastes, oxygen, and other substances between the blood and body cells

The Human Heart

Heart Facts• The heart acts as a pump• Muscular organ• Approx. the size of your fist

• The human heart consists of four chambers:– 2 upper thin-walled chambers called atria– 2 lower thick-walled chambers called ventricles– The right and left sides a separated by a wall called a septum.

The septum prevents oxygen-rich blood of the left side from mixing with the oxygen-poor blood of the right side.

Evolution of the Heart

• 2-Chambered Hearts– E.g. Fish– One atrium and one ventricle– Blood flow is very slow…enhanced by swimming

• 3-Chambered Hearts– E.g. Amphibians– 2 atria and 1 ventricle– Allows for partial separation of oxygen-rich and

deoxygenated blood; however the two still mix

HIV and Immunity

• Read page 210 – 212 (Tiger Textbook)• Record jot notes on:– What is AIDS – How is AIDS spread– How can AIDS be prevented

Blood• Blood is made up of:

– Plasma • Mainly water• Carries nutrients, enzymes, hormones, and cellular waste products

– White Blood Cells• Responsible for fighting disease by destroying organisms or

producing antibodies– Red Blood Cells

• Lack nucleus therefore they can’t reproduce• Contain hemoglobin (a pigment that carries oxygen)

– Platelets• Responsible for clotting blood

AIDs

Understanding HIV and AIDShttp://www.youtube.com/watch?v=P91nIGt1axs&feature=channelhttp://www.youtube.com/watch?v=68I7JlVhuhYAIDS in South Africa• http://www.youtube.com/watch?v=vyGYrwLJ

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