B30 The Circulatory System

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
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
through specialized
transport tubes in the
body (arteries, veins,
• Requires energy
Open vs. Closed Circulatory Systems
• There are two main types of circulatory
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 System
• Heart/Lungs/Kidneys
• 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 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
Understanding HIV and AIDS
AIDS in South Africa
• http://www.youtube.com/watch?v=vyGYrwLJ

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