1. By Jenny Walton, Rebecca Logue, Andrew Tarbox, and Piers Conway
The Circultory System 
By Jenny Walton, Rebecca Logue, Andrew Tarbox, and Piers Conway

2. The Structure of the Circulatory System
The Circulatory System Consists of the Heart, Blood, Blood Vessels, Arteries,                             Capillaries, and Veins, and the lungs 

3. Structures and their Functions
Heart = An organ that helps for blood circulation which can be found in the chest between the lungs. Consists of a left ventricle, a right ventricle, a right atrium, and a left atrium 
Ventricle = A part of the heart that pumps blood throughout the body and the lungs
Right Ventricle = Pumps blood via pulmonary artery for oxygenation in lungs
Left Ventricle = Pumps oxygenated blood via aorta throughout body
 Atrium = Receives blood that has been passed throughout the body / Lungs
Right Atrium = Receives blood pumped throughout body
Left Atrium = Receives oxygenated blood through pulmonary veins
Blood = Carries oxygen / nutrients to the cells / takes waste away
Vessels = Blood distribution throughout the body
Arteries 
Capillaries 
Veins 

5. Types of Circulation
There are three main parts to the circulatory system
Pulmonary circulation 
Movement of blood from the heart to the lungs, and back to the heart
Coronary circulation 
Movement of blood through the tissues of the heart
Systemic Circulation 
Supplies nourishment to all the tissues in your body (with the exception of the heart and lungs)

6. The three types of blood vessels are
Arteries
Carry Blood away from the heart  
Capillaries
Connects arteries and veins 
Veins
Transport blood at a low pressure to the heart

7. Arteries Has three layers:
An outer layer of tissue, a muscular middle, and an inner layer of epithelial cells
Ephitheal Cells = cells that cover surface of the body / line cavities 
The muscle is used to help pump blood, and when the heart beats it expands, filling with blood
When the heart relaxes, the artery contracts, pushing the blood along
The inner layer is smooth so that blood can flow with no obsticles in its way

8. Veins Not as strong as arteries
Same structure as arteries: an outer layer of tissue, muscular middle, inner layer of epithelial cells 
Carry oxygen rich blood from the capillary back to the heart 
 Valves in the veins play role in 
keeping blood flowing toward the 
heart
Valves keep blood flowing 
against gravity

9. Capillaries One epithelial cell thick
 Where exchange of oxygen / Carbon Dioxide takes place
 Connects arteries and veins
 Arteries pass oxygen rich blood to capillaries then capillaries pass waste rich blood to veins after tissues use up nutrients

10. Gas Exchange at the Cellular Level
Capillaries provide the exchange of gas at the cellular level
Oxygen diffuses across capillary walls, and goes into the blood
It does so because the concentration of oxygen is higher in the aveoli than it is in the capillary wall
Carbon dioxide then diffuses from the blood into the aveoli
This is because the concentration of CO2 is higher in the blood than it is in the aveoli

11. Gas Exchange Transportation
Hemoglobin ( iron-containing protein in red blood cells that binds oxygen and transports it into the body) binds with oxygen that diffuses from the aveoli to the capillaries, in a passive process. 
This process stops when the concentration of oxygen is the same in both the blood and aveoli
Hemoglobin also increases the efficiency of gas exchange 
Carbon diffuses from body tissues to capillaries three ways:
Enters red blood cells and combines with water to form carbonic acid
Dissolves in plasma
Binds to hemoglobin and proteins in plasma

12. Prevention of Gas Exchange
Prevention of Gas Exchange in Non-Optimal Places:
Gas exchange is carried out by the heart and lungs
Process of air moving in and out of lungs = ventilation
 Inhaled oxygen is carried throughout bloodstream to every cell in the body
 Cells use oxygen to produce carbon dioxide 
 Blood carries the carbon dioxide to lungs, where it is exhaled into the air
 Diffusion: causes gas exchange
As carbon dioxide is moved out, oxygen is brought in to where it is needed
Rate of Diffusion depends on...
 Surface area for exchange to take place
Distance over which diffusion occurs 
Thickness of the membrane the molecules will diffuse across
Process of Diffusion prevents gas exchange from occurring at non-optimal (not the best) places

13. Bibliography http://www.biology-online.org/dictionary/Epithelial_cells
Kenneth Miller and Joesph Levine, Biology, Prentice Hall textbook, 2010