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The Circulatory System
The Systems of the Human Body
What are the Human Body Systems We Have Studied So Far?
Skeletal Muscular Digestive Respiratory Now… Circulatory Nervous Immune
The Circulatory System
Is Blood Blue? Blood is a bright red in its oxygenated form (i.e.,
leaving the lungs), when hemoglobin is bound to oxygen to form oxyhemoglobin. It's a dark red in its deoxygenated form (i.e., returning to the lungs), when hemoglobin is bound to carbon dioxide to form carboxyhemoglobin.
Veins appear blue because light, penetrating the skin, is absorbed and reflected back to the eye.
Functions of the Circulatory System (Blood)
1. Carries oxygen (O₂) from the lungs to all of your body cells (RBC’s)
2. Helps the body get rid of waste products (CO ₂)
3. Transports nutrients to cells4. Fights infections & heals wounds (WBC’s
The Composition of Blood The Plasma (Fluid)
makes up 55% of the blood volume.
The Solids (Cells) make up 45% of the blood volume.
Composition of Blood
97% Water Other 3% -Antibodies and
Proteins - Nutrients and
Red Blood Cells -Carry oxygen -Contain Hemoglobin White Blood Cells -Attack bacteria &
other invaders Platelets -Control the blood
Plasma Blood Solids
3 Types of Blood Vessels1. Arteries (Away)
- The Aorta is the largest artery2. Veins
- The Vena Cava is the largest vein3. Capillaries
- Very Small - Site of O₂ & CO₂ exchange - Connect Veins & Arteries
Our circulatory system is a double circulatory system. This means it has two parts parts.
the right side of the system
deals with deoxygenated
the left side of the system deals with
Pathway of Blood
Structures of The Heart
Left AtriumRight Atrium
Vein from Lungs
Artery to Head and BodyArtery to Lungs
Vein from Head and Body
Types of Circulation
Coronary Within the heart
Pulmonary Flow of blood from the heart to the lungs
Systemic Blood moving to other parts of the body
Pathway of blood
Blood Circulation Animation https://
Where is pressure the greatest? Veins or Arteries? Why?
Blood Pressure Blood pressure is the force of the
blood pushing against the walls of the arteries.
Blood Pressure There are two kinds of numbers
that make up a blood pressure reading. These numbers are written like a fraction -- the top number refers to systolic blood pressure (while the heart is beating), and the bottom number measures the diastolic blood pressure (while the heart is at rest).
Normal numbers for blood pressure range from 90/60 to 120/80.
Cardiovascular Disease Leading cause of death
Atherosclerosis: fatty deposits on artery walls
Hypertension: High blood pressure
Credits Graphics courtesy of Crystalcafe.com &
The Franklin Institute online.