Download Unit 2 Notes - Ballymoney High School

12DA Biology
Circulatory System
UNIT 2
Unit 2 REVISION: Circulatory System.
The function of the circulatory system is to transport materials and to protect the body
against disease.
What does the circulatory system transport?
Red Blood Cells; White Blood Cells; Digested food molecules (glucose); Carbon dioxide;
Hormones (insulin); Urea (waste substance removed in the kidney).
You must be able label the chambers of the heart and the blood vessels.
Pulmonary Artery
Aorta
Vena Cava
RIGHT Atrium
RIGHT Ventricle
Pulmonary Vein
LEFT Atrium
LEFT Ventricle
Oxygenated blood is blood that contains large volumes of oxygen.
Deoxygenated blood is blood that contains little oxygen and lots of carbon dioxide.
Coronary Blood Vessels are the vessels which supply the heart muscle with blood
(containing oxygen and glucose)
The circulation of blood around the body is referred to as DOUBLE CIRCULATION.
Double Circulation is when the blood goes twice through the heart for every once around
the body.
BLOOD VESSELS
There are 3 types of blood vessel in your body.
1. Arteries (away from heart)
2. Veins (into heart)
3. Capillaries
12DA Biology
Circulatory System
UNIT 2
Arteries can take HIGH BLOOD PRESSURE, are thick and elastic. They usually carry
OXYGENATED BLOOD, the only artery which carries Deoxygenated blood is the
Pulmonary artery because it travels to the lungs to get O2.
Veins can only take LOW BLOOD PRESSURE, they are thin. They usually carry
DEOXYGENATED BLOOD, the only vein which carries Oxygenated blood is the
Pulmonary vein because it has just come from the lungs. They also have VALVES which
prevent blood from flowing backwards!
Capillaries can only take LOW BLOOD PRESSURE because they are thin. They allow
the diffusion of substances into and out of cells, therefore they have permeable walls.
Key Blood vessels in the body (LEARN!)
Heart Attacks and Strokes
Cause:
12DA Biology
Circulatory System
UNIT 2
Cholesterol builds up inside the arteries.
This makes it difficult for blood to flow through.
LESS Oxygen and LESS Glucose reach the cells beyond this point.
LESS Respiration occurs in the cells (lack of energy).
When this occurs in the CORONARY ARTERIES, it causes a heart attack. Heart muscle
cells die!
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blood vessels in coronary arterty get blocked
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lack of oxygen and glucose reaches brain cells
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no respiration occurs
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cells die
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loss of function in these heart cells – heart stops beating.
When this occurs in the Brain, it causes a stroke. Brain cells die leading to reduced brain
function, partial paralysis of the body.
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blood vessels in brain get blocked
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lack of oxygen and glucose reaches brain cells
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no respiration occurs
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cells die
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loss of function in these brain cells.
Increased Risk of Stroke or Heart Attack?
Lifestyle factors
Too much alcohol, Smoking cigarettes, Stress, Lack of exercise,
Obesity, Poor diet, High Blood Pressure
Genetics can also increase your risk of Heart Attacks or Strokes.