| 3.2 |
Blood Circulatory System |
| Definition |
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A tubular system that has pumps and valves that consist of three components, namely the heart, blood vessels, and blood to ensure blood flow occurs in one direction only
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The circulatory system for 3 classes of vertebrates:
The structure and function of the human heart:
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Structure
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Function
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Left atrium
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Pumping oxygenated blood to the left ventricle
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Right atrium
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Pumping deoxygenated blood to the right ventricle
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Left ventricle
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Pumps blood to all parts of the body except the lungs
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Right ventricle
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Pumping deoxygenated blood from the heart to the lungs
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Vena cava
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Carries deoxygenated blood from the rest of the body to the right atrium
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Pulmonary artery
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Carries deoxygenated blood from the right ventricle to the lungs
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Aorta
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Carries oxygenated blood from the left ventricle to all parts of the body (largest artery)
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Pulmonary vein
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Carries oxygenated blood from the lungs to the left atrium
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Septum
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Isolate the left chamber and the right chamber of the heart
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Tricuspid valve
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Prevents the recirculation of blood from the right ventricle to the right atrium during ventricular contraction
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Bicuspid valve
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Prevents the re-flow of blood into the left ventricle from the left atrium during ventricular contraction
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Sickle valve
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Prevents the re-flow of blood to the ventricles when the ventricles relax
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The functional efficiency of the human heart:
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The heart wall is built of cardiac muscle that can contract and relax rhythmically
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The ventricle has a thicker wall and contracts more strongly than the atrium
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Has a valve that keeps the blood flowing in one direction only
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Has a septum that ensures oxygenated blood and deoxygenated blood do not mix
The structure and function of human blood vessels:
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Types of blood vessels
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Vena
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Function
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Brings blood to the heart
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Lumen size
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Big
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Wall thickness
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- Thin
- Less muscular
- Less elastic
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Valve
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There is
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Blood flow
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Slow and under very low pressure
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Type of blood transported
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The blood is deoxygenated except the pulmonary veins
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Types of blood vessels
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Blood capillaries
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Function
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- Connecting arteries and veins
- Allows the exchange of substances between the blood and body cells
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Lumen size
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Very small
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Wall thickness
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The wall is one cell thick
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Valve
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None
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Blood flow
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Very slow and under very low pressure
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Type of blood transported
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Both types of blood is oxygenated and deoxygenated
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Types of blood vessels
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Artery
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Function
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Bringing blood out of the heart
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Lumen size
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Small
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Wall thickness
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- Thick
- Muscular
- Elastic
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Valve
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None
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Blood flow
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Fast and under very high pressure
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Type of blood transported
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Oxygenated blood except for pulmonary arteries
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The human circulatory system:
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The human circulatory system is a closed tubular system that is pumped throughout the body
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Double circulatory system
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Pulmonary circulation - blood is transported from the heart to the lungs and back to the heart
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Systemic circulation - blood is transported from the heart to other parts of the body (except the lungs) and back to the heart
The blood pressure:
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The pressure exerted on the walls of blood vessels due to blood circulation
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Two readings, namely systolic reading (upper number) and diastolic reading (lower number)
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Systolic readings
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Diastolic readings
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Low blood pressure
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Under 90
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Under 60
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Normal
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90 - 120 mmHg
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60 - 80 mmHg
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Pre high blood pressure
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120 - 139 mmHg
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80 - 89 mmHg
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High blood pressure
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140 - 160 mmHg
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90 - 100 mmHg
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The systole and diastole:
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When the heart beats, there are two phases namely the diastolic phase and the systolic phase
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Diastolic phase - the ventricles relax and blood fills the ventricles
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Systolic phase - the ventricles contract and blood fills the ventricles
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Lub dub sounds result from closed tricuspid and bicuspid valves (lub) and closed sickle valves (dub)
The factors that affect the heart rate:
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Gender
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Females have higher pulse rates than males due to small body size and less muscle mass
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Age
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The normal pulse rate for adolescents at rest is 75/min and lower for the elderly
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Health rates
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Healthy individuals have low pulse rates at rest
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Activity fitness
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During vigorous activity, the pulse rate increases
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The cardiac care measures:
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Reduce salt and sugar in food
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Control blood pressure and diabetes
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Exercise regularly at least five times a week
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Eat vegetables and fruits
