Blood Circulatory System

3.2

Blood Circulatory System

Definition

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

The circulatory system for 3 classes of vertebrates:

The structure and function of the human heart:

Structure	Function
Left atrium	Pumping oxygenated blood to the left ventricle
Right atrium	Pumping deoxygenated blood to the right ventricle
Left ventricle	Pumps blood to all parts of the body except the lungs
Right ventricle	Pumping deoxygenated blood from the heart to the lungs
Vena cava	Carries deoxygenated blood from the rest of the body to the right atrium
Pulmonary artery	Carries deoxygenated blood from the right ventricle to the lungs
Aorta	Carries oxygenated blood from the left ventricle to all parts of the body (largest artery)
Pulmonary vein	Carries oxygenated blood from the lungs to the left atrium
Septum	Isolate the left chamber and the right chamber of the heart
Tricuspid valve	Prevents the recirculation of blood from the right ventricle to the right atrium during ventricular contraction
Bicuspid valve	Prevents the re-flow of blood into the left ventricle from the left atrium during ventricular contraction
Sickle valve	Prevents the re-flow of blood to the ventricles when the ventricles relax

The functional efficiency of the human heart:

The heart wall is built of cardiac muscle that can contract and relax rhythmically
The ventricle has a thicker wall and contracts more strongly than the atrium
Has a valve that keeps the blood flowing in one direction only
Has a septum that ensures oxygenated blood and deoxygenated blood do not mix

The structure and function of human blood vessels:

Types of blood vessels	Vena
Function	Brings blood to the heart
Lumen size	Big
Wall thickness	- Thin - Less muscular - Less elastic
Valve	There is
Blood flow	Slow and under very low pressure
Type of blood transported	The blood is deoxygenated except the pulmonary veins
Types of blood vessels	Blood capillaries
Function	- Connecting arteries and veins - Allows the exchange of substances between the blood and body cells
Lumen size	Very small
Wall thickness	The wall is one cell thick
Valve	None
Blood flow	Very slow and under very low pressure
Type of blood transported	Both types of blood is oxygenated and deoxygenated
Types of blood vessels	Artery
Function	Bringing blood out of the heart
Lumen size	Small
Wall thickness	- Thick - Muscular - Elastic
Valve	None
Blood flow	Fast and under very high pressure
Type of blood transported	Oxygenated blood except for pulmonary arteries

The human circulatory system:

The human circulatory system is a closed tubular system that is pumped throughout the body
Double circulatory system
Pulmonary circulation - blood is transported from the heart to the lungs and back to the heart
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:

The pressure exerted on the walls of blood vessels due to blood circulation
Two readings, namely systolic reading (upper number) and diastolic reading (lower number)

	Systolic readings	Diastolic readings
Low blood pressure	Under 90	Under 60
Normal	90 - 120 mmHg	60 - 80 mmHg
Pre high blood pressure	120 - 139 mmHg	80 - 89 mmHg
High blood pressure	140 - 160 mmHg	90 - 100 mmHg

The systole and diastole:

When the heart beats, there are two phases namely the diastolic phase and the systolic phase
Diastolic phase - the ventricles relax and blood fills the ventricles
Systolic phase - the ventricles contract and blood fills the ventricles
Lub dub sounds result from closed tricuspid and bicuspid valves (lub) and closed sickle valves (dub)

The factors that affect the heart rate:

Gender	Females have higher pulse rates than males due to small body size and less muscle mass
Age	The normal pulse rate for adolescents at rest is 75/min and lower for the elderly
Health rates	Healthy individuals have low pulse rates at rest
Activity fitness	During vigorous activity, the pulse rate increases

The cardiac care measures:

Reduce salt and sugar in food
Control blood pressure and diabetes
Exercise regularly at least five times a week
Eat vegetables and fruits