Systemics - Circulatory System (The circulatory system is also known as the cardiovascular system.)

The circulatory system is powered by the constant beating of the heart, it cycles blood throughout the body to carry substances to the places they're needed, or to where they can be removed.

Main functions:

• Move blood

• Delivers nutrients
  from food, such as glucose and vitamins, to cells

• Delivers oxygen
  to cells

• Collects wastes
  such as carbon dioxide and urea for removal from the body

Blood:

A bit over half of it is plasma (water with nutrients and waste dissolved). In the plasma, there are white blood cells, platelets and red blood cells

• White blood cells - fight infections

• Platelets - help clot blood

• Red blood cells - transport oxygen and move carbon dioxide, contains haemoglobin molecules

What blood flows in:

• Arteries carry blood away from the heart (to the body)

• Veins carry blood to the heart (from the body)

• Capillaries transfer materials between blood and close cells, the waste diffuses out while nutrients diffuse into the capillary walls

The heart:

Oxygenated blood - blood rich in oxygen, shown in red in the diagram (usually on the left of the heart)

De-oxygenated blood - blood depleted in oxygen, shown in blue in the diagram (usually on the right of the heart)

Parts of the heart:

• White blood cells - fight infections

• Platelets - help clot blood

• Red blood cells - transport oxygen and move carbon dioxide, contains haemoglobin molecules

What blood flows in:

• Arteries carry blood away from the heart (to the body)

• Veins carry blood to the heart (from the body)

• Capillaries transfer materials between blood and close cells, the waste diffuses out while nutrients diffuse into the capillary walls

The heart:

• Oxygenated blood: blood rich in oxygen, shown in red in diagrams (usually on the left side of the heart)

• Deoxygenated blood: blood depleted in oxygen, shown in blue in diagrams (usually on the right side of the heart)

Parts of the heart:

• Right atrium: receives deoxygenated blood returning from the body via the superior and inferior vena cava

• Right ventricle: pumps deoxygenated blood to the lungs through the pulmonary artery

• Left atrium: receives oxygenated blood returning from the lungs via the pulmonary veins

• Left ventricle: pumps oxygenated blood out to the rest of the body through the aorta (has the thickest muscular wall)

• Septum: muscular wall dividing the left and right sides of the heart to prevent oxygenated and deoxygenated blood from mixing

• Valves: ensure blood flows in only one direction and prevent backflow

  • Tricuspid valve: located between the right atrium and right ventricle

  • Pulmonary valve: located between the right ventricle and pulmonary artery

  • Bicuspid (mitral) valve: located between the left atrium and left ventricle

  • Aortic valve: located between the left ventricle and aorta

• Major blood vessels connected to the heart:

  • Vena cava (superior and inferior): large veins bringing deoxygenated blood into the right atrium

  • Pulmonary artery: carries deoxygenated blood from the right ventricle to the lungs

  • Pulmonary veins: carry oxygen-rich blood from the lungs into the left atrium

  • Aorta: largest artery, carries oxygen-rich blood from the left ventricle out to the body

• Coronary arteries: blood vessels branching from the aorta to supply the heart muscle tissue itself with oxygen and nutrients

Close connections to other systems:

• The respiratory system, to pick up oxygen and remove carbon dioxide

• The digestive system, to pick up nutrients from food

• The urinary system, to remove solid and liquid cell wastes

Close connections to other systems:

the respiratory system, to pick up oxygen and remove carbon dioxide

the digestive system, to pick up nutrients from food

the urinary system, to remove solid and liquid cell wastes