Cell Nutrition and Circulatory System: Importance and Functions

Unit 5: Cell Nutrition

All living beings need food used as follows:

• For growth: it provides the substances needed for making new cells and tissues.
• As a source of energy: required for the chemical reactions which take place in living organisms to keep them alive.
• For replacement: of worn and damaged tissues, for example, red blood cells that break down each day and to replace the skin which is worn away and to repair wounds.

Nutrition can be defined as obtaining organic substances and mineral ions from which organisms obtain their energy and their raw materials for growth and tissue repair. Several systems are involved in cell nutrition: this process is carried out by organ systems which working together allow cells to obtain matter and energy.

• Digestive system: provides essential nutrients and expels faeces.
• Respiratory system: provides with oxygen and releases CO2.
• Excretory system: filters the blood and expels toxic substances in the urine.
• Circulatory system: transports all substances throughout the body.

Topic 8: Circulatory SystemThe Heart: is actually two pumps; the right side pumps deoxygenated blood to the lungs to collect oxygen and remove CO2. Then the left side pumps this oxygenated blood around the body. Blood Vessels: the three types of blood vessels are quite different in terms of their structure because they are adapted to do different jobs: arteries carry blood away from the heart at high pressure. The arteries eventually split off into thousands of tiny capillaries which take blood to every cell in the body. The veins then collect blood and carry it back to the heart at low pressure to be pumped round again. Blood: consists of a straw-colored liquid called plasma in which are suspended white blood cells, red blood cells, and platelets.