Recognise that humans are multicellular organisms that demonstrate significant levels of organisation.
Discuss the role of each system within the human body.
Humans are the most complex multicellular organism. Over time, our cells, tissues and organs have evolved to carry out specialised and separate roles. For example, red blood cells adapted to transport oxygen around the body and white blood cells adapted to protect us from disease.
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The adaptation of a cell, tissue, organ or system to carry out a special job is called specialisation.
The separate jobs carried out by the different parts of an organism is called division of labour.
Together, specialisation and division of labour make an organism very efficient.
Human Systems A system is a group of organs that work together. There are nine different human systems: 1. Digestive system 2. Circulatory system 3. Respiratory system 4. Reproductive system 5. Musculoskeletal system 6. Nervous system 7. Endocrine system 8. Excretory system 9. Immune system
Each system carries out a special job in the body. For example, the immune system protects us against disease and the musculoskeletal system helps us move around.
All of these systems work together and form an organism.
Digestive z Fig. 8.1.1 Human systems Endocrine Circulatory 129 129 Respiratory F
An average adult human is made up of approximately 100 trillion cells!
