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B2 A) Cell Organisation
B2 A) Cell Organisation
Large multicellular organisms (such as humans, animals and plants) are made from organ systems. Organ systems can be split down into different parts. The relationship between the different parts is shown below.
Here are the definitions of the different parts.
Cells
Multicellular organisms are made up of cells, which are the basic building blocks of all living organisms. Humans are made from trillions of cells. Cells differentiate and specialise to carry out their particular roles. For example, red blood cells are specialised to take oxygen around the body. Muscle cells are specialised to contract, which allows parts of the body to move.
Tissue
Similar cells group together to form tissue. Tissue is a group of cells with a similar structure and function. An example of tissue is blood, which is made from different blood cells (red blood cells, white blood cells & platelets) and plasma. Another example of tissues is epithelial tissue, which covers all internal and external surfaces of your body. A final example of tissue is muscle tissue.
Organs
Different tissues are organised together to form organs. Organs are groups of different tissues performing specific functions. Some examples of organs in the body are the heart, lungs, stomach, pancreas, liver, brain, kidneys and many more.
Organ Systems
Different organs are organised into organ systems. Organ systems are groups of organs that work together to perform a particular function in the body. There are 11 organ systems in the body, and some examples are the respiratory system, circulatory system, skeletal system, endocrine system, nervous system and a few more.
Overall
The relationship between cells, tissue, organs and organ systems is shown below.
Cells
Multicellular organisms are made up of cells, which are the basic building blocks of all living organisms. Humans are made from trillions of cells. Cells differentiate and specialise to carry out their particular roles. For example, red blood cells are specialised to take oxygen around the body. Muscle cells are specialised to contract, which allows parts of the body to move.
Tissue
Similar cells group together to form tissue. Tissue is a group of cells with a similar structure and function. An example of tissue is blood, which is made from different blood cells (red blood cells, white blood cells & platelets) and plasma. Another example of tissues is epithelial tissue, which covers all internal and external surfaces of your body. A final example of tissue is muscle tissue.
Organs
Different tissues are organised together to form organs. Organs are groups of different tissues performing specific functions. Some examples of organs in the body are the heart, lungs, stomach, pancreas, liver, brain, kidneys and many more.
Organ Systems
Different organs are organised into organ systems. Organ systems are groups of organs that work together to perform a particular function in the body. There are 11 organ systems in the body, and some examples are the respiratory system, circulatory system, skeletal system, endocrine system, nervous system and a few more.
Overall
The relationship between cells, tissue, organs and organ systems is shown below.
Let’s have an example.
The Digestive System
The digestive system is responsible for breaking down and absorbing food molecules into the bloodstream. The digestive system is split up into cells, tissue and organs:
The digestive system is responsible for breaking down and absorbing food molecules into the bloodstream. The digestive system is split up into cells, tissue and organs:
- Cells form tissue:
- Epithelial cells form epithelial tissue, which covers all internal and external surfaces of your body
- Muscle cells form muscle tissue, which contracts or relaxes to allow parts of the body to move
- Glandular cells form glandular tissue, which secretes chemicals in the body
- Tissue is organised into organs:
- The stomach is an organ in the digestive system. The inside and outside of the stomach is covered in epithelial tissue. The epithelial tissue is surrounded by muscle tissue, which allows the walls of the stomach to move, which churns up food. The stomach also has glandular tissue that produces the chemicals needed for digestion – the chemicals produced are digestive enzymes, hydrochloric acid, mucus and bicarbonate.
- Organs are organised into organ systems. The stomach is one of the organs involved in the digestive system. Other organs in the digestive system are:
- The liver produces bile, which is stored in the gall bladder. The contents that come out of the stomach are very acidic. Bile is alkaline that neutralises what comes out of the stomach and makes the contents slightly alkaline. Bile also emulsifies fats – click here for more information on bile.
- The small intestine absorbs soluble food molecules (glucose, amino acids, glycerol and fatty acids).
- The large intestine absorbs water from undigested food, which leaves the body through faeces.