Cell Organisation

• Human beings, like most multicellular organisms, are hugely complex and can be understood by breaking everything down into layers such as cells, tissues, organs, and organ systems.
• Cells act as the basic building blocks of life and are themselves made up of sub-solar structures such as a nucleus, mitochondria, and ribosomes.
• Most of our cells are specialized to perform a particular function such as a nerve cell or a muscle cell.
• Tissues are groups of similar cells that work together to carry out a particular function, for example, muscle cells group together to form muscle tissue, while epithelial cells form epithelial tissue which aligns parts of the body such as the lungs and intestines.
• Xylem cells combine together to form xylems which allow plants to transport water up the stem.
• Different types of tissue can combine to form organs, examples include the heart, stomach, pancreas, kidneys, and teeth.
• Other structures such as teeth, tendons, bronchi, and salivary glands also count as organs when groups of these organs combine for a particular function they become known as an organ system, such as the cardiovascular system, digestive system, and muscular system.