Organisation of cells

• Multicellular organisms consist of specialised cells. The specialised cells are organised into groups of cells called tissue. These tissues consist of one or more types of cells carrying out a function in the body. Many tissues are further organised into organs.
• Tissues are groups of cells that all develop from the same kind of cell. There are only four main types in the human body - epithelial tissue, connective tissue, muscle tissue and nervous tissue
• Epithelial tissue lines the surfaces both inside and outside the body. All cells in epithelial tissues originate from the basement membrane.
• Squamous epithelium is frequently found lining the surfaces of blood vessels and forms the walls of capillaries and the lining of the alveoli
• Ciliated epithelia often contain goblet cells that produce mucus, they form the surfaces of tubes in the gas exchange system.
• Compound epithelia are found where the surface is continually scratched and abraded, such as the skin
• Connective tissue is the main supporting tissue in the body, and includes bone tissue and cartilage tissue as well as packing tissue that supports and protects and some other organs.
• 1. Simple squamous
  2. Cuboidal
  3. Columnar
  4. Compound

  
• An organ is a structure made of several different tissues grouped into a structure so that they can work efficiently together to carry out a particular function
• Several organs work together as an organ system to perform large scale functions in the body e.g the digestive system