15. Levels of Organisation

This video outlines how multicellular organisms, like humans, are organized into increasingly complex levels, from individual subcellular structures to the entire organism.

1. Organelles (Subcellular Structures)

These are the microscopic parts that make up a cell. Each has a specific role.

• Examples: Nucleus (stores DNA), Ribosomes (make proteins), and Mitochondria (release energy).

2. Cells

Cells are the basic building blocks of all living things. They contain various combinations of organelles.

• Specialized Cells: Cells that have a specific shape and structure to perform a particular job.

• Examples: Epithelial cells, muscle cells, and glandular cells.

3. Tissues

A tissue is a group of similar cells that work together to carry out a particular function.

• Muscle Tissue: Formed by muscle cells; its function is to contract and relax for movement.

• Epithelial Tissue: Formed by epithelial cells; it covers surfaces like skin or the lining of intestines.

• Glandular Tissue: Formed by glandular cells; it produces and secretes chemicals like hormones and enzymes.

4. Organs

An organ is a group of different tissues working together to perform a specific function.

• Example - The Stomach: This organ is made of muscular tissue (to churn food), glandular tissue (to produce digestive juices), and epithelial tissue (to line the stomach). Its role is to kill microorganisms and break down proteins.

5. Organ Systems

An organ system is a group of organs that work together to perform a particular function.

• Digestive System: Includes organs like the stomach, liver, and pancreas. Its role is to digest food and absorb nutrients.

• Other Systems: Cardiovascular, respiratory, reproductive, immune, nervous, endocrine, and urinary systems.

6. Organism

The highest level of organisation. Multiple organ systems work together to form a complete living being, such as a human, animal, or plant.

Summary Table