Cell tissues and organs

Atomic Structure and Biological Molecules

• Atoms are the smallest and most fundamental units of matter that make up all matter, including biological molecules.
• Biological molecules, such as lipids and proteins, form organelles and cell membranes, which make up cells.
• Macromolecules, such as deoxyribonucleic acid (DNA), contain instructions for the structure and function of all living things.

Levels of Organisation

• Cells combine to form tissues, which combine to form organs, and organs combine to form organ systems.
• This hierarchical organisation enables the body to function properly.

Tissue Types

• There are four main types of tissue: muscle, nerve, epithelial, and connective.
• Connective tissue provides structure and support to the body, and includes fat, bone, cartilage, ligaments, tendons, and blood.
• Bone is a type of dense connective tissue that supports and holds up the body.
• Blood is a liquid connective tissue that supplies oxygen to the body.

Epithelial Tissue

• Epithelial tissue covers and protects the body, and is made up of continuous sheets of cells that cover the surface of the body or line body cavities.

Muscle Tissue

• Muscle tissue enables movement through the contraction and relaxation of muscle cells.
• Multiple muscle cells must contract together to produce movement.

Nerve Tissue

• Nerve tissue enables control and communication through the transmission of electrical signals.
• Nerve cells must communicate with each other to function properly.

Organs and Organ Systems

• Organs contain multiple types of tissues working together to perform a specific function.
• Examples of organs include the heart, which contains cardiac muscle tissue, nerve tissue, and connective tissue.
• Organ systems consist of functionally related organs, such as the digestive system, which includes the stomach, mouth, oesophagus, small intestines, and large intestines.