Cell Differentiation and Organisation

Learning Objectives: What are the advantages of cellular differentiation? How are cells arranged into tissues? How are tissues arranged into organs? How are organ arranged into organ systems?

Cell Differentiation Cell differentiation – the process by which cells become specialised for different functions. HOW? All cells contain the same genes, so why do they look and act differently? Different genes are switched on and off in each of the specialised cells.

How do cells differ? They differ in shape They differ in the number of each organelle - Examples? This has occurred through evolution, but means that some cell functions have been lost by the specialised cells. Sperm cell – many mitochondria / White blood cell – many lysosomes / Muscle cells – many mitochondria

Tissues Tissue – a collection of cells (not necessarily identical ones) that perform a specific function. Examples: Epithelial Tissues Xylem Tissues http://en.wikipedia.org/wiki/Tissue_%28biology%29

Organs Organ – a combination of tissues that are coordinated to perform a variety of functions. Examples: Stomach – What tissues is it made from? Leaf – What tissues is it made from? Stomach – made from muscle (to churn), epithelium (to protect and produce secretions) and connective (to hold together the other tissues) Leaf – palisade (photosynthesis), mesophyll (gas exchange), phloem (sucrose), xylem (water)

Organ Systems Organ Systems – organs work together as a single unit. Examples: Digestive System – What organs is it made from? Respiratory System – What organs is it made from? Circulatory System – What organs is it made from? Digestive System – salivary glands, oesophagus, stomach, duodenum, ileum, pancreas, liver Respiratory System – trachea, bronchi, lungs Circulatory – heart, arteries, veins, NOT capillaries (these are a tissue)

Task Example 1 Example 2 Organ System Organ Tissue Cell CELL- myocardiocyteal muscle cells TISSUE- Cardiac Muscle Tissue ORGAN- Heart ORGAN SYSTEM- Cardiovascular System