Living Systems Introduction

What is a Living System? Every living thing has parts that work together to create a whole – This is called a system. Your body works because it runs on an organized set of systems. From cells to organs, each part of the system has a job. The parts are called structures and the work or jobs they do are called functions.

Cell Organization Cells Tissues Organs Organ Systems Organism

1. CELLS: Ex. Muscle Cell Single Cells do everything by themselves. Cells in multicellular organisms divide up the work and depend on other cells to help them do their jobs. All living systems are made up of cells, the basic unit of life. Ex. Muscle Cell

2. TISSUES: Groups of cells that look ALIKE, and work together to perform the same function. Ex: Muscle Tissue, Nerve Tissue

3. ORGANS: Made up of different kinds of TISSUES that work together to do the same FUNCTION. Ex: Your heart is an organ made of muscle, nerve and blood tissues

4. ORGAN SYSTEM: A group of organs working together to do a certain job. Ex: Circulatory System

5. ORGANISM: All organ systems working together in the body to make a complete organism. Ex: Human

SPECIALIZED CELLS Cells have different STRUCTURES (sizes and shapes), based on their FUNCTION (job) Some can be very SMALL and some can be very BIG

Muscle Cells: Bone Cells: Structure - long, thin fibers Function – contracts and relaxes to make your body move Bone Cells: Structure – surrounded by hardened minerals that form a matrix and lock together Function – provide support for the body

Red Blood Cells Flow through vessels to deliver oxygen to tissues. Need to be small/round to fit through tubes & smooth to not get stuck

Nerve cells Carry messages from brain to body & body to brain Very long (up to 1 meter!) to reach through body and branched at the end to connect to next one

Skin Cells Make a protective barrier to waterproof, block bacteria, viruses, chemicals and UV rays (sun). Geometric shape to stack together like a brick wall.