Living Systems Levels of Organization

Levels of Organization

Learning Objectives
- Describe the structure of the body from simpliest to most complex.
- Describe the interrelationship between organ systems.

Life is organized into different levels based upon size (from small to large).

Cell Theory and Levels of Organization in Living Things

Cell theory has helped scientists to better understand the importance of cells and the role they play as the building blocks of all living organisms. Cell theory has three main components.

1. The first part of cell theory states that Cells are the basic unit of all living organisms.

2. The second part states that all living organisms are made up of one or more cells.

3. The third part states that all cells come from pre-existing cells.

In unicellular organisms, all life functions are performed by a single cell. However, multicellular organisms have several different levels of organization within them. Let's look at the levels from the simplest to the most complex:

Cells are considered the basic unit of structure and function of all living things

Tissues are groups of similar cells working together to perform the same function. (Examples: connective, muscular, and nerve tissue)

Organs are made up of groups of tissues that work together to perform the same function. There are 78 organs in the human body. (Examples: heart, lungs, kidneys, and liver)

Organ Systems - organs that work together to perform specific functions

Organism - Organ systems work together to form the overall organism

Body Organization

​The human is an organism, the human body is made up of different organ systems. The smallest component of the human body is considered the cell.

How is the Body Organized?

A cell is the smallest independently functioning unit of a living organism. Even bacteria, which are extremely small, independently-living organisms, have a cellular structure. Each bacterium is a single cell.

In humans, as in all organisms, cells perform all functions of life.
A tissue is a group of many similar cells that work together to perform a specific function.
An organ is an anatomically distinct structure of the body composed of two or more tissue types. Each organ performs one or more specific physiological functions.
An organ system is a group of organs that work together to perform major functions or meet the needs of the body.

Multiple Choice

Patterns: What is the level of organization in the human body from the least to the most complex?

• cell-organ-tissue, organs system

• cells- tissue- organs- organ system

• organ system-organs- tissue- cells

Develop a Model

The body organization starts at the smallest operating thing and moves to higher functioning groups of cells that work together for one purpose. You need to compare the body organization to a city. Begin by thinking of the smallest things in a city that work together. Then larger groups, larger groups, and finally systems that work together to keep the city running.

Multiple Choice

If you are relating the levels of organization of the human body to the levels of organization of a city, what would you relate the cells to?

• bricks

• houses

• buildings

• roads

Multiple Choice

If you are relating the levels of organization of the human body to the levels of organization of a city, what would you relate the buildings to?

• organs

• organs systems

• cells

• tissue

Multiple Choice

If you are relating the levels of organization of the human body to a city, what would the city government be compared to?

• cells

• tissue

• organs

• organ systems

Systems and Models

The respiratory system exchanges oxygen and carbon dioxide between the air and cells in the body.

Multiple Choice

You breathe out ________ and breathe in _____________.

• oxygen, carbon dioxide

• carbon dioxide, oxygen

How can you tell that your Immune System is functioning well?

Multiple Choice

If you are sick all the time and it's hard to get to feeling better, You immune systems is?

• not working

• working, you just get sick sometimes

If the brain is the control center of the body, why do we need nerves in our fingers?

​

Multiple Choice

If the brain is the control center of the body, why do we need nerves in our fingers?

• we don't

• the nerves in our fingers send a message to the brain, the brain then sends message on what to do

• the nerves in the fingers or hands are complex and we don't understand them or how they control the body

• the brain sends all the messages, we don't need nerves in our hands

Match

Drag the images to match the labels

Cell

Tissue

Organ

Organ System

Organism

• Cell

• Tissue

• Organ

• Organ System

• Organism

Multiple Choice

When a group of organs work together to perform a particular function they create a/an

• organ system
• organism
• tissue
• organ

Multiple Choice

A group of similar cells that come together to perform a specific function is a/an

• organ
• organism
• organ system
• tissue

Multiple Choice

Which of the following is the correct order of organization in living things from most basic (simple) to most complex?

• a.  Organism, cell, tissue, organ, organ system
• a.  Organ system, organ, tissue, cell, organism
• a.  Cell, tissue, organ, organ system, organism
• a.  Cell, organ, tissue, organ, organism, organ system