Discovering Cells

Cell Pronunciation: (How to say it) [Sel] Definition: Basic organizational unit of structure (how it’s built) and function (how it works) in living organisms. (Organism = living thing. Cells form the parts of an organism and carry out all of an organism’s processes, or functions.

Cells form all the parts of our bodies and carry out all the jobs different parts of our bodies have to do. Carrying messages

Cells are very tiny, and most individual cells can only be seen with a microscope. /cells/scale/

The invention of the microscope made it possible for people to discover and learn about cells.

Cells & Structure Living things are built differently because of the different kinds of cells they have and the different ways their cells are put together. The way a body is built determines how it works.

Cells and Function Cells do all the different jobs our bodies need, carrying out a wide range of functions, like…

Cells in Our Bodies Do This Job Maintaining chemical concentrations

Expelling (getting rid of) wastes Cells in Our Bodies Do This Job

Ingesting food

Cells in Our Bodies Do This Job Responding to the environment

Cells in Our Bodies Do This Job Growing

Cells function similarly in all organisms, doing the same kinds of jobs no matter what kind of living thing they’re in.

Robert Hooke Named cells when looking at a thin slice of cork through a compound microscope he made himself.

Anton van Leeuwenhoek Also made his own simple microscope and observed living cells from pond water and scrapings from teeth (bacteria in plaque)

Matthias Schleiden All plants are made of cells

Theodor Schwann All animals (and all living things) are made of cells

Rudolf Virchow All cells come from other cells

Cell Theory Pronunciation: [Sel theer-ee] Definition: Widely accepted explanation of the relationship between cells and living things Parts of cell theory: –All living things are composed or made of cells –Cells are the basic unit of structure and function in living things –All cells are produced from pre-existing cells

Cells function similarly in all organisms. Regardless of the organism they are a part of, cells carry out the basic processes of life in similar ways. Organisms may be composed of one cell or many trillions of cells

Unicellular Pronunciation: [you-knee-SEL- yuh-ler] Uni=one Definition: Single-celled or made of one cell

Multicellular Pronunciation: [muhl-tee- SEL-yuh-ler] Multi = many Definition: Composed or made of many cells

As multicellular organisms develop, their cells differentiate. This means that their cells become different, and that the shape of the cell is linked to its specialized function, or the job it does. Differentiation

Cells take on specialized functions; some become the heart, brain, etc.

After Differentiation After differentiation, most cells lose the ability to become another type of cell.

Nerve Cell Specialization The long, fingerlike extensions of the nerve cell help transmit information from one part of your body to another.

Blood Cell Specialization Red blood cells carry oxygen throughout your body. Their flattened shape enables them to fit through tiny blood vessels.

Cells: Organizational Units In multicellular organisms, cells are often organized into differentiated tissues, organs, and organ systems with specialized functions

Tissue Pronunciation: [tish-oo] Definition: a group of similar cells that work together to perform a specialized function Examples: muscle tissue, nerve tissue

Brain The brain is made of nervous tissue, which consists of nerve cells.

Organ Pronunciation: [ore-gun] Definition: Made of different kinds of tissues that work together Example: Brain contains other types of tissues, like blood vessels and the connective tissue that protects the brain

Other Organs Heart, liver, and kidneys

Organ System Pronunciation: [ORE-gun-SIS- tem] Definition: Group of organs that work together to perform a major function or job Examples: Brain is part of nervous system, which directs body activities and processes

Other Organ Systems Musculoskeletal Digestive Circulatory

Organ systems function because of the contributions of individually specialized organs, tissues, and cells. The failure of any part can affect the entire system.