The human body is made up of many parts like bones, blood, heart, stomach, lungs, and brain. These parts are made up of cells, which are the basic building blocks of life that perform all activities needed to sustain life. Cells group together to form tissues that work together to perform specific functions. Living things can either be unicellular, consisting of a single cell like an amoeba, or multicellular, made up of billions of cells like humans, animals and plants. Cells are microscopic in size and each type of cell has a different shape, size and specialized function in the body. Different cells have varying lifespans, from taste bud cells living 7 days to nerve cells living up to 130

1. Building units of the body

2. What is our body made up of ?
The human body is made up of many different
parts, for example, bones, blood, a heart, a
stomach, a pair of lungs, a brain, etc. What are all
these parts of the body made of? Think of the way
bricks are used to build a house. Cells build living
things in a similar way. Cells are the building blocks
of life. They make up living things and perform all
the activities needed to keep living things alive.
Groups of cells that are alike and work together
one specific function are called tissues.

3. UNICELLULAR AND MULTICELLULAR
ORGANISMS
Some living things are made up of only one cell and
are called unicellular.
Human beings, other animals, and plants are made
of billions of cells and are called multicellular.
The amoeba is the unicellular organism that lives in
water and wet soil.

4. The building blocks of life
Cells are so small that they can only be seen
with the help of a microscope. Your body
contains cells of different kinds and of
different sizes and shapes. Each kind of cell
has a different function or job to do.

6. How long does a cell live?
•Every cell has a different life span. Taste bud
cells live for About seven days. Red blood cells
live for about four months. Nerve cells live for
18 to 130 years!