Cells, tissues and organs
Cell
Definition:
A cell is the smallest living unit of a living organism. All plants and animals are made of cells.
Main points:
Cells are very tiny (you need a microscope to see most of them).
Different cells do different jobs (muscle cells, nerve cells, etc.).
Cells are the building blocks of life.
Fun fact:
Your body has trillions of cells working together right now!
Tissue
Definition:
A tissue is a group of similar cells that work together to do the same job.
Main points:
Cells join together to form tissues.
Each tissue has a special function.
Examples of tissues:
Muscle tissue – helps in movement
Nervous tissue – sends messages
Epithelial tissue – covers and protects the body
Connective tissue – supports and connects body parts
Fun fact:
When you smile, your muscle tissues are working hard
Organ
Definition:
An organ is a group of different tissues working together to perform a specific function.
Main points:
Organs are bigger than tissues.
Each organ has a special job.
Examples of organs:
Heart – pumps blood
Lungs – help us breathe
Stomach – digests food
Brain – controls the body
Fun fact:
Your heart beats about 100,000 times a day
Order
Cells → Tissues → Organs → Organ system → Body