Grade 5 Science Definitions
Unit: Human Body Systems
Cells: Your body is made up of about a trillion tiny bits of living material called cells. Each cell is a building block of the body.
Tissues: Tissues are groups of cells that work together to do one kind of job in the body, based on their body system/part.
Organs: Two or more kinds of tissues that work together to perform a certain job, form an organ. Your heart is an organ for example. It is made up of muscle tissue, nerve tissue, and connective tissue. It’s job is to pump blood throughout the body.
Human Organ Systems: Groups of organs work together to form an organ system. Each system carries out a major function. The human organ systems we will be learning about this year are: the respiratory system, the circulatory system, the digestive system, the skeletal system, the muscular system, the brain, the nervous system, and skin.
The Respiratory System: This system allows us to breathe in oxygen that our cells need to work, and exhale carbon dioxide/waste that the cells produce. Your respiratory system begins on the outside of your body with your nose and mouth, and reaches down into your lungs and diaphragm.
The Circulatory System: This system delivers food and oxygen to your body’s cells through your blood. Energy is carried through your blood to your organs, and blood also takes waste to your kidneys. Blood also transports messenger chemicals through your body.
The Digestive System: This system allows your body to take in food, and break it down to make energy for cells. Your digestive system begins with your nose and mouth, and ends with your stomach and rectum. Food is important because it gives your body’s cells energy to breathe, move, and do many other things. Food also provides your body with proteins, vitamins, and minerals.
The Skeletal System: This system supports the body and protects our delicate organs. The human body has about 206 bones - this makes up the human skeleton. Bones are strong and lightweight, and have many different shapes and sizes.
The Muscular System: Your bones and joints need muscles to help them move. Your muscular system powers all body actions and motions, from jumping and lifting heavy weights, to smiling and blinking, and even breathing! There are about 660 muscles in your body. These skeletal muscles also shape the body and hold it upright.
The Brain: The human brain has been called the most complicated object in the entire universe. It is made up of billions and billions of brain cells, packed tightly together. These cells are arranged in columns that go deep into the brain, and sheets that stack up like layers of a cake. Every single brain cell branches like a tree and is connected to hundreds of other cells and their branches. The brain controls everything from your senses, memory, planning, language, movement, speech, information processing, vision, and much more!
The Nervous System: This is the control centre of your body. It automatically regulates many of your body’s processes, including feeling, seeing, hearing, moving, and thinking. The central nervous system is made up of your brain and spinal cord. They are linked to your body through a network of nerve cells. These nerves use electricity and chemicals to transmit messages to and from the brain.
Skin: Skin is also a human body system. It protects the entire body and all it’s systems from the outside world. Skin is like a snug-fitting blanket, that keeps everything inside your body warm and safe. It keeps you cool when it’s hot, and it keeps you from losing heat when it’s freezing outside. Luckily, skin comes in layers, so that when we get cut or scraped, our inside body systems are not exposed to germs and bacteria from the outside world.
