Systems
Name two systems in the body
The nerve system
The muscles
The skeleton (bones)
Vision (seeing)
Hearing
Can bones bend?
No! Bones are stiff and hard.
Can blind people see?
Not all of them.
Some blind people see nothing, others see just light and dark, and others see things in an extremely blurry way.
Why do animals' eyes shine in the dark?
They have a light-reflecting coating in their retinas that reflects light. The coating can be yellow, green or even red.
How is the brain connected to other parts of the body?
The brain is connected to nerves - long wires.
The nerves are connected to the brain in two ways:
1) Nerves run from the five senses to the brain, providing information.
2) Nerves run through the body from the brain, sending messages to the muscles and making the body move.
How do you see? How do the parts work together as a system?
Pupil: Light travels through the pupil into the dark eye.
Cornea Lens: Focuses the light into a picture and projects the picture to the back of the eye.
Retina: The "screen" in the back of your eye captures the picture.
Nerves: The retina is connected to nerves that send the picture to the brain.
What connects the bones to one another in a way that makes it possible for you to move your body?
Joints - they connect bones and allow each bone to move in a different direction.
If all bones were connected without joints, we would be stiff like a chair and wouldn't be able to move.
What is the retina?
The retina is the "screen" in the back of our eye. The light goes through the cornea lens and creates a picture on the retina.
Why do our pupils get larger in the dark?
We need light in order to see.
When it's dark, our pupils enlarge to let in more light so we can see better.
How do scientists learn about the brain? Do they look inside brains of people who are dead?
The brain only works when it is alive, so scientists learn about the brain by observing people who are alive.
Scientists think of experiments to understand the brain by trying to challenge it and trick it. They observe the brain's response and get a better idea of how the brain works.
What systems work together to help a person catch a ball?
Vision: the eyes capture a picture and send the information to the brain.
Muscles: the brain sends commands to the muscles to move. There are several groups of muscles that work together as a system to help catch a ball - legs for moving and balancing, arms for reaching, hands for catching.
Why do you need both muscles and tendons in order to move your bones?
Muscles can only squeeze and relax, they cannot pull or push. The bones are attached to tendons that connect to the muscles. When the muscle squeezes, the tendon stretches and that moves the bone.
Why do we need a cornea lens? Why can't we just see through the pupil without a lens?
The cornea lens gathers light that is reflected from objects and projects the light as a picture on the retina.
If we only had a pupil, our retina would only see light, but not a picture.
What is the job of the iris - the colored part around the pupil?
The iris is a muscle that is in charge of adjusting the size of the pupil, making is smaller or larger as needed.
Why is it hard to react immediately to something? Why does it take a second or so for us to react?
Information needs to travel, the brain needs to make decisions, and then commands need to travel from the brain to the muscles. This is done extremely fast, but not immediately.
The brain takes the information it receives from all the senses. It then combines this information with other knowledge that it has. Finally, the brain makes a decision, and then sends messages to the muscles telling the body what to do next.