Anna Cajiga
SME 301
Physiology Summary
April 13, 2005
Purpose
The purpose of teaching this unit would be to help students understand not just the
overall structure of the skeletal system, but also why this system is important to our bodies and
how it helps keep our cells alive. Also, this unit would explain how the skeletal system connects
to other systems of the body in order to emphasize the fact that each system depends on the
others to help our bodies function properly.
Benchmark
Area: Life Science
Category: Organization of Living Things
Benchmark: Explain how selected systems and processes work together in animals (Middle
School).
Background
A body system is a group of organs in the body that work together to perform certain
functions that we need to survive. There are several body systems in the human body, including
the circulatory system, the digestive system, the endocrine system, the lymphatic system, the
muscular system, the nervous system, the excretory system, the reproductive system, the
respiratory system, and the skeletal system. Each of these systems has a different function in the
body, but they all work together to keep us, and our cells that make up each part of our body,
alive. The skeletal system works with almost every other body system to keep cells alive. The
main purposes of the skeletal system are to provide structure and support to the body, to enable
movement, to protect vital tissues and organs in our body, to store important minerals like
calcium and phosphorus, and to create red and white blood cells. All of these functions allow us
to survive.
Materials and Directions
9 Plastic Milk Jugs
Scissors
Exacto Knife
Pipe Cleaners
Duct Tape
Hole Punch
1) Turn a milk jug upside down. In the corner opposite the handle cut out a large pair of eyes, the
mouth and two holes for the nostrils.
2) Slice down the center of a jug opposite the handle. Cut the plastic to make a rib cage, making
sure each rib wraps all the way around the milk jug, leaving about 4 inches between the two sets
of ribs on the BACK side of the milk jug. Connect the ribs on the right side to the corresponding
rib on the right side using a white pipe cleaner. Tape a pipe cleaner to the top of the milk jug and
hang it vertically. Connect the pipe cleaners between the right and left ribs to this vertical pipe
cleaner. The ribs should look like this:
3) Tape the head to the chest section.
4) Cut off two jug handles leaving a small collar on each end. Use duct tape to attach them to the
chest section. Punch a hole at the outside end of each shoulder.
5) Cut out two spouts, leaving a 1/2 inch collar on each. Duct tape the spouts together. Tape
them to the bottom of the chest to create a waist.
6) Cut the bottom 4 1/2 inches of a jug into a pelvic shape. Tape it to the bottom of the waist.
7) Cut two longer bone shapes of equal length and two shorter bone shapes of equal length from
the milk jugs. Punch a hole in each end of the bones and use pipe cleaners to attach the longer
bones to the pelvis and the shorter bones to the shoulders.
8) Cut four bones that look like this:
Two of the bones should be shorter in length (but equal to each other) and two of the bones
should be longer in length (but equal to each other). Punch a hole in each end of the bones and
attach the shorter ones to the lower part of the arms and the longer ones to the lower part of the
legs.
9) Trace your hands and feet on a milk jug. Cut these shapes out of the jugs. Punch holes into the
hands and feet and attach them to the arms and legs using pipe cleaners.
Results
The finished model should look like this:
The main bones that the model shows are the skull, the vertebral column, the ribs, the sternum,
the pelvis, the clavicle, and the bones of the arms and legs. The skull, the vertebral column, the
sternum and the ribs are all axial bones. The pelvis, the clavicle and the bones of the arms and
the legs are appendicular bones.
Discussion
Our model is a skeleton made of milk jugs. It includes the skull, the vertebral column, the
ribs, the sternum, the pelvis, the clavicle, and the bones of the arms and legs. All of these bones
are made of milk jugs, with the exception of the sternum, which is represented by a pipe cleaner.
The skull, sternum, ribs and vertebral column represent the axial bones and the clavicle, bones of
the arm, bones of the leg and pelvis represent the appendicular bones. The bones are connected
to each other using pipe cleaners. These pipe cleaners represent the joints of the body, or places
where two bones meet. It is these flexible connections that allow for our bodies to move, just as
it is these pipe cleaners that allow the milk jug skeleton to move. This model also works to
illustrate the main purpose of the axial bones and of the appendicular bones. By looking at our
model, it is easy to see that the appendicular bones have more pipe cleaners, or joints, than the
axial bones, which shows that the appendicular bones work to help us move. Also, you can also
see that the axial bones have large “empty” spaces inside of them, suggesting that these bones
mainly function to protect the organs that would fill these cavities. While this model effectively
shows where each type of bone is located, there are weaknesses. It is a very “rough” model, since
in reality there are about 206 bones in the body. It also does not show the scapula bones in the
appendicular group, and in reality the sternum does not connect to every single rib, as it does in
this model.
There are about 206 bones in the human body. These bones can be divided into two
groups. One is the axial bones, and the other is the appendicular bones. The axial bones are the
skull, ribs, vertebral column and the sternum. The appendicular bones are the bones of the arms
and legs, the scapula, the clavicle and the pelvis. Axial bones mainly work to protect vital
organs. For example, the skull protects the brain, the ribs protect the heart and lungs, and the
vertebral column protects the spinal cord. The vertebral column also helps support the weight of
the body. On the other hand, appendicular bones mainly work to help us move. Appendicular
bones have numerous joints and attachment points for muscles, which allows for movement. The
pelvis protects some of our organs, including the bladder and some reproductive organs. The
bones that make up the legs are the largest in our bodies. They are very strong so they are able to
support the weight of the entire body. All bones, whether appendicular or axial, are living parts
of our bodies that have blood flowing through every part of them. They are constantly growing
and remodeling because bones have certain cells with special jobs in them. Some cells break
down and discard worn bone cells, and other types of cells build new bone. This cycle is
continuously happening in our bodies. All bones also have a canal on the inside that is filled with
fatty tissues, blood vessels and bone marrow. Bone marrow is where red blood cells are created.
Some white blood cells are also created in the bone marrow. Minerals are also stored in bones,
including calcium and phosphorus. Calcium gives the bones strength so they are better able to
protect organs and provide structure and support to our bodies. Calcium is also used by muscles
for muscle contraction.
The skeletal system works with almost every other system of the body to help keep us
and our cells alive. Without the skeletal system, there would be no protection for the vital organs
of the nervous system. The spinal cord is protected by the vertebral column. Our brain, and the
cells that make it up, is protected by the skull. Without the skull, the fragile brain would be very
vulnerable to injury. The skeletal system also has locations where muscles attach to the bones.
The muscular system and the skeletal system then work together to allow us to move our bodies.
Without having the skeletal system to attach to, the muscles in our bodies would have no
structure or support, and would be useless! Without the skeletal system, our bodies would not be
able to create red blood cells. Red blood cells are needed by every other part of the body because
they carry oxygen through the blood stream. If we did not have red blood cells, our cells simply
would not be able to survive. Some white blood cells are also created in bone marrow. White
blood cells fight infection in our bodies, and without bones we would not have as many white
blood cells in our blood stream. This means we would be more prone to disease and infection,
making it more difficult for us to stay alive. Bones also store minerals like phosphorous and
calcium that are essential to the cells of our bodies, especially in muscles, which need calcium
for muscle contraction.
Understanding more about the skeletal system helps us to understand things we
experience in our everyday lives. For example, almost everyone was told to drink all their milk
as a child. This is because milk has calcium in it, which is stored in bones and makes them
stronger so they can provide adequate support and protection to our bodies. Understanding the
importance of bone marrow to our bodies explains why we hold bone marrow drives. Bone
marrow is where red and some white blood cells are produced. Our bodies need these cells to
fight off infection and to carry oxygen to all the cells in the body. If a person has problems with
their own bone marrow, marrow provided through a bone marrow drive can help them survive.
Many people may have noticed that the bones in the legs are the largest bones in our bodies.
Learning about the skeletal system helps us understand why. These bones are used to support the
weight of our entire body. Being so large and strong allows them to adequately provide structure
and support to our bodies so we can carry out all of our daily activities. Understanding that bones
are constantly being broken down and rebuilt by special cells also explains why osteoporosis
occurs in some people. If a person has too many special cells that break down bones and not
enough special cells that rebuild bones, their bones will slowly become weaker and more brittle,
and therefore break more easily.
Resources
1) The Bones Book & Skeleton by Stephen Cumbaa
This book would be an excellent resource for a classroom because it discusses details about the
skeletal system and it’s connection to other systems in the body using interesting (and sometimes
gross) facts that appeal to children, and a build-it-yourself model of the human skeleton is
included!
2) Human Skeletal System Video
This award-winning video covers all the important information about the skeletal system,
including how it supports and protects our bodies, helps us move, stores minerals and an in-depth
look at how blood cells are created.
3) <http://www.innerbody.com/image/skelfov.html>
This website allows students to take an interactive “tour” of the skeletal system, and even see a
cross section bones, so that they can better understand the structure of our bones.
Credits
After recalling that we made milk jug skeletons in elementary school, we searched the
internet to find directions for the task. We used the directions provided at
<http://prairiewebs.com/skeleton.html>, but made slight alterations to the instructions so that our
skeleton model also included a Vertebral Column.