Animal Systems
Fourth Grade Mr. Seid
SKELETONS INSIDE AND OUT
Skeletal systems come in many forms. You have a skeleton inside of your body
(endoskeleton) made up of bones. Insects and crustaceans have skeletal systems on the
outside or their bodies (exoskeletons) that are made of hard plates.
WHAT DOES THIS SYSTEM DO?
We already hinted at the purpose of a skeletal system.
Protection and support are the two big reasons that
organisms have skeletal systems. In your body, the
skeleton works very closely with the muscular system to
help you move. Without the bones of your skeleton, you
would be a blob of water-filled tissues. The bones create
a frame to which your muscles and organs can connect.
Your skeleton also plays a role in protection, especially in
your head. The bones of your skull protect your brain.
Your ribs protect your heart. Other animals with exoskeletons receive obvious protection from
their skeleton. Crabs and insects have hard shells made of chitin to protect their entire bodies.
INTERACTING WITH OTHER SYSTEMS
Your skeletal system does not work alone. We already
mentioned the interaction with your muscular system.
Muscles connect to your skeleton and they contract and
move the skeleton along. Your skeletal system is made
up of cartilage and bones that work together. They help
the process of movement happen in a smoother manner.
The calcified bones of your skeleton also work with the
circulatory system. Marrow inside of your bones helps
produce the cells inside of you blood. Both red blood cells and white blood cells are created in
your bones.
If everything is working correctly, bones are able to break
and then heal. Even older people who break their bones
can grow new bone and connective tissue that returns the
bone to a usable state.
MUSCULAR SYSTEM - MEAT ON THE BONES
Many advanced animals have muscular systems. You know you do. Did you know that your
muscular system is made up of three different types of muscular tissue? You
have smooth, cardiac, and voluntary muscle tissue in your body. Smooth muscle is muscle
you rarely control such as the muscle in your stomach. Cardiac or Heart Muscle is very
specific tissue found in your heart. Voluntary muscle is the muscle that helps you move. All of
those tissues add up to a muscular system that is found through your body. There is more to the
muscular system than the muscles that help you move.
WHAT DOES THIS SYSTEM DO?
The big purpose of the muscles found in your body is movement. We could be talking about the
movement of your legs while you walk. We could be talking about the beating of your heart. We
could also be talking about the contraction of a very small blood vessel in your brain.
MUSCLES HELP YOU MOVE
The main parts of your voluntary muscular system include the muscles, and tendons. The
muscle is called the meatus. It happens to be the meat you eat from cows, sheep, and includes
the muscle in your biceps. So your bicep is the meat, that meat needs to connect to the bones
so that you can move.
CIRCULATION IS THE KEY
The circulatory is a system of vessels that pass through your entire body. You may read about
two types of circulatory systems in animals. There are open circulatory systems in primitive
organisms where you will find a heart that pumps fluids through the creature, but no complete
system of vessels. More advanced organisms, including you, have closed circulatory
systems where the heart is connected to a complete system of vessels. The fluids of a closed
circulatory system never leave the vessels.
WHAT DOES THIS SYSTEM DO?
How does a circulatory system help you? It is the transportation system for your body. The
circulatory system carries chemicals to all points in your body. The fluids also carry waste
products and dissolved gases for your cells.
Think of the chemical compounds as cars and the circulatory system as a network of freeways,
main streets, and side streets. The cars can pass from one building to another using these
streets in the same way that a compound might be created in the brain and sent to the kidneys.
INTERACTING WITH OTHER SYSTEMS
The circulatory system touches every organ and system in your body. The system is connected
to all of your body's cells so that it can transport oxygen efficiently. When you breathe, the
circulatory system carries oxygen to your cells and carries dissolved carbon dioxide back to the
lungs.
BASIC PARTS
The core components of your circulatory system are the heart and vessels. You happen to
have a four-chambered heart while other organisms may have one, two, or three chambers.
The heart is the pump for the system. As blood is pumped from the heart, it passes through a
system of arteries, and capillaries. The capillaries are the vessels that allow for most of the
transfer of compounds and dissolved gases. After the capillaries, your blood passes through
veins. The veins lead the circulatory fluids back to the heart.
RESPIRATORY SYSTEM - ALL ABOUT BREATHING
Your respiratory system is all about exchanging
gases with the environment. Some animals such as
amphibians are able to exchange gases through their
moist skin. Fish have gills while mammals, birds, and
reptiles have lungs. Your respiratory system is made of
your nose and mouth, a tube called the pharynx, another
tube called the trachea, and your lungs. You have two
lungs and the exchange of gases between the circulatory
and respiratory systems happens in the lungs.
WHAT DOES THIS SYSTEM DO?
Animals need oxygen (O) to survive. In fact, all organisms need oxygen to complete the
process to burning glucose for fuel. Even protists and plants need oxygen, but as you become
more active, you need a lot of oxygen. That's where your respiratory system comes in.
It's purpose is to bring oxygen into your body. One of the products of cellular respiration is
carbon dioxide. Your respiratory system also helps your body get rid of that carbon dioxide.
While you have lungs, fish have gills that serve as the location for that transfer of gases.
Whatever animal you study, oxygen is taken in and carbon dioxide let out.
EATING AND ELIMINATION! Digestive System
This is our favorite system. We love to eat and we love to poop. For the rest of the page we will
refer to pooping as elimination. It's more technical that way. Anyway, your digestive system is
all about getting food into your body, digesting the food, absorbing the nutrients you need, and
elimination of the materials you don't need (feces). All animals have one sort of digestive
system or another. Why? Anything that eats another creature (heterotrophs) must have a way
of bringing nutrients in and getting rid of what they don't need.
WHAT DOES THIS SYSTEM DO?
What does the system do? We're going to use you as the basis for our explanation of the
digestive system. Let's start with eating. You get hungry and you eat. Once you put the food in
your mouth, you start to chew and begin a process of mechanical digestion that grinds food
down into a pulp. Your body also starts to release chemicals that start the process of chemical
digestion and the breakdown the cells of the stuff you’re eating. Most chemical digestion
happens in the stomach. The food moves through your digestive system and is eventually
broken down into compounds and nutrients that your small intestine can absorb into the blood
stream. The material you don't absorb continues into the large intestine where water is removed
from the material and then whatever is left can be eliminated at your convenience. That's a
decent overview of the process.
Calcium Rich Diet
You probably learn about getting enough calcium in your diet. Your bones, tissues, and nervous
system all need that calcium. Did you know that some people who don't have
enough calcium (Ca) in their diets replace the calcium in
their bones with magnesium? It can happen because
calcium and magnesium are so similar on an atomic level.
NERVOUS SYSTEM - I'M SENSING SOMETHING
Since you're reading this page, we figure you've got
a nervous system. If you were an insect you would also
have a nervous system, but it would be a lot simpler. Even
animals that don't think have simple nervous systems called
nerve nets that help them move.
Your nervous system is divided into two parts. Your central
nervous system includes your brain and your spinal cord.
Your peripheral nervous system is made up of the network
of neurons that spans your organs, muscles, and body. The
neurons in both systems work together to help you think,
survive, and change the world around you.
WHAT DOES THIS SYSTEM DO?
The nervous system is about letting animals feel things.
All of your feelings and senses are taken in through the
nervous system and this sends messages to your brain.