Science - CROSS CURRICULAR

Science - CROSS CURRICULAR​

DIGESETIVE SYSTEM, EXCRETORY SYSTEM, and the CIRCULATORY SYSTEM​

​The circulatory system is the transport system of the human body.

Your body is like a map fi lled with passageways of different sizes that

are fi lled with blood. Arteries and veins are the body’s largest blood

vessels. Arteries carry oxygen-rich blood from the lungs and through the

heart so it can be delivered to all the cells of the body. Veins carry carbon

dioxide waste back to the heart and into the lungs so the carbon dioxide

can be exhaled. Capillaries are the tiniest blood vessels. They are

especially helpful in the lungs, where the gas exchanges take place in air

sacs called alveoli. Under a microscope, alveoli look like grape clusters.

​It Circulates

​Blood looks like a simple red liquid when you have a cut or a

scrape. That’s only because your eyes cannot see what is going on

inside the blood at the microscopic level. The reason blood looks red

to us is because it contains an iron-rich substance called hemoglobin.

Hemoglobin allows blood to hold on to oxygen and carry it around the

body. Hemoglobin is found in disc-shaped cells called red blood cells.

There are also white blood cells in our blood. They are larger than

red blood cells and are important because they help us fi ght disease.

Platelets, another kind of cell found in our blood, help us form scabs

when we are injured so we don’t lose too much blood. All of these cells

fl oat in a liquid called plasma. Plasma also carries sugar to cells and

waste products away from cells.

​At the very center of the circulatory system is the heart. Your heart

is about the same size as your fi st, but it is made of muscle. Its job is to

pump your blood through all those blood vessels. It never stops working,

even when you are sleeping. It is the strongest muscle in your body. Your

heart has four chambers, or spaces, inside it. They are the left and right

ventricles, and the left and right atriums. Each chamber is separated

by a valve that allows blood flow in only one direction. The opening and

closing of the valves is what you can hear through a stethoscope when

you visit the doctor. The blood being pushed through the valves is what

you feel as your pulse.

Multiple Choice

What is the function of the WHITE BLOOD CELLS?

• they help prevent weight loss

• they help fight disease

• they help create blood

• they help blood flow to the rest of the body

Multiple Choice

How are arteries and veins alike?

• they are both a part of the digestive system

• they both help create blood

• they are both blood vessels that carry blood around the body

• they help protect the body

Multiple Choice

Based on other information in the passage, what gases are being exchanged in the alveoli?

• capillaries

• carbon dioxide

• oxygen

• oxygen and carbon dioxide

Multiple Choice

What is the MAIN IDEA of the passage "IT CIRCULATES"?

• The circulatory system transports blood throughout the body

• The circulatory system has a lot of parts

• The circulatory system is all about plasma

• The circulatory system is the most important system in your body

​DOWN the HATCH

​A car needs energy to get where it’s going. Your body must have

fuel to do all the things it needs to do so you can grow up healthy and

stong. The digestive system takes care of the body’s need for fuel. It

is made up of a group of organs that work together. They pass fuel in

the form of food from one organ to the next until the entire process is

complete. Waste products then pass out of the body.

​The digestive system goes to work the moment you put food into

your mouth. Immediately, the salivary glands in your mouth moisten the

food. The saliva begins breaking down the food into smaller and smaller

pieces. Your teeth also get involved, biting and grinding the large pieces.

Finally, the pieces are small enough to swallow. Your tongue is kind of

like a traffic director, pushing food around in your mouth to make the

most of your saliva and teeth. Then, your tongue pushes your food to

the back of your mouth so you can swallow.

​As your food leaves your mouth, it enters a tube called the

esophagus. Gravity and muscles push your food down to the stomach.

In the stomach it is greeted by strong acids. During the next couple of

hours, acids and enzymes break your food into a soupy liquid.

​Believe it or not, your body has still not received energy from your

food. Your liquefi ed food fi nally passes into the small intestine. This is

a long tube that is coiled back and forth inside your body. The food will

remain there for up to six hours. During that time, special chemicals

digest the liquid even further. Nutrients your body needs are pulled from

it. The nutrients enter your blood through tiny little fi nger-like projections

called villi that line the insides of your small intestine.

​What happens to the leftovers? The things your body does not need

pass into your large intestine. Water and minerals are absorbed out of

the food and into your blood over the next 10-36 hours. After most of

the liquid is removed, the rest of the leftover material passes out of your

body as solid waste.

Multiple Choice

What is the name for the tube from the mouth to the stomach?

• villi

• esophagus

• intestine

• throat

Multiple Choice

What are villi?

• a tube that leads to your stomach

• small projections in the large intestines

• small projections in the small intestine

• salivary glands in your mouth

Multiple Choice

At what point during the digestive process does your body begin to receive energy from the food?

• when the food is in the stomach

• when the food is in the small intestine

• when the food is in the large intestine

• when the food is in the mouth

Multiple Choice

Where is food likely to be two hours after you eat?

• small intestine

• large intestine

• mouth

• stomach

​THE EXCRETORY SYSTEM

​Your body is approximately 60% water. Water is part of all the

cells in your body and the plasma in your blood. Water helps your cells

receive the nutrients they need, and it helps take away the wastes.

All living things produce wastes. It is the job of the excretory system

to regulate the amount of water that you have in your body and to help

remove wastes from your system. If wastes build up in your blood and in

your cells, your body becomes toxic, which can be deadly.​

​Several different organs are involved in your excretory system. Even

your skin participates in the process! You have sweat glands that can

release water onto the surface of your skin to keep you from getting

overheated. You might fi nd it inconvenient to sweat in certain situations,

but people who physically cannot sweat are in constant danger of dying

from heat stroke, so be glad if you can sweat!

​Your liver is an important part of the process as well. Whenever

your body recycles parts of cells that are damaged or old, they become

part of the wastes that need to be removed. This recycling puts a lot

of nitrogen into your blood. Your liver fi lters the nitrogen out of your

blood, changing it into urea. Without your liver, you could die of nitrogen

poisoning.

​Just inside your lower back are two large bean-shaped organs

called your kidneys. Their main job is to filter out the urea in your

blood. The kidneys have a sophisticated system of pumps and tubes.

Most of the liquid is returned to the blood, where it continues on its way

through the circulatory system. Your kidneys have sensors that tell it

how much water to release. If you’ve been drinking a lot of water, your

blood will have more water in it. Your kidneys can tell. They send only

the right amount of water back into the blood. The small portion of liquid

that remains behind becomes urine. It drains through tiny tubes called

ureters into a muscular bag called the bladder. Your body knows when

your bladder is full and needs to be emptied. Your brain receives a

signal to let you know that it’s time to visit the bathroom.

Multiple Choice

Why is the Excretory System important to your body?

• it removes harmful waste from the body

• keeps us cool

• it removes harmful waste from the body and keeps us cool

• it is not important

Multiple Choice

Why is it dangerous to be unable to sweat?

• you may lose heat

• you may get warm

• you may have to use the restroom more

• you could die

Multiple Choice

What substance does the liver turn into urea?

• nitrogen

• urine

• water

• excretory

Multiple Choice

Which organs turns liquid into urine

• the kidneys

• the bladder

• blood

• skin

Multiple Choice

What happens if waste builds up in the body?

• we use the restroom

• our body begins to sweat

• our blood becomes toxic, which could be deadly

• our kidneys produce urine