UNIT 1:THE HUMAN BODY

VOCABULARYskinepidermisdermisporessubcutaneous digestion

From the textbook:producerconsumerfood chainpredatorpreyfood web

YOUR SKINIt covers and protects everything

inside your body.Your skin is the largest organ in

your body.It:

protects our bodies,helps keep our bodies at just the

right temperatureallows us to have the sense of

touch

THE THREE LAYERS OF THE SKIN

FIRST LAYER: EPIDERMIS

The layer outside is called the epidermis.

The epidermis is the part of your skin you can see.

THE DERMIS IS UNDER THE EPIDERMIS

The dermis tells you how things feel when you touch them.

Sweat comes up through pores, tiny holes in the skin that allow it to escape.

SUBCUTANEOUS FATIt is the third layer of the skin.

It is made of fat and helps your body stay warm and absorb shocks, like if you fall down.

This layer is where you will find the start of hair, too.

YOUR BONESBones give your body structure, let you move in many ways, protect your internal organs, and more.

You have 206 bones.

MUSCLESYou have more than 600 muscles.

You have three different types of muscles in your body: smooth muscle, cardiac (say: kar-dee-ak) muscle, and skeletal (say:skel-uh-tul) muscle.

DIGESTIVE SYSTEMDigestion allows your body to get the nutrients and energy it needs from the food you eat.

Digestion begins in your mouth.

PARTS OF THE DIGESTIVE SYSTEMESOPHAGUS The esophagus is like a stretchy pipe that’s

about 10 inches (25 centimeters) long. It moves food from the back of your throat to

your stomach.

STOMACHYour stomach is a stretchy sack

shaped like the letter J. It has three important jobs:1. to store the food you have eaten2. to break down the food into a

liquidy mixture3. to slowly empy that liquidy

mixture into the small intestine

THE SMALL INTESTINEThe small intestine is a log tube that

is about 3.5 to 5 centimeters around, and 6.7 meters long.

The small intestine breaks down the food mixture even more so your body can absorb all the vitamins, minerals, proteins, carbohydrates, and fats.

It gets help from three friends: the pancreas, liver, and gallbladder.

LIVERThe liver filters out harmful substances or wastes, turning some of the waste into more bile.

The liver stores certain vitamins and a type of sugar your body uses for energy.

THE LARGE INTESTINEIt is about 7 to 10 centimeters around.

It is fatter than the small intestine and it is almost the last stop on the digestive tract.

THE RECTUMIt is the very last stop on the digestive tract.

The solid waste stays here until you are ready to go to the bathroom.

THE RESPIRATORY SYSTEMLUNGS

Your lungs are in your chest.You have two lungs.The lung on the left side of your

body is a bit smaller than the lung on the right.

They are protected by your rib cage, which is made up of 12 sets of ribs.

Lungs are pink and a bit squishy, like a sponge.

THE DIAPHRAGMBeneath the lungs is the diaphragm.

It is a dome-shaped muscle that works with your lungs to allow you to inhale (breath in) and exhale (breath out) air.

TRACHEAAt the bottom of the trachea, or

windpipe, there are two large tubes.

These tubes are called the main stem bronchi, and one heads left into the left lung, while the other heads right into the right into the right lung.

The tiniest tubes are called bronchioles, and there are about 30,000 of them in each lung.

At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli.

YOUR HEART AND CIRCULATORY SYSTEMYour heart is really a muscle.It is located a little to the left of

the middle of your chest, and it is about the size of your fist.

The heart sends blood around your body.

The blood provides your body with the oxygen and nutrients it needs.

HOW DOES THE HEART BEAT? Before each beat, your heart fills with

blood. Then its muscle contracts to squirt the

blood along. When the heart contracts, it squeezes. Your heart does this all day and all

night, all the time.

HEART PARTSThe heart is made up of four

different blood-filled areas, and each of these areas is called a chamber.

There are two chambers on each side of the heart.

One chamber is on the top (atria) and one chamber is on the bottom (ventricles).

CIRCULATION Blood moves through many tubes called

arteries and veins, which together are called blood vessels.

These blood vessels are attached to the heart.

The blood vessels that carry blood away from the heart are called arteries.

The ones that carry blood back to the heart are called veins.

It takes your heart less than 60 seconds to pump blood to every cell in your body.