What’s up with our Lungs and Respiratory System? Why do we breathe?

Why we breathe b Our bodies need oxygen, one of several gasses in our air, to stay alive b When we breathe air into our lungs, oxygen passes through the thin walls of the air sacs and into our blood b Our heart pumps the blood and oxygen around our body

Breathing cont’d b The oxygen we breathe in mixes with a sugar called glucose, which we get from our food b Oxygen and Glucose combined give us energy b Energy produces water and the gas Carbon Dioxide

Breathing cont’d b Our body does not need these two things together and carries them back to our lungs so we may breathe them out

Our Lungs b Our lungs are one of the largest organs in our body b They work with our Respiratory system to take in fresh air, expel stale air and to help us talk b Our lungs take up most of the space in our chests b But they aren’t the same size (Left is a bit smaller, leaves room for our heart)

Our Lungs b The right lung has 3 sections or lobes b The left has 2 lobes b They are protected by our rib cage b Beneath our lungs is the diaphragm, dome shaped muscle that works with lungs to inhale and exhale air b From the outside healthy lungs are pink and squishy

Lungs b b The RIGHT LUNG is divided into three LOBES, or sections. b b The left lung is divided into two LOBES. b b The PLEURA are the two membranes, that surround each lobe of the lungs and separate the lungs from the chest wall.

Lungs b b The DIAPHRAGM is the strong wall of muscle that separates the chest cavity from the abdominal cavity. By moving downward, it creates suction to draw in air and expand the lungs. b b The smallest subdivisions of the bronchi are called BRONCHIOLES, at the end of which are the alveoli (plural of alveolus).

Lungs b b The ALVEOLI are the very small air sacs that are the destination of air breathed in. The CAPILLARIES are blood vessels that are imbedded in the walls of the alveoli. Blood passes through the capillaries, brought to them by the PULMONARY ARTERY and taken away by the PULMONARY VEIN. While in the capillaries the blood discharges carbon dioxide into the alveoli and takes up oxygen from the air in the alveoli.

Ribs and Lungs b b The RIBS are bones supporting and protecting the chest cavity. They move to a limited degree, helping the lungs to expand and contract. b b The trachea divides into the two main BRONCHI (tubes), one for each lung. These, in turn, subdivide further into bronchioles.

Pharynx and Epiglottis b b The PHARYNX (throat) collects incoming air from the nose and passes it downward to the trachea (windpipe). b b The EPIGLOTTIS is a flap of tissue that guards the entrance to the trachea, closing when anything is swallowed that should go into the esophagus and stomach.

Larynx,Esophagus and Trachea b b The LARYNX (voice box) contains the vocal cords. It is the place where moving air being breathed in and out creates voice sounds. b b The ESOPHAGUS is the passage leading from the mouth and throat to the stomach. b b The TRACHEA (windpipe) is the passage leading from the pharynx to the lungs.

Bronchial Tubes b b The bronchial tubes are lined with CILIA (like very small hairs) that have a wave-like motion. This motion carries MUCUS (sticky phlegm or liquid) upward and out into the throat, where it is either coughed up or swallowed. The mucus catches and holds much of the dust, germs, and other unwanted matter that has invaded the lungs and thus gets rid of it.

Bronchial Tubes b At the bottom of our trachea (windpipe) there are 2 large tubes, Main stem bronchi b One main stem bronchus (sing.) goes to the left, the other to the right b The main stem bronchus branches off into bronchi (other tubes that get smaller and smaller, like tree branches) b The tiniest tubes are called bronchioles

Bronchial Tubes and Aveoli b About 30,000 bronchioles in each lung b Each bronchiole is about the thickness of a hair b At the end of each bronchiole are teeny tiny air sacs called aveoli b About 600 million aveoli in the lungs, stretched out they’d cover a tennis court

Alveoli b Each alveolus (sing.) has mesh covering of small blood vessels (capillaries- so small cells in blood need to line up single file to pass through)

When we Inhale b Diaphragm contracts and flattens out, moves down so lungs have more room to get larger as they fill with water b Rib muscles also lift ribs up and outward to give lungs more space b On the way down the windpipe, the tiny hairs (cilia) move to keep mucus and dirt out of lungs

Inhaling b Air then goes through bronchi and bronchioles (series of branches) b Air finally reaches 600 million alveoli b As the millions of alveoli fill up with air, the lungs get bigger b The alveoli allow oxygen from the air to pass into the blood

Inhaling cont’d b All cells in the body need oxygen every minute b Oxygen enters blood in the capillaries and hitches a ride on red blood cells traveling through layers of blood vessels to the heart b The heart then sends all oxygenated blood out to cells in the body

Exhaling b The reverse, diaphragm moves up, pushing air out, rib muscles relax, ribs move in b Cells have used oxygen, blood carries out CO2 – Carbon dioxide and other wastes that must leave the body b Lungs covered by pleural membranes that keep junk from getting in

Other Parts of the Respiratory System b b The SINUSES are hollow spaces in the bones of the head. Small openings connect them to the nasal cavity. The functions they serve are not clearly understood, but include helping to regulate the temperature and humidity of air breathed in, as well as to lighten the bone structure of the head and to give resonance to the voice.

Oral Cavity b b Air also enters through the ORAL CAVITY (mouth), especially in people who have a mouth-breathing habit or whose nasal passages may be temporarily obstructed, as by a cold.

Nasal Cavity b b The NASAL CAVITY (nose) is the preferred entrance for outside air into the Respiratory System. The hairs that line the inside wall are part of the air-cleansing system.

Adenoids b b The ADENOIDS are overgrown lymph tissue at the top of the throat. When they interfere with breathing, they are generally removed. The lymph system, consisting of nodes (knots of cells) and connecting vessels, carries fluid throughout the body. This system helps resist body infection by filtering out foreign matter, including germs, and producing cells (lymphocytes) to fight them.

Tonsils b b The TONSILS are lymph nodes in the wall of the pharynx that often become infected. They are an unimportant part of the germ- fighting system of the body. When infected, they are generally removed.

Sources b Looking at Your Lungs b Kittredge, Mary. The Respiratory System. Philadelphia: Chelsea House Publishers, 2000.

Other Resources b Parker, Steve. Lungs. Brookfield, Connecticut: Copper Beech Books, b Parker, Steve. The Lungs and Respiratory System. Austin, Texas: Raintree Steck-Vaugn Publishers. b Stille, Darlene. The Respiratory System. New York, NY: Children’s Press, b Ylvisaker, Anne. Your Lungs. Mankato, Minnesota: Capstone Press, 2002.