Respiratory System
1. The energy for all activity that you do comes from your food.
a. The process of releasing the energy from food is called cellular respiration.
b. This process requires oxygen and produces carbon dioxide. We get the oxygen by breathing.
c. The respiratory system is made up of the lungs and the tubes through which air moves.
d. The job of the respiratory system is to get oxygen and get rid of carbon dioxide
2. When you inhale, air enters the respiratory system through the nose and mouth.
a. The nose has short hairs which filter out dirt and dust.
b. Once inside the nasal cavity, the air is moistened and warmed.
c. The cells are also covered by cilia which sweep mucus back toward the nose.
d. Cells inside the nasal cavity produce mucus which traps more dirt and dust. If this mucus gets trapped it can irritate the nose, causing a sneeze.
3. Pharynx
a. The pharynx, or throat, is where the esophagus (leading to the stomach) and the trachea (leading to the lungs) meet.
b. When you swallow, the epiglottis covers the trachea so that food does not enter the lungs.
c. When you inhale, the epiglottis raises and air moves into the trachea.
d. When this system fails, food can enter the trachea and cause choking. Coughing usually forces the food back out.
4. Trachea
a. The trachea, or windpipe, is the tube which leads from the pharynx to the lungs.
b. At the top of the trachea is a structure made of cartilage called the larynx.
i. Inside the larynx are two folds of tissue called the vocal cords.
ii. When you speak, your vocal cords tighten and as you breathe out, the air passing over them causes them to vibrate. This makes the sound of your voice.
c. The trachea is lined with two different kinds of cells.
i. Some produce mucus to trap dirt and dust that get past the hairs in the nasal cavity.
ii. Others contain cilia. These tiny hairs sweep the mucus toward the top of the trachea.
iii. This mucus is swallowed when it reaches the esophagus.
iv. If the mucus collects, coughing can result to expel it.
5. Bronchi and Bronchioles
a. The trachea divides into two tubes called bronchi, one leading to each lung.
b. Inside the lungs, the bronchi divide into smaller tubes called bronchioles.
c. All these tubes are also lined with cells that produce mucus and have cilia.
6. Alveoli
a. At the ends of the bronchioles are tiny air sacs called alveoli. They look like bunches of grapes.
b. The alveoli are surrounded by capillaries.
c. The thin walls of the alveoli and capillaries allow oxygen and carbon dioxide to pass easily between the blood and the alveoli
7. Gas Exchange
a. The most important part of the respiratory system is the gas exchange that occurs.
b. The exchange happens because of diffusion.
c. In the alveoli, the air has a high level of oxygen and a low level of carbon dioxide.
d. Blood in the capillaries is low in oxygen and high in carbon dioxide.
e. Diffusion causes oxygen in the alveoli to move into the blood and carbon dioxide in the blood to move into the alveoli.
f. The oxygen is carried by the circulatory system to all cells of the body.
g. When blood reaches the cells of the body, oxygen diffuses out of the blood into cells and carbon dioxide diffuses from the cells into the blood.
h. The blood is then carried back to the lungs and carbon dioxide leaves your body when you exhale.
8. Breathing
a. Breathing and respiration are NOT the same.
i. Breathing is the process of getting air into and out of the lungs. It is how we get the oxygen we need for respiration.
ii. Respiration (or cellular respiration) is the process your cells use to convert food into energy
b. The diaphragm and the rib muscles make breathing possible.
i. Inhaling
(1) When you inhale your rib muscles contract, moving your ribs upward.
(2) Your diaphragm contracts, moving downward.
(3) These two actions make your chest cavity larger and air moves in to fill the lungs.
ii. Exhaling
(1) The opposite happens when you exhale. The chest cavity gets smaller, forcing air out of it.
c. There is a small part of your brain that controls breathing so you don’t have to worry about it.
9. Respiratory Diseases
a. Pneumonia
i. This is an inflammation of the lungs usually caused by bacteria (but sometimes by viruses).
ii. The bacterial infection causes fluid to develop in the alveoli.
iii. This fluid interferes with the gas exchange between the alveoli and the blood.
iv. As a result, the cells of the body cannot get enough oxygen.
v. Symptoms include fever, chills, coughing, fatigue, and tightness in the chest.
b. Bronchitis
i. This is an inflammation of the bronchi.
ii. It is caused when dust, dirt, or bacteria in the air we breathe are not filtered by the hairs and mucus in the nose and trachea. These can irritate the cells in the bronchi.
iii. The symptom is a serious, persistent couch
c. Asthma
i. In some people, the dust and dirt in the air can irritate the walls of the bronchioles causing them to contract and become narrow.
ii. This makes breathing difficult.
iii. Symptoms include difficulty catching your breath and it is treated by taking medications that cause the bronchioles to relax.
iv. Some cases of asthma are caused by an immune reaction to harmless particles such as dust, dirt, smoke or pollen.
d. Emphysema
i. This disease occurs when the walls of the alveoli become less flexible.
ii. This makes the gas exchange more difficult and the person would have trouble getting enough oxygen.
iii. It often results from chronic bronchitis when the airways become clogged with mucous and air becomes trapped within the alveoli
iv. In serious cases, the patient would have to wear an oxygen mask and carry an oxygen tank.
e. You should note that ALL of these diseases can be caused by smoking cigarettes.