oy, all that running and jumping sure has me out of breath,” observed Bill, “and my heart is just racing, too.” You see, Bill’s mitochondria were busy doing cellular respiration to provide his muscle cells with enough energy to play volleyball. However, in order to do that, his mitochondria needed lots of oxygen to burn sugar for fuel, and produced a lot of carbon dioxide, of which his body needed to rid itself. Thus, his circulatory and respiratory systems were working to keep up with his mitochondria.

Circulatory and Respiratory Systems

Our circulatory (or cardiovascular) system is made up of our heart, veins, arteries, capillaries, and blood. The job of the circulatory system is to do just as its name suggests: to circulate various chemicals around within our bodies. Oxygen is carried from the lungs to all of our other cells, and carbon dioxide, given off as “exhaust fumes” is carried back to the lungs to be exhaled. Nutrients absorbed from the digestive tract are carried to our liver for storage and/or processing, or to other cells that need them. Various waste products and any excess water are carried to places such as the kidneys, skin, or lungs, to be released. Hormones, our internal chemical messengers, are also distributed from the organs which secrete them, via the circulatory system, to the target organs which need to receive them.

Pretty much whatever you put into your body will be circulated via the circulatory system. Drugs which a person ingests or inhales, chemicals absorbed through the skin (like a nicotine or nitroglycerine patch), alcohol, caffeine, cholesterol (LDL and HDL), mercury from a person’s dental fillings, aluminum from deodorants, and all sorts of other chemicals that find their way into someone’s body are transported by the circulatory system. That could be “good” or “bad,” depending on what’s being circulated and where it ends up. If the circulatory system is carrying nutrients and oxygen to our cells or carbon dioxide to the lungs, that’s a “good” thing, but if the oxygen-carrying sites in the red blood cells have gotten “clogged up” with carbon monoxide from cigarette smoke and can’t carry oxygen, or if alcohol or mercury (from dental fillings) are being carried to a person’s brain, those are “bad” things.

The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, and lungs. The lungs are made of many small bronchi and the alveoli, the sacs where air is actully exchanged. The walls of the alveoli are very thin, and they are directly in contact with very small capillaries, so it’s easy for oxygen to diffuse from the alveoli into the capillaries and carbon dioxide to diffuse from the capillaries into the alveoli. Interestingly, there are no muscles in our lungs – our lungs do not “breathe” in the sense of inhaling and exhaling. Rather, when the diaphragm, a muscle which forms the bottom of the chest cavity and separates the chest from the abdomen, contracts, that increases the available space within the chest cavity, and that pulls air into the lungs. For comparison, when a frog breathes, it fills its mouth with air, then uses the expandable floor of its mouth to push air into its lungs.

The insides of our trachea and bronchi are coated with a layer of cells which have a really long name:

pseudostratified ciliated columnar epithelial cells.

Let’s go through that word-by-word and explain what that means.

pseudostratified

This means the cells look like but are not (pseudo) layered (stratified). Notice in Dr. Fankhauser’s photo that the cells’ nuclei (the round, red structures) are not all at a uniform height.

ciliated

This means the top surfaces of the cells are covered with many short “hair-shaped” structures called cilia. Notice the “brushy” structures at the top of the photo.

columnar

This means the cells are relatively tall and thin, thus, are the shape of a column. Because these cells are pseudostratified and not all “neatly” lined up next to each other, that’s a bit harder to see in the photograph.

epithelial

This means the cells belong to a group of types of cells, all referred to as “epithelial cells”, which coat or line various body organs. Other examples of epithelial cells include skin and mucous membrane.

The cilia play an important role in keeping us healthy, and thus, it’s important to keep them healthy. As we inhale, along with the air, we also breathe in small particles of dust, and of course, smokers breathe in a lot of smoke particles. Any of those particles can be rough enough to scrape against and damage the delicate cells in the alveoli in the lungs. To protect against that, first, our respiratory system coats all those particles with nice, soft, slippery mucus. The cilia are in constant motion (unlike my animation), sweeping upward like little, miniature brooms, and that action sweeps all those coated particles up and out of the lungs, bronchi, and trachea, and up into a person’s throat where they can be gotten rid of. By keeping all that debris out of the lungs, that eliminates a source of “food” for bad bacteria, and thus, helps to keep us healthy.

However, when a person smokes and inhales all the toxic chemicals in the smoke, the first thing that does is to paralyze the cilia so they stop working. Then, if the person keeps smoking, the pseudostratified cililated columnar epithelial cells are all killed. That means the person can’t eliminate all those mucus-coated smoke particles from his/her lungs, and they may serve as “food” to encourage bacteria to grow, hence smokers typically have more respiratory illnesses than non-smokers. In an attempt to rid the lungs of that mess, the person’s body reacts in what we call a “smoker’s cough.” When a smoker coughs, you can hear both how “deep” the cough is, plus all that trapped “gunk” moving around (and after several such coughs, hopefully, up and out).

I’m guessing that probably, most smokers didn’t know before they began smoking that nicotine is one of the most addictive drugs around. Now, many of those smokers wish they could stop smoking, but find it extremely difficult to do so. However, one more reason to quit is that, if a person successfully does so, the pseudostratified ciliated columnar epithelial cells that have been killed will be replaced by new, healthy cells and the cilia will start sweeping, again, and thus, the “gunk” and the smoker’s cough will go away.

Background Information

Links to Related Information on Our Web Server

The following Web pages contain information related to the circulatory and respiratory systems.

Bio Lecture Circulatory System

Information on the system used to circulate nutrients, wastes, and gases throughout our bodies

Bio Lecture Respiratory System

Information on the system used to get oxygen into our bodies and expel carbon dioxide

Bio Lab Pulse and Blood Pressure Activity

An activity to learn how to take pulse and blood pressure measurements

Your Assignment
Effects of Smoking

You are asked to research the effects of smoking on the respiratory, circulatory, nervous, and immune systems. Also, pick one of either the integumentary, digestive, endocrine, excretory, or reproductive system, and also research the effects of smoking on that system. Use the Web and any available library resources, but think critically about the credibility of the sources you use – remember there are a lot of people putting information out there on the Web that is not always right, and in this case, you might run across tobacco-industry-sponsored Web sites which may be trying to convince people that their products are totally harmless, just because they’re trying to make money. Keep in mind such things as what kind of research was done, did the researchers properly follow the scientific method or are some things missing, and are the conclusions which they drew based on cited data or, seemingly, “pulled out of thin air”? The grading criteria for this assignment are given below, and you should also refer to those as you work on the assignment. A total of 16 points is possible.

1. As mentioned above, research the effects of smoking on five body systems:
   1. respiratory
   2. circulatory
   3. nervous, and
   4. immune systems, plus
   5. one of either the
      • integumentary
      • digestive
      • endocrine
      • excretory, or
      • reproductive
      systems.
2. Use the information you gained to write a letter, as though to a friend or relative, explaining to that person what you found out. Let’s say the person is a smoker who says (s)he wants to quit, but is having trouble doing so. You want to encourage this person to quit and help him/her to see some of the benefits of quitting. Remembering that nicotine is one of the most physically-addicting drugs of which we are aware, and that, therefore, quitting is hard to do, you don’t want to berate that person for not being able to quit, yet, but rather provide him/her with more information to encourage him/her to want to quit.
3. At this point, if you are a registered student, you should submit your work.

Grading Criteria

1.   Overall:
2	—	The respiratory system information was thoroughly researched and clearly presented
1	—	The respiratory system information was adequately researched and presented
0	—	The respiratory system information was sketchy and/or mostly incorrect
2	—	The circulatory system information was thoroughly researched and clearly presented
1	—	The circulatory system information was adequately researched and presented
0	—	The circulatory system information was sketchy and/or mostly incorrect
2	—	The nervous system information was thoroughly researched and clearly presented
1	—	The nervous system information was adequately researched and presented
0	—	The nervous system information was sketchy and/or mostly incorrect
2	—	The immune system information was thoroughly researched and clearly presented
1	—	The immune system information was adequately researched and presented
0	—	The immune system information was sketchy and/or mostly incorrect
2	—	The 5th system information was thoroughly researched and clearly presented
1	—	The 5th system information was adequately researched and presented
0	—	The 5th system information was sketchy and/or mostly incorrect
2	—	Overall, the letter was appropriately-worded, well-written, and informative
1	—	Overall, the letter was adequate
0	—	Overall, the letter was poorly-worded, poorly-written, and/or didn’t contain much information
2	—	The student, obviously, went beyond the minimum requirements of the assignment
1	—	The student adequately completed the assignment
0	—	The student completed considerably less of the assignment than what was required
2	—	It is evident that the student used much insight, thoughtfulness, and critical thinking when completing this assignment
1	—	The student adequately thought about the assignment – there was, perhaps, a bit of “fuzzy thinking” in a couple places
0	—	The assignment gives the appearance of being “slapped together” just to get it done, with little evidence of thoughtfulness
Total Possible:
16	—	total points