Objective 53 & 64: Laws and gas transportation

Objective 53: Define Dalton's law of partial pressure, Boyle's gas law and relate both to respiratory physiology
Objective 64: Discuss how oxygen and carbon dioxide are transported

When I was scoping out the textbooks website, I came across the MP3 tutor sessions and found this one that was a lot of help. They are very lengthy, I admit but they gave me some very helpful information. What I love about these tutor sessions is that they simplify the topics that they are going over in the session, which helps tremendously. It describes both Dalton's law of partial pressure and Boyle's gas law, and was able to help me understand how the relate to respiratory physiology. Another thing I really like about these tutor sessions is that they always provide multiple examples on how the topics discussed are related to real life. So basically Dalton's law explains how gases behave when they are mixed together and Boyle's law explains how gas pressure and volume are inversley related, or the smaller the space than the greater the pressure. This session was also helpful in finding out how oxygen and carbon dioxide are transported because it gave a great deal of information about the two gases. Being able to listen and read along with the session made the two topics more clear to me and im glad that I was able to come across it.







Pearson welcomes you to MP3 Tutor Sessions for Anatomy and Physiology.
Gas Exchange During Respiration
Section 1: Tough Topics

Take a deep breath. Now hold it, hold it hold it. Okay, let it out. We don't usually think about our breathing under resting conditions. It is something that just happens. Oxygen goes in and carbon dioxide goes out. It seems simple, until something disrupts the process—like holding your breath—at which point we start to appreciate the complexity of the respiratory system. So, what does happen when you breathe in and out? And what happens when you hold your breath?
This tough topics section explores how gas exchange occurs during respiration. Gas exchange associated with the respiratory system involves the exchange of oxygen for carbon dioxide at the lungs and carbon dioxide with oxygen at the tissues. To better organize our discussion, we'll break the discussion into four parts. First, we will discuss the anatomy of the respiratory system. Then we will talk about how pressure affects breathing and gas exchange. The third section will focus on pulmonary ventilation, the process of getting the air in and out of your lungs. Finally, we'll discuss alveolar ventilation, the process of actual gas exchange. So, take a deep breath... and let's begin.
Your respiratory system consists of the nose, nasal cavity, the pharynx, larynx, trachea, bronchi, and lungs. Within the respiratory system are the conducting zone and the respiratory zone. The conducting zone includes everything from the nose to the respiratory bronchioles. It is called the conducting zone because its job is to get the air to the actual site of gas exchange, the alveoli.
The respiratory zone includes the respiratory bronchioles and alveoli. Alveolar ducts lead toalveolar sacs containing the alveoli. The alveolar sacs resemble grape clusters. An alveolus (the singular form of alveoli) is like a single grape in the cluster. The walls of the alveolar sacs are very thin; expanding when air enters and recoiling when it is exhaled. Think of a balloon that you blow up. The balloon expands to a certain volume safely. Then when the air is released, it deflates, recoiling to close to its original size. The alveoli act in much the same way.
The three hundred million alveoli in the lungs comprise a huge surface area for gas exchange. In fact, if they were spread out in a single layer, the alveoli would be the size of a tennis court! The alveoli expand when air enters, using a mechanism called pulmonary ventilation that generally costs us very little energy to perform.
Before we talk about how ventilation works, we need to learn a little bit about the musculature that helps pulmonary ventilation occur and about gas exchange that results from alveolar ventilation. Let's start with the muscles that facilitate breathing. The diaphragm is the primary muscle involved with breathing. It effectively separates your thoracic cavity from your abdominal cavity. Its main function is to increase the volume of the thoracic cavity by contracting downward into the abdomen. The external and internal intercostal muscles increase or decrease the volume by causing expansion or contraction of the ribcage.
That explains how air gets into the lungs. But how does it get into the cells? This is the process of alveolar ventilation. Gases, namely oxygen and carbon dioxide, are exchanged through the respiratory epithelium. This means that the oxygen diffuses out of the lungs into the blood circulation, where it is picked up by the hemoglobin in red blood cells. At the same time, carbon dioxide diffuses from the red blood cells and plasma through the respiratory epithelium where it is exhaled. The gases can diffuse because they are following pressure gradients, which behave similarly to concentration gradients.
To understand more about how these pressure gradients work, we will discuss three important laws that describe how gas behaves in confined spaces. These gaslaws are fundamental to understanding how we can take air in, move oxygen into our cells, and expel carbon dioxide. Boyle's Law of Gas Pressure and Volume explains how air is drawn into and expelled from the lungs. Dalton's Law of Partial Pressures describes how pressure gradients can facilitate diffusion for individual gases between your blood and lungs. And Henry's Law explains how gases can move into and out of solution—in the case of our bodies, how oxygen and carbon dioxide can dissolve and diffuse out of the blood. Let's start the discussion with Boyle's Law.
Boyle's Law basically states that gas pressure and volume are inversely related. What this means is that the smaller the space the gas is contained in, the greater the pressure of the gas in that container. Imagine that gas molecules are ping pong balls in a big box. They don't interact very much. Then you put the same amount in a smaller box and a smaller box, they interact more and more. As they interact more, the pressure increases.
Boyle's Law explains how the air gets in and out of your lungs, that is, how it travels through the conducting system and fills the alveolar sacs. It works like this: Gas pressure changes in your thoracic cavity in response to your muscles contracting and your ribcage expanding.
At rest, your diaphragm contracts in a downward movement and the external intercostal muscles pull the ribcage up and out. This causes the volume in the thoracic cavity to increase. But when this happens, the air that did not leave the lungs during the previous exhale completely fills the available space. But since the space is much larger, the air molecules are farther apart, so the air pressure decreases. This drop in pressure prompts you to inhale because the lungs passively expand at the same time as the thoracic cavity does. This is due to the pleural fluid's surface tension which keeps the visceral and parietal pleurae very close together -- literally pulling the lungs outward with the thoracic wall. Air moves into the expanding lungs because air, like any fluid, moves from an area of greater (atmospheric) to lower (intrapulmonary) pressure.
Breathing out is the result of the opposite situation: the pressure in your thoracic cavity is higher than the pressure of the atmosphere around you. Your body wants to equalize the pressure. It does this simply by relaxing the diaphragm and the external intercostal muscles. During forced breathing, for instance, when you are exercising, muscles are recruited for both inhalation and exhalation. They serve the function of not only increasing your respiratory rate, but also the volume in your thoracic cavity in an effort to get rid of oxygen debt.
Let's talk more about how gas exchange occurs between the lungs, blood, and tissues of the body. For this, we have to discuss Dalton's Law of Partial Pressures.
Air is made of a mixture of several gases, including about twenty percent oxygen, eighty percent nitrogen, and minute quantities of carbon dioxide. When these separate gases are mixed together, the total pressure is a result of all the gas pressures combined. When these gases are mixed together the pressure of each is in direct proportion to the percentage the gas takes up in the mixture. So the pressure of the oxygen is twenty and nitrogen is eighty. This is called the partial pressure.
Now, Henry's Law demonstrates that gases mixed together as in air, will dissolve in the liquid based on their partial pressures. Henry's Law deals with partial pressures of gases in two different phases, liquid and gas. So the gases will go in and out of these two phases – BUT – they always follow Dalton's finding on partial pressures. So let's take blood as an example.
You breathe in because the partial pressure in your lungs attached to your thoracic cavity is lower than outside your body. That helps push the air in. Now let's look at what happens at the gas exchange surface, that is, where the oxygen gas gets dissolved in your blood. The blood coming into your lungs has very low oxygen content, which means the partial pressure made up by the oxygen is low. But you just took a breath. So the partial pressure of oxygen in your lungs is much higher. When the oxygen in your alveolar sacs comes in contact with your blood plasma, it dissolves into the plasma until the partial pressures between your lungs and blood plasma are equalized.
The same type of exchange happens with the carbon dioxide – only in reverse. There is more carbon dioxide in your blood plasma than in your lungs, so the partial pressure is higher. Therefore, the carbon dioxide becomes a gas again in order to equalize the partial pressures between the two different phases.
But there are two other factors that will determine how much and how quickly a gas can dissolve into solution. The first is the solubility of the gas. Carbon dioxide is most soluble. Oxygen is only five percent as soluble as carbon dioxide and nitrogen is less than three percent as soluble as carbon dioxide. So at a specific partial pressure, more carbon dioxide dissolves in plasma than oxygen and practically no nitrogen dissolves. That is why having nitrogen make up most of the composition of air is not a big deal. In addition, even though carbon dioxide dissolves more readily, there is so little carbon dioxide in air that you don't have to worry about suffocating. So the only component you get dissolving into your plasma in substantial quantities is oxygen.
The other factor that affects how efficiently gas dissolves into a liquid is temperature. The warmer the liquid, the lower the gas solubility will be. For this example, think of soda – which is only carbonated sugar-water. Carbon dioxide is forced into solution because high pressures are used. As long as the cap stays on, it stays carbonated. If you take off the cap two things happen. First, some of the excess carbon dioxide immediately escapes because you relieved some of the pressure by removing the cap. Second, at room temperature, a soda goes flat--that is, all the excess carbon dioxide has escaped and now you have flavored water without the fizz. As the temperature increased, the carbon dioxide became less soluble, and left the solution.
Applying this to humans, we see that as body temperature rises, oxygen exchange is less efficient because the solubility of oxygen in the heated plasma decreases. That is why many athletes don't perform as well in hot weather. They prefer cooler temperatures because their oxygen exchange is better.
Okay, before we move on to discussing gas exchange between the lungs, blood, and tissues, let's summarize what we have learned about gas laws. Boyle's Law tells us that the decrease of pressure in your lungs causes you to inhale because the internal pressure is less than that outside your body. After you inhale, the pressure in the confined space of your lungs is greater than outside and as a result, you exhale. Dalton's Law of Partial Pressures explains how gases behave when they are mixed together. The pressure in a confined space is the total of all the gas pressures combined. Henry's Law explains how gases can dissolve in a solution. For us, that is air dissolving in our blood plasma. This directly relates to the partial pressure of the gas in the air and in the blood. If the partial pressure is higher in the lungs, the gases will dissolve into the plasma. If the pressure is lower in the lungs, the dissolved gases will come out of solution and become a gas again.
Now let's talk about the mechanisms involved in Alveolar Ventilation. These are the actual events that are occurring between our lungs, blood, and tissues to make gas exchange possible.
Keep in mind that gas exchange occurs by simple diffusion along pressure gradients. So no energy is expended and the gas goes from high to low pressures. The space between your alveoli and the blood—called the respiratory membrane—is extremely small, only half a micrometer wide, facilitating diffusion. The respiratory membrane consists of the alveoli cell membranes, the fused basal lamina of endothelial and alveolar epithelial cells, and the endothelial cells that make up the lining of the capillaries. This space is only half a micrometer wide. So the gas molecules have a very small distance to go. They are small enough to slip right through the cell membranes.
Now when you inhale, the amount and partial pressure of oxygen is greater in the alveolar sacs. This pressure gradient causes the oxygen to traverse the respiratory membrane and enter the blood plasma, where it quickly binds to hemoglobin. Oxygen has such a high attraction for the iron in hemoglobin that under normal conditions, less than five percent of the oxygen is freely circulating. The rest is bound to hemoglobin.
The red blood cells carry oxygen to all parts of the body, where the partial pressure of oxygen is lower in the tissues. This causes the oxygen to again follow the pressure gradient, dissociating from the iron and flowing into the tissues. That is how oxygen gets delivered to the tissues.
The process of expelling carbon dioxide works in reverse, so we will start at the tissues. There, cellular metabolism generates carbon dioxide as a by-product. As a result, the partial pressure of carbon dioxide is greater in the tissues than in the plasma. Therefore, as oxygen is released, carbon dioxide is picked up by the red blood cell in exchange and transported to the lungs. It isn't released anywhere along the way because the pressure of carbon dioxide is higher in tissues than in the red blood cells. Carbon dioxide is released in the lungs because the partial pressure of carbon dioxide in the alveoli is very low.
To summarize, partial pressure and gas solubility are key factors in efficient gas exchange. The partial pressure difference for oxygen between the lungs and tissues is twelve to fifteen times greater than the partial pressure differences for carbon dioxide. But due to the higher solubility of carbon dioxide, the same amounts are exchanged. In addition, the distance across the respiratory epithelium is small enough to allow simple diffusion to occur rapidly, facilitating effective gas exchange.
So, to return to the question we asked at the beginning of this section, what happens when you hold your breath? Your body has central chemoreceptors that are more sensitive to increases in carbon dioxide than decreases in oxygen. And during normal breath-holding it's the increase in carbon dioxide, not the oxygen decrease, that stimulates taking a breath.

Objective 51: Describe kidney function

When I was trying to understand the function of the kidneys, I referred to these two slides from chapter 24 lecture power point because they were to the point and provided the important functions of the kidneys. These slides that were provided for the lecture summarized the functions of the kidneys and it was easier to understand all of the functions when they are short and simple. I read and reread the section on the kidneys, but with all the information in the book it made it hard for me to pinpoint the exact functions that the kidneys were responsible for. I am grateful for the slides because they aided in my understanding of the basic information.

Another source of information that I came across in my quest for understanding kidney function was from National Kidney Foundation: How your kidneys work. This passage from the article is also to the point, but it provides a little more information about the functions of the kidneys that was helpful to me and provided me with a little bit of an "ah ha" spark. The kidneys are a very important part of our body system, and also an organ that I didn't realize played such a vital vole in our bodies homeostasis. I never realized how important the kidneys functions were to our body until my mother was diagnosed with a rare disease called Wegener's Granulomatosis. Although Wegener's disease is known as an autoimmune disease, this disease majorly effects the upper respiratory tract, lungs and kidneys. My mother was seriously ill for almost a year, but she thankfully caught the disease in time and is currently in remission. If the disease was left untreated, Glomerulonephritis may develop and the kidneys won't be able to filter out wastes and excess fluids from the body properly. This causes accumulation of wastes products in the blood stream and cause kidney failure. Until my mother was diagnoised with this disease, I always took forgranted the importance the kidneys play in our body. Now I have a better understanding of the function of this organ.

The kidneys perform several important jobs including the removal of chemical and mineral impurities from the blood, balancing acid in the blood, and controlling body fluids. These delicate processes take place when blood flows through the kidneys. The kidneys also help to control your body’s production of red blood cells, regulate blood pressure, and help keep bones strong and healthy. Each kidney has about a million tiny nephrons. Each nephron has a group of tiny blood vessels called a glomerulus. The glomerulus is the small structure in charge of filtering and cleaning the blood as it flows through the kidney. The rate at which the glomerulus filters the blood is called the glomerular filtration rate or “GFR”.
The kidneys filter almost 200 quarts of blood every day and make approximately two quarts of urine as the waste product. When the kidneys don't work like they should, products in the blood which are supposed to be removed, like the blood urea nitrogen (BUN), and creatinine (Cr) stay in the blood and can be easily measured with a blood test. Other products that are supposed to stay in the blood, like proteins, end up in the urine and can be measured with a urine test.



Objective 52: Detail the kidney involvement in blood pressure and blood volume regulation

Trying to pinpoint the kidneys involvement in blood pressure and blood volume proved to be very difficult for me, but this chart that I included from page 849 briefly and accurately describes all of the process that effect blood pressure and blood volume. Whenever I have to figure out lenghty process that have multiple steps, it is very hard for me to grasp. Just reading the textbook confuses me because it seems like there are hormones and mechanisms involved in something that sounds so uncomplicated as blood pressure. I never realized how much our body has to do just to regulate the blood pressure and volume of our bodies, and if just one step of this process failed we could be in a world of hurt. Blood pressure is something that I need to pay close attention to because my family has a history of high blood pressure, and if something goes wrong with one of the hormones or organs that are involved it could seriously throw things off. I still have a hard time understanding the entire process of blood pressure and blood volume regulation, but this chart and portion of the textbook are very informative in showing how the body works to regulate the two. I personally think the chart helped clear things up better than the passage of the textbook because it shows things step by step and doesn't involve excess information to throw you off.

Objective 27: Listen to heart sounds

This objective was pretty easy to learn, since I listen to heart sounds everyday as a certified nursing assistant. I took the C.N.A course about a year and a half ago through T.C.L continuing education, and the course is where I learned how to listen to heart sounds using a stethoscope. Beside our course online, I had to complete a couple skills classes and we took turns listening to each others heartbeats. My class performed clinicals at Bayview Nursing Home. We were required to use to the stethoscope to listen to our assigned patients heartbeat and to hear the systolic and diastolic beats of the blood pressure. I currently work as a C.N.A. at NHC nursing home in Bluffton, so it was beneficial that I've had prior experience listening to heart sounds. In our A & P II class this semester, I had a lab that required us to use the stethoscope and listen to different parts of another classmate's chest to hear the aortic valve, pulmonary valve, mitral valve, and tricuspid valve. This was helpful to me because I didn't know that by placing the stethoscope by different valves of the heart produced different heart sounds. This lab helped reinforce the information that I had previously learned in my C.N.A. course.

Objective 36, 39, 40, 41, 42: Immunity

Objective 36: Recognize pathogen types and outline how the body protects itself
Objective 39: Explain why development of self-tolerance is important
Objective 40: Describe cellular and non-cellullar immunity
Objective 41: Summarize developmnet and maturation of B- and T- lymphocytes
Objective 42: Distinguish non-specific, innate, or natural immunity from specific or acquired immunity

I found this MP3 tutor session on our textbooks website under chapter 19. I was trying to figure out a way to just upload the audio version of the tutor session so I didn't have to include the whole passage (since the audio version was about 17 mins by itself), but I've spent the last 45 minutes trying to figure out how to get it on this site and I gave up. When I came across this session, it went over five of our objectives which was very beneficial to me. Listening to the session helped me learn the information because they describe the information accurately, but they also shorten the information into easier language for me to understand. It's hard to grasp the concepts of the different types of immunity, or about the B and T lymphocytes because the book describes them in lengthy detail in scientific words that make it difficult for me to actually know what they are trying to tell me. This passage not only sums up all of these objectives, but it relates the immunities and lymphocytes to real life situations like when they talked about the kid eating someone else's gum or how vaccines help our bodies make antibodies. By this passage giving everyday examples, It helps me relate all these objectives to real life and the information stuck better. This tutor session was more helpful than reading the textbook alone.

Our body is equipped with some of the most amazing defenses we could ask for. Our body is like kind of like a military force, always there to protect us and ward off any dangers that may come our way. Our body is equipped with mechanical barriers ( such as skin) and chemical barriers in charge of destroying those harmful pathogens that come our way. The type of pathogens that our bodies are faced with are bacteria, viruses, fungi and protists. Our skin is a highly effective first line of defense in warding off those pesky pathogens, but when our skin fails to get the job done thats when innate immunity and adaptive immunity come into play. These two immunities, along with cellular and non cellular immunity, work closely together to get rid of the pathogen that threatens to distrupt our bodies normal functioning. With all of this hard work going on, it is very important that our bodies develop a sense of self-tolerance. In other words, it is very important for our body recognize its own antigens and refrain from attacking them. If they do attack them, this is when an auto-immune disease takes place and causes our immune system to attack its own antigens as well as foreign ones. I know how how important self-tolerance is first hand because my mother suffers from a rare auto-immune disease and she struggled for the last few years trying to get help so her body would stop attacking its own antigens, causing her to always be sick from the slightest things. Its an ongoing battle, but thankfully she is winning at this moment in time.

Along with this MP3 tutor session, I came across this slideshow called Defending Against Infection that went along with objective 36 and helped summarize how the body defends itself from these harmful pathogens.

Pearson welcomes you to MP3 Tutor Sessions for Anatomy and Physiology.
Differences Between Innate and Adaptive Immunity
Section 1: Tough Topics

HIV, SARS, Ebola virus, STDs. They are all around us. Sometimes it feels like we are losing a war against microbes. But let's take stock for a moment. Little kids play outside all day long. They pick up frogs, eat bugs, and chew someone else's gum and they are almost always fine. In most cases, the worst thing that happens is that they get a runny nose. The fact is that even though you are exposed to millions of different microbes everyday, you seldom get sick. All because of the vigilance of your immune system.
In this tough topics section, we will discuss the two major parts of the immune system: innate immunity and adaptive immunity. Innate immunity is the immunity you are born with, and adaptive immunity, also called specific immunity, is acquired through exposure to pathogens throughout your lifetime. Pathogens can be bacteria, viruses, or parasites. Basically anything that disrupts homeostasis. We will begin by defining immunity, highlighting the key players--the white blood cells. In the next section we will discuss innate immunity. We will finish the discussion with a description of adaptive immunity. Let's get started.
The immune system is composed of millions of molecules and cells working to destroy anything identified as not being part of you. The foot soldiers in this war on microbes are the white blood cells. Let's look at the various types.
White blood cells are large, translucent blood cells with an arsenal of organelles. All white blood cells are leukocytes. Leukocytes form in the bone marrow. After their formation they follow different, preprogrammed destinies to dispose of microbes by engulfing them, lysing them, or synthesizing products to help destroy them.
White blood cells can be divided into different subsets based on the type of immunity that is triggered for defense. Monocytes, which become macrophages, neutrophils and eosinophils, are all considered phagocytes. Phagocytes destroy pathogens by engulfing them in vesicles, internalizing them, breaking them down, and spitting out the remains. Another important subset of white blood cells is the lymphocytes, which include B cells, T cells, and natural killer cells. Lymphocytes are more subtle assassins. They poke holes in cells, injecting enzymes that kill the microbe, or they produce antibodies that smother the intruder, targeting it for destruction.
Phagocytes and natural killer cells are important members of innate immunity, while B cells and T cells are active members of specific immunity. Let's discuss innate immunity and the leukocytes that play an important role in its success at stopping pathogens.
Innate immunity is your first line of defense. This defense begins with your skin and mucous membranes. But what happens if you get a cut that breaches the skin's defenses, and it gets infected? At that point, the internal defenses take over, using immune cells and chemicals to attack invading pathogens. We will discuss the cellular defenses first.
Innate immunity relies on two broad categories of cells for defense: phagocytes and natural killer cells. As we discussed, phagocytes destroy pathogens by engulfing them in vesicles, after which they break them down and spit out the remains.
Natural killer, or NK, cells are derived from lymphocytes. They migrate over all the tissues of the body looking for and destroying abnormal cells like cancer cells and virally-infected cells. The NK cells can recognize these cells as different because they lack the appropriate signals identifying the cell as being "you." This lack of "you" traits is usually in the form of a tag such as a specific cell membrane receptor or the presence of unidentified sugars that belong to the pathogen.
Unlike phagocytes that engulf their prey, NK cells come in direct contact with the target cell, poke holes in the membrane, and inject it with toxic chemicals. This type of attack is very similar to another lymphocyte we will talk about later called the T cell. NK cells also secrete potent chemicals that act like flare guns to augment the inflammatory response. This flare gun signals macrophages, other lymphocytes and some of the chemical defenses to help combat the infection.
Okay, we've discussed the various cellular responses to microbial attacks. Now let's talk about how your immune system wages chemical warfare on invading pathogens. The arsenal of chemical weapons includes the inflammatory response, the secretion of antimicrobial proteins, and fever. The inflammatory response kicks into gear when you suffer from some physical injury, such as getting kicked. It also becomes activated by injury from intense heat, irritating chemicals, or infection from viruses, bacteria, or fungi. Let's look more closely at the inflammatory response.
At some point, you have probably experienced an infected cut. You knew it was inflamed because it was red, swollen, hot, and painful--the four signs of inflammation. Inflammation begins with a warning siren made up of chemicals secreted by the injured tissues. These chemicals act as a homing beacon for macrophages and mast cells to migrate to the injury site. Macrophages start engulfing bacteria and debris while mast cells secrete histamine. Histamine is a very potent inflammatory chemical that causes the symptoms we associate with allergies, like a runny nose, hives, and watery eyes. Histamine causes the surrounding arterioles to dilate. This brings warm blood to the area and increases the local temperature. In addition to this, the histamine increases permeability of the local capillaries to promote exudation, the leaking of capillary fluid into the tissues, carrying antibodies and clotting factors with it. This is what causes the swelling. And the swelling in turn presses on nerves, causing the pain.
If the injury is badly infected, pus can develop. This creamy-yellow substance is a mixture of dead white blood cells, ruined tissue, and living and dead pathogens. If the area is very badly infected, it can be walled off from the rest of the body by scar tissue. The scar tissue is made from collagen fibers and can form an abscess. At this point, the pus and fluid build-up within the abscess will have to be drained before the injured area will heal properly.
Besides the inflammatory response, innate immunity also includes antimicrobial proteins. These antimicrobial proteins include the interferons and complement proteins. Interferons are proteins secreted by infected cells in a last ditch effort to save adjacent uninfected cells from viral attack. Interferons diffuse into adjacent cells and cause the still healthy cell to synthesize proteins that stop viral protein synthesis and degrade the viral RNA.
The complement system, usually just called complement, includes a group of more than twenty plasma proteins that circulate in an inactive state. Their function is to "jack up" the response by the immune system to its highest active status. It does this through chemical mediators that enhance every aspect of immunity—hence the name complement. Complement can be activated either by antibodies or when certain complement factors interact with microbial molecules and target them for destruction.
The final component of innate immunity is fever. While inflammation is a localized response, fever is a systemic response—that means it affects your whole body. Fever usually occurs if the infection is widespread and internal. Fever is an increase in the body temperature that occurs when your internal thermostat—regulated in your hypothalamus—is reset to a higher point. The reason your thermostat gets reset is because leukocytes and macrophages secrete chemicals called pyrogens. Low and moderate fever is an effective immune response; it speeds up the body's metabolic rate, which in turn accelerates the repair process.
Let's summarize what we have discussed so far. Immunity is your body's defense against pathogens. There are two types of immunity: innate and adaptive. Innate immunity is the immunity you are born with and includes both physical barriers such as the skin and internal defenses. Internal defenses include cellular defenses performed by phagocytes and natural killer cells, as well as inflammation, antimicrobial proteins, and fever.
Now let's talk about adaptive or specific immunity.
Adaptive immunity is the body's specific immunity. Unlike your innate immunity which is nonspecific and attacks anything it recognizes as foreign, damaged or unknown, adaptive immunity is very choosy. Adaptive immunity will only attack specific threats. Adaptive immunity is carried out by two types of lymphocytes, the B cells and the T cells. Like all blood cells, the lymphocytes first develop in the bone marrow. B cells stay and mature there. Immature T cells migrate to the thymus where they mature. These lymphocytes become immunocompetent and have to be self-tolerant. In other words, these cells have to be able to evoke an immune response and make sure that response isn't against your own normal cells.
Adaptive immunity has three underlying traits. First, it is specific. It recognizes and attacks only specific pathogens. Secondly, it is systemic. This is a widespread reaction, not limited to a localized region of the body. Lastly, adaptive immunity has memory. In many cases, once you are exposed to a virus, your body remembers and you become resistant to reinfection.
Adaptive immunity has two components: humoral immunity and cellular or cell-mediated immunity. Humoral immunity produces antibodies. Cell-mediated immunity relies on a particular lymphocyte called a T cell, rather than antibodies, to defend the body. Both of these components work by recognizing antigens. Let's talk about antigen recognition next.
Antigens are cell surface proteins. You, as an individual, have a unique set of self-antigens called your Major Histocompatibility Complex, or MHC. However, when cells are infected by a pathogen or are abnormal, like a cancer cell, non-self antigens are presented. The change can be initiated by the infectious agent or because the cell no longer responds to normal control signals. It is these changed cells that the humoral and cell-mediated immune processes recognize and destroy.
There are two classes of MHC proteins. Class 1 MHC proteins are on all the cells of your body. Class 2 MHC proteins are only found on specific cells of the adaptive immune response. Let's talk in more detail about the humoral and cell-mediated immune responses next.
Humoral immunity works like this. The B cells are formed in the red bone marrow where they mature and become immunocompetent. These are the cells responsible for producing antibodies against foreign antigens. Once a B cell is exposed to a foreign antigen it becomes activated and undergoes cell division. One of the daughter cells becomes a memory cell. That is why you can be resistant to reinfection of say, chicken pox, once you have been exposed. These memory cells may live up to 20 years or longer. The other daughter cell has a different fate. It will continue to divide and produce an army of B cells. Each B cell will go on to produce antibodies that are secreted into general circulation to seek out and destroy the antigen they were exposed to. Antibodies mark the target cells for destruction by causing them to clump together, smothering their surfaces, acting like beacons for complement proteins and phagocytes and causing toxic cell by-products to precipitate out of solution.
But there are limitations to their defenses. B cells can only detect an obvious threat, like bacteria floating around in your blood. They can't detect viruses and bacteria that infiltrate the cells. For this, another defense is mounted by the cell-mediated arm of immunity. Cell-mediated immunity has a more direct approach. Let's look at that next.
T cells are formed in the red bone marrow, and then migrate to the thymus where they become immunocompetent. T cells recognize infected or abnormal cells differently than B cells. They recognize antigens that have been processed into fragments and sent to the cell surface. Once it detects one of these fragments, the T cell binds to it and becomes active. The T cell then divides like the B cell, with one daughter cell becoming a memory T cell and the other the cytotoxic T cell that targets cells with that antigen fragment for destruction "up close and personal." The cytotoxic T cell binds to the foreign cell, pokes holes in it, injects enzymes and toxins into it, and breaks up the cell membrane.
Let's summarize the difference in your humoral and cell-mediated immune responses. The B cells are responsible for the humoral response. This response involves identification of foreign antigens. This activates the B cells to produce antibodies specific for the targeted antigen. They attack and destroy these antigens or antigen-producing cells by clumping, lysing, and precipitating them out of the blood. So humoral immunity can be considered an indirect attack on pathogens by the B cells. In contrast, the T cells initiate a specific immunity response in which the T cell is presented with antigen fragments that cause the T cell to become immunocompetent. Once this occurs, the T cells destroy the unwanted cell by poking holes in the membrane and injecting enzymes to break the targeted cell into pieces.
With adaptive immunity, the first time the B and T cells are exposed to a new antigen, the response is slow. So you get really sick. This is called the primary response. The second time you are exposed, the B and T memory cells have a record of this antigen or antigens like it. So they can respond and divide really quickly, acting like a first strike against the developing infection. That is why you don't get sick when exposed at a later time. This is called the secondary response. So, when you are exposed to chicken pox the first time, you get an intense illness. But you don't get it a second time because your B and T cells can very quickly replicate and destroy the pathogen. That is how vaccines work. A vaccine initiates a primary response at low levels, deliberately introducing the B cells to the antigens. The B cells produce antibodies against the antigens and form a memory of these antigens. Then the next time you get infected, the B cells can respond quickly because they already know to attack the pathogen.
Let's summarize adaptive immunity. It is specific and self-tolerant. B and T cells are the major players. Upon exposure to an unknown antigen, they produce memory cells. B cells produce antibodies, which mount an indirect attack on the infected cells and noncellular pathogens. T cells attack directly to kill the cells by poking holes into them and injecting cytotoxic compounds.
That's the end of this section.

   © 2011 Pearson Education. Publishing as Benjamin Cummings.

Objective 35 & 38: Lymph flow and Edema

Objective 35: Describe the formation and flow of lymph
Objective 38: Relate edema and lymph flow


The Lymphatic System was a very short chapter, so it for me was very easy to understand and get through since it wasn't 10 pages of information to try and soak in. The lymphatic system works quietly, but is a major part of our body because without them our cardiovascular system would stop working and our immune system would be impared. These two paragraphs from our textbook on page 655-656 provide the helpful information that described the formation of lymph. I was actually very surprised that there wasn't much to the formation of lymph. I thought it would have been a longer process than what the book described to me. I also included two of the slides from our class lecture outlines that talked about the formation of lymph and what vessels they flow through. Then the two photos were very beneficial in showing the flow of lymph and where the lymph nodes are located throughout the body. The photos helped me alot because of me being a visual learner. The last photo was definately helpful because it not only showed me where are the lymph nodes were, it showed me the entrance of the thoracic duct into the vein and the right lymphatic duct into the vein.

(pg  658)

Understanding the flow of lymph was relatively easy, but being able to relate edema to lymph flow was not. The book didn't seem to hit the topic for very long, in a way it just seemed to breeze right by it. So that left me wondering, what relation does edema have on lymph flow? Well, anything that prevents the normal return of lymph to the blood results in short, severe localized edema. Edema= swelling. When lymphatic vessels are blocked, leaked protein accumulates in the intersitial fluid and causes an increasing collid osmotic pressure. This draws fluid from the blood and holds it in the interstitial space. This is usually called lymphedema, and cancer patients are an example of people prone to it. Along with the short pieces of information that I found in chapter 25 page 873, this video talking about lymphedema in breast cancer patients was very helpful. It showed me where this occurs in everyday life, and it gives me an appreciation for what cancer patients have to go through.

Objective 4: Differentiate the differences between endocrine and exocrine glands

When I was trying to figure out the differences between the endocrine and exocrine glands, I referred to both my textbook and lab book because they had a very short, simple explanation that was also very detailed and straight to the point. It's harder for me to learn about certain glands or process when the book goes on and on for paragraphs or even pages trying to explain them. So when the paragraphs are short but still give you adequate information, then it was easier for me to learn the concept. The first picture is the short paragrah from the textbook from Chapter 15 (pg. 519), that tells the basic information of the two glands, but it is easy for me to understand the differences when they describe the two side by side. The rest of the pictures are the ones I found from my lab book, the second picture has another little paragraph that gave me a little more basic information about the two glands. Then the next two pictures after that actually showed how the exocrine and endocrine glands are formed from epithelial sheets. It gave me a better understanding on how the two glands actually appear in our bodies.

 (1) Page 519 from our textbook

(2) Page 69 from our lab book

(3) page 69 figure 6 A. 2 from our lab book

(4) page 69 figure 6 A. 2 from our lab book

(5) page 69. the caption under 6 A. 2