Notes

Lymphatic:

You're thirsty. So you go to get a glass of water from the sink. The excess water runs over the glass and goes down the drain. Your lymphatic system works somewhat like that drain, returning the body fluid, the excess fluid from the tissue, back into the body, just like the drain would return the water to another water source. Today we're going to talk about the lymphatic system.
00:00:30 We'll describe the functions of the lymphatic system, identify where lymph comes from, and we'll explain how lymph organs fight infections. Let's look at an overview of the lymphatic system. Like I said, it kind of works like the drain in the sink. If there's excess fluid, the drain will collect that water. Well that's what your lymphatic system does when there's excess body tissue fluids.
00:01:02 That fluid is called lymph. And lymph is what is produced after fluid diffuses into the lymphatic capillaries. But what's a lymphatic capillary? Well it's kind of like a vein that would carry the blood in your body, except that it carries this lymph, this excess tissue fluid. Also inside the lymph is something called lymphocytes.
00:01:31 The lymphocytes are a type of white blood cell and they help to keep your body healthy. They help defend it against disease-causing organisms. These are called helper T cells, but we'll talk about that in a minute. Lymph system has its own organs. These organs are called lymph nodes. Before lymph enters the blood, it passes
00:01:56 through these lymph nodes. These nodes help to filter out microorganisms. So you can kind of imagine if you had a sponge on the top of a drain, and you were pouring a bucket of dirty water through it, that sponge would let the water go through, but it would collect all the yucky stuff that's on the top of the sponge. That's pretty much what a lymphatic organ does or the
00:02:27 lymph nodes. Now you can get diseases in the lymphatic system. The most well known is HIV. HIV attacks and destroys lymphocytes. These lymphocytes, like I said, are called the helper T cells. These T cells are what help boost immunity. They send out B cells to help fight off antigens or the bad
00:02:55 things that we find in our blood. Once we lose these helper T cells that are in the lymphatic system, it affects the person's immunity. In fact, with HIV, you don't actually die from that virus. It depletes the helper T cell so much that you can't fight off any infections, and you become susceptible to diseases like pneumonia. And that's usually how somebody will die if they are
00:03:22 infected with AIDS or HIV. Let's review a little with the lymphatic system. We've described the functions of the lymphatic system and that it returns body fluids back to the blood. We've also identified where the lymph comes from. Lymph is that fluid that also contains lymphocytes. And we've explained how the lymph organs help to fight infections with the helper T cells.

Blood:

Did you know that blood plays a major effect in every major function of your body? It's very important tissue. Let's look closer at blood. We're going to identify the parts and functions of blood. Yep, it's made up of more than just one thing. We'll also explain why blood types are checked before transfusion.
00:00:26 And we'll give examples of blood diseases. First, let's look at the functions of blood. One of the functions is that it carries oxygen from lungs to the body. When we breathe in, the oxygen moves into our lungs. But oxygen is needed in all different parts of our body, and the blood is what moves it. It also carries waste products from the cells to the kidneys.
00:00:54 The kidneys filter the blood in order to get things like urea, and different waste, out of the blood, and keep what is needed. It transports nutrients to body cells. When we eat food, we can't just automatically get the nutrients. They're broken down and digested, and then the blood carries those nutrients to the different parts of the body.
00:01:20 Cells and molecules in blood also help to fight infections and heal wounds, like white blood cells. There are different parts of the blood, as I said. There's red and white blood cells. And the blood makes up about 8% of our entire body mass. The other thing that makes up blood is plasma. Plasma is the liquid part of blood. The cells, the red and white blood cells, aren't liquid,
00:01:53 but they flow through our veins in this liquid called plasma. The plasma actually makes up more than half the volume of the blood in our body. The plasma also dissolves the nutrients, minerals, and oxygen that we need in all the different areas of our body. And the plasma also helps to carry the waste away. Blood cells are a little different from other cells.
00:02:20 They don't have a nucleus. What they have is hemoglobin, and hemoglobin carries oxygen and carbon dioxide. It's made of an iron compound, and that's actually what gives blood its color. Also, there are platelets. Platelets are irregularly-shaped cell fragments.
00:02:42 These are what help blood to clot. Now let's look a little closer at blood clotting. Those platelets that we were talking about, those irregularly-shaped cell particles or fragments, these are released, and they stick to a wound. They release chemicals. Those chemicals cause thread-like fibers to form a sticky net that will help keep you from bleeding.
00:03:12 In the picture that you see, you can see some of those thread-like fibers starting to accumulate as the platelets move into the clotting. Those then become hard. That's the scab. Then skin cells actually repair themselves underneath the scab, and eventually, the scab will fall off.
00:03:36 Did you know that there are different blood types? They're actually four different types. There's A, B, AB, and O. Each type has a specific antibody in its plasma. Remember, the plasma is that liquid part of the blood. Certain blood types can't be mixed because of these antibodies. So that's why they have to test for blood type before
00:04:05 doing a transfusion. You could get very sick if you get the wrong type of blood. Now, there are also diseases that can be in the blood, another reason that they have to test blood before transfusion. Anemia is one type of blood disease. It means that the body can't get enough oxygen. In the picture that you see, you see a
00:04:30 normal red blood cell. Also, you see a sickled red blood cell. This means it can't carry enough oxygen. There are different reasons for anemia. It can be through diet-- that you're not getting enough iron-- or things like sickle-cells. Another disease of the blood is leukemia.
00:04:54 This is where the white blood cells are made in excessive numbers. The white blood cells are off the charts high. These cells unfortunately are immature, so they don't help to fight infection. And what happens is, there are so many of them that they crowd out the normal cells. And leukemia, if not treated correctly, can cause death.
00:05:20 Let's review. We've identified the parts and functions of blood. We've also explained why blood types are checked before transfusion. And we've given two examples of diseases of blood, like leukemia and anemia.

Circulatory System:

When you take a shower do you know where that water comes from? It moves through pipes in your house, or the plumbing system. Clean water comes out through the shower head, and the dirty water is removed by the drain. The circulatory system works in kind of the same way. Today we're going to compare and contrast arteries, veins and capillaries.
00:00:27 Also, we're going to explain how blood moves through the heart. Lastly, we'll identify the functions of the pulmonary and systemic circulation systems. So how do but how do materials move through the body? Well oxygen and nutrients are moved through the body by the circulatory system. This includes the heart and the blood vessels.
00:00:52 The blood moves the oxygen and nutrients through the body in the circulatory system. First let's look at the heart. The heart has four chambers, the atriums and the ventricles. The atriums are the two upper chambers of the heart. And the ventricles are the two lower chambers of the heart. And the atriums and the ventricles will pump at
00:01:19 different times. Of atriums will pump, and then the ventricles will pump. There's three different types of circulation that occur. One of those is called coronary circulation. Kind of sounds difficult but really what it is, it's that the heart has its own circulatory system. And this is just the flow of blood to and from the tissues of the heart.
00:01:44 It doesn't go anywhere else except in the heart. Next you have the pulmonary circulation. Again it sounds kind of complicated, but it's not. The flow of blood through the heart, to the lungs and back. So it didn't go anywhere else in the body except between the heart and the lungs. This is called the pulmonary circulation. Lastly, there's the systemic circulation.
00:02:10 The systemic circulation is the largest of the three sections. Oxygen rich blood moves to all the organs and the body tissues, except for the heart and lungs-- because like we said, they have their own special circulation systems. Now there's blood vessels there's arteries, veins and capillaries.
00:02:31 Arteries carry blood away from the heart. So this is oxygen rich blood. It's kind of like the clean water that comes out of the shower. It goes out to the body, then the veins carry the blood back to the heart, so that it can get oxygenated. This is kind of like the drain taking the water back that's dirty, that needs to be cleaned up.
00:02:55 There's also capillaries. And capillaries are microscopic blood vessels. They're only about one cell thick. These are where the nutrients and oxygen diffuse into the body cells. Sometimes you can see capillaries. If you ever have a red eye and you can see the little tiny veins, those are actually capillaries.
00:03:20 Now let's talk about blood pressure. Measuring blood pressure. We've all probably sat there with that cuff that gets really tight around our arms. Well it's measured by the large arteries that are running through our arms. These blood pressures are expressed by two numbers. There's the systolic and the diastolic.
00:03:42 The systolic is when the ventricles contracts. And the diastolic is the pressure that occurs as the ventricles fill with blood. So if that pressure gets too high, it can become dangerous. Controlling blood pressure is usually done by your body. The body will try to control itself by slowing or speeding up heart rates, but sometimes if the blood pressure gets too out of control, doctors may prescribe different
00:04:11 medications to help lower the pressure of the blood. Now there's different types of cardiovascular diseases that can occur. One of these is arteriosclerosis. This is fatty deposits that build up on arterial walls, or the walls of the arteries. This can be especially dangerous if these are coronary arteries, or the arteries around the heart,
00:04:37 because if they get too blocked, they can cause a heart attack. It means that the blood is not being able to get back and forth throughout the heart, and a bypass may be necessary. Hypertension is just another word for high blood pressure. Like I said, the body will usually try to control it. But if not, medical intervention may be necessary. Then there's heart failure.
00:05:04 Heart failure is when the heart not pump the blood properly. It can be caused by a few different things. One of them could be that it's a weakened heart tissue that's been caused by either disease or old age. Also, it means that the heart valves could possibly not be working properly. Unfortunately, with heart failure, it means that the
00:05:28 heart stops, and will usually result in death. There's also ways to prevent cardiovascular disease. Healthy lifestyles are key in keeping a healthy heart. Get good sleep patterns going, so you're sleeping a regular amount of hours every night. Also, have a good diet. Make sure you choosing healthy foods that help keep not only your heart, but your body healthy.
00:05:57 Exercise. Aerobic exercise for at least 20 minutes a day helps to keep the cardiac muscles, or the heart muscles healthy. And don't smoke. Smoking is one of the leading causes of heart attacks. Let's review. We've compared and contrasted arteries, veins, and capillaries.
00:06:18 We've also explained how blood moves through the heart. And we identified the functions of the pulmonary and systemic circulation systems.