The next organ is the spleen and the spleen is a funny shaped little organ. Your liver is on your right side, your spleen is on your left, about the same position. And the spleen is funny looking because it's smushed on all sides.
It's like the guy that is in a crowd and everyone is pushing against him. It has a gastric impression where the stomach pushes against it. It has a colic impression where the... colon pushes against it and a renal impression where the kidney pushes against it. This is one of those solid vessels that has a hilum or hilus where all the blood vessels are going and lymphatics are going to enter and exit.
It's about five inches long. The stroma consists of the capsule, the trabeculae, fibers and fibroblasts and the parenchyma consists of white pulp and red pulp. White pulp is lymphatic tissue around the branches of the splenic artery.
And the red pulp is venous sinuses that are filled with blood and splenic tissue. This is a place where we store platelets in the spleen. So the red pulp consists of red blood cells, macrophages, lymphocytes, plasma cells, and granulocytes.
This is a place where worn out and defected red blood cells wipe blood cells. The platelets are going to be removed by fixed macrophages. It also stores blood platelets.
And the red pulp is involved in production of blood cells during the second trimester of pregnancy. The spleen doesn't really have a lot of protection, and any type of abdominal trauma can cause it to rupture. If it ruptures, it's usually better to give the person a splenectomy. than it is to try to fix it because it has such a rich blood supply, it's very hard to prevent internal bleeding.
So once it's removed, you don't have quite as much immunity as you had previously. So antibiotics are going to be required to be taken prophylactically for the rest of a person's life. So if you're going to get surgery done, you have to take antibiotics before surgery. If you're going to have dental work done.
You have to take antibiotics before dental work if you have a splenectomy. And this shows how blood rich it is. This is a ruptured spleen. You can see all the blood inside it and all the blood around it. It really, if it's ruptured badly, it isn't really an essential organ that you have to have no matter what.
It just weakens your immune system somewhat. Now there's concentrations of lymphatic tissue that doesn't have a capsule around it. And this is found throughout connective tissue of mucous membranes.
So we have mucosa-associated lymphoid tissue or MALT. We actually have more lymphatic tissue in our GI tract. than anywhere else and that's where you find this. Which makes sense because you're bringing something foreign into your body every time you eat and drink and it's best to have your lymphatic system checking it out. So Peyer's patches are clusters of lymphatic tissue in the ilium that's the terminal portion of the small intestine where it connects to the colon.
The appendix is found right at the very beginning of the colon in an area called the cecum. And we also have tonsils. And we have five tonsils.
We have lingual tonsil, two palatine tonsils, and adenoids, which are pharyngeal tonsils. So here you can see in the small intestine, this is the lumen or the hollow interior, and these are the Peyer's patches. You can see them even better here.
They're dark purple because they're packed full of cells. And what you see when you have some kind of infection is these cells, these pyros patches kind of empty out, and these immune system cells are moving to other areas of the tissue. So this is the hollow interior, the ileum, and then found in the submucosa, you have this layer of cells. It's groupings of cells called pyros.
pyres patches. Here is the appendix. Here's the ileum.
The ileum connects to the colon. And the first part of it is called the cecum. and the appendix or the variform appendix dangles from there.
When it becomes inflamed, you can develop appendicitis, and if this ruptures, it can be fecal material in there. It could be any type of material gets stuck in there. There can be an infection of it.
Different things can cause problems with the appendix. And like the spleen, it's not necessary for our survival. So it's better to remove the appendix than it is to have it rupture. If it ruptures, all the materials going through your GI tract can now enter into your peritoneal cavity and cause a very serious life-threatening problem called peritonitis.
Here are the tonsils, the adenoids found there, and then we have our palatine tonsils and the lingual tonsil. And this shows tonsillitis. You can see here you have the palatine tonsils are swollen up and infected, the adenoid lingual tonsil.
The goals for lecture two are to differentiate between primary and secondary lymphatic organs. Define the following terms, stroma, parenchyma, capsule, trabecula, cortex, medulla. hilum, efferent, afferent, metastasis, red pulp, and white pulp. Describe the specific functions of the thymus, spleen, and lymph nodes. List and describe the location of the five tonsils.
List the different types of tissue referred to as MALT. Describe the structure and function of lymph nodes, the thymus, and the spleen. Why is a splenectomy often a better option than repair?
Why is the thymus in a child so large compared to the thymus of an adult? What feature of lymph nodes makes them ideal sites to detect whether cancer has spread?