Lymphoid Organs

Lymphoid Organs

We had lymphatic capillariesThe smallest blood vessels where gas, nutrient, and waste exchange occurs between blood and tissues. we have lymphatic vessels we have lymph nodes and there are 3 specialized lymphoid organs. The thymus is easily mistaken for the thyroid when it’s late at night and I’m trying to give this lecture. It actually lies above the heart, inferiorBelow or toward the lower part of the body. to the neckNarrow region just below the head; common fracture site. and the thyroid gland Endocrine gland regulating metabolism through thyroid hormones..  Your tonsils are lymphoid organs they contain folliclesStructures in the ovaries that contain developing oocytes. and germinal centers with lymphocytes. Some people consider tonsils simply to be malt and not a proper lymphoid organ. However tonsils have follicles germinal centers and a capsule. The spleen is located only on the left side of your abdomen. It is somewhat tucked underneath the stomach and pancreasA gland that produces digestive enzymes and hormones like insulin and glucagon.. It is known as the red and white blood cell graveyard. The spleen has white pulp containing an abundance of leukocytes. There is also red pulp with an abundance of erythrocytes(RBCs): Red blood cells responsible for oxygen transport.. These erythrocytes are broken down into their component parts for recycling. I have lymph nodes here with? Technically, lymph nodes fit the definition of a lymphoid organ. They are encapsulated organs of follicles and germinal centers. However, some people don’t consider them lymphoid organs. Actually there are many people who don’t consider anything the lymphoid organ. On that topic, some people think red bone marrow is a lymphoid organ. Others consider it related due to its role in producing red blood cellsThe basic structural and functional units of life.. Some people do not

Red Bone Marrow

I do consider red bone marrow to be a lymphoid organ.  Yellow bone marrow is composed of adipose connective tissue. Red bone marrow is composed of reticular connective tissue. This tissue is also contained in the lymph nodes. Caught among the reticular network of fibers are mostly B cells in the bone marrow. There are also macro phages however there are no T cells. The blood capillaries in red bone marrow are sinusoidal capillaries. These were the most permeable and largest capillaries. As you can see right here, white blood cells are made in the bone marrow. They must diffuse into the sinusoidal capillaries to be released into circulation. In this picture, you can see some other capillaries. These are the stellate cells or macrophages. We even have some adipocytes with their triglyceride oil droplet and nucleusThe control center of the cell that contains DNA and directs cellular activities. pushed to the side.

Thymus

Gets confused with the thyroid. I think this is because they are both in the general area of your neck. Additionally, they both begin with TH. The thymus is the home for developing T cells. Lymphocytes are designated as either a CD4 helper or a CD8 cytotoxic cell. They then proceed to the thymus to mature. As you age, the thymus becomes smaller. As you grow older, you enter into immunosenescence. This state reflects your decreased ability to create lymphocytes. The thymus is divided into globules by dense connective tissue SEPTA. You can see the white lines in the histological picture of the thymus on the left. As with many organs, each lobule has a cortex or an outer covering and a medulla or an inner center. T cells begin in the cortex. As they differentiate their cell surface receptorsProteins located on the surface or inside cells that bind specific molecules (e.g., neurotransmitter, they identify themselves as either a CD4 helper cell. Alternatively, they become a CD8 cytotoxic cell.

Spleen

The spleen is considered the largest lymphoid organ. It is tucked away on the right side of your abdominal cavityThe body cavity containing the stomach, intestines, liver, and other digestive organs. kind of between the pancreas and the stomach. Just like the thymus the spleen has lobules that are separated by dense connective tissue. However in the picture on the right of the spleen that dense connective tissue is taking up a pink stain. Each lobule of the spleen has an inner medulla and an outer cortex. The inner medulla is usually made-up of white pulp. This pulp acts as a standing army of lymphocytes and monocytes. They are ready to begin battle if necessary. The red pulp which is more toward the inside of the spleen is essentially an erythrocyte graveyard. This is where erythrocytes are broken down phagocytosed and broken into their useful recycled elements.

Tonsils

Tonsils are considered lymphoid organs as well. However it depends on who you ask if they consider the tonsils to be lymphoid organs or lymphoid tissues. Tonsils lack a main characteristic that the spleen and a thymus have. They do not have an outer capsule separating them from the mucosal tissue around them. The capsule around tonsils is incomplete. You have three sets of tonsils. The lingual tonsils are under your tongue. The palatineL-shaped bones forming posterior part of hard palate and floor of nasal cavity. tonsils are at the roof of your mouthThe opening of the digestive tract where food enters and mastication begins.. The pharyngeal tonsils are at the back of your throat and are technically called the adenoids. Many people work in healthcare, retail, and teaching. These workers are exposed to other people and their poor immune systems throughout the day. This exposure causes repeated infection of the adenoids. If you’re a teacher who needs to speak, repeated infection of the adenoids is a job killer. This is why some people choose to have their adenoids removed.