Lymphoid Follicles – Secondary Lymphoid Organs (Nursing)

00:02 So, now let's switch gears and talk a little bit about the non-encapsulated lymphoid organs.

00:10 And I'm using "organs" because we really don't refer to these as organs and instead we refer to these as lymphoid nodules or follicles.

00:21 First, we start with the MALT or the Mucosa-Associated Lymphoid Tissue.

00:27 This is going to be lymphoid tissue that is found in the mucous membranes throughout the body.

00:32 They're going to protect us from pathogens that enter the body, and are found in the mucosa of places like the respiratory tract, the genitourinary tract, and the digestive tract.

00:45 The largest collections of MALT can be found in places like the tonsils, the peyre's patches in the intestines, and the appendix in the large intestines.

00:58 A second type of lymphoid nodule are the tonsils.

01:01 The tonsils are the simplest of our lymphoid organs, and they form a ring of lymphatic tissue around the pharynx area or their throat.

01:12 And in this area they appear as swellings of the mucosa.

01:18 The tonsils are named based on where they are located.

01:21 You have the Palatine tonsils, which are the poster end or the oral cavity.

01:27 The Lingual tonsils, which are lumpy collection of follicles at the base of the tongue, The Pharyngeal tonsils, which are going to be located in the posterior wall of the nasal pharynx, and are also sometimes referred to as adenoids.

01:43 And you have the Tubal tonsils, which surround openings of the auditory tubes in the pharynx.

01:51 So the interesting thing about our tonsils are these lymphoid nodules here are that they are in the perfect position to come in contact with antigens that we breathe in or antigens that come in through our food.

02:10 The tonsils function to gather and remove pathogens from our air and from our food.

02:18 They have follicles that are found in germinal centers with some scattered lymphocytes within.

02:26 As I said before, this lymphoid organ is not fully encapsulated and is therefore considered a lymphoid nodule.

02:37 The overlying epithelium of the tonsil is invaginated forming these crypts known as tonsillar crypts.

02:46 These are important because they allow for bacteria and other matter and debris to kind of go into the crypts and be trapped there.

02:56 And it is there where they can be destroyed.

02:59 But this is a little bit of a risky behavior, because it's risky to lure bacteria into this part of the tissue, because then they could kind of proliferate and reproduce in this tissue, and make you sicker.

03:12 But we do this because it allows the immune cells to become activated, and build memory cells against these potential pathogens.

03:23 So another lymphoid nodule is going to be the Peyer's patches.

03:28 These are going to be a cluster of lymphoid follicles found in the wall of the distal portion of our small intestines.

03:36 Sometimes we refer to these as the aggregated lymphoid nodules.

03:40 They are very structurally similar to our tonsils, and their location aids in their function, which is to destroy bacteria and prevent them from breaching our intestinal wall.

03:54 Also, they are there to generate memory against these pathogens, so that we can fight them if we can come in contact with them later.

04:03 Another lymphoid nodule or lymphoid organ is going to be the appendix.

04:08 The appendix is actually a small offshoot of the first part of the large intestines.

04:15 The appendix also contains a very large number of lymphoid follicles.

04:21 Like the payer's patch, this location allows for it to destroy and prevent bacteria from breaching the intestinal wall as well as generating memory lymphocytes that are able to help us fight against these pathogens if we were to come in contact with them again.