Anatomy and physiology tonsils

A brief knowledge on anatomy & physiology of Tonsils

1. ANATOMY AND PHYSIOLOGY TONSILS MRS. Priya Gerard

2. TONSILS The  tonsils  are a set of  lymphoid  organs facing into the  aerodigestive tract , which is known as  Waldeyer's tonsillar ring  and consists of the  adenoid tonsil , two  tubal tonsils , two  palatine tonsils , and the  lingual tonsils . These organs play an important role in the immune system. When used unqualified, the term most commonly refers specifically to the palatine tonsils, which are two lymphoid organs situated at either side of the back of the human throat. The palatine tonsils and the adenoid tonsil are organs consisting of lymphoepithelial tissue located near the  oropharynx  and  nasopharynx  (parts of the throat).

3. Humans are born with four types of tonsils: the pharyngeal tonsil, two tubal tonsils, two palatine tonsils and the lingual tonsils. Type Epithelium capsule Crypts Location Adenoid  (also termed "pharyngeal tonsil") Ciliated pseudostratified columnar  ( respiratory epithelium ) Incompletely encapsulated No crypts, but small folds Roof of  pharynx Tubal tonsils Ciliated pseudostratified columnar (respiratory epithelium) Roof of pharynx Palatine tonsils Non-keratinized stratified squamous Incompletely encapsulated Long, branched [2] Sides of  oropharynx  between palatoglossal and palatopharyngeal arches Lingual tonsils Non-keratinized stratified squamous Incompletely encapsulated Long, unbranched Behind  terminal sulcus (tongue)

4. DEVELOPMENT OF TONSILS The palatine tonsils tend to reach their largest size in  puberty , and they gradually undergo  atrophy  thereafter. However, they are largest relative to the diameter of the throat in young children. In adults, each palatine tonsil normally measures up to 2.5 cm in length, 2.0 cm in width and 1.2 cm in thickness . The adenoid grows until the age of 5, starts to shrink at the age of 7 and becomes very small in adulthood.

5. Function The tonsils are  immunocompetent  organs which serve as the  immune system 's first line of defense against ingested or inhaled foreign  pathogens , and as such frequently engorge with blood to assist in immune responses to common illnesses such as the  common cold . The tonsils have on their surface specialized antigen capture cells called  M cells  that allow for the uptake of antigens produced by pathogens. These M cells then alert the underlying  B cells  and  T cells  in the tonsil that a pathogen is present and an immune response is stimulated .  B cells are activated and proliferate in areas called germinal centers in the tonsil. These germinal centres are places where B memory cells are created and  secretory antibody ( IgA )  is produced.

6. CLINICAL SIGNIFICANCE The palatine tonsils can become enlarged ( adenotonsillar   hyperplasia ) or inflamed ( tonsillitis ). The most common way to treat tonsillitis is with  anti-inflammatory drugs  such as  ibuprofen , or if bacterial in origin,  antibiotics , e.g.  amoxicillin  and  azithromycin . Surgical removal ( tonsillectomy ) may be advised if the tonsils  obstruct the airway  or interfere with swallowing, or in patients with severe or recurrent  tonsillitis .

7. Contd …. However, different mechanisms of pathogenesis for these two subtypes of tonsillar hypertrophy have been described, and may have different responses to identical therapeutic efforts. In older patients, asymmetric tonsils (also known as asymmetric tonsil hypertrophy) may be an indicator of  virally infected  tonsils, or tumors such as  lymphoma  or  squamous cell carcinoma .

8. Contd …. A  tonsillolith  (also known as a “tonsil stone”) is material that accumulates on the palatine tonsil. This can reach the size of a  peppercorn  and is white or cream in color. The main substance is mostly  calcium , but it has a strong unpleasant odor because of  hydrogen sulfide   and methyl   mercaptan  and other chemicals.

9. Contd …. Palatine tonsil enlargement can affect speech, making it  hypernasal  and giving it the sound of  velopharyngeal incompetence  (when space in the mouth is not fully separated from the nose's air space ).  Tonsil size may have a more significant impact on upper airway obstruction for obese children than for those of average weight.

10. Contd …. As mucosal lymphatic tissue of the  aerodigestive tract , the palatine tonsils are viewed in some classifications as belonging to both the  gut-associated lymphoid tissue  (GALT) and the  mucosa-associated lymphoid tissue  (MALT). Other viewpoints treat them (and the  spleen  and thymus) as large lymphatic organs contradistinguished from the smaller tissue loci of GALT and MALT.