World Library  
Flag as Inappropriate
Email this Article

Palatine tonsils

Article Id: WHEBN0005404367
Reproduction Date:

Title: Palatine tonsils  
Author: World Heritage Encyclopedia
Language: English
Subject: List of subjects in Gray's Anatomy: XI. Splanchnology, Tonsil
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Palatine tonsils

Palatine tonsil
Mouth (oral cavity).
The Palatine tonsils with the soft palate, uvula, and tongue visible.
Latin tonsilla palatina
Gray's subject #243 1138
Artery tonsillar branch of the facial artery
Nerve tonsillary branches of lesser palatine nerves
Precursor pharyngeal arches[1]

Palatine tonsils, occasionally called the faucial tonsils,[2] are the tonsils that can be seen on the left and right sides at the back of the throat.

Tonsillitis is an inflammation of the tonsils and will often, but not necessarily, cause a sore throat and fever. In chronic cases tonsillectomy may be indicated.[3]

Functions of palatine tonsils

Local immunity

Tonsillar (relating to palatine tonsil) B cells can mature to produce all the five major Immunoglobulin (Ig, aka antibody) classes. Furthermore, when incubated in vitro with either mitogens or specific antigens, they produce specific antibodies against diphtheria toxoid, poliovirus, Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and the lipopolysaccharide of E. coli. Most Immunoglobulin A produced by tonsillar B cells in vitro appears to be 7S monomers, although a significant proportion may be l0S dimeric IgA.

In addition to humoral immunity elicited by tonsillar and adenoidal B cells following antigenic stimulation, there is considerable T-cell response in palatine tonsils. Thus, natural infection or intranasal immunization with live, attenuated rubella virus vaccine has been reported to prime tonsillar lymphocytes much better than subcutaneous vaccination. Also, natural infection with varicella zoster virus has been found to stimulate tonsillar lymphocytes better than lymphocytes from peripheral blood.

Combined tonsillectomy and adenoidectomy had a profound detrimental effect on the local IgA response in the nasopharyngeal fluid against poliovirus. These immunological observations paralleled the increased incidence of paralytic poliomyelitis after this operation. Thus, it is obvious that the tonsils have an important role to play in the defense of the host against bacterial and viral infections, and the success of regional mucosal immunity induced by intranasal vaccines most likely depends on these immunocompetent tissues in the oropharynx and nasopharynx.

Altogether, therefore, several pieces of direct and indirect evidence indicate that the palatine tonsils are continuously engaged in local immune responses to microorganisms. If the tonsillar lymphocytes became overwhelmed with this persistent stimulation they may be unable to respond to other antigens; the immunological response, particularly in recurrent tonsillitis, may then be impaired. Once this immunological impairment occurs, the tonsil is no longer able to function adequately in local protection nor can it appropriately reinforce the secretory immune system of the upper respiratory tract.

Cytokine action

Cytokines are humoral immunomodulatory proteins or glycoproteins which control or modulate the activities of target cells, resulting in gene activation, leading to mitotic division, growth and differentiation, migration, or apoptosis. They are produced by wide range of cell types upon antigen-specific and non-antigen specific stimuli. It has been reported by many studies that the clinic outcome of many infectious, autoimmune, or malignant diseases appears to be influenced by the overall balance of production (profiles) of pro-inflammatory and anti-inflammatory cytokines. Therefore, determination of cytokine profiles in tonsil study will provide key information for further in-depth analysis of the cause and underlying mechanisms of these disorders, as well as the role and possible interactions between the T- and B-lymphocytes and other immunocompetent cells. [4]

The cytokine network represents a very sophisticated and versatile regulatory system that is essential to the immune system for overcoming the various defense strategies of microorganisms. Through several studies, the Th1 and Th2 cytokines and cytokine mRNA are both detectable in tonsillar hypertrophy (or obstructive sleep apnea, OSA) and recurrent tonsillitis groups. It showed that human palatine tonsil is an active immunological organ containing a wide range of cytokine-producing cells. Both Th1 and Th2 cells are involved in the pathophysiology of TH and RT conditions. Indeed, human tonsils persistently harbor microbial antigens even when the subject is asymptomatic of ongoing infection. It could also be an effect of ontogeny of the immune system.

Anatomy

Blood supply and innervation

The palatine tonsils are located inside the oropharynx between two mucosa-covered pillars on the lateral sides of the cavity, the anterior being the palatoglossal arch, and the posterior being the palatopharyngeal arch. Collectively they are referred to as the fauces. Between these arches is the tonsillar bed, within which lie the palatine tonsils and the nervous and arterial structures that supply them.

The palatine tonsils receive afferent nervous innervation via the tonsillar plexus, which has contributions from GSA fibers of the maxillary division of the trigeminal nerve via the lesser palatine nerves, and GVA fibers from the tonsillar branches of the glossopharyngeal nerve (CN ix). The glossopharyngeal nerve continues past the palatine tonsil and innervates the tongue to provide general and taste sensation. This nerve is most likely to be damaged during a tonsillectomy, which leads to reduced or lost general sensation and taste sensation to the posterior third of the tongue.

Blood supply is provided by tonsillar branches of five arteries: the dorsal lingual artery (of the lingual artery), ascending palatine artery (of the facial artery), tonsillar branch (of the facial artery), ascending pharyngeal artery (of the external carotid artery), and the lesser palatine artery (of the descending palatine artery). The tonsils venous drainage is by the peritonsillar plexus, which drain into the lingual and pharyngeal veins, which in turn drain into the internal jugular vein.

The palatine tonsil is one of the mucosa-associated lymphoid tissues (MALT), located at the entrance to the upper respiratory and gastrointestinal tracts to protect the body from the entry of exogenous material through mucosal sites. In consequence it is a site of, and potential focus for, infections, and is one of the chief immunocompetent tissues in the oropharynx. It forms part of the Waldeyer's ring, which comprises the nasopharyngeal tonsil or adenoid (NT), the paired tubal tonsils (TT), the paired palatine tonsils (PT) and the lingual tonsil (LT). From the pharyngeal side, they are covered with a stratified squamous epithelium, whereas a fibrous capsule links them to the wall of the pharynx. Through the capsule pass trabecules that contain small blood vessels, nerves and lymphatic vessels. These trabecules divide the tonsil into lobules.

In children, the tonsils are common sites of infections that may give rise to acute or chronic tonsillitis. However, it is still an open question whether tonsillar hypertrophy is also caused by a persistent infection. Tonsillectomy is one of the most common major operations performed on children. The indications for the operation have been complicated by the controversy over the benefits of removing a chronically infected tissue and the possible harm caused by eliminating an important immune inductive tissue.

The information that is necessary to make a rational decision to resolve this controversy can be obtained by understanding the immunological potential of the normal palatine tonsils and comparing these functions with the changes that occur in the chronically diseased counterparts.

Tonsillar crypts

Main article: tonsillar crypts

Palatine tonsils consist of approximately 15 crypts, which result in a large internal surface. The tonsils contain four lymphoid compartments that influence immune functions, namely the reticular crypt epithelium, the extrafollicular area, the mantle zones of lymphoid follicles, and the follicular germinal centers. In human palatine tonsils, the very first part exposed to the outside environment is tonsillar epithelium.

Diseases

The pathogenesis of infectious/inflammatory disease in the tonsils most likely has its basis in their anatomic location and their inherent function as organ of immunity, processing infectious material, and other antigens and then becoming, paradoxically, a focus of infection/inflammation. No single theory of pathogenesis has yet been accepted, however. Viral infection with secondary bacterial invasion may be one mechanism of the initiation of chronic disease, but the effects of the environment, host factors, the widespread use of antibiotics, ecological considerations, and diet all may play a role.

Acute tonsillitis

Tonsillitis is the inflammation of tonsils. Acute tonsillitis is the most common manifestation of tonsillar disease. It is associated with sore throat, fever, and difficulty swallowing. The tonsils may appear normal sized or enlarged but are usually erythematous. Often, but not always, exudates can be seen. Not all these signs and symptoms are present in every patient.

Recurrent tonsillitis

Recurrent infection has been variably defined as from four to seven episodes of acute tonsillitis in one year, five episodes for two consecutive years or three episodes per year for 3 consecutive years.

Tonsillar hypertrophy

Tonsillar hypertrophy is the enlargement of the tonsils, but without the history of inflammation. Obstructive tonsillar hypertrophy is currently the most common reason for tonsillectomy. These patients present with varying degrees of disturbed sleep which may include symptoms of loud snoring, irregular breathing, nocturnal choking and coughing, frequent awakenings, sleep apnea, dysphagia and/or daytime hypersomnolence. These may lead to behavioral/mood changes in patients and facilitate the need for a polysomnography in order to determine the degree to which these symptoms are disrupting their sleep.

Additional images

References

External links

  • 05287.011-1

de:Tonsilla palatina fr:Tonsille palatine hr:Nepčana tonzila nl:Keelamandel no:Mandler (anatomi) pt:Tonsila palatina fi:Nielurisa te:టాన్సిల్స్‌

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.