Download A Rough look at the tonsils and adenoids, for Bonny Peppa!

A Rough look at the tonsils and
adenoids, for Bonny Peppa!
Lymphoid organs include:
adenoids (two glands located at the back of the
nasal passage)

appendix (a small tube that is connected to the
large intestine)
blood vessels (the arteries, veins, and capillaries
through which blood flows)
bone marrow (the soft, fatty tissue found in bone
cavities)
lymph nodes (small organs shaped like beans,
which are located throughout the body and connect
via the lymphatic vessels)
lymphatic vessels (a network of channels
throughout the body that carries lymphocytes to the
lymphoid organs and bloodstream)
Peyer's patches (lymphoid tissue in the small
intestine)
spleen (a fist-sized organ located in the abdominal
cavity)
thymus (two lobes that join in front of the trachea
behind the breast bone)
tonsils (two oval masses in the back of the throat)
Lymphoid
Organs
• Tonsils: 3 sets
Fig. 14.3
Lymphoid
Organs
• Thymus:
atrophies with
age
• Spleen: can live
without this
Figure 20.8
Other Lymphoid
Organs
• Include:
– Tonsils
– Thymus
– Spleen
– Peyer’s Patches
– Appendix
– Bone Marrow-Stem cells
– All contain reticular CT and
lymphocytes, but none of them
actively filter lymph
– These other lymphoid organs
contain efferent but no afferent
lymphatic vessels.
largest
• So we see the tonsils and adenoids are
lymphoid organs
• They have a PROTECTIVE FUNCTION
Tonsils
• Small masses of lymphoid tissue around
the pharynx
• Trap and remove bacteria and other
foreign materials
• Tonsillitis is caused by congestion with
bacteria
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Tonsils
• The tonsils are accumulations of lymphoid tissue
located in a protective ring - called Waldeyer's ring under mucous membranes in the mouth and back of
the throat surrounding the openings of the digestive
and respiratory tracts.
• Help protect against bacteria that may invade tissues
in the area around the openings between the oral and
nasal cavities.
• The tonsils serve as the first line of defense from the
exterior and as such are subject to chronic infection.tonsillitis.
• Depending on their localisation we distinguish
between palatine, pharyngeal (adenoids) or lingual
tonsils.
Tonsils
• Form a ring of lymphoid
tissue around the
entrance to the pharynx
• 3 main sets:
– Palatine
• Located on either side of
the posterior oral cavity
• Largest and infected
most often
– Lingual
• Lie at the base of the
tongue
– Pharyngeal
• Found in the posterior
wall of the nasopharynx
• Called adenoids when
infected
•
•
Contain
multiple
lymphoid
follicles
overlain by
epithelial crypts
Crypts trap
bacteria which
work their way
into the
lymphoid tissue
where they are
destroyed
– Why is this a
risky method
of fighting
pathogens?
– What
advantage
does this
method
Tonsils
Tonsils
• Incompletely encapsulated lymphoid nodules
• Simple lymphoid organs /“Lymph nodules” in
the mouth/pharynx
• Palatine or adenoids: covered by stratified
squamous nonkeratinized epithelium; crypts;
underlying connective tissue barrier, lateral to
the pharynx
• Pharyngeal: covered by ciliated
pseudostratified epithelium, no crypts
• Lingual: smaller, at base of tongue posteriorly;
covered by stratified squamous nonkeratinized
epithelium; one crypt in each nodule
Palatine tonsils--located on each side of the
throat.
•
• The Palatine tonsils
• are those which we loosely refer to as “the
tonsils” in laymens terms and every day
speech.
• are located in the lateral wall of the
oropharynx and covered by a stratified
squamous epithelium
• contains T and B cells and antigen
presenting cells
• are deep crypts
• are large masses of lymphoid tissue
• When we speak of the “tonsils” in
Barbados we mean the Palatine tonsil
• When we speak of the “adenoids” in
Barbados we mean the Pharyngeal
tonsil
• Note that they have a different location!
• The pharyngeal tonsils (also called
nasopharyngeal tonsils or adenoids)
• are located in the upper posterior part of
the throat (nasopharynx) and
• covered by a pseudostratified ciliated
epithelium with goblet cells.
Lingual tonsils are situated in the lamina propria at near the
base of the tongue. They are covered by a stratified
squamous epithelium.
• The tonsils do not have afferent lymph vessels but
efferent lymph vessels are present.
• Exposure to antigens relies on the contact of antigens
with cells of the immune system across the epithelium
which covers the tonsils.
• The epithelium of the palatine and lingual tonsils
forms deep crypts into the lymphoid tissue, and the
resulting increase of the surface area is one way to
facilitate the contact of antigens with the immune
cells.
• In addition, the epithelium may specialise in places to
form an open meshwork of cells with an incomplete
basal lamina (a reticulated epithelium) which allows
the infiltration of the epithelium by lymphocytes and
macrophages.
• Tonsillar lymphoid nodules consist mainly of Blymphocytes.
Other areas are occupied by T-lymphocytes,
activated B-lymphocytes and other cells of the
immune system.
The tonsils share some histological features with
lymph nodes:
• cells in the tonsils are supported by a fine
network of reticular fibres and
• high-endothelial (postcapillary) venules function
in the "homing" of circulating lymphocytes - this
is actually a shared feature of all lymphoid
tissues and organs.
• The palatine tonsils are surrounded by a thick
hemicapsule of connective tissue, which