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8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
1/20
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Lymphatic System: Overview
3 Parts to Lymphatic System
1. Lymphatic vessels – passive, one way return; has
valves; green on models
2. Lymphoid tissues and organs
3. Lymph – interstitial fluid in lymphatic vessels
eturns interstitial fluid and lea!ed plasma
proteins "ac! to the "lood
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Lymphatic System: Overview: Vessels & nodes
Figure 20.2a
## green area drained "y rt
lymphatic duct
##rest of "ody drained "ythoracic duct
arising from cisterna chyli
$ransports cancercells, inflammatory
products;
pathogens;edema if
"loc!ed; immo"ili%elocal infections
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Lymphatic System: Overview: Collects !issue "uice#
Figure 20.$a
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Lymphatic Capillaries: One %ay inivalves
Figure 20.$'
&i
gger than cardiovessels; more permea"le
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Lymphoid Cells
Lymphocytes – immune responders
$ cells
& cells plasma cells
'acrophages, 'onocytes – phagocytes; antigen processing
(endritic cells) phagocytes
ecticular cells) ma!e up stroma structure of
lymphoid organs
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Lymphoid !issue
eticular connective tissue
Lymphoid structures are site of many macrophages * huge
num"ers of lymphocytes that proliferate within tissue
'ay "e (iffuse or in +ollicles
(iffuse lymphatic tissue – scattered; in all organs
Lymphatic follicles nodules- – solid, spherical "odies
consisting of tightly pac!ed reticular elements and cells
erminal center composed of dendritic and & cells
+ound in isolation and as part of larger lymphoid organs
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
7/20Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20.(a
Lymph )odes
Principal lymphoid organs of the "ody
/lusters along lymphatic vessels
0ear the "ody surface
nguinal
4illary
/ervical Sentenil node- 1st node in lymphatic path to
receive lymph- from cancerous area
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
8/20Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Lymph )odes
$wo "asic functions
+iltration – macrophages destroy microorganisms
and de"ris
mmune system activation – monitor for antigensand mount an attac! against them
5nlargement due to lymphocyte proliferation
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
9/20Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Structure o* a Lymph )ode
Figure 20.(a+ '
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Other Lymphoid Organs
Figure 20.,
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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Spleen
Largest lymphoid organ
left side of the a"dominal cavity "eneath the diaphragm
Splenic artery * splenic vein) highly vascular tissue
+unctions
Site of lymphocyte proliferation – splenomegaly
&rea!s down old "lood cells, pathogens;
Stores, releases "rea!down products of 6g"
Stores platelets
6ematopoietic site in fetus
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
12/20Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Structure o* the Spleen
Figure 20.-a+ '
+i"rous
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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!hymus
&ilo"ed organ)secretes thymosin * thymopoietin
nfants) in the inferior nec!, into the mediastinum
t increases in si%e and is most active during
childhood t stops growing during adolescence and then
gradually atrophies
T cell maturation
n stroma, epithelium secretes hormones
Antigens do not enter; blood thymus barrier
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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nternal /natomy o* the !hymus
/orte4
(ensely pac!ed lymphocytes
Scattered macrophages
'edulla +ewer lymphocytes
Hassall’s corpuscles
7horls of !eratini%ed epithelial cells
Site of $ cell "rea!down
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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!onsils
Simplest lymphoid organs; form a ring of
lymphatic tissue around the pharyn4
Location
Palatine tonsils – either side of the posterior end ofthe oral cavity
Lingual tonsils – lie at the "ase of the tongue
Pharyngeal tonsil – posterior wall of thenasopharyn4
$u"al tonsils – surround the openings of theauditory tu"es into the pharyn4
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!onsils
Lymphoid tissue of tonsils contains follicles with
germinal centers
$onsil masses are not fully encapsulated
5pithelial tissue overlying tonsil massesinvaginates, forming "lind)ended crypts
/rypts trap and destroy "acteria and particulate
matter – ma!e memory cells
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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/ggregates o* Lymphoid Follicles
Peyer8s patches – isolated clusters of lymphoid
tissue, similar to tonsils
+ound in the wall of the distal portion of the smallintestine
Similar structures are found in the appendi4
Peyer8s patches and the appendi4
(estroy "acteria, preventing them from "reachingthe intestinal wall
enerate 9memory: lymphocytes for long)termimmunity
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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/L!
'L$ – mucosa)associated lymphatic tissue
Peyer8s patches, tonsils, and the appendi4
digestive tract-
Lymphoid nodules in the walls of the "ronchi
respiratory tract-
'L$ protects the digestive and respiratory
systems from foreign matter these areas are open
to e4terior-
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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evelopmental /spects
&eginnings of the lymphatic vessels and main
clusters of lymph nodes are apparent "y the fifthwee! of em"ryonic development
$hese arise from the "udding of lymph sacs from
developing veins
Lymphatic organs e4cept the thymus- arise from
mesoderm
$hymus – from endoderm
8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Lymphatic Chapter 20
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evelopmental /spects
$he thymus endodermal origin- forms as an
outgrowth of the pharyn4
54cept for the spleen and tonsils, lymphoid organs
are poorly developed at "irth