2. Lymphatic System
protects body against foreign material
assists in circulation of body fluids between cel
ls and bloodstream
transports dietary fats
3. Lymphatic System (co
nt.)
Consists of:
- lymph
- network of vessels
- lymph nodes and nodules
- tonsils
- spleen
- thymus gland
- bone marrow
4.
5. Lymph (lympha = clear fluid)
derived from tissue fluid
contains more white blood cells than plasma
enters node through afferent lymphatic vessels
flows through node in one direction
6.
7. Lymph (con
t.)
flows through sinuses in lymph node cortex a
nd then into the medulla
exits the lymph node through efferent lymph
atic vessels
must be returned to blood stream to maintain
blood volume and pressure
8.
9. Lymph Capillaries
microscopic closed-ended vessels
located next to blood capillaries in tissue spaces
larger diameter than blood capillaries
are very permeable and collect tissue fluid and prot
eins
lymph capillaries merge to form larger lymph vesse
ls
10. Lymph Vessels
resemble veins but have thinner walls and m
ore valves
ends of endothelial cells overlap
- act as one-way valves allowing interstitial fl
uid to flow in but not out
attached to surrounding tissue by anchoring f
ilaments
11.
12. Lymph Vessels (cont.)
no pump for lymph
Lymph is kept moving by:
- constriction of vessels
- skeletal muscle pump
- respiratory pump
at intervals along vessels lymph flows into lymp
h nodes
lymphatic vessels unite to form lymph trunks
13. Lymph Trunks
formed by lymphatic vessels uniting
large tubes
empty their lymph into lymphatic ducts
14. Lymphatic Ducts
Lymph empties into two conducting ducts:
- the thoracic duct (left lymphatic duct)
- the right lymphatic duct
Lymph from these ducts enters the blood stre
am via the left subclavian vein and the right s
ubclavian vein
15.
16. Thoracic Duct
(left lymphatic duct)
about 15-18 inches (38-45 cm) in length
begins as a dilation called the cisterna chyli
main collecting duct of lymphatic system
receives lymph from lower body and upper le
ft quadrant
empties into the left subclavian vein
17. Cisterna Chyli
large lymph vessel
formed by the union of lymph vessels from l
ower body
located anterior to the second lumbar vertebr
a
continues superiorly as thoracic duct
18. Right Lymphatic Duct
about 0.5 inches (1.5 cm) in length
receives lymph from upper right quadrant
empties into the right subclavian vein
19. Lymph Nodes
oval or bean-shaped
masses of lymphatic tissue
aid in defense and white blood cell formation
located along length of lymphatic vessels
scattered throughout the body usually in clusters
20.
21. Lymph Nodes (cont.)
covered by a capsule
contain capsular extensions called trabecula
e (form partitions within node)
internal to capsule are reticular fibers and fi
broblasts
- form framework of a lymph node
Two main regions of a lymph node:
- cortex
- medulla
23. Cortex
outer region directly beneath the capsule
contains densely packed lymphocytes arrang
ed in masses called follicles
- outer rim of follicle contains T cells, macro
phages, and follicular dendritic cells (ai
d in T cell activation)
24. Medulla
inner region
lymphocytes are arranged in strands called m
edullary cords
- contain macrophages and plasma cells
25. Biological Filtration
as lymph passes through a node bacteria and
other foreign materials are trapped by reticul
ar fibers within the node
- bacteria are then phagocytized by macropha
ges
26. Biological Filtration (con
t.)
plasma cells produce antibodies to antigens i
n the lymph
antibodies, lymphocytes, and monocytes are
eventually returned to the blood via subclavia
n veins
31. Inguinal
located in groin area
filter lymph from lower extremities and exter
nal genital organs
32. Mesenteric
located in abdominal peritoneum
aid in infection control after abdominal surge
ry
filter lymph from abdominal cavity
33. Metastasis
process by which bacteria or body cells are
spread from one body part to another throug
h lymphatic or circulatory systems
cancer cells migrate to nearby nodes, eg. bre
ast cancer to axillary nodes - chemotherapy
is necessary once metastasis occurs
34. Diffuse Lymphatic Tissue
not enclosed by a capsule
consists of reticular connective tissue that co
ntains lymphatic nodules
Found in:
- small amounts in almost every organ, espec
ially mucous membranes that line tracts of bo
dy
35. Isolated Lymphatic Nodules
(B cells)
oval-shaped concentrations of lymphatic tissue
most are solitary, small, and discrete
Scattered in lamina propria of mucous membran
es of:
- gastrointestinal tract
- respiratory airways
- urinary and reproductive tract
36. Isolated Lymphatic Nodules
(B cells) (cont.)
when activated by antigens they differentiate
into plasma cells and produce antibodies agai
nst specific antigens
plasma cells secrete IgA antibodies
- provide protection against bacterial and vira
l infections in lumen of tracts
37. Isolated Lymphatic Nodules
(B cells) (cont.)
located in mucus membranes of gastrointesti
nal tract
Examples:
- tonsils
- ileum of small intestine (Peyer’s patches)
- appendix
38. Tonsils
aggregations of large lymphatic nodules
embedded in mucous membrane
located beneath epithelium of pharynx and
oral cavities
protect nasal and oral cavities
Three types:
- nasopharyngeal tonsils
- palatine tonsils
- lingual tonsils
39. Nasopharyngeal Tonsils
commonly called adenoids
Located:
- behind nose
- on roof of posterior wall of pharynx
- posterior opening of nasal cavity
40. Palatine Tonsils
usually referred to as the “tonsils”
Location:
- back of mouth
- lateral walls of pharynx
most commonly removed - tonsillectomy
42. Spleen
largest lymphatic organ
located in upper left abdominal quadrant
between fundus of stomach and diaphragm
5-6 inches long, 2-3 inches wide
resembles a large lymph node
filters blood
43.
44. Structure of Spleen
capsule
- covering of dense connective tissue
hilum
- depression on medial surface
- nerves and arteries enter spleen, veins and l
ymphatic vessel exit
45. Structure of Spleen (con
t.)
trabeculae
- extensions of capsule, form partitions withi
n the spleen
pulp
- tissue inside
- divided into red and white
46. White Pulp
consists of lymphatic tissue
mostly lymphocytes arranged around central
arteries
47. Red Pulp
Consists of:
- venous sinuses filled with blood
- cords of splenic tissue
consists of red blood cells, macrophages, ly
mphocytes, plasma cells, and granulocytes
48. Functions of Spleen
phagocytosis of bacteria and worn out or damag
ed red blood cells and platelets
stores and releases blood in times of demand, e.
g., hemorrhage
functions in immunity as a site of B cell prolifer
ation into plasma cells
does not filter lymph because it has no afferent l
ymphatic vessels or lymph sinuses
49. Thymus Gland
two-lobed organ
located in upper part of chest along trachea
inferior to thyroid gland, posterior to sternum
largest and most active during prenatal perio
d and infancy
after puberty it decreases in size
50. Thymus Gland (co
nt.)
composed of lymphatic tissue
subdivided into lobules
immature T cells originating in the bone marr
ow migrate to thymus via blood
in thymus, cells develop into mature T cell
s for release into circulation
thymic hormones aid in maturation of T cells
51. Thymus Gland (co
nt.)
mature T cells travel to lymph nodes, spleen,
and diffuse lymphatic tissues where they resi
de
responsible for cell-mediated immune respon
ses
52. Removal of Thymus
(thymectomy)
can be removed but decreased T-cell producti
on results
possible acute susceptibility to infection
53. Removal of Spleen
(splenectomy)
can be removed
other organs, e.g. the liver and bone marrow
can compensate for it
increased susceptibility to disease may result