Lymphatic System and Immunity - PowerPoint PPT Presentation

1 / 50
About This Presentation
Title:

Lymphatic System and Immunity

Description:

large tubes. empty their lymph into lymphatic ducts. Lymphatic Ducts ... in thymus, cells develop into mature T cells for release into circulation ... – PowerPoint PPT presentation

Number of Views:670
Avg rating:3.0/5.0
Slides: 51
Provided by: rarit
Category:

less

Transcript and Presenter's Notes

Title: Lymphatic System and Immunity


1
Lymphatic System and Immunity
2
Lymphatic System
  • protects body against foreign material
  • assists in circulation of body fluids between
    cells and bloodstream
  • transports dietary fats

3
Lymphatic System (cont.)
  • Consists of
  • - lymph
  • - network of vessels
  • - lymph nodes and nodules
  • - tonsils
  • - spleen
  • - thymus gland
  • - bone marrow

4
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

5
Lymph (cont.)
  • flows through sinuses in lymph node cortex and
    then into the medulla
  • exits the lymph node through efferent lymphatic
    vessels
  • must be returned to blood stream to maintain
    blood volume and pressure

6
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
    proteins
  • lymph capillaries merge to form larger lymph
    vessels

7
Lymph Vessels
  • resemble veins but have thinner walls and more
    valves
  • ends of endothelial cells overlap
  • - act as one-way valves allowing interstitial
    fluid to flow in but not out
  • attached to surrounding tissue by anchoring
    filaments

8
(No Transcript)
9
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 lymph
    nodes
  • lymphatic vessels unite to form lymph trunks

10
Lymph Trunks
  • formed by lymphatic vessels uniting
  • large tubes
  • empty their lymph into lymphatic ducts

11
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 stream
    via the left subclavian vein and the right
    subclavian vein

12
(No Transcript)
13
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 left
    quadrant
  • empties into the left subclavian vein

14
Cisterna Chyli
  • large lymph vessel
  • formed by the union of lymph vessels from lower
    body
  • located anterior to the second lumbar vertebra
  • continues superiorly as thoracic duct

15
Right Lymphatic Duct
  • about 0.5 inches (1.5 cm) in length
  • receives lymph from upper right quadrant
  • empties into the right subclavian vein

16
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

17
(No Transcript)
18
Lymph Nodes (cont.)
  • covered by a capsule
  • contain capsular extensions called trabeculae
    (form partitions within node)
  • internal to capsule are reticular fibers and
    fibroblasts
  • - form framework of a lymph node
  • Two main regions of a lymph node
  • - cortex
  • - medulla

19
lymphatic vessel
arteriole
vein
valve
germinal center
cortex
trabeculae
medulla
20
Cortex
  • outer region directly beneath the capsule
  • contains densely packed lymphocytes arranged in
    masses called follicles
  • - outer rim of follicle contains T cells,
    macrophages, and follicular dendritic cells (aid
    in T cell activation)

21
Medulla
  • inner region
  • lymphocytes are arranged in strands called
    medullary cords
  • - contain macrophages and plasma cells

22
Biological Filtration
  • as lymph passes through a node bacteria and other
    foreign materials are trapped by reticular fibers
    within the node
  • - bacteria are then phagocytized by macrophages

23
Biological Filtration (cont.)
  • plasma cells produce antibodies to antigens in
    the lymph
  • antibodies, lymphocytes, and monocytes are
    eventually returned to the blood via subclavian
    veins

24
Major Lymph Nodes
  • cervical
  • axillary
  • inguinal
  • mesenteric

25
(No Transcript)
26
Cervical
  • located in neck area
  • filter lymph from head and neck

27
Axillary
  • located in armpits
  • filter lymph from hand, arm, breast

28
Inguinal
  • located in groin area
  • filter lymph from lower extremities and external
    genital organs

29
Mesenteric
  • located in abdominal peritoneum
  • aid in infection control after abdominal surgery
  • filter lymph from abdominal cavity

30
Metastasis
  • process by which bacteria or body cells are
    spread from one body part to another through
    lymphatic or circulatory systems
  • cancer cells migrate to nearby nodes, eg. breast
    cancer to axillary nodes - chemotherapy is
    necessary once metastasis occurs

31
Diffuse Lymphatic Tissue
  • not enclosed by a capsule
  • consists of reticular connective tissue that
    contains lymphatic nodules
  • Found in
  • - small amounts in almost every organ,
    especially mucous membranes that line tracts of
    body

32
Isolated Lymphatic Nodules(B cells)
  • oval-shaped concentrations of lymphatic tissue
  • most are solitary, small, and discrete
  • Scattered in lamina propria of mucous membranes
    of
  • - gastrointestinal tract
  • - respiratory airways
  • - urinary and reproductive tract

33
Isolated Lymphatic Nodules (B cells)
(cont.)
  • when activated by antigens they differentiate
    into plasma cells and produce antibodies against
    specific antigens
  • plasma cells secrete IgA antibodies
  • - provide protection against bacterial and viral
    infections in lumen of tracts

34
Isolated Lymphatic Nodules (B cells)
(cont.)
  • located in mucus membranes of gastrointestinal
    tract
  • Examples
  • - tonsils
  • - ileum of small intestine (Peyers patches)
  • - appendix

35
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

36
Nasopharyngeal Tonsils
  • commonly called adenoids
  • Located
  • - behind nose
  • - on roof of posterior wall of pharynx
  • - posterior opening of nasal cavity

37
Palatine Tonsils
  • usually referred to as the tonsils
  • Location
  • - back of mouth
  • - lateral walls of pharynx
  • most commonly removed - tonsillectomy

38
Lingual Tonsils
  • base of tongue
  • first line of defense from exterior

39
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

40
(No Transcript)
41
Structure of Spleen
  • capsule
  • - covering of dense connective tissue
  • hilum
  • - depression on medial surface
  • - nerves and arteries enter spleen, veins and
    lymphatic vessel exit

42
Structure of Spleen (cont.)
  • trabeculae
  • - extensions of capsule, form partitions within
    the spleen
  • pulp
  • - tissue inside
  • - divided into red and white

43
White Pulp
  • consists of lymphatic tissue
  • mostly lymphocytes arranged around central
    arteries

44
Red Pulp
  • Consists of
  • - venous sinuses filled with blood
  • - cords of splenic tissue
  • consists of red blood cells, macrophages,
    lymphocytes, plasma cells, and granulocytes

45
Functions of Spleen
  • phagocytosis of bacteria and worn out or damaged
    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
    proliferation into plasma cells
  • does not filter lymph because it has no afferent
    lymphatic vessels or lymph sinuses

46
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 period
    and infancy
  • after puberty it decreases in size

47
Thymus Gland (cont.)
  • composed of lymphatic tissue
  • subdivided into lobules
  • immature T cells originating in the bone marrow
    migrate to thymus via blood
  • in thymus, cells develop into mature T cells
    for release into circulation
  • thymic hormones aid in maturation of T cells

48
Thymus Gland (cont.)
  • mature T cells travel to lymph nodes, spleen, and
    diffuse lymphatic tissues where they reside
  • responsible for cell-mediated immune responses

49
Removal of Thymus(thymectomy)
  • can be removed but decreased T-cell production
    results
  • possible acute susceptibility to infection

50
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
Write a Comment
User Comments (0)
About PowerShow.com