1. Unit 4: The Lymphatic and Immune Systems
Nursing Physiology (NRS237)
Dr. Moattar Raza Rizvi
2. • Lymphatic System: ReturnsLymphatic System: Returns
interstitial fluid and leakedinterstitial fluid and leaked
plasma proteins back to theplasma proteins back to the
bloodblood
• Consists of two semi-
independent parts
– A meandering network of
lymphatic vessels
– Lymphoid tissues and
organs scattered
throughout the body
Lymphatic System: Overview
LymphLymph – interstitial fluid once it has entered lymphatic vessels
5. • Is straw colored fluid, similar in composition to blood
plasma
• Lymph fluid bathes the surrounding spaces between
tissue cells and it is referred to as interstitial fluid or
tissue fluid
• Lymph fluid is made up of water, lymphocytes,
granulocytes (neutrophils), O2, digested nutrients
(proteins), sodium ions, hormones, salts, CO2 and
urea
Lymph fluid
6. • Main structures of the lymphatic system
– Lymphatic vessels
• Main components of the immune system
– Lymph
– Lymphocytes
– Lymphoid Nodules (Tonsils)
– Lymphoid Organs
Components of the Lymphatic System
8. • A one-way system in whichA one-way system in which
lymph flows toward the heartlymph flows toward the heart
• FLOW OF LYMPH TOWARDS
THE HEART
• Blood capillaries (blood)>
interstitial spaces (interstitial
fluid)>lymphatic capillaries
(lymph)> lymphatic vessels
(lymph)>lymphatic ducts
(lymph)>subclavian veins (blood)
Lymphatic Flow
9. • Similar to blood capillaries, with modifications
– Remarkably permeable
– Loosely joined endothelial minivalves
– Withstand interstitial pressure and remain open
• The minivalves function as one-way gates
that:
– Allow interstitial fluid to enter lymph capillaries
– Do not allow lymph to escape from the capillaries
Lymphatic Capillaries
How does blood capillary
differ from lymphatic capillary
10. Lymphatic Capillaries
• During inflammation, lymph capillaries can absorb:
– Cell debrisCell debris
– PathogensPathogens
– Cancer cellsCancer cells
• Cells in the lymph nodes:
– Cleanse and “examine” this debrisCleanse and “examine” this debris
11. • During inflammation, lymph capillaries can
absorb:
– Cell debrisCell debris
– PathogensPathogens
– Cancer cellsCancer cells
• Cells in the lymph nodes:
– Cleanse and “examine” this debrisCleanse and “examine” this debris
Lymphatic Capillaries
12. • Lacteals – specialized lymph capillaries
present in the villi of the small intestines
– Absorb digested fat and deliver chyle to the blood
Specialized Lymphatic Capillaries- Lacteals
13. • The walls of lymphatic vessels are similar to those of
cardiovascular veins (have the same three tunics as
veins)
• Have thinner walls, with more internal valves
• Anastomose more frequently
• Collecting vessels in the skin travel with superficial
veins
• Deep vessels travel with arteries
• Nutrients are supplied from branching vasa vasorum
Lymphatic Collecting Vessels
Write short notes on lymphatic
collecting vessels
14. The walls of lymphatic vessels are similar to those of veins but
have thinner walls and more valves.
Lymph vessels in the skin follow veins.
Lymph vessels in the viscera follow arteries.
Lymph vessels are NOT found in avascular tissue, CNS, parts of
spleen and red bone marrow.
Lymphatic Collecting Vessels
15. Lymphatic Trunks
Large vessels lead to lymph
nodes and then to larger
lymphatic trunks
Lymphatic trunks are named for
the body region they drain
Lumbar trunk –drains lymph
from lower limbs and pelvic
organs
Intestinal trunk- drains
abdominal viscera
Bronchomediastinal trunk-
drains portions of the thorax
Subclavian trunk – drains upper
limbs
Jugular trunk – drains portions of
the neck and head
16. • Lymphatic trunks are formed by the union ofLymphatic trunks are formed by the union of
the largest collecting ductsthe largest collecting ducts
• Major trunks include:
– Paired lumbar, bronchomediastinal, subclavian, and
jugular trunks
– A single intestinal trunk
• Lymph is delivered into one of two large trunksLymph is delivered into one of two large trunks
– Right lymphatic ductRight lymphatic duct – drains the right upper arm
and the right side of the head and thorax
– Thoracic ductThoracic duct – arises from the cisterna chyli and
drains the rest of the body
Lymphatic Trunks
17. Lymph capillaries converge to
become collecting vessels and
end up as either
Thoracic duct or right
lymphatic duct
Thoracic (left lymphatic)
duct
Left subclavian vein
Right
lymphatic
duct
Right
subclavian
vein
Cysterna Chyli
Lymphatic Trunks
18. The right and left (thoracic duct) lymphatic duct empties directly
into the left subclavian vein
Lymphatic Ducts
19. • The lymphatic system lacks an organ that acts
as a pump
• Vessels are low-pressure conduits
• Method to propel lymph:
• Uses the same methods as veins
1. Pulsations of nearby arteries
2. The main activity that causes fluid to flow
through lymphatic vessels is smooth muscle
contraction in the walls of the lymphatics
Lymph Transport
20. • Lymphocytes are the main cells involved in
the immune response
• The two main varieties are T cellsT cells and B cellsB cells
• T cells and B cells protect the body against
antigens
• Antigen – anything the body perceives as
foreign
– Bacteria and their toxins; viruses
– Mismatched RBCs or cancer cells
Lymphoid Cells
21. • T cells (T lymphocytes):
– Manage the immune
response
– Attack and destroy
foreign cells
• B cells (B-Lymphocytes)
– basic functional unit of the immune system
– Produce plasma cells, which secrete antibodies
– Antibodies immobilize antigens
Lymphoid Cells
Describe lymphoid cells
23. • MacrophagesMacrophages – phagocytize foreign substances and
help activate T cells
• Dendritic cellsDendritic cells – spiny-looking cells with functions
similar to macrophages
• Reticular cellsReticular cells – fibroblastlike cells that produce a
stroma, or network, that supports other cell types in
lymphoid organs
Other Lymphoid Cells
24. • Primarylymphatic organs - site of B and T cell production
– bone marrow - produces B cells, pre-T cells
– thymus gland – pre-T cells migrate to thymus gland
and mature in thymus gland
• Secondary lymphatic organs - site of most immune
responses
– lymph nodes,
– spleen – surrounded by connective tissue capsule
– lymphatic nodules – not surrounded by capsule
Lymphoid Organs
Differentiate between primary
and secondary lymphatic organs
26. • Nodes are bean shaped and
surrounded by a fibrous capsule
• Lymph nodes are the principal
lymphoid organs of the body
• Nodes are imbedded in
connective tissue and clustered
along lymphatic vessels
• Aggregations of these nodes
occur near the body surface in
inguinal, axillary, and cervicalinguinal, axillary, and cervical
regions of the bodyregions of the body
Only lymph nodes filter lymph
Lymphoid Nodes
27. Lymphoid Nodes
The breast tissue
fluid will drain into the
axillary nodes
The following cavity contain
lymph node
• Abdominopelvic cavity
• Thoracic cavity
• Mediastinum
Cranial cavity is
an area where
lymph nodes is
not present
30. • Their two basic functions are:
– Filtration – macrophages destroy
microorganisms and debris
– Immune system activation – monitor for
antigens and mount an attack against them
• Lymph vessels
– Afferent lymphatic vessels
– carrying fluid towards lymph node
– Efferent lymphatic vessels:
– carrying fluid away from the lymph node
Lymphoid Nodes
Give the basic functions
of lymph nodes
31. • Nodes have two histologically distinct regions: a
cortex and a medulla
• The cortex contains follicles with germinal centers,
heavy with dividing B cells
• Dendritic cells nearly encapsulate the follicles
• The deep cortex houses T cells in transit
• T cells circulate continuously among the blood,
lymph nodes, and lymphatic stream
Microscopic Anatomy of a Lymph Node
32. Largest lymphoid organ, located
on the left side of the abdominal
cavity beneath the diaphragm
Function:
Immune function
removal of worn out or
damaged RBC’s
storage of platelets
production of RBC’s
during fetal life
Lymphatic Tissue - Spleen
33. • Two distinct areas of the spleen are:
– White pulp – area responsible for producing lymphocytes
suspended on reticular fibers and involved in immune functions
– Red pulp – remaining splenic tissue concerned with
phagocytizing old or senescent RBCs and bloodborne pathogens
Lymphatic Tissue - Spleen
34. • A bilobed organ that
secrets hormones
(thymosin and
thymopoietin) that cause
T lymphocytes to become
immunocompetent
– Located in pleural cavity
between sternum, heart
– Composed of cortex
and medulla
Thymus Gland
35. – The size of the thymus varies with age
– It stops growing during adolescence and then
gradually atrophies
– Largest lymphatic organ in a child is thymus
gland
– It functions strictly in T lymphocyte maturation
– It does not directly fight antigens
Thymus Gland
36. • Location of the tonsils
– Palatine tonsils – either side
of the posterior end of the
oral cavity
– Lingual tonsils – lie at the
base of the tongue
– Pharyngeal tonsil – posterior
wall of the nasopharynx
– Tubal tonsils – surround the
openings of the auditory
tubes into the pharynx
• Simplest lymphoid organs; form a ring of lymphatic
tissue around the pharynx
Tonsils
37. • Peyer’s patches – isolated clusters of lymphoid
tissue, similar to tonsils
– Found in the wall of the distal portion of the small
intestine
– Similar structures are found in the appendix
• Peyer’s patches and the appendix:
– Destroy bacteria, preventing them from breaching
the intestinal wall
– Generate “memory” lymphocytes for long-term
immunity
Aggregates of Lymphoid Follicles
38. • MALT – mucosa-associated lymphatic tissue is
composed of:
– Peyer’s patches, tonsils, and the appendix
(digestive tract)
– Lymphoid nodules in the walls of the bronchi
(respiratory tract)
• MALT protects the digestive and respiratory
systems from foreign matter
MALT
41. Innate/Natural/ Nonspecific
– Present from birth
– Operates against any substance
– Not enhanced by prior exposure
Acquired/Adaptive/Specific
– Defense mechanisms
tailored to individual
pathogens
– enhanced by prior exposure
2 Type of Immunity: Innate & Acquired
42. • Innate (nonspecific) system responds
quickly and consists of:
– First line of defense – intact skin and mucosae
prevent entry of microorganisms
– Second line of defense – antimicrobial proteins,
phagocytes, and other cells
• Inhibit spread of invaders throughout the body
• Inflammation is its hallmark and most important
mechanism
Immunity: Two Intrinsic Defense Systems
43. • Refers to various PHYSICAL, CHEMICAL, and
CELLULAR attributes that collectively represent the
first line of defense against infectious disease.
• Skin – acts as a physical barrier to invasion
• Sweat – has chemicals which can kill different
pathogens.
• Tears – have lysozyme protective chemical that lyses
cells
• Saliva – also has lysozyme.
• Mucus - can trap pathogens, which are then
sneezed, coughed, washed away, or destroyed by
chemicals.
• Stomach Acid – destroys pathogens
Innate Immune System: First Line of Defense
44. • The body uses nonspecific cellular and
chemical devices to protect itself
– Phagocytes and natural killer (NK) cells
– Antimicrobial proteins in blood and tissue fluid
– Inflammatory response enlists macrophages,
mast cells, WBCs, and chemicals
• Harmful substances are identified by surface
carbohydrates unique to infectious
organisms
Internal Defenses: Cells and Chemicals
45. • Macrophages are the chief phagocytic cells
• Free macrophages wander throughout a region in
search of cellular debris
• Kupffer cells (liver) and microglia (brain) are fixed
macrophages
• Neutrophils become phagocytic when encountering
infectious material
• Eosinophils are weakly phagocytic against parasitic
worms
• Mast cells bind and ingest a wide range of bacteria
Phagocytes
46. • Next line of defense (with phagocytes)
• Lymphocytes – but do not respond to specific antigens
• Can kill a variety of microbes plus tumor cells.
• May release perforins, or attack directly
• Cell may not display correct MHC antigens
Natural Killer Cells
CYTOKINE
A cytokine is a protein hormone which regulates
normal cell functions, like growth and differentiation.
47. Interferon
• Naturally occurring proteins produced by virus-infected cells that
helps other cells resist viral infection.
• There are 3 types of interferon, alpha, beta and gamma
• Standard interferon is broken down relatively fast by the body
• Has to be injected 3 times a week
• Effectiveness decreases, allowing HCV to multiply in between
injections
49. • The adaptive immune system is a functional
system that:
– Recognizes specific foreign substances
– Acts to immobilize, neutralize, or destroy foreign
substances
– Amplifies inflammatory response and activates
complement
Adaptive (Specific) Defenses
50. • 10- 20 normally inactive proteins
• When activated, they “complement” or enhance
certain immune, allergic and inflammatory
reactions.
– Activation of inflammation
– Opsonization – enhances phagocytosis
– Cytolysis – membrane attack complex
The Complement System
51. • The adaptive immune system is antigen-
specific, systemic, and has memory
• It has two separate but overlapping arms
– Humoral, or antibody-mediated immunity
• B cells (mature in bone) make antibodies: specific
proteins that bind to specific antigens
– Cellular, or cell-mediated immunity
• T-cytoxic lymphocytes attack virus infected or tumor
cells directly
Adaptive Immune Defenses
Differentiate between
cellular and humoral
immunity
53. • B cells encounter antigens and produce antibodies against them
– Naturally acquired – response to a bacterial or viral infection
– Artificially acquired – response to a vaccine of dead or attenuated pathogens
– Regarding acquired immunity, the introduction into a recipient of dead or attenuated
pathogens, via a vaccine, is an example of Active, artificially acquired immunity
A vaccination artificially acquired active immunity
Active Humoral Immunity
54. • Differs from active immunity in the antibody source
and the degree of protection
– B cells are not challenged by antigens
– Immunological memory does not occur
– Protection ends when antigens naturally degrade in the
body
• Naturally acquired – from the mother to her fetus
via the placenta
• Artificially acquired – from the injection of serum,
such as gamma globulin
Passive Humoral Immunity
55. Gamma Globulin: A Gamma Globulin shot is purely an
injection of antibodies to provide temporary immunity.
You might receive an Gamma Globulin shot if you travel
outside of the country.
Artificially acquired passive immunity could be the result
of gamma globulin injection.
Gamma Globulin
56. Antibodies
An antibody is a protein produced in response to an
antigen.
“Y” shaped proteins – gamma globulins
have a variable region that matches a specific antigen (Fab
region)
Have a constant region – activates complement (Fc region)
57. There are 5 classes of antibodies:
– IgG—most abundant; about 80% of all antibodies in the
blood; can cross the placenta from mother to fetus, giving
newborns immune protection
– IgA—makes up 10-15% of antibodies in the blood; levels
decreased during stress
– IgM—makes up 5-10% of antibodies in the blood; first
secreted by plasma cells
– IgD—makes up only about 0.2% of antibodies in the blood
– IgE—makes up less than 0.1% of all antibodies in the blood;
involved in allergic reactions
Antibodies - Immunoglobulin
58. • Substances that can mobilize the immune system and
provoke an immune response
• The ultimate targets of all immune responses are mostly
large, complex molecules not normally found in the body
(nonself)
Antigens
