This document is a lecture outline on the lymphatic system and immunity from a textbook on anatomy and physiology. It covers the key components and functions of the lymphatic system including lymphatic vessels, lymph nodes, the spleen, thymus gland, and tonsils. It also discusses the immune system, including innate immunity through physical barriers and chemical mediators, and adaptive immunity carried out by B and T lymphocytes through antibody-mediated and cell-mediated responses. Diagrams and figures are provided to illustrate these concepts.

1. Seeley’s
ESSENTIALS OF
Anatomy &
Physiology
Tenth Edition
Cinnamon Vanputte
Jennifer Regan
Andrew Russo
See separate PowerPoint slides for all figures and tables
pre-inserted into PowerPoint without notes.
© 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education.

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Chapter 14
Lymphatic System
and Immunity
Lecture Outline

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Functions of the Lymphatic System
1. Fluid balance
2. Fat Absorption
3. Defense

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Lymphatic System and
Lymph Drainage
Figure 14.1

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Components of the Lymphatic System
Lymph:
• fluid that enters lymphatic capillaries composed of
water and some solutes
Lymphocytes
Lymphatic vessels
Lymph nodes
Tonsils
Spleen
Thymus gland

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Lymphatic Capillaries
Carries fluid in one direction from tissues to
circulatory system
Fluid moves from blood capillaries into tissue spaces
Lymphatic capillaries:
• tiny, closed-ended vessels
• fluid moves easily into
• in most tissues
• join to form lymphatic vessels

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Lymphatic Vessels1
Lymphatic vessels:
• resemble small veins
• where lymphatic capillaries join
• one way valves
Right lymphatic duct:
• where lymphatic vessels from right upper limb and
right head, neck, chest empty
• empties into right subclavian vein

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Lymphatic Vessels2
Thoracic duct:
• rest of body empties from lymphatic vessels
• empties into left subclavian vein

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Lymph Formation and Movement
Figure 14.2

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Lymphatic Organs
Tonsils:
• palatine tonsils on each side of oral cavity
• pharyngeal tonsils near internal opening of nasal
cavity (adenoid)
• lingual tonsils posterior surface of tongue
• form a protective ring of lymphatic tissue around
nasal and oral cavities

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The Tonsils
Figure 14.3

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Lymph Nodes1
Lymph nodes are:
• rounded structures that vary in size
• located near lymphatic vessels
• groin, armpit, neck
• lymph passes through lymph nodes before entering
blood

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Lymph Nodes2
lymph moves through and immune system
is activated (lymphocytes produced) if foreign
substances are detected
removal of microbes by macrophages

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Lymph Node
Figure 14.4

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The Spleen1
The spleen is:
• size of clenched fist
• located in abdomen
• filters blood
• detect and respond to foreign substances
• destroy old red blood cells
• blood reservoir

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The Spleen2
white pulp: lymphatic tissue surrounding
arteries
red pulp: contains macrophages and red blood
cells that connect to veins

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The Spleen3

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The Thymus Gland1
The thymus gland is:
• bilobed gland
• located in mediastinum behind the sternum
• stops growing at age 1
• at age 60 decreases in size
• produces and matures lymphocytes

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The Thymus Gland2
Figure 14.6
(b) ©Trent Stephens

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Overview of the Lymphatic System
Figure 14.7

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Immunity
Immunity is the ability to resist damage from
foreign substances.
Immunity can protect against microbes, toxins,
and cancer cells.
Types of immunity:
• innate
• adaptive

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Innate Immunity
Innate immunity is:
• present at birth
• defense against any pathogen
• accomplished by physical barriers, chemical
mediators, cells, inflammatory response

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Physical Barriers
First line of defense
Skin and mucous membranes to act as barriers
Tears, saliva, urine wash away pathogens

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Chemical Mediators1
Chemical mediators are chemicals that can kill
microbes and prevent their entry into cells
Lysozyme:
found in tears and saliva to kill bacteria
Mucous membranes:
prevent entry of microbes

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Chemical Mediators2
Histamine:
promote inflammation by causing vasodilation
Interferons:
proteins that protect against viral infections by
stimulating surrounding cells to produce antiviral
proteins

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Cells of the Immune System1
White blood cells:
produce in red bone marrow and lymphatic
tissue that fight foreign substances
Phagocytic cells:
• ingest and destroy foreign substances
• Example—neutrophils and macrophages

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Cells of the Immune System2
Neutrophils:
first to respond to infection but die quickly
Eosinophils:
• produced in red bone marrow
• release chemicals to reduce inflammation
Basophils:
• made in red bone marrow
• leave blood and enter infected tissues
• can release histamine

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Cells of the Immune System3
Macrophages:
• initially were monocytes
• leave blood and enter tissues
• can ingest more than neutrophils
• protect lymph in lymph nodes and blood in
• spleen and liver
• given specific names for certain areas of body
(Kupffer cells in liver)

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Cells of the Immune System4
Mast cells:
• made in red bone marrow
• found in skin, lungs, gastrointestinal tract, urogenital tract
• can release leukotrienes
Natural Killer Cells:
• type of lymphocyte
• produce in red bone marrow
• recognize classes of cells such as tumor cells or virus
infected cells
• release chemicals to lysis cells

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Inflammatory Response1
The inflammatory response:
• involves chemical and cells due to injury
• signaled by presence of foreign substance
• stimulates release of chemical mediators

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Inflammatory Response2
Figure 14.8

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Adaptive Immunity
Adaptive immunity is defense that involves
specific recognition to a specific antigen.
This immunity:
• is acquired after birth
• reacts when innate defenses don’t work
• slower than innate immunity
• has memory
• uses lymphocytes (B and T cells)
• 2 types antibody-mediated and cell-mediated

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Terms Related to Adaptive Immunity
Antigen:
• substance that stimulates an immune response
• Example—bacteria, virus, pollen, food, drugs
Self-antigen:
• molecule produced by the person’s body that
stimulates an immune system response
Antibody:
• proteins the body produces in response to an antigen

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Origin and Development of
Lymphocytes
Stem cells:
• red bone marrow
• give rise to all blood cells
• give rise to some pre T cells and pre B cells

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Lymphocytes1
Lymphocytes are:
• type of white blood cell
• involved in adaptive immunity
• develop from stem cells
• differentiate into specific lymphocytes such as B or T
cells

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Lymphocytes2
B cells:
• type of lymphocytes
• involved in antibody-mediated immunity
• originate from stem cells
• mature in red bone marrow
• move to lymphatic tissue after mature
• lead to production of antibodies

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Lymphocytes3
T cells:
• type of lymphocyte
• involved in cell-mediated immunity primarily and
antibody-mediated immunity
• mature in thymus gland
• move to lymphatic tissue after mature
• 4 types

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Origin and Processing of B Cells
and T Cells
Figure 14.9

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Antigen Recognition
Lymphocytes have antigen receptors on their
surface
Called B-cell receptors on B cells and T-cell
receptors on T cells
Each receptor only binds with a specific antigen
When antigen receptors combine with the
antigen, the lymphocyte is activated and
adaptive immunity begins

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The MHC Molecule
The major histocompatibility complex molecule
(MHC):
• contain binding sites for antigens
• specific for certain antigens
• hold and present a processed antigen on the surface
of the cell membrane
• bind to antigen receptor on B or T cells and stimulate
response

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Cytokines
Cytokines are:
• proteins secreted by a cell that regulates
neighboring cells
• Example—interleukin 1 released by macrophages
stimulates helper T cells

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Proliferation of Helper T Cells
Figure 14.10

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Lymphocyte Proliferation
1. After antigen is processed and present to
helper T cells, helper T cell produces
interleukin-2 and interleukin 2-receptors
2. Interleukin-2 binds to receptors and
stimulates more helper T cells production
3. Helper T cells are needed to produce B cells
4. B cells produce antibodies

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Proliferation of B Cells
Figure 14.11

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Dual Nature of the Immune System
Lymphocytes give rise to 2 types of immune
responses: antibody-mediated and cell-
mediated
Antigens can trigger both types of responses
Both types are able to recognize self versus
nonself, use specificity, and have memory

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Antibody-Mediated Immunity
Antibody-mediated immunity is:
• effective against antigens in body fluids
(blood and lymph)
• effective against bacteria, viruses, toxins
• uses B cells to produce antibodies

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Antibody Structure1
Letter Y shape
Variable region:
• V of Y
• bind to epitopes of antigen using antigen- binding site
Constant region:
• stem of Y
• each class of immunoglobulin has same structure

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Antibody Structure2
Figure 14.12

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Antibody Structure3
Antigen-binding site:
site on antibody where antigen binds
Valence:
number of antigen-binding sites on antibody
5 classes of immunoglobulins used to destroy
antigens:
IgG, IgM, IgA, IgE, IgD

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Antibody Structure4

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Antibodies1
IgG
• 80 to 85% in serum
• activates compliment and increases phagocytosis
• can cross the placenta and provide protection to
the fetus
• responsible for Rh reactions, such as hemolytic
disease of the newborn

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Antibodies2
IgM
• 5 to 10% in serum
• activates compliment
• acts as an antigen binding receptor on the surface
of B cells
• responsible for transfusion reactions in the ABO
blood system
• often the first antibody produced in response to an
antigen

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Antibodies3
IgA
• 15% in serum
• secreted into saliva, into tears, and onto mucous
membranes
• protects body surfaces
• found in colostrum and milk to provide immune
protection to the newborn

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Antibodies4
IgE
• 0.002% in serum
• binds to mast cells and basophils and stimulates
the inflammatory response

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Antibodies5
IgD
• 0. 2% in serum
• functions as an antigen-binding receptor on B cells

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Effects of Antibodies1
Inactivate antigen
Bind antigens together
Active complement cascades
Initiate release of inflammatory chemicals
Facilitate phagocytosis

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Effects of Antibodies2
Figure 14.13

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Antibody Production1
The primary response
• 1st exposure of B cell to antigen
• B cell undergoes division and forms plasma cell and
memory cells
Plasma cells:
• produce antibodies
• 3 to 14 days to by effective against antigen
• person develop disease symptoms

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Antibody Production2
The secondary response involves:
• Memory cells:
• occurs when immune system is exposed to antigen
that has been seen before
• B memory cells quickly divided to form plasma cells
which produce antibodies
• produces new memory cells

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Antibody Production3
Figure 14.14

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Cell-Mediated Immunity
Cell-mediated immunity is used against antigens
in cells and tissues.
It is effective against intracellular bacteria,
viruses, fungi, and protozoa.
It uses different types of T cells.

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Types of T Cells for Cell-Mediated
Immunity1
Helper T cells (TH):
• activate macrophages
• help form B cells
• promote production of Tc
Cytotoxic T cells (Tc):
• precursor to cytotoxic T lymphocytes (CTL)

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Types of T Cells for Cell-Mediated
Immunity2
Cytotoxic T lymphocytes (CTL):
• destroys antigen on contact
Regulatory T cells (Tr):
• turn off immune system response when antigen is
gone

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Proliferation of Cytotoxic T Cells
Figure 14.15

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Stimulation and Effects of T Cells
Figure 14.16

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Immune Interactions
Figure 14.18

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Types of Adaptive Immunity1
Naturally Acquired Immunity
Active:
• natural exposure to antigens causes production of
antibodies
• can be lifelong immunity
• Example—mononucleosis
Passive:
• transfer of antibodies from mother to child
• Example—breast milk or placenta

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Types of Adaptive Immunity2
Artificially Acquired Immunity
Active:
• injection of antigens using vaccines which cause the
production of antibodies
• immunization is a process of introducing killed, live,
or inactivated pathogen
Passive:
• injection of antibodies from another person or animal

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Ways to Acquire Adaptive Immunity
Figure 14.17