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Chapter 16Lecture
PowerPoint
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2402Anatomy and Physiology II
Chapter 16
Susan Gossett
Department of Biology
Paris Junior College
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Hole’s Human Anatomyand Physiology
Twelfth Edition
Shier Butler Lewis
Chapter 16
Lymphatic Systemand Immunity
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16.1: Introduction
• The lymphatic system is a vast collection of cells and biochemicals that travel in lymphatic vessels• It is a network of vessels that assist in circulating fluids• It is closely associated with the cardiovascular system• It transports excess fluid away from the interstitial spaces• It transports fluid to the bloodstream• It transports fats to the bloodstream• It helps defend the body against diseases
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16.2: Lymphatic PathwaysCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lymphaticcapillaries
Pulmonarycapillarynetwork
Lymphnode
Lymphaticvessels
Bloodflow
Lymphnode
Lymphflow
Systemiccapillarynetwork
Lymphaticcapillaries
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Lymphatic Capillaries
Tissue cells
ArterioleVenule
Lymphaticcapillary
Capillarybed
Lymphaticvessel
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Lymphatic Vessels• The walls are similar but thinner than those of veins• Lymphatic vessels are composed of three layers:
• An endothelial lining (inner)• Smooth muscle (middle)• Connective tissue (outer)
• Larger vessels lead to lymph nodes and then to larger lymphatic trunks
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© The McGraw-Hill Companies, Inc./Dennis Strete, photographer
Lymphatic Trunks and Collecting Ducts
• The trunks drain lymph from the lymphatic vessels• They are named for the regions they serve such as lumbar, intestinal, intercostal, bronchomediastinal, subclavian, and jugular
Jugular trunk
Right lymphatic duct
Brachiocephalic vein
Bronchomediastinal trunk
Intercostaltrunk
Internal jugular vein
Thoracic duct
Subclavian trunk
Thoracic duct
Intestinaltrunk
Lumbartrunk
Lymphaticvessels
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Lymph nodes Thoracic duct
Thoracic duct
Right lymphatic duct
Right internal jugular vein
(a)
(b)
Area drainedby right lymphatic duct
Right lymphaticduct
Lymphatictrunks
Lymphaticvessels
Left internaljugular vein
Left subclavianvein
Cisternachyli
Right subclavianvein
Axillary lymphnodes
Lymphatics ofmammary gland
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Afferent lymphatic vessel
Collecting duct
Subclavian vein
Efferent lymphatic vessel
Lymphatic capillary
Lymph node
Lymphatic trunk
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16.3: Tissue and Fluid Lymph
• Lymph is essentially tissue fluid that has entered a lymphatic capillary• Lymph formation depends on tissue fluid formation
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Tissue Fluid Formation
• Capillary blood pressure filters water and small molecules from the plasma
• The resulting fluid has:
• Much the same consistency as plasma
• Contains water and dissolved substances
• Contains smaller proteins which create plasma colloid osmotic pressure
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Lymph Formation
• Filtration from the plasma normally exceeds reabsorption, leading to the net formation of tissue fluid
• This increases the tissue fluid hydrostatic pressure within interstitial spaces forcing fluid into lymphatic capillaries forming lymph
• This process prevents accumulation of excess tissue fluid or edema
Lymph Function
• Lymphatic vessels play a role in:• Absorption of dietary fats• Delivering fats to the bloodstream• Collecting of excess interstitial fluids• Delivering excess fluids to the bloodstream• Delivering foreign particles to the lymph nodes
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Flow of lymph
Epithelialcell
Filamentsanchored toconnectivetissue
Movement oftissue fluid
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16.4: Lymph Movement
• Hydrostatic pressure of tissue fluid drives the lymph into the lymphatic capillaries• Muscle activity largely influences the movement of lymph through the lymphatic vessels via:
• Action of skeletal muscles• Respiratory movements• Smooth muscle in the larger lymphatic vessels• Valves in the lymphatic vessels
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Lymph FlowCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
SinusCapsule
(a)
Nodule HilumArtery
Medulla(macrophages, T cells)
Capsule
Subcapsule(macrophages, B cells)
Efferent lymphatic vessel
Lymph flow
Germinalcenter(B cells)
Vein
Lymph flow
Afferentlymphaticvessel
Germinalcenter
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
(b)
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Obstruction of Lymph MovementCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Blood vessels
Lymph node
Muscle
Lymphaticvessels
© Dr. Kent M. Van De Graaff
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16.5: Lymph Nodes
• Lymph nodes or lymph glands are located along the lymphatic pathways• They contain lymphocytes and macrophages to fight invading pathogens
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Structure of a Lymph NodeCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lymph flow
SinusCapsule
(a)
Nodule Hilum
Lymph flowArtery
Vein
Afferentlymphaticvessel
Germinalcenter(B cells)
Subcapsule(macrophages, B cells)
Medulla(macrophages, T cells)
Efferentlymphaticvessel
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Locations of Lymph Nodes• Lymph nodes are found in groups or chains along the paths of the larger lymphatic vessels throughout the body, including the:
• Cervical region• Axillary region• Supratrochlear region• Inguinal region• Pelvic cavity• Abdominal cavity• Thoracic cavity
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Thoraciclymphnode
Axillarylymphnode
Cervicallymphnode
Supratrochlearlymph node
Abdominallymph node
Pelvic lymphnode
Inguinallymphnode
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Functions of Lymph Nodes
• Lymph nodes have two primary functions:• Filter potentially harmful particles from the lymph• Act with immune surveillance provided by macrophages and lymphocytes
• Along with the red bone marrow, the lymph nodes are centers for lymphocyte production
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16.6: Thymus and Spleen
• These are two other lymphatic organs with functions similar to those of the lymph nodes
Thymusin fetus
Thymusin adult
Thymus
• The thymus is:• Larger in infancy and during puberty• Small in an adult• Replaced by fat and connective tissue in the elderly• Site of T lymphocyte (or T cell) production• Secretes protein hormones called thymosins
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Larynx
Thymus
Lung
Liver
(a)
(b)
Diaphragm
Thyroid gland
Heart
StomachSpleen
Lobule
Trachea
Connectivetissue
b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer
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Spleen
• The spleen is:• The largest lymphatic organ• Located in the upper left abdominal quadrant• Has sinuses filled with blood• Contains two tissue types:
• White pulp (lymphocytes)• Red pulp (red blood cells, lymphocytes and macrophages)
Spleen
Artery of pulp
White pulp
Red pulp
(a)
(b)
CapillaryCapsule
CapsuleWhite pulp
Red pulp
Splenicartery
Splenicvein
Connectivetissue
Venous sinus
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
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16.7: Body Defenses Against Infection
• The presence and multiplication of a pathogen in the body may cause an infection• Pathogens are:
• Disease causing agents• Bacteria, viruses, complex microorganisms, and spores of multicellular organisms
• The body can prevent entry of pathogens or destroy them with defense mechanisms such as:
• Innate defenses :• These are general defenses• They protect against many pathogens
• Adaptive defenses:• Known as immunity• More specific and precise targeting specific antigens • Are carried out by lymphocytes
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16.8: Innate (Nonspecific) Defenses
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Species Resistance
• Refers to a given type of organism, or species, that develops diseases unique to it
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Mechanical Barriers
• The skin and mucous membranes create mechanical barriers• Mechanical barriers are considered the first line of defense (all other non-specific defenses are part of the second line of defense)
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Chemical Barriers
• Enzymes in body fluids provide a chemical barrier to pathogens, and they may include:
• Interferons are horomone-like peptides and stimulate phagocytosis• Defensins are peptides produced by neutrophils and other granulocytes. They cripple microbes.• Collectins are proteins with broad protection against bacteria, yeast and some viruses• Complement is a group of proteins in plasma and other body fluids that stimulate inflammation, attract phagocytes and enhance phagocytosis
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Natural Killer (NK) Cells
• NK cells are a small population of lymphocytes defending against viruses and cancer by secreting cytolytic substances called perforins that destroy the infected cell• NK may also enhance inflammation
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Inflammation
• Inflammation produces local redness, swelling, heat and pain• Table 16.2 summarizes the process
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Phagocytosis
• Phagocytosis removes foreign particles from the lymph• Phagocytes are also in the blood vessels and in the tissues of the spleen, liver or bone marrow• The most active phagocytic cells are neutrophils and monocytes• Chemicals attract these phagocytic cells to the injury and this is called chemotaxis
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Fever
• A fever begins when a viral or bacterial infection stimulates lymphocytes to proliferate, producing cells that secrete a substance called interleukin-1 (IL-1)
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16.9: Adaptive (Specific) Defenses or Immunity
• This is the third line of defense and known as immunity• It is resistance to particular pathogens or to their toxins or metabolic by-products• It is based on the ability to distinguish molecules that are part of the body (“self” from “non-self”)• Antigens are molecules that can elicit an immune response
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Antigens
• Antigens may be:• Proteins • Polysaccharides• Glycoproteins• Glycolipids
• The most effective antigens are large and complex• Haptens are small molecules that are not antigenic by themselves, but when they combine with a large molecule can stimulate an immune response
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Lymphocyte Origins
B cell
Thymus
T cell
T cell
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2
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B cell
Stem cellsin red bonemarrow giverise tolymphocyteprecursors.
Redbonemarrow
Some lymphocyteprecursors areprocessed withinthe bone marrowto become B cells.
Both T cells and B cells are transported through the blood to lymphatic organs, such as the lymph nodes, lymphatic ducts, and spleen.
Some lymphocyteprecursors areprocessed in thethymus to becomeT cells.
BloodtransportBlood
transport
Lymphocyteprecursors
Bloodtransport
Lymphnode
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T Cells and the Cellular Immune Response
• A lymphocyte must be activated before it can respond to an antigen• T cell activation requires antigen-presenting cell (accessory cell) and may include macrophages, B cells and several other types of cells• Requires major histocompatibility complex (MHC) or human leukocyte antigens (HLA) to recognize “non-self”• T cells can synthesize and secrete polypeptides called cytokines• Types of specialized T cells include:
• Helper T cells• Cytotoxic T cells• Memory T cells
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B Cells and the Humoral Immune Response
• B cells can be activated when an antigen fits the shape of its receptor• Most of the time B cell activation requires T cells• T cells release cytokines that stimulate B cells• Some B cells may become memory B cells while others differentiate into plasma cells and produce and secrete large globular proteins called antibodies or immunoglobulins
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Cytokines
Antigen
B cells
Activated B cell
Interleukin-2
1
3
2
4
5
(a)
Macrophage
Helper T cell
(b)
CytotoxicT cell
Cytotoxic T cell contactsDisplayed antigen
Helper T cell contacts displayed antigen and proliferates
CytotoxicT cell
HelperT cells
Activated helper T cell interacts with cytotoxic T cell (which has combined with an identical antigen) and releases interleukin-2, which activates the cytotoxic T cell
ProliferationandDifferentiationMemory
T cellCytotoxicT cell
Antigenreceptor
B cell combineswith antigen
Macrophage displays ingestedantigen on its surface
Displayedantigen
b: © Manfred Kage/Peter Arnold
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Activated B cell
Proliferation
B cells
Antigen
Cytokines
Activation1
2
3
Antigenreceptor
Stimulation byactivated helper T cell
Clone ofB cells
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Antigen
Proliferation
AntigenReceptor (antibody)
Receptor-antigencombination
ActivatedB cell
Cytokinesfrom helperT cell
Clone ofB cells
Proliferation andDifferentiation
Proliferation andDifferentiation
Endoplasmicreticulum
Releasedantibodies
Plasma cell(antibody-secreting cell)
Memory cell(dormant cell)
Plasma cell(antibody-secreting cell)
Memory cell(dormant cell)
Clone ofB cells
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16.1 From Science to Technology
Immunotherapy
Immune ResponsesP
las
ma
an
tib
od
y c
on
ce
ntr
ati
on
100 20 30
Primary response
Secondary response
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Days after exposure to antigen
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Practical Classification of Immunity
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Allergic Reactions Type I
• Immediate-reaction allergy• Occurs minutes after contact with allergen• Symptoms include hives, hay fever, asthma, eczema, gastric disturbances, and anaphylactic shock
Type II• Antibody-dependent cytotoxic reaction• Takes 1-3 hours to develop• Transfusion reaction
Type III• Immune-complex reaction• Takes 1-3 hours to develop• Antibody complexes cannot be cleared from the body• Damage of body tissues
Type IV• Delayed-reaction allergy• Results from repeated exposure to allergen• Eruptions and inflammation of the skin• Takes about 48 hours to occur
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B cell
Plasma cell
Mast cell
IgE receptor
Granule
(a)
1
2
3
5
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Allergen
Allergen
Allergicreaction
Histamineand otherchemicals
Mast cell releasesallergy mediators
Subsequentcontact withallergen
Antibodiesattach tomast cell
Released IgEantibodies
Initial B cellcontact withallergen
Plasma cellsecretesantibodies
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Transplantation and Tissue Rejection
• Successfully transplanted tissues and organs:• Cornea• Kidney• Liver• Pancreas
• When the donor’s tissues are recognized as foreign there is a tissue rejection reaction• Resembles the cellular immune response against antigens• Important to match MHC antigens• Immunosuppressive drugs used to prevent rejection
• Heart• Bone marrow• Skin
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Autoimmunity
• The immune system fails to distinguish “self” from “non-self” and the body produces antibodies called autoantibodies, and cytotoxic T cells to attack the body’s tissues and organs
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16.10: Lifespan Changes
• The immune system declines early in life as the thymus gland shrinks (only 25% as powerful as it once was)• There is a higher risk of infection• Antibody response to antigens becomes slower• IgA and IgG antibodies increase• IgM and IgE antibodies decrease• Elderly may not be candidates for certain medical treatments that suppresses immunity
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16.1 Clinical Application
Immunity Breakdown: AIDS
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Important Points in Chapter 16:Outcomes to be Assessed
16.1: Introduction
Describe the general functions of the lymphatic system.
16.2: Lymphatic Pathways
Identify and describe the parts of the major lymphatic pathways.
16.3: Tissue Fluid and Lymph
Describe how tissue fluid and lymph form, and explain the function of lymph.
16.4: Lymph Movement
Explain how lymphatic circulation is maintained, and describe the consequence of lymphatic obstruction.
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Important Points in Chapter 16:Outcomes to be Assessed
16.5: Lymph Nodes
Describe a lymph node and its major functions.
Describe the location of the major chains of lymph nodes.
16.6: Thymus and Spleen
Discuss the locations and functions of the thymus and spleen.
16.7: Body Defenses Against Infection
Distinguish between innate (nonspecific) and adaptive (specific) defenses.
16.8: Innate (Nonspecific) Defenses
List seven innate body defense mechanisms, and describe the action of each mechanism.
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Important Points in Chapter 16:Outcomes to be Assessed
16.9: Adaptive (Specific) Defenses, or Immunity
Explain how two major types of lymphocytes are formed, activated, and how they function in immune mechanisms.
Discuss the origins and actions of the five different types of antibodies.
Distinguish between primary and secondary immune responses.
Distinguish between active and passive immunity.
Explain how allergic reactions, tissue rejection reactions, and autoimmunity arise from immune mechanisms.
16.10: Lifespan Changes
Describe lifespan changes in immunity.
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Quiz 16
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Read Chapter 17.