Chapter 22 - The Lymphatic System and Immunity Flashcards
What is Disease Resistance?
1- Nonspecific Resistance (Innate Immunity):
Present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens
2- Immunity (Adaptive Immunity):
Involves activation of specific lymphocytes that combat particular pathogen or other foreign substance
The body system that carries out Immunes Responses is the Lymphatic System
What is Lymphatic System?
Lymphatic System consists of several structures and organs that contain:
1- Lymphatic Tissue
2- Bone Marrow
3- Lymph:
Fluid that flows within Lymphatic Vessels
What are the Functions of the Lymphatic System?
The Lymphatic System functions are:
1- Drain interstitial fluid
2- Transport dietary fats
3- Carry out Immune Responses
What is Lymphatic Vessels and Capillaries?
1- Lymphatic Vessels
Begin as Lymphatic Capillaries, which are closed on one end
2- Lymphatic Capillaries:
Located between cells of many tissues
Merge to form Lymphatic Vessels, which have thin walls and many valves
What is Lymphatic Capillary Components?
1- Lymph inside
2- Endothelium of Lymphatic Capillary
3- Anchoring Filaments:
Anchor the Lymphatic Capillary between tissue cells
4- Openings:
Allow interstitial fluid to drain into Lymphatic Capillary
What is Lymph Trunks and Ducts?
From the Lymphatic Vessels, Lymph passes through Lymph Nodes and then into Lymph Trunks
Lymph Trunks include:
1- Lumbar Trunk
2- Intestinal Trunk
3- Bronchomediastinal Trunk
4- Subclavian Trunk
5- Jugular Trunk
Lymph Trunks then merge to form:
1- Thoracic Duct:
(drains most of the body)
2- Right Lymphatic Duct:
(drains right upper quarter of body)
What is Formation and Flow of Lymph?
1- Interstitial fluid:
Blood plasma filtered from blood capillaries into interstitial spaces to become interstitial fluid
2- Lymph Capillaries:
Absorb interstitial fluid and pass Lymph to Afferent Lymphatic Vessels
Afferent Lymphatic Vessels: (in)
Carry Lymph from Lymphatic Capillaries to Lymph Nodes
Lymph Nodes:
Remove foreign substances through filtering Lymph, Phagocytosis, and Immune Reactions
Efferent Lymphatic Vessels: (out)
Carry Lymph from Lymph Nodes
Valve:
Ensures one-way flow of Lymph
3- Lymph Vessels:
Pass Lymph to Lymphatic Ducts
4- Lymph Trunks
5- Lymph Ducts:
Thoracic Duct or Right Lymphatic Duct
Empty Lymph into the junction of Jugular and Subclavian Veins of the CV System
6- Subclavian Veins
What is Primary Lymphatic Organs and Tissues?
Primary Lymphatic Organs:
Organs where Immune Cells become Immunocompetent
(mature T Cell or B Cell, and checked themselves)
1- Red Bone Marrow
2- Thymus
What is Histology of Thymus?
1- Capsule:
Surrounds Thymus
2- Lobule:
T Cells
Epithelial Cells
Cortex
Medulla
Thymic Corpuscle (Hassall’s Corpuscle)
3- Trabeculae:
Surrounds each Lobule
What is Secondary Lymphatic Organs and Tissus?
Secondary Lymphatic Organs and Tissues:
1- Lymph Nodes
2- Spleen
3- Lymphatic Nodules
What is Structure of a Lymph Node?
1- Afferent Lymphatic Vessels (go in):
Has Valves
2- Subcapsular Sinus
3- Trabecular Sinus
4- Medullary Sinus:
5- Efferent Lymphatic Vessels (go out):
Has Valves
What are the Cells in a Lymph Node?
1- Cells of Medulla:
B Cells
Plasma Cells
Macrophages
2- Cells of Inner Cortex:
T Cells
Dendritic Cells
3- Cells around Germinal Center of Outer Cortex:
B Cells
4- Cells in Germinal Center of Outer Cortex:
B Cells
Follicular Dendritic Cells
Macrophages
What is Structure of Spleen?
1- Visceral Surface:
Splenic Artery
Splenic Vein
Gastric Impression
Colic Impression
Hilum
Renal Impression
2- Internal Structure:
Capsule
Trabeculae
White Pulp (has Central Artery)
Red Pulp (has Venous Sinus and Splenic Cord
What is Lymphatic Nodules?
Lymphatic Nodules:
Masses of Lymphatic Tissue that are not surrounded by a capsule
They are scattered throughout the Lamina Propria of Mucous Membranes lining the GI, Urinary, and Reproductive Tracts and the Respiratory Airways
Mucosa-Associated Lymphatic Tissue (MALT):
Lymphatic Nodules in these areas
What is Innate Immunity?
Innate Immunity:
Wide variety of body responses that serve to protect us against invasion by a wide variety of pathogens and their toxins
We are born with this kind of immunity
2 Lines of defense:
1- Skin and Mucous Membranes
2- Internal Defenses
What is Skin and Mucous Membranes in Immunity?
1- Mechanical Defenses:
Skin
Mucous membranes
Tears
Saliva
Mucus
Cilia
Epiglottis
Urine flow
Defecating
Vomiting
2- Chemical Defenses:
Sebum
Lysozyme
Gastric juice
What is Internal Defenses?
1- Antimicrobial proteins
2- Phagocyte
3- NK Cells
4- Inflammation
5- Fever
What is Phagocytosis Steps?
1- Chemotaxis:
Phagocyte detects chemicals and microbe
2- Adhesion:
Phagocyte sticks to microbe
Uses Pseudopods (feet) to engulf microbe)
3- Ingestion:
Phagosome made from cell membrane around the microbe
4- Digestion:
Lysosome containing Digestive Enzymes fuses with Phagosome
Digested microbe by Phagolysosome
5- Killing:
Microbe killed
Residual Body (vesicle containing indigestible material)
What is Inflammation?
Emigration (Diapedesis) of cells that will help at the site of an injury
Vasodilation opens sinuses for cells to go from vessels to injury site
What is First Line Defense of Innate Defenses by Epidermis?
Function:
Physical barrier to entrance of microbes
What is First Line Defense of Innate Defenses by Mucous Membranes?
Function:
Inhibit entrance of microbes, traps them, not as effective as intact skin
What is First Line Defense of Innate Defenses by Mucus?
Function:
Traps microbes in Respiratory and GI Tracts
What is First Line Defense of Innate Defenses by Hairs?
Function:
Filters out microbes and dust in nose
What is First Line Defense of Innate Defenses by Cilia?
Function:
Together with mucus, trap and remove microbes and dust from Upper Respiratory Tract
What is First Line Defense of Innate Defenses by Lacrimal Apparatus?
Function:
Tears dilute and wash away irritating substances and microbes
What is First Line Defense of Innate Defenses by Saliva?
Function:
Washes microbes from surfaces of teeth and mucous membranes of mouth
What is First Line Defense of Innate Defenses by Urine?
Function:
Washes microbes from Urethra
What is First Line Defense of Innate Defenses by Defecation and Vomiting?
Function:
Expel microbes from body
What is First Line Defense of Innate Defenses by Sebum?
Function:
Forms protective acidic film over skin surface that inhibits growth of microbes
What is First Line Defense of Innate Defenses by Lysozyme?
Function:
Antimicrobial substance in perspiration, tears, saliva, nasal secretions, and tissue fluids
What is First Line Defense of Innate Defenses by Gastric Juice?
Function:
Destroy bacteria and most toxins in stomach
What is First Line Defense of Innate Defenses by Vaginal Secretions?
Function:
Slight acidity discourages bacterial growth
Flush microbes out of Vagina
What is Second Line Defense of Innate Defenses by Interferons (INFs)?
Function:
Protect uninfected host cells from viral infections
What is Second Line Defense of Innate Defenses by Complement System?
Function:
Causes cytolysis of microbes
Promotes phagocytosis
Contributes to inflammation
What is Second Line Defense of Innate Defenses by Iron-Binding Proteins?
Function:
Inhibit growth of certain bacteria by reducing amount of available iron
What is Second Line Defense of Innate Defenses by Antimicrobial Proteins (AMPs)?
Function:
Have broad-spectrum antimicrobial activities
Attracts Dendritic Cells and Mast Cells
What is Second Line Defense of Innate Defenses by NK Cells?
Function:
Kill infected target cells by releasing granules that contain Perforin and Granzymes
Phagocytes then kill released microbes
What is Second Line Defense of Innate Defenses by Phagocytes?
Function:
Ingest foreign particulate matter
What is Second Line Defense of Innate Defenses by Inflammation?
Function:
Confines and destroys microbes
Initiates tissue repair
What is Second Line Defense of Innate Defenses by Fever?
Function:
Intensifies effects of IFN
Inhibits growth of some microbes
Speeds up body reactions that aid in repair
What is Adaptive Immunity?
Adaptive Immunity:
Body’s ability to defend itself against specific invading agents
Antigens:
Substances recognized as foreign that provoke immune responses
Adaptive Immunity has both Specificity and Memory and is divided into 2 Types:
1- Cell-Mediated
2- Antibody-Mediated
What is Cell-Mediated Immunity?
Cell-Mediated Immunity:
Directed against intracellular pathogens, some cancer cells, and tissue transplants
1- Red Bone Marrow makes T Cells
2- T Cells go to Thymus and mature
3- Mature T Cells go to Secondary Lymphatic Organs and Tissues
4- CD4 Protein activates Helper T Cells
5- Formation of Helper T Cell Clone, so Memory Helper T Cells
6- CD8 Protein and Active Helper T Cells activate Cytotoxic T Cells
7- Formation of Cytotoxic T Cell Clone, so Memory Cytotoxic T Cell
8- Active Cytotoxic T Cells exit Secondary Lymphatic Organs and Tissues to attack invading Antigens
What is Antibody-Mediated Immunity?
Antibody-Mediated Immunity:
Directed against extracellular pathogens
1- Red Bone Marrow makes B Cells
2- B Cells go to Secondary Lymphatic Organs and Tissues
3- Memory Helper T Cells help activate B Cells
4- Formation of B Cell Clone, so Memory B Cells
5- Activated B Cells become Plasma Cells and produce Antibodies
6- Antibodies exit Secondary Lymphatic Organs and Tissues
7- Antibodies bind to and inactivate Antigens in body fluids
What is Antigens and Antigen Receptors?
Immunogenicity:
Effectiveness of system at killing pathogens
Reactivity:
How Antigens stick to Antibodies
Entire microbes or just parts of microbes act as Antigens
Epitopes:
Certain small parts of a large Antigen molecule acts as the triggers for immune responses
What is Pathway of Antigen Processing?
For an immune response to occur, B Cells and T Cells must recognize that a foreign Antigen is present
B Cells can recognize and bind to Antigens in Lymph, interstitial fluid, or blood Plasma
T Cells only recognize fragments of Antigenic Proteins that are processed and presented in a certain way
In Antigen Processing, Antigenic Proteins are broken down into peptide fragments that associate with MHC molecules
Antigen Presentation:
The Antigen-MHC Complex is then inserted into the plasma membrane of a body cell
What is Exogenous Antigen Processing?
(Microbe was outside cell)
(Antigen-Presenting Cell APC)
1- Phagocytosis or Endocytosis of Exogenous Antigen:
Antigen-Presenting Cell (APC) takes the Antigen in a Phagosome or Endosome
2- Digestion of Antigen into peptide fragments
3- Synthesis of MHC-II molecules:
By the Endoplasmic Reticulum
4- Packaging of MHC-II molecules into a vesicle
5- Vesicles containing Antigen peptide fragments and MHC-II molecules fuse
6- Antigen peptide fragments bind to MHC-II molecules
7- Vesicle undergoes Exocytosis and Antigen-MHC-II Complexes are inserted into the plasma membrane
What is Endogenous Antigen Processing?
(Microbe is in cell)
(Infected cell)
1- Digestion of Endogenous Antigen into peptide fragments
2- Synthesis of MHC-I molecules:
By the Endoplasmic Reticulum
3- Antigen peptide fragments bind to MHC-I molecules
4- Packaging of Antigen-MHC-I molecules into a vesicle
5- Vesicle undergoes Exocytosis and Antigen-MHC-I Complexes are inserted into the plasma membrane
What is Cytokines?
Cytokines:
Small protein hormones that stimulate or inhibit many normal cell functions
What is Origin and Functions of Interleukin-1 (IL-1)?
Produced by Macrophages
Promotes proliferation of Helper T Cells
Acts on Hypothalamus to cause fever
What is Origin and Functions of Interleukin-2 (IL-2)?
Secreted by Helper T Cells
Costimulates proliferation of Helper T Cells, Cytotoxic T Cells, and B Cells
Activates NK Cells
What is Origin and Functions of Interleukin-4 (IL-4)
Interleukin-4 (IL-4) also knowns as B Cell Stimulating Factor
Produced by Helper T Cells
Costimulator for Tar B Cells
Causes Plasma Cells to secrete IgE Antibodies
Promotes growth of T Cells
What is Origin and Functions of Interleukin-5 (IL-5)?
Produced by some Helper T Cells and Mast Cells
Costimulator for B Cells
Causes Plasma Cells to secrete IgA Antibodies
What is Origin and Functions of Interleukin-6 (IL-6)?
Produced by Helper T Cells
Enhances B Cell proliferation, B Cell differentiation into Plasma Cells, and secretion of Antibodies by Plasma Cells
What is Origin and Functions of Tumor Necrosis Factor (TNF)?
Produced mainly by Macrophages
Stimulates accumulation of Neutrophils and Macrophages at sites of Inflammation
Stimulates their killing of microbes
What is Origin and Functions of Interferons (IFNs)?
Produced by Virus-infected cells to inhibit viral replication in uninfected cells
Activates Cytotoxic T Cells and NK Cells
Inhibit cell division
Suppress the formation of tumors
What is Origin and Functions of Macrophage Migration Inhibiting Factor?
Produced by Cytotoxic T Cells
Prevents Macrophages from leaving sites of Infection
What is Cell-Mediated Immunity?
1- Antigen is recognized and bound
2- Small number of T Cells proliferate and differentiate into a clone of effector cells
3- The Antigen is eliminated
What is Activation and Clonal Selection of a Helper T Cell?
1- APC presents Antigen to Inactive Helper T Cell with CD4 protein
2- Helper T Cell activated
3- Clonal Selection:
Proliferation and differentiation
Formation of Helper T Cell Clone
4- Result:
Active Helper T Cells and Memory Helper T Cells
What is Activation and Clonal Selection of a Cytotoxic T Cell?
1- Infected Cell presents Antigen to Inactive Cytotoxic T Cell with CD8 protein
2- Helper T Cell secretes IL-2 to help activate Inactive Cytotoxic T Cell
3- Cytotoxic T Cell activated
4- Clonal Selection:
Proliferation and differentiation
Formation of Cytotoxic T Cell Clone
5- Result:
Active Cytotoxic T Cells and Memory Cytotoxic T Cells
What is Activity of Cytotoxic T Cell?
1- Activated Cytotoxic T Cell recognize and attaches to infected cell’s held Antigen
2- Release Granzymes into infected cell
Or Granulysin and Perforin
3- Infected cell undergoes Apoptosis if Granzymes, or Cytolysis if Granulysin and Perforin
4- Microbes released from dead infected cell are phagocytized if Granzymes, or destroyed if Granulysin
What is Antibody-Mediated Immunity?
1- Antigen is recognized and bound
2- Helper T Cells costimulates the B Cell so the B Cell can proliferate and differentiate into a clone of effector cells that produce Antibodies
3- Antigen is eliminated
What is Characteristics and Function of IgG?
Most abundant, about 80% of all Antibodies in blood
Found in blood, Lymph, and Intestines
Monomer (one-unit) structure
Protects against bacteria and viruses by enhancing Phagocytosis, neutralizing toxins, and triggering Complement System
The only class of Antibody to cross Placenta from mother to fetus, conferring considerable immune protection in newborns
What is Characteristics and Function of IgA?
Found mainly in sweat, tears, saliva, mucus, breast milk, and GI secretions
Smaller quantities
Present in blood and Lymph
10-15% of all Antibodies in blood
Occurs as monomers and dimers
Levels decrease during stress, lowering resistance to infection
Provides localized protection of mucous membranes against bacteria and viruses
What is Characteristics and Function of IgM?
About 5-10% of all Antibodies in blood
Also found in Lymph
Also present as monomers on surfaces of B Cells, where they serve as Antigen recptors
First Antibody to be secreted by Plasma Cells after initial exposure to any Antigen
Activates Complement System and causes Agglutination and lysis of microbes
In blood Plasma, Anti-A and Anti-D Antibodies of the ABO blood group, which bind to A and B Antigens during incompatible blood transfusions
Are also IgM Antibodies
What is Characteristics and Function of IgD?
Mainly found on surfaces f B Cells as Antigen receptors, where it occurs in monomers
About 0.2% of all Antibodies in blood
Involved in activation of B Cells
What is Naturally Acquired Active Immunity?
Following exposure to a microbe
Antigen recognition by B Cells and T Cells and costimulation lead to formation of Antibody-Secreting Plasma Cells, Cytotoxic T Cells, and B and T Memory Cells
What is Characteristics and Function of IgE?
Less than 0.1% of all Antibodies in blood
Occurs as monomers
Located on Mast Cells and Basophils
Involved in allergic and hypersensitivity reactions
Provides protection against parasitic worms
What is Naturally Acquired Passive Immunity?
IgG Antibodies are transferred from mother to fetus across Placenta
IgA Antibodies are transferred from mother to baby in milk
What is Artificially Acquired Active Immunity?
Antigens introduce during vaccination stimulates Cell-Mediated and Antibody-Mediated Immune Responses, leading to production of Memory Cells
Antigen are pretreated to be immunogenic but not pathogenic
What is Artificially Acquire Passive Immunity?
Intravenous injection of Immunoglobulins (Antibodies)
What is T Cell Self-Recognition and Self-Tolerance?
T Cells undergo both positive and negative selection to ensure that they can recognize Self-MHC Antigens (Self-Recognition) and that they do not react to other Self-Proteins (Self-Tolerance)
What is B Cell Self-Recognition and Self-Tolerance?
B Cells develop tolerance through deletion (death) and Anergy (Inactivation)
What is Function of Macrophage?
APC
Processing and presentation of foreign Antigens to T Cells
Secretion of IL-1, which stimulates secretion of IL-2 by Helper T Cell and induces proliferation of B Cells
Secretion of IFNs that stimulate T Cell growth
What is Function of Dendritic Cell?
APC
Processes and presents Antigen to T Cells and B Cells
Found in mucous membranes, skin, and Lymph Nodes
What is Function of B Cell?
APC
Processes and presents Antigen to Helper T Cells
What is Function of Cytotoxic T Cell?
Lymphocyte
Kills host target cell by releasing:
Granzymes that induce Apoptosis
Perforin that forms channels to cause Cytolysis
Granulysin that destroys microbes
Lymphotoxin that destroys target cell DNA
Gamma-Interferon that attracts Macrophages and increase their phagocytic activity
Macrophage Inhibition Factor that prevents Macrophage migration from site of infection
What is Function of Helper T Cell?
Lymphocyte
Cooperates with B Cells to amplify Antibody production by Plasma Cells
Secrete IL-2 which stimulates proliferation of T and B Cells
Maye secrete Gamma-IFN and TNF which stimulate inflammatory response
What is Function of Memory T Cell?
Lymphocyte
Remains in Lymphatic tissue and recognizes original invading Antigens even years after first encounter
What is Function of B Cell?
Lymphocyte
Differentiates into Antibody producing Plasma Cells
What is Function of Plasma Cell?
Descendent of B Cell that produces and secretes Antibodies
What is Function of Memory B Cell?
Descendent of B Cell that remains after immune responses and is ready to respond rapidly and forcefully should the same Antigen enter the body in future
What is Stress and Immunity?
Psychoneuroimmunology (PNI):
Field that deals with common pathways that link the nervous, endocrine, and immune systems
Study in this field indicate that thoughts, feelings, mood, and beliefs influence your level of health and the course of disease
How does Aging affect Immune System?
Aging results in:
1- Increased susceptibility to infections and malignancies
2- Increased production of Autoantibodies
3- Decreased response to vaccines
4- Decreased immune system function
What is HIV/AIDS?
Acquired Immunodeficiency Syndrome (AIDS)
Condition in which a person experiences an assortment of infections due to the progressive destruction of immune system cells by the Human Immunodeficiency Virus (HIV)
What is Allergies?
Allergies:
Occur when a person is overly reactive to a substance that is well-tolerated by most others
When an allergic reaction occurs, so does tissue damage
4 Types of Hypersensitivity Reactions
What is Autoimmune Diseases?
Autoimmune Disease:
Occurs when the immune system fails to display Self-Tolerance and instead attacks the person’s own body tissues
