The Lymphatic System and Immunity Flashcards
the ability to ward off damage or disease through our defenses
Immunity
2 General Types of Immunity
- Innate Immunity
- Adaptive Immunity
• defenses that are present at birth
• Fast, non-specific and no memory
— Barriers, pH extremes, Phagocytes & NK cells, fever, inflammation, complement, interferon
Innate Immunity
• Slower, specific & has a memory
• adapts or adjusts to handle a specific microbe.
— Lymphocytes: T-cells & B-cells
Adaptive Immunity
• Lymphatic tissue
— Reticular connective tissue containing lymphocytes
• Bone marrow
• Lymph- interstitial fluid in lymphatic vessels
Lymphatic System
Reticular connective tissue containing lymphocytes
Lymphatic tissue
interstitial fluid in lymphatic vessels
Lymph
Functions:
1. Drains excess interstitial fluid.
2. Transports dietary lipids. - lipid-soluble vitamins
(A, D, E, and K) absorbed by the GIT.
3. Carries out immune responses.
Lymphatic System
n Begin at lymphatic capillaries
q Slightly larger than blood capillaries q Overlapping cells like one-way valve q Pressure will force fluid in
n Merge to form larger & larger vessels q Thin walled and more valves than veins
n Periodically have lymph nodes
q Lymphocytes in capsuled structure
n à thoracic duct à L subclavian vein q At junction with jugular
n à R. lymphatic duct à R. subclavian vein
Lymphatic Vessels
• From tissue to veins
• Pumped by muscle & respiratory pumps like venous return
Lymphatic Flow
Two Groups of Lymphatic Organ
• Primary lymphatic organs
• Secondary lymphatic organs
site where stem cells divide & become immunocompetent.
Primary lymphatic organs
Primary lymphatic organs
• develop into mature B & T-cells
• Red bone marrow
• Thymus
site for most immune responses occur
Secondary lymphatic organs
Secondary lymphatic organs
• Lymph nodes
• spleen
• lymphatic nodules (follicles)
Two lobed organ (bilobed)
Thymus
located in the mediastinum between the sternum and the aorta
Thymus
• T-cells divide & mature
— Self reactive cells are removed
Thymus
• Scattered throughout the body
— Concentrated near mammary glands, axilla &
groin
Lymph Nodes
Contain mature B-cells, T-cells, dendritic cells and macrophages
Lymph Nodes
• Function as a type of filter, trap foreign substances — macrophages destroy some foreign
substances by phagocytosis
— lymphocytes destroy others by immune responses.
Lymph Nodes
• Metastasis - the spread of a disease from one part of the body to another.
• Cancer cells may travel in the blood or lymph and establish new tumors where they lodge.
• Cancerous lymph nodes feel enlarged, firm, nontender, and fixed to underlying structures.
• Lymph nodes that are enlarged due to an infection are softer, tender, and movable.
Metastasis through Lymphatic Vessels
the spread of a disease from one part of the body to another.
Metastasis
Between stomach & diaphragm
Spleen
Contains blood filled venous sinuses and RBCs, macrophages, lymphocytes plasma cells & granular leukocytes
Spleen
Performs three functions related to blood cells:
(1) removal by macrophages of ruptured, worn out,
or defective blood cells and platelets;
(2) storage of platelets, up to one-third of the body’s supply; and
(3) production of blood cells (hemopoiesis) during fetal life.
Spleen
• organ most often damaged in cases of abdominal trauma.
• crushing injury may result in a ruptured spleen, which causes significant hemorrhage and shock.
• Splenectomy - removal of the spleen
• The spleen’s absence also places the patient at higher risk for sepsis (a blood infection) due to loss of the filtering and phagocytic functions of the spleen.
Ruptured Spleen
sepsis
blood infection
removal of the spleen
Splenectomy
egg-shaped masses of lymphatic tissue that are not surrounded by a capsule.
Lymphatic Nodules
occur in multiple large aggregations in specific parts of the body.
Lymphatic Nodules
Includes tonsils in the pharyngeal region and the aggregated lymphatic follicles (Peyer’s patches) in the ileum of the small intestine
Lymphatic Nodules
Tonsils are strategically positioned to participate in immune responses against inhaled or ingested foreign substances.
Lymphatic Nodules
- physical and chemical
— Epidermal structure & constant shedding
Skin
Sticky mucus layer straps microbes, etc. and cilia
move it out
Mucous membranes
- tears, saliva, perspiration, nasal secretions
— Dilute and antibacterial action
Fluids
flow of urine, defecation & vomiting
Movement
Four main types of antimicrobial substances
A. Interferons (alpha-, beta-, and gamma-IFN)
B. Complement System
C. Iron-binding proteins
D. Antimicrobial peptides
Interfere with viral reproduction in a cell
Interferons
— Enhance other immune actions
— Break cell membranes
— Attract phagocytes
— Tag microbial cells for destruction
Complement System
bind iron and starve bacteria
Iron-binding proteins
lyse microbes
Antimicrobial peptides
specialized to ingest microbes and cellular debris (phagocytosis)
Phagocytes
Two major types of phagocytes
• Neutrophils
• Monocytes -> macrophages
Natural Killer (NK) Cells
5-10% of lymphocytes
Present in lymph nodes & red bone marrow
Natural Killer (NK)
Destroy microbes & tumor cells
Natural Killer
Perforin
cytolysis
Granzymes
apoptosis
nonspecific, defensive response of the body to tissue damage.
Inflammation
Conditions that may produce inflammation
pathogens,
abrasions,
chemical irritations,
distortion or disturbances of cells, and
extreme temperatures.
Four characteristic signs and symptoms of inflammation
redness,
pain,
heat, and
swelling
Can also cause a ___________ in the injured area.
loss of function
prime symptom of inflammation.
Pain
mast cells, basophils & platelets release histamine -> increased permeability & vasodilation in blood vessels
Damage
Isolate bacteria behind clot
Leakage of clotting proteins into tissue
Neutrophils & macrophages eat & die
Phagocytes attracted to site (chemotaxis)
- pus
— Moves to body surface or into cavity & is cleared
Pocket of dead cells
The three stages of inflammation
(1) vasodilation and
increased permeability of blood vessels,
(2) phagocyte emigration
(3) tissue repair
• Abnormally high body temperature
— occurs because the hypothalamic thermostat is reset q Normal temperature control action with new set point
Fever
• Stimulated by many toxins or internal signals
— Interleukin-1-cytokine that plays a role in the regulation of immune and inflammatory responses to infections.
Fever
cytokine that plays a role in the regulation of immune and inflammatory responses to infections.
Interleukin-1
Elevated body temperature intensifies the effects of interferons, inhibits the growth of some microbes, and speeds up body reactions that aid repair.
Fever
(1) specificity for particular foreign molecules
(antigens)
(2) memory for most previously encountered antigens
Adaptive Immunity
for particular foreign molecules
(antigens)
specificity
for most previously encountered antigens
memory
Antigen can be any substance:
microbe,
food,
pollen,
tissue
Does not attack normal body tissue
Normally self–tolerant
From stem cells in red bone marrow
Maturation of T and B cells
mature in bone marrow
B cells
migrate to thymus
T cells
During maturation both make particular proteins in plasma membranes
antigen receptors (molecules capable of recognizing specific antigens)
Two Types of Responses
- Cell-mediated
- Antibody-mediated/Humoral Immunity
• cytotoxic T cells directly attack invading antigens
— Killer T-cells
Cell-mediated
• B cells become plasma cells
— Produce specific proteins called antibodies (Abs) or immunoglobulins (Igs)
Antibody-mediated/Humoral Immunity
Produce specific proteins
antibodies (Abs) or immunoglobulins (Igs)
Helper T cells aid both cell- and antibody-mediated responses
Antibody-mediated/Humoral Immunity
• self antigens on cells surface
— Unique to each individual
Major Histocompatability Complex (MHC)
a rare inherited disorder in which both B cells and T cells are missing or inactive by
Severe Combined Immunodeficiency Disease
aka bubble boy disease
Severe Combined Immunodeficiency Disease
Control:
— Bolstering nutrition, bone marrow transplant, enzymatic replacement therapy, and gene therapy
Severe Combined Immunodeficiency Disease
• Requires recognizing the foreign antigen
• B-cells can find it anywhere
• T-cells need presentation with MHC
• Antigen presenting cells (APC) process and present exogenous antigens.
• APCs macrophages, dendritic cells & B cells n
• Location: respiratory, GI, urinary, reproductive
tracts & lymph nodes
Triggering Adaptive Response
• Ingestion of the antigen by APC
• Digestion of antigen into peptide fragments - protein-digesting enzymes split large antigens into short peptide fragments.
• Synthesis of MHC-II molecules.
• Packaging of MHC-II molecules into vesicles.
• Fusion of vesicles -peptide fragments and MHC-II molecules merge and fuse.
• Binding of peptide fragments to MHC-II molecules.
• Insertion of antigen–MHC-II complexes into the plasma membrane - combined vesicle that contains antigen–MHC-II complexes undergoes exocytosis.
Processing & Presenting Antigens
protein-digesting enzymes split large antigens into short peptide fragments.
Digestion of antigen into peptide fragments
peptide fragments and MHC-II molecules merge and fuse.
Fusion of vesicles
MHC-II complexes into the plasma membrane - combined vesicle that contains antigen–MHC-II complexes undergoes exocytosis.
Insertion of antigen
Interleukin-2 (IL-2)
T-cells also need costimulator
Release IL2, attract phagocytes, stimulate
macrophages & B cells
Helper T cells (CD4 Tcells)
• kill cells
— Work against tumor cells transplanted cells &
infected cells
Cytotoxic T cells
hang around for years, give rapid response if the same antigen enters the body again in the future
Memory T cells
• Hang out in lymph nodes
• Respond to antigen (faster if presented)
• With IL-2 enlarge, divide and become a clone of plasma cells
• Plasma cells produce & release antibodies that bind the antigen
• Some remain as Memory B Cells
— Ready to respond quickly if antigen met again
B-cells and Antibody-Mediated Response
Example of Immunological memory provides the basis for immunization by vaccination against certain diseases
polio
When you receive the vaccine, which may contain __________(weakened) or killed whole microbes or portions of microbes, your B cells and T cells are activated.
attenuated
Antibody Class Actions
• Neutralizing antigen
• Immobilizing bacteria
• Agglutinating
• Activating complement
• Enhancing phagocytosis
Binds and neutralizes toxins
Neutralizing antigen
Connect pathogens to one anotheràeasier phagocytosis
Agglutinating
Binding attracts phagocytes
Enhancing phagocytosis
• Long lasting antibodies & lymphocytes
• Many sensitive memory cells à
• Much larger & quicker response next time = Secondary Response
• Primary response can be naturally acquired n Or artificially acquired by vaccination
— Killed cells, isolated antigens, parts of viruses
Immunological Memory
deals with communication pathways that link the nervous, endocrine, and immune systems.
psychoneuroimmunology (PNI)
a hormone secreted by the adrenal cortex in association with the stress response, inhibits immune system activity.
cortisol
• psychoneuroimmunology (PNI) deals with communication pathways that link the nervous, endocrine, and immune systems.
• cortisol, a hormone secreted by the adrenal cortex in association with the stress response, inhibits immune system activity.
• under stress, people are less likely to eat well or exercise regularly, two habits that enhance immunity.
• to increase stress resistance, cultivate an optimistic outlook, get involved in your work, and build good relationships with others.
• adequate sleep and relaxation
STRESS AND IMMUNITY
• tend to produce more autoantibodies
• Thymus atrophies = decreased production of
thymic hormones
• Fewer responsive T cells
• Thus poorer B cell response
• Poorer response to new infection
Aging
decreased production of thymic hormones
Thymus atrophies
