ch21 lymphatic Flashcards
what is the immune system?
a cell population that inhabits all organs and defends the body from agents of disease
What is the lymphatic system?
Network of organs and vein-like vessels that recover fluid
What are the functions of the lymphatic system?
Fluid recovery
Immunity
Lipid absorption
What is lymph?
A clear colourless fluid, similar to plasma, but low in protein.
Chemical composition varies in different locations
Where/How does lymph originate?
It originates as extracellular fluid drawn into lymphatic capillaries
what is a specific feature of lymphatic capillaries that differentiates them from other capillaries ?
They are non continuous (Terminal lymphatics)
What is the lymphatic capillary wall made up of?
Endothelial cells overlapping eachother like roof tiles
Lymphatic capillaries are found in most tissues, apart from?
CNS, cartilage, cornea, bone, and bone marrow
How are lymphatic capillaries tethered to surrounding tissues?
protein filaments
The gaps between cells in the wall of a lymphatic capillary are large enough to allow what to pass through?
Bacteria and cells
What is the mechanism of fluid moving in and out of lymphatic capillaries?
Endothelium creates valve-like flaps that open when interstitial fluid pressure is high and close when it is low
describe the anatomy of the larger lymphatic vessels.
Composed of three layers
Tunica interna
Tunica media
Tunica externa
Other than moderating flow of fluid in and out of vessels, what is another function of lymphatic valves?
prevent backflow of lymph
How many lymphatic trunks are there?
6
Name the lymphatic trunks
Jugular
subclavian
bronchomediastinal
intercostal
intestinal (unpaired)
lumbar
Name the 2 collecting ducts
Right lymphatic duct
Thoracic duct
What is the function of the right lymphatic duct?
receives lymph from right arm, right side of head and thorax; empties into right subclavian vein
What is the function of the thoracic duct?
receives lymph from below diaphragm, left arm, left side of head, neck, and thorax; empties into left subclavian vein
Which of the collecting ducts is the larger?
Thoracic duct
Where does the thoracic duct originate?
begins as a prominent sac in abdomen called the cisterna chyli
What significantly increases lymphatic return?
Exercise
Does lymph flow at low pressure low speed, or high pressure high speed?
Low pressure
Low speed
What mechanisms aid the flow of lymph?
rhythmic contractions of lymphatic vessels
Skeletal muscle pump
Arterial pulsation
Plasma cells are also known as
B cells
What are B cells also known as
plasma cells
What are natural killer (NK) cells?
Large lymphocytes that attack and destroy bacteria, transplanted tissue, host cells infected with viruses or that have turned cancerous
What are B lymphocytes? (B cells)
lymphocytes that when activated, become plasma cells that produce antibodies
What are T lymphocytes (T cells)
Lymphocytes that mature in the thymus
What are macrophages?
Large phagocytic cells of connective tissue
What cell does a macrophage develop from?
Monocytes
Name the functions of macrophages
Phagocytize tissue debris, dead neutrophils, bacteria and other foreign matter
Antigen presenting cell
What is an antigen presenting cell (APC)?
A cell that processes foreign matter and displays antigenic fragments to certain T cells alerting immune system to the presence of the enemy
What are dendritic cells?
Branched, mobile APCs found in epidermis, mucous membranes, and lymphatic organs
What is the function of a dendritic cell?
Alert immune system to pathogens that have breached the body surface
What is a reticular cell?
Branched stationary cells that contribute to the stroma of a lymphatic organ
How does a reticular cell function?
Engulfs pathogens using receptor mediated endocytosis
What is lymphatic (lymphoid tissue)
aggregations of lymphocytes in the connective tissues of mucous membranes and various organs
What is diffuse lymphatic tissue?
Lymphocytes are scattered (not clustered)
Prevalent in body passages open to the exterior
Respiratory, digestive, urinary, and reproductive tracts
Mucosa-associated lymphatic tissue (MALT)
What are lymphatic nodules?
Dense masses of lymphocytes and macrophages that congregate in response to pathogens
Constant feature of the lymph nodes, tonsils, and appendix
What are the types of lymphatic tissue?
diffuse lymphatic tissue
lymphatic nodules
peyer patches
What is a peyer patch?
dense clusters of lymphocytes in the ileum, the distal portion of the small intestine
How are lymphatic organs anatomically defined?
By the connective tissue capsule that separates the lymphatic tissue from neighbouring organs
Which are the primary lymphatic organs?
Red Bone marrow and thymus
What happens in the primary lymphatic organs?
T and B cells become immunocompetent: able to recognize and respond to antigens
Which are the secondary lymphatic organs?
Lymph nodes, tonsils and spleen
Where do all lymphocytes originate?
Red bone marrow
What happens in the secondary lymphatic organs?
Immunocompetent cells populate the tissues
Which organ systems does the Thymus belong to?
endocrine, lymphatic and immune
Reticular epithelial cells seal off cortex from the medulla forming which barrier?
Blood Thymus Barrier
What are the functions of the Thymus in the lymphatic system?
Houses developing lymphocytes
secretes hormones, regulating their activity
which signalling molecules does the Thymus produce?
interleukins
Interferon
thymosin
thymopoietin
thymulin
How many lymph nodes does the average young adult have?
450
What are the functions of the lymph nodes?
Cleanse the lymph
Act as a site of T and B cell activation.
What occurs in the the Germinal center?
B cells multiply and differentiate into plasma cells
Describe the anatomy of a lymph node
Elongated, bean-shaped structure with hilum
Enclosed with fibrous capsule with trabeculae that divide interior into compartments
Stroma of reticular fibers and reticular cells
What is the function of afferent lymph vessels?
Bring lymph into the node along its convex surface
How many efferent vessels are on a lymphatic node?
1-3
What is the function of efferent lymphatic vessels?
Lymph leaves the node through these
Which lymph nodes are especially concentrated within the body?
Cervical lymph nodes
Axillary lymph nodes
Thoracic lymph nodes
Abdominal lymph nodes
Intestinal and mesenteric lymph nodes
Inguinal lymph nodes
Popliteal lymph nodes
Where do you find cervical lymph nodes and what is their function?
in deep and superficial groups in the neck,
monitor lymph coming from the head and neck.
Where do you find axillary lymph nodes and what is their function?
in the armpit (axilla)
receive lymph from the upper limb and breast.
Where do you find thoracic lymph nodes and what is their function?
in the thoracic cavity, mediastinum,
receive lymph from the mediastinum, lungs, and airway.
Where do you find Abdominal lymph nodes and what is their function?
in the posterior abdominopelvic wall
receive lymph from the urinary and reproductive systems.
Where do you find Intestinal and mesenteric lymph nodes and what is their function?
in the mesenteries and adjacent to the appendix and intestines;
they receive lymph from the digestive tract.
Where do you find Inguinal lymph nodes and what is their function?
in the groin
receive lymph from the entire lower limb.
Where do you find popliteal lymph nodes and what is their function?
at the back of the knee
receive lymph from the leg proper.
What is Lymphadenitis?
swollen, painful node responding to foreign antigen
What is Lymphadenopathy?
collective term for all lymph node diseases
what is a Metastasis of cancer?
cancerous cells break free from original tumor, travel to other sites in the body, and establish new tumors
What is the typical path of metastasized cancer cells through the lymph nodes?
Metastasizing cells easily enter lymphatic vessels
Tend to lodge in the first lymph node they encounter
Multiply there and eventually destroy the node
Tend to spread to the next node downstream
What are tonsils?
patches of lymphatic tissue located at the entrance to the pharynx
Covered with epithelium
Have deep pits: tonsillar crypts lined with lymphatic nodules
What is the main function of tonsils?
Guard against ingested or inhaled pathogens
What is Tonsillitis?
Acute Inflammation due to Strep infection
What is a Tonsillectomy?
Surgical removal of the tonsils
Name the three sets of tonsils
Palatine tonsils
Lingual tonsils
Pharyngeal tonsils (adenoids)
Where are the Palatine tonsils located?
At posterior margin of oral cavity
Where are the Lingual tonsils located?
at root of tongue
Where are the Pharyngeal tonsils (adenoids) located?
Single tonsil on wall of nasopharynx
What is the largest lymphatic organ?
The spleen
What are the two types of parenchyma of the spleen?
Red pulp (erythrocytes) White pulp (lymphocytes, macrophages)
What are the functions of the spleen?
Healthy RBCs come and go
RBC graveyard
Blood cell production in fetus
White pulp monitors blood for foreign Ags and keeps an army of monocytes for release when needed
Stabilizes blood volume through plasma transfers to lymphatic system
What are the two types of immune response?
Non-specific (innate)
Specific (immune system)
What are the bodies’ 3 lines of defenses against pathogens?
1: skin and mucous membranes
2: several nonspecific defense mechanisms
3: the immune system
(Defeats a pathogen, and leaves the body with a “memory” of it so it can defeat it faster in the future)
What is the function of Nonspecific defenses?
guard equally against a broad range of pathogens
They lack capacity to remember pathogens
What are the 3 kinds of nonspecific defenses?
Protective proteins
Protective cells
Protective processes
What is Specific or adaptive immunity?
body must develop separate immunity (memory) to each pathogen
Body adapts to a pathogen and wards it off more easily upon future exposure
Name the external barriers of the non-specific immune system
skin
acid mantle
peptides in skin
mucus membranes
lysosymes
what is the acid mantle?
thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth
Name the peptides in the skin that kill microbes
Dermicidin, defensins, and cathelicidins
Where are the mucus membranes located?
Digestive, respiratory, urinary, and reproductive tracts
What are the 5 types of leukocytes?
Neutrophils
Eosinophils
Basophils
Monocytes
Lymphocytes
What are phagocytes?
cells that engulf foreign matter
What is the function of neutrophils?
Wander in connective tissue killing bacteria
Can kill using phagocytosis and digestion
What is the function of eosinophils?
Found especially in mucous membranes
Guard against parasites, allergens
What are mast cells?
Type of connective tissue cell very similar to basophils
What is the function of basophils?
Secrete chemicals that aid mobility and action of other leukocytes
Leukotrienes
Histamine
Heparin
What are the three categories of lymphocytes?
T cells, B cells, NK cells
What is the function of Monocytes?
emigrate from blood in to connective tissue and transform in to macrophages.
What are the two types of Macrophages?
Wandering macrophages: actively seek pathogens
Fixed macrophages: phagocytize only pathogens that come to them:
Where do you find microglia?
in CNS
Where do you find alveolar macrophages?
in lungs
Where do you find hepatic microphages?
in liver
What are antimicrobial proteins?
Proteins that inhibit microbial reproduction and provide short-term, nonspecific resistance to pathogenic bacteria and viruses
What are the two types of antimicrobial proteins?
Interferons
Complement system
What is the function of interferons?
Alert neighboring cells and protect them from becoming infected
Bind to surface receptors on neighboring cells
Activate 2nd-messenger systems within
The alerted cell synthesizes various proteins that defend it from infection
Also activates NK cells and macrophages
What is the complement system?
a group of 30 or more globular proteins that make powerful contributions to both nonspecific resistance and adaptive immunity
What are the four methods of pathogen destrtuction in a complement system?
Inflammation
Immune clearance
Phagocytosis
Cytolysis
what are the 3 routes of complement activation?
Classical pathway
Alternative pathway
Lectin pathway
Which complement pathway is antibody dependant?
Classical pathway
Which complement pathways are not antibody dependant?
Alternative pathway
Lectin pathway
Where do all complement pathways merge?
The point at which C3 is activated
Which mechanism results from the C3a path?
inflammation
Which mechanisms result from the C3b path?
Immune clearance
Phagocytosis
Cytolysis
What is the membrane attack complex?
Complement proteins form ring in plasma membrane of target cell causing cytolysis
How does the membrane attack complex destroy a cell?
The complex forms a hole in the target cell
electrolytes leak out, water flows rapidly in, and the cell ruptures.
(Cytolysis)
Are NK cells stationary or mobile cells?
Mobile. they continually patrol body looking for pathogens and diseased host cells
How do NK cells kill pathogenic cells?
Recognize enemy cell and bind to it
Release proteins called perforins
Secrete a group of protein-degrading enzymes—granzymes
Enter through pore and degrade cellular enzymes and induce apoptosis (programmed cell death)
What are antipyretics?
fever-reducing medications (aspirin)
How does fever aid the adaptive immune response?
Promotes interferon activity
Elevates metabolic rate and accelerates tissue repair
Inhibits reproduction of bacteria and viruses
What are the stages of fever?
onset
stadium
effervescence
what is apoptosis?
programmed cell death
What is inflammation?
local defense response to a tissue injury caused by trauma or infection
What is the function of inflammation?
Limits spread of pathogens, then destroys them
Removes debris from damaged tissue
Initiates tissue repair
What are the 4 signs of inflammation?
redness
swelling
heat
pain
Name the 5 steps of an inflammatory reaction
- release of inflammatory chemicals
- margination
- diapedesis
- chemotaxis
- phagocytosis
Which inflammatory chemical is released in an inflammatory reaction?
Histamine
What are the three sources of inflammatory chemicals?
Basophils
mast cells
blood plasma
What is leukocyte margination?
adhesion of a leukocyte to the capillary wall
What is diapedesis?
Process of a leukocyte crawling through the wall of a capillary
What is chemotaxis?
movement of a leukocyte towards inflammatory chemicals
What are the two distinguishing characteristics of the adaptive immune system?
Specificity
Memory
What do we mean by specificity in the immune system?
immunity directed against a particular pathogen
What do we mean by memory in the immune system?
when re-exposed to the same pathogen, the body reacts so quickly there is no noticeable illness
What are the two types of adaptive immunity?
Cellular, cell mediated
Humoral, antibody mediated
How does cellular immunity work?
Lymphocytes directly attack and destroy foreign cells or diseased host cells
Rids the body of pathogens
Kills cells that harbor them
How does Humoral immunity work?
Mediated by antibodies (Abs) that tag pathogens for destruction
Many Abs are dissolved in body fluids (“humors”)
Can only work against the extracellular stages of infections by microorganisms
What is Natural active immunity?
Production of one’s own Abs or T cells as a result of infection or natural exposure to antigen (Ag)
What is Artificial active immunity?
Production of one’s own Abs or T cells as a result of vaccination against disease
What is Natural passive immunity ?
Temporary immunity that results from Abs produced by another person (Fetus acquires Abs from mother through placenta, milk)
What is Artificial passive immunity?
Temporary immunity that results from the injection of immune serum (Abs) from another person or animal
Treatment for snakebite, botulism, rabies, tetanus, and other diseases
What is an antigen?
any molecule that triggers an immune response
What are epitopes?
certain regions of an Ag-molecule that stimulate immune responses
What are haptens?
Are too small to be an antigen, but can trigger an immune response by combining with a host macromolecule and creating a complex that the body recognizes as foreign
Name the major cells of the immune system
Lymphocytes
macrophages
dendritic cells
Which cells within the thymus stimulate maturation of a T Lymphocyte?
Reticular epithelial cells (RE)
What do T lymphocytes have to develop to be considered mature?
surface Ag receptors (TCRs)
once a T lymphocyte is mature, what does it become?
immunocompetent
T-cells that fail the self antigen test are eliminated by what type of selection?
Negative selection
How can a T cell fail the self antigen test?
Failure to recognize the self antigen
reacting to the self antigen
What are the removal processes of negative selection?
Clonal deletion
Anergy
What happens to T-cells that survive negative selection in the thymus?
They undergo positive selection
What is the naive lymphocyte pool
immunocompetent T cells that have not yet encountered foreign antigens
What is lymphocyte deployment ?
Naive T cells leave thymus and colonize lymphatic tissues and organs everywhere in the body
Where do B Cells mature?
bone marrow
What are the processes of elimination for B-cells that react to self antigens?
anergy
clonal deletion
What is the function of self tolerant B cells?
synthesize antigen surface receptors (BCRs)
divide rapidly
produce immunocompetent clones
Which cells function as Antigen Presenting Cells?
Dendritic cells
macrophages
reticular cells
B cells function
Function of an APC depends on which protein?
major histocompatibility (MHC) complex proteins
What are the 6 steps of Antigen processing and presenting?
- Phagocytosis of antigen
- Lysosome fuses with phagosome
- Antigen and enzyme mix in phagolysosome
- Antigen is degraded
- Exocytosis
- Epitope displayed
What are the four types of T-cells?
Cytotoxic
Helper
Regulatory
Memory
What is the function of Tc (Cytotoxic T-cells)
Effectors, carry out the attack on pathogens
What is the function of TH (Helper T-cells)
Promote T and B cell action/ non specific resistance
What is the function of TR (Regulatory T-cells)
inhibit multiplication and cytokine secretion by other T cells. Limit immune response
What is the function of Tm (Memory T-cells)
Responsible for memory in cellular immunity
What are the three R’s of Cellular and Humoral immunity?
Recognize
React
Remember
what are the steps of antigen recognition in cellular immunity?
APC encounters and processes an Ag
Migrates to nearest lymph node
Displays it to the T cells
When T cells encounter displayed antigen on the MHC protein, and initiate the immune response
What are the two classes of MHC proteins?
MHC I
MHC II
Where are MHC I proteins found?
on all nucleated cells
Where are MHC II proteins found?
only on APC’s and displayed on foreign antigens
Which T-cells react to MHC I?
Tc (cytotoxic) cells
Which T-cells react to MHC II?
TH (helper) cells
What is happening at number 1?
Antigen recognition
What is happening at number 2?
Costimulation
What is happening at point 3?
clonal selection
What is happening at point 4 for the MHC I protein path?
T-Cells attack
What is happening at point 4 for the MHC II path?
Interleukin secretion
What is the result of the MHC I path shown in the green box?
Destruction of the enemy cell
What is the result of the MHC II protein path as shown in the pink box?
Activation of NK T or B cells
Inflammation and other non specific defenses
Development of memory T cells
which types of immunity do TH (Helper T cells) activate?
Non-specific
Humoral
Cellular
(All)
How do TC (Cytotoxic )cells kill foeriegn cells?
Same as NK cells
Docks to HC I protein
secretes perforin and granzymes into cell
Apoptisis occurs
What is the function of interferons?
inhibit viral replication
Recruit and activate macrophages
What is the function of Tumor Necrosis factor?
aids in macrophage activation and kills cancer cells
What is the functional difference between the Cellular and Humoral immune responses?
Humoral uses B cells to tag foreign cells for destruction by T cells, Cellular immunity attacks the cells directly
What is happening at point 1
Antigen recognition
What is happening at point 2
Antigen presentation
What is happening at point 3
Clonal selection
What is happning at point 4?
Differentiation
What is happening at point 5?
Attack
What is the structure labelled A?
Disulfide bonds
What is the structure labelled B?
Antigen binding site
What is the structure labelled C?
Light chain
What is the structure labelled D?
hinge region
What is the structure labelled E?
Complement binding site
What is the structure labelled F?
Heavy chain
What is the structure labelled G?
Constant regions
What is the structure labelled H?
Variable regions
What are the five classes of antibodies?
IgA
IgD
IgE
IgG
IgM
What are the two mechnisms by which the variety of proteins are accomplished?
Somatic recombination
Somatic hypermutation
What are the Antibodies 4 mechanisms of attack againts Ags?
Neutralization
Complement fixation
Agglutination
Precipitation
What are the two types of adaptive immune response?
Primary immune response
Secondary immune response
When does the primary immune response occur?
On first exposure to a pathogen
when does the secondary immune response occur?
when re-exposed to the same antigen
What are the characteristics of a primary Immune response?
Takes 3-5 days for antibodies to activate
IgM appears first and peaks after 10 days
IgG comes after
Leaves immune system with memory of the Ag
What are the characteristics of a Secondary immune response?
Plasma Abs form within hours not days
IgG rises sharply and peaks in a few days
Lower levels of IgM secreted and quickly decline
No illness occurs
What type of response does this graph show?
Primary response
What type of response does the graph show?
Secondary response
What is hypersensitivity?
an excessive immune reaction against Ags that most people tolerate
What is type 1 hypersensitivity?
Food allergies and Asthma
What is type II Hypersensitivity?
Blood transfusion reaction and Drugs
What is type III Hypersensitivity?
Autoimmune diseases
What is type IV sensitivity?
TB skin test reaction and Type I Diabetes mellitus
What is anaphylaxis?
–Immediate, severe type I immune reaction
What is an autoimmune disease?
failure of immune system to distinguish self-antigens from foreign ones. (Self tolerance)
What are the reasons for failure of self-tolerance?
–Cross-reactivity
–Abnormal exposure of self-Ags in the blood
–Changes in structure of self-Ags
–Not all are eliminated in thymus and are normally kept in check by regulatory T (TR) cells
What is an immunodeficiency Disease?
Immune system fails to react vigorously enough
What is the most common immunodeficiency Disease?
Severe Combined Immunodeficiency Disease (SCID)
What is Acquired immunodeficiency syndrome (AIDS)
– Nonhereditary disease
– severely depresses the immune response
–caused by infection with the human immunodeficiency virus (HIV)
–Invades helper T cells, macrophages, and dendritic cells
- strikes at the central coordinating agent of nonspecific defense, humoral immunity, and cellular immunity
- Incubation period several months to 12-15 years
