Innate & Adaptive Immunity Flashcards
These cells are unique, because they arise from a hematopoietic stem cell and then are further differentiated in the primary lymphoid organs.
Lymphocytes
Lymphocytes
They can be separated into two main classes, depending on where this differentiation takes place.
The primary lymphoid organs in humans are the (2)
bone marrow and the thymus.
Once lymphocytes mature in the primary organs, they are released and make their way to secondary organs, which include the…
spleen, lymph nodes, appendix, tonsils, and other mucosal-associated lymphoid tissue.
PRIMARY LYMPHOID ORGANS
Bone marrow
Thymus
SECONDARY LYMPHOID ORGANS
spleen
lymph nodes
mucosal-associated lymphoid tissues (MALT)
cutaneous-associated lymphoid tissue (CALT)
It is in the ______ that the main contact with foreign antigens takes place.
The____ serves as a filtering mechanism for antigens in the bloodstream, and_____ filter fluid from the tissues.
secondary organs
spleen
lymph nodes
Lymphocyte circulation is complex and is regulated by different cell surface adhesion molecules and by chemical messengers called______.
cytokines
Lymphocytes are segregated within the secondary organs according to their particular functions.
_______are effector cells that serve a regulatory role, and ______produce antibody.
Both types of cells recirculate continuously from the bloodstream to the secondary lymphoid organs and back, in an attempt to increase contact with foreign antigens.
T lymphocytes
B lymphocytes
. A third type of lymphocyte, the______, is large, granular, and plays a role in both the innate and adaptive immune response.
NK cell
All lymphocytes arise from ____________ that appear initially in the yolk sac of the developing embryo and are later found in the fetal liver.
pluripotential hematopoietic stem cells
It can be considered the largest tissue of the body
Bone marrow
Bone marrow fills the core of all ______and is the main source of_____, which develop into…
long FLAT bones
hematopoietic stem cells
erythrocytes, granulocytes, monocytes, platelets, and lymphocytes.
Bone Marrow
Main Functions
Source of hematopoietic stem cells
Development into erythrocytes, granulocytes, monocytes, platelets, and lymphocytes
Most authorities agree that T, B, and NK cells arise from a common precursor known as the…
common lymphoid precursor (CLP)
The_____ functions as the center for antigenindependent lymphopoiesis
bone marrow
Lymphocyte stem cells are released from the marrow and travel to additional ________ where further maturation takes place.
One subset goes to the thymus and develops into_____.
In humans, _____maturation takes place within the bone marrow itself.
primary lymphoid organs
T cells
B-cell
BONE MARROW
• Lymphocyte subsets
B cells
T cells
B Cells
Named after the…
Maturation occurs in…
bursa of Fabricius in birds
bone marrow
T Cells
Precursors go to the____ for
maturation
Immature T cells appear as early as _____in gestation
thymus
8 weeks
T cells develop their identifying characteristics in the______, which is a small, flat, bilobed organ found in the thorax, or chest cavity, right below the thyroid gland and overlying the heart
thymus
Thymus
Function
Site of T-cell maturation and differentiation
Once differentiation occurs, mature T and B lymphocytes are released from the bone marrow and the thymus. They migrate to_______ and become part of a______
secondary lymphoid organs
recirculating pool.
Each lymphocyte spends most of its life span in______, entering the_____ only periodically to go from one secondary organ to another.
solid tissue
circulation
The secondary lymphoid organs include the…
spleen
lymph nodes
tonsils
appendix
Peyer’s patches in the intestines
other mucosal-associated lymphoid tissue (MALT)
Lymphopoiesis, or reproduction of lymphocytes, occurs in the secondary tissue, but this is strictly dependent on______, while formation of lymphocytes in the bone marrow is______.
antigenic stimulation
antigen-independent
The______ is the largest secondary lymphoid organ, having a length of approximately_____ and weighing____ in the adult.
It is located in the _________and surrounded by a thin connective tissue capsule.
spleen
12 cm
150 g
upper-left quadrant of the abdomen, just below the diaphragm
The organ can be characterized as a large discriminating filter, as it removes old and damaged cells and foreign antigens from the blood.
Spleen
Splenic tissue can be divided into two main types:
red pulp
white pulp
The red pulp makes up more than onehalf of the total volume, and its function is to…
destroy old red blood cells.
Blood flows from the arterioles into the_____ and then exits by way of the splenic vein.
red pulp
The _____comprises approximately 20 percent of the total weight of the spleen and contains the lymphoid tissue, which is arranged around arterioles in a______
white pulp
periarteriolar lymphoid sheath
Periarteriolar lymphoid sheath. This sheath contains mainly_____
Attached to the sheath are primary follicles, which contain_____ that are not yet stimulated by antigen.
T cells
B cells
Surrounding the PALS is a______ containing _____that trap antigen.
Lymphocytes enter and leave this area by means of the many capillary branches that connect to the arterioles.
marginal zone ; dendritic cells
Each day, an adult’s blood volume passes through the spleen approximately____ times, where_____ and ____ can constantly survey for infectious agents or other foreign matter.
four
lymphocytes and macrophages
LYMPH NODES
• Function
Central collecting points for lymph fluid from adjacent tissues
Filtration of interstitial fluid allows contact between lymphocytes and foreign antigens
Lymph node
Filtrate of blood from water and low-molecular-weight solutes
Lymph fluid
Lymph node
Location
Along lymphatic ducts, numerous near joints and where arms and legs join the body
Lymph nodes
________is a main function of these organs. The lymph fluid flows slowly through spaces called sinuses, which are lined with _____, creating an ideal location for phagocytosis to take place.
Filtration
macrophages
If contact with antigen takes place, lymphocyte traffic shuts down due to the proliferation of activated cells.
Accumulation of lymphocytes and other cells causes the lymph nodes to become enlarged, a condition known as______. Recirculation of expanded numbers of lymphocytes then occurs.
lymphadenopathy
Secondary lymphoid organs
OTHERS
• Mucosal-Associated Lymphoid Tissue (MALT)
• Cutaneous-Associated Lymphoid Tissue (CALT)
Mucosal-Associated Lymphoid Tissue (MALT)
Tonsils
Appendix
Peyer’s patches
is found in the gastrointestinal, respiratory, and urogenital tracts
MALT, the mucosal associated lymphoid tissue
represent a specialized type of MALT and are located at the lower ileum of the intestinal tract.
Peyer’s patches
The______ are another area of lymphoid tissue found in the mucous membrane lining of the oral and pharyngeal cavities.
Their function is to respond to pathogens entering the respiratory and alimentary tracts.
tonsils
near the junction of the small intestine and the large intestine and has abundant infection-fighting lymphoid cells
Appendix
small masses of macrophage lining oral and pharyngeal cavities
Tonsils
The epidermis contains a number of intraepidermal lymphocytes. Most of these are_____, which are uniquely positioned to combat any antigens that enter through the skin.
This association of lymphocytes is known as the______
T cells
cutaneous-associated lymphoid tissue
differentiate into memory cells and plasma cells and are responsible for humoral immunity or antibody formation
B cells
play a role in cell-mediated immunity, and as such, they produce sensitized lymphocytes that secrete cytokines
T cells
are small polypeptides that regulate the functions of lymphocytes and other cells involved in the immune response.
The characteristics and markers for each type of lymphocyte are considered separately.
Cytokines
certain humoral, or circulating, factors called_______ acted to coat bacteria so that they became more susceptible to ingestion by phagocytic cells.
opsonins
BRANCHES OF IMMUNITY
INNATE (NATURAL) IMMUNITY
ADAPTIVE IMMUNITY
Natural, or innate, immunity
is the ability of the individual to resist infection by means of normally present body functions.
These are considered nonadaptive or nonspecific and are the same for all pathogens or foreign substances to which one is exposed.
No prior exposure is required, and the response does not change with subsequent exposures.
Many of these mechanisms are subject to influence by such factors as nutrition, age, fatigue, stress, and genetic determinants.
is the ability of the individual to resist infection by means of normally present body functions.
Natural, or innate, immunity
These are considered nonadaptive or nonspecific and are the same for all pathogens or foreign substances to which one is exposed.
Natural, or innate, immunity
No prior exposure is required, and the response does not change with subsequent exposures.
Natural, or innate, immunity
Many of these mechanisms are subject to influence by such factors as nutrition, age, fatigue, stress, and genetic determinants.
Natural, or innate, immunity
Acquired immunity, in contrast,
is a type of resistance that is characterized by specificity for each individual pathogen, or microbial agent, and the ability to remember a prior exposure, which results in an increased response upon repeated exposure.
is a type of resistance that is characterized by specificity for each individual pathogen, or microbial agent, and the ability to remember a prior exposure, which results in an increased response upon repeated exposure.
Acquired immunity, in contrast,
The natural defense system is composed of two parts:
the external defense system
the internal defense system.
is designed to keep microorganisms from entering the body.
If these defenses are overcome, then the internal defense system must clear invaders as quickly as possible.
external defense system
can be categorized into cellular mechanisms and humoral factors.
Internal defenses
Internal defenses can be categorized into
cellular mechanisms
humoral factors
results in the destruction of foreign cells and organisms.
phagocytosis
The process of______ brings cells and humoral factors to the area in need of healing. If the healing process is begun and resolved as quickly as possible, the tissues are less likely to be damaged.
inflammation
NON-SPECIFIC DEFENCES
(INNATE IMMUNITY)
First line of defense
Second line of defense
First line of defense
• Skin
• Mucous membranes
• Secretions of skin and mucous membranes
Second line of defense
• Phagocytic leukocytes
• Antimicrobial proteins
• Inflammatory response
• Fever
Third line of defense
SPECIFIC DEFENCES (ADAPTIVE IMMUNITY)
SPECIFIC DEFENCES (ADAPTIVE IMMUNITY)
Third line of defense
• Lymphocytes
• Antibodies
• Memory cells
Function: Responds rapidly to pathogens; provides initial protection.
Innate immunity
Innate Immunity
Components:
Anatomical barriers (e.g., skin, mucous membranes) that prevent pathogen entry.
Activated if external barriers are breached; includes cellular responses and phagocytosis.
External Defense System:
Internal Defense System:
INNATE IMMUNITY
EXTERNAL DEFENSE
- Physical
- Chemical
- Biological
External defense
Chemical
Skin:
Respiratory tract:
Stomach:
Vagina:
tears and saliva:
lactic acid, fatty acids, psoriasin
cilia and mucus
gastric acid/ Hydrochloric acid
lactic acid
Lysozyme
THE UNBROKEN SKIN
Physical barriers
Consists of tightly packed epithelial cells coated with keratin, making it impermeable to most infectious agents.
Epidermis
THE UNBROKEN SKIN
Physical barriers
Contains connective tissue, blood vessels, hair follicles, sebaceous glands, sweat glands, and white blood cells (WBCs) such as macrophages, dendritic cells, and mast cells.
Dermis
THE UNBROKEN SKIN
Secretions
_______(in sweat) and______(produced by sebaceous glands)
helps maintain an acidic skin pH of approximately______, inhibiting microbial growth
Lactic acid
fatty acids
5.6
is composed of structural barriers that prevent most infectious agents from entering the body
external defense system
EXTERNAL DEFENSE SYSTEM
RESPIRATORY TRACT
Mucous Secretions:
Ciliary Action:
Coughing and Sneezing:
EXTERNAL DEFENSE SYSTEM
RESPIRATORY TRACT
Block bacterial adherence and contain surfactants that bind to and help remove microorganisms.
Mucous Secretions:
EXTERNAL DEFENSE SYSTEM
RESPIRATORY TRACT
Cilia in the nasopharyngeal passages move approximately 90% of deposited material out of the respiratory tract.
Ciliary Action:
EXTERNAL DEFENSE SYSTEM
RESPIRATORY TRACT
Mechanisms to expel pathogens.
Coughing and Sneezing:
EXTERNAL DEFENSE SYSTEM
GENITOURINARY TRACT
Flushing action and slight acidity help
remove pathogens.
Urine:
EXTERNAL DEFENSE SYSTEM
GENITOURINARY TRACT
Female Genital Tract:
______production maintains a vaginal pH of about 5, preventing pathogen invasion.
Lactic acid
EXTERNAL DEFENSE SYSTEM
DIGESTIVE TRACT
The________ acidic (hydrochloric acid) environment (pH around____)
inhibits microbial growth from ingested food and drink.
stomach’s
1
EXTERNAL DEFENSE SYSTEM
• Found in tears and saliva, this enzyme attacks the cell walls of microorganisms, particularly gram-positive bacteria.
LYSOZYME
In many locations of the body, there is normal flora that often keeps pathogens from establishing themselves in these areas. This phenomenon is known as…
competitive exclusion
. The significance of the presence of normal flora is readily demonstrated by looking at the side effects of antimicrobial therapy. Frequently, yeast infections due to ______occur, the result of wiping out normal flora that would ordinarily compete with such opportunists.
Candida albicans
Activated once the external defenses are breached
INTERNAL DEFENSE
consists of cells and soluble factors that perform specific and crucial functions in combating infections.
The internal defense system
is designed to recognize molecules that are unique to infectious organisms.
This typically involves recognizing a carbohydrate such as mannose that is found in microorganisms and is not evident on human cells.
internal defense system
White blood cells seek out and destroy foreign cells by participating in______, which is the engulfment of cells or particulate matter by leukocytes, macrophages, and other cells.
This process destroys most of the foreign invaders that enter the body, and it is the most important function of the internal defense system.
phagocytosis
Phagocytosis is enhanced by soluble factors called
acutephase reactants.
are found on various cells, including neutrophils, eosinophils, monocytes, mast cells, T cells, and epithelial cells.
PATHOGEN RECOGNITION
RECEPTORS (PRRs)
PRRs
These receptor’s serve as sensors for extracellular infections.
PATHOGEN RECOGNITION
RECEPTORS (PRRs)
Upon binding to a pathogen, ____ activate phagocytic cells, enhancing their ability to engulf and destroy invaders.
PATHOGEN RECOGNITION
RECEPTORS (PRRs)
PRRs distinguish self from non-self by recognizing _____, which are specific to microorganisms.
PATHOGEN-ASSOCIATED
MOLECULAR PATTERNS (PAMPs)
PATHOGEN-ASSOCIATED
MOLECULAR PATTERNS (PAMPs)
peptidoglycan in gram-positive bacteria lipoproteins in gram-negative bacteria zymosan in yeast
flagellin in bacteria with flagella
Ten TLRs have been identified in humans
(5) are found on cell surfaces.
(4) are found in the endosomal compartment of a cell
TLR1, TLR2, TLR4, TLR5, and TLR6
Structure:
TLRs are membrane-spanning glycoproteins with…
leucine-rich repeats (LRRs).
Binding of TLRs to pathogens results in the:
production of cytokines and chemokines
recruitment of neutrophils
enhanced macrophage and dendritic cell activity
• Normal serum constituents that increase rapidly because of infection, injury, or trauma to the tissues.
ACUTE PHASE REACTANTS
ACUTE PHASE REACTANTS
They are produced primarily by…
hepatocytes (liver parenchymal cells)
Functions:
Bind to microorganisms and promote adherence (first step in phagocytosis)
Limit destruction caused by proteolytic enzymes from WBCs during phagocytosis
ACUTE PHASE REACTANTS
Acute-Phase
Reactants:
C-reactive protein
Serum amyloid A
Complement components
Alpha1-antitrypsin
Haptoglobin
Fibrinogen
Ceruloplasmin
is a trace constituent of serum originally thought to be an antibody to the c-polysaccharide of pneumococci. It increases rapidly within 4 to 6 hours following infection, surgery, or other trauma to the body.
C-reactive protein (CRP)
CRP
It is a member of the family known as the_____, all of which are proteins with five subunits.
pentraxins
acts somewhat like an antibody, as it is capable of opsonization (the coating of foreign particles), agglutination, precipitation, and activation of complement by the classical pathway.
CRP
CRP
However, binding is_____-dependent and nonspecific, and the main substrate is_____, a common constituent of microbial membranes.
It also binds to small ribonuclear proteins; phospholipids; peptidoglycan; and other constituents of bacteria, fungi, and parasites
calcium
phosphocholine
binds to specific receptors found on monocytes, macrophages, and neutrophils, which promotes phagocytosis.
Thus, it can be thought of as a primitive, nonspecific form of antibody molecule that is able to act as a defense against microorganisms or foreign cells until specific antibodies can be produced.
CRP
Because the levels rise and then decline so rapidly,____ is the most widely used indicator of acute inflammation.
Although it is a nonspecific indicator of disease or trauma, monitoring of its levels can be useful clinically to follow a disease process and observe the response to treatment of inflammation and infection
CRP
C-reactive protein binds_____
on bacterial surfaces, acting as an_____ and also as an activating complement
phosphocoline
opsonin
The body’s overall reaction to injury or invasion by an infectious agent.
Involves cellular and humoral mechanisms
INFLAMMATION
The five cardinal signs of inflammation:
Redness (erythema)
Swelling (edema)
Heat
Pain
Loss of function
Combats early stages of infection, repairs tissue damage
Acute inflammation
Prolonged inflammation due to failure to remove microorganisms or injured tissue, leading to continued tissue damage and loss of function
Chronic inflammation
INFLAMMATION causes
Increased Blood Supply
Increased Capillary Permeability
Migration of Neutrophils
Migration of Macrophages
Phagocytosis Stimulated by Acute-Phase Reactants
Dilation of blood vessels due to chemical mediators (e.g., histamine)
Results in redness and heat
Increased Blood Supply
Contraction of endothelial cells lining vessels
Plasma fluids leak into tissues causing swelling and pain
Increased Capillary Permeability
Process called diapedesis
Neutrophils move from capillaries to surrounding tissue
Migration of Neutrophils
Diapedesis
Controlled by______
Neutrophils mobilized within ______, lasting_____
soluble mediators (acute-phase reactants, chemokines, cytokines)
30-60 minutes
24-48 hrs
Occurs several hours after injury, peaks at 16-48 hours
Includes dendritic cells
Migration of Macrophages
Macrophages, neutrophils, and dendritic cells clear area through phagocytosis
Healing process completes with normal tissue structure restoration
Phagocytosis Stimulated by Acute-Phase Reactants
Most active phagocytes:
neutrophils, monocytes, macrophages, and dendritic cells
Steps of Phagocytosis
Physical contact between WBC and foreign cell
Outflowing of cytoplasm to surround the microorganism
Formation of a phagosome
Fusion with lysosomal granules
Formation of the phagolysosome and release of lysosomal contents
Digestion of microorganisms by hydrolytic enzyme
Release of debris by exocytosis
NEUTROPHILS
A.k.a.
Polymorphonuclear Neutrophilic Leukocytes, Segmenters
Most abundant WBC in adults
Neutrophils
Neutrophils
Lobes of nucleus
2-5
Neutrophil
Main function is____, leading to the destruction of foreign particles.
phagocytosis
First cell to migrate toward the site of infection
______: Movement through blood vessel walls to tissues.
______: Migration towards specific areas guided by chemotactic factors.
Neutrophils
Diapedesis
Chemotaxis
Resident microorganisms that inhabit specific body sites and help prevent pathogen establishment by competing for resources and producing antimicrobial substances.
NORMAL FLORA (MICROBIOTA)
NORMAL FLORA (MICROBIOTA)
Example:
In the gut, normal flora produce____, proteins that disrupt the membranes of certain bacteria.
colicins
Acute-Phase Reactants:
C-reactive protein
Serum amyloid A
Complement components
Alpha1-antitrypsin
Haptoglobin
Fibrinogen
Ceruloplasmin
Innate immunity
What are involed?
Epithelial barriers
Phagocytes
Dendritic cells
NK cells
Adaptive immunity
What are involved
B lymphocytes
T lymphocytes
Antibodies
