Innate & Adaptive Immunity Flashcards by Kyra Catedral

These cells are unique, because they arise from a hematopoietic stem cell and then are further differentiated in the primary lymphoid organs.

Lymphocytes

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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.

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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.

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PRIMARY LYMPHOID ORGANS

Bone marrow
Thymus

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SECONDARY LYMPHOID ORGANS

spleen
lymph nodes
mucosal-associated lymphoid tissues (MALT)
cutaneous-associated lymphoid tissue (CALT)

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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

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Lymphocyte circulation is complex and is regulated by different cell surface adhesion molecules and by chemical messengers called______.

cytokines

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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

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. A third type of lymphocyte, the______, is large, granular, and plays a role in both the innate and adaptive immune response.

NK cell

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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

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It can be considered the largest tissue of the body

Bone marrow

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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.

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Bone Marrow

Main Functions

Source of hematopoietic stem cells

Development into erythrocytes, granulocytes, monocytes, platelets, and lymphocytes

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Most authorities agree that T, B, and NK cells arise from a common precursor known as the…

common lymphoid precursor (CLP)

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The_____ functions as the center for antigenindependent lymphopoiesis

bone marrow

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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

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BONE MARROW
• Lymphocyte subsets

B cells
T cells

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B Cells
Named after the…
Maturation occurs in…

bursa of Fabricius in birds

bone marrow

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T Cells
Precursors go to the____ for
maturation
Immature T cells appear as early as _____in gestation

thymus

8 weeks

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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

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Thymus

Function

Site of T-cell maturation and differentiation

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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.

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Each lymphocyte spends most of its life span in______, entering the_____ only periodically to go from one secondary organ to another.

solid tissue

circulation

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The secondary lymphoid organs include the…

spleen
lymph nodes
tonsils
appendix
Peyer’s patches in the intestines
other mucosal-associated lymphoid tissue (MALT)

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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.

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

1. Physical 2. Chemical 3. 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)

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

Innate & Adaptive Immunity Flashcards

(136 cards)