What is the difference between nonspecific and specific defense, and the role of lymphocytes in the immune response?

What is the difference between nonspecific

and specific defense, and the role of lymphocytes in the immune response?

????????? • The ability to resist infection and

disease

Immunity • The ability to resist infection and

disease

?????????? Defenses • Lymphocytes:

– part of the immune response • Identify, attack, and develop

immunity:– to a specific pathogen

Specific Defenses • Lymphocytes:

– part of the immune response • Identify, attack, and develop

immunity:– to a specific pathogen

Nonspecific Defenses • Block or attack any potential

infectious organism• Cannot distinguish one attack from

another

Immunity: Nonspecific DefensesPLAY

What are the major components of the

lymphatic system and their functions?

4 Parts of the Lymphatic System

What are they?

4 Parts of the Lymphatic System

1. Lymph: – a fluid similar to plasma– does not have plasma proteins

2. Lymphatic vessels (lymphatics): – network that carries lymph from

peripheral tissues to the venous system

4 Parts of the Lymphatic System

3. Lymphoid tissues and lymphoid organs:

– found throughout the body4. Lymphocytes, phagocytes, and

other immune system cells

Organization of the Lymphatic System

3D Rotation of the Lymphatic SystemPLAYFigure 22–1

Lymphocyte Production• 3 places that lymphocytes are

produced:

Lymphocyte Production• Lymphocytes are produced:

– lymphoid organs (e.g., spleen, thymus)

– and in red bone marrow– in lymphoid tissues (e.g., tonsils)

Lymphocyte Distribution• Lymphocytes:

– detect problems– travel into site of injury or infection

???????? • Are special lymphatic capillaries in

small intestine• Transport lipids from digestive

tract

Lacteals • Are special lymphatic capillaries in

small intestine• Transport lipids from digestive

tract

Figure 22–3

Lymphatic Vessels and Valves

??????????????• Blockage of lymph drainage from a

limb• Causes severe swelling• Interferes with immune system

function

Lymphedema• Blockage of lymph drainage from a

limb• Causes severe swelling• Interferes with immune system

function

Why are lymphocytes important, and how are they distributed in the

body?

Lymphocytes• Make up ????????????? % of

circulating leukocytes– Most are stored, not circulating

Lymphocytes• Make up 20–30% of circulating

leukocytes• Most are stored, not circulating

3 Classes of Circulating Lymphocytes

3 Classes of Circulating Lymphocytes

1. T cells:– thymus-dependent– Make up 80% of circulating

lymphocytes2. B cells:

– bone–marrow derived3. NK cells:

– natural killer cells

3 Main Types of T Cells

3 Main Types of T Cells1. Cytotoxic T cells2. Helper T cells3. Suppressor T cells

Cytotoxic T Cells• Attack cells infected by viruses• Produce cell-mediated immunity

Helper T Cells• Stimulate function of T cells and B

cells

Suppressor T Cells• Inhibit function of T cells and B

cells

“Regulatory T Cells”• Are helper and suppressor T cells• Control sensitivity of immune

response

B Cells • Make up 10–15% of circulating

lymphocytes• Differentiate into ???????????????

cells

B Cells • Make up 10–15% of circulating

lymphocytes• Differentiate into plasma cells

Plasma Cells• Produce and secrete ????????????

(immunoglobin proteins)

Plasma Cells• Produce and secrete antibodies

(immunoglobin proteins)

???????????? • Targets which identify any

pathogen or foreign compound

Antigens • Targets which identify any

pathogen or foreign compound

Natural Killer (NK) Cells • Also called large granular

lymphocytes • Make up 5–10% of circulating

lymphocytes

Natural Killer (NK) Cells • Responsible for immunological

surveillance• Attack:

– foreign cells– virus-infected cells– cancer cells

Figure 22–5

Production and Distribution of Lymphocytes

Lymphoid Stem Cells • Group 1:

– remain in bone marrow– produce B cells and natural killer cells

Lymphoid Stem Cells• Group 2:

– migrate to thymus– produce T cells in environment

isolated by blood-thymus barrier

T Cells and B Cells • Migrate throughout the body:

– to defend peripheral tissues• Retain their ability to divide:

– is essential to immune system function

What are the structures and functions of lymphoid

tissues and organs?

Lymphoid Tissues • Connective tissues dominated by

lymphocytes

Figure 22–6

Lymphoid Nodules

Lymphoid Nodule• Areolar tissue with densely packed

lymphocytes• Germinal center contains dividing

lymphocytes

Distribution of Lymphoid Nodules

• Lymph nodes• Spleen• Respiratory tract (tonsils)• Along digestive and urinary tracts

Mucosa-Associated Lymphoid Tissue (???????????????)

• Lymphoid tissues associated with the digestive system:– aggregated lymphoid nodules:

• clustered deep to intestinal epithelial lining

• Appendix:– mass of fused lymphoid nodules

Mucosa-Associated Lymphoid Tissue (MALT)

• Lymphoid tissues associated with the digestive system:– aggregated lymphoid nodules:

• clustered deep to intestinal epithelial lining

• Appendix:– mass of fused lymphoid nodules

The 5 ?????????? • In wall of pharynx:

– left and right palatine ??– pharyngeal ? (adenoid)– 2 lingual ??

The 5 Tonsils • In wall of pharynx:

– left and right palatine tonsils– pharyngeal tonsil (adenoid)– 2 lingual tonsils

Lymphoid Organs• Are separated from surrounding

tissues• By a fibrous connective-tissue

capsule – Lymph nodes– Thymus – Spleen

Figure 22–7

Lymph Nodes• Range from 1–25 mm diameter

??????????????• Chronic or excessive enlargement

of lymph nodes may indicate infections, endocrine disorders, or cancer

Lymphadenopathy• Chronic or excessive enlargement

of lymph nodes may indicate infections, endocrine disorders, or cancer

Antigen ????????????? • First step in immune response• Extracted antigens are

“presented” to lymphocytes:– or attached to dendritic cells to

stimulate lymphocytes

Antigen Presentation • First step in immune response• Extracted antigens are

“presented” to lymphocytes:– or attached to dendritic cells to

stimulate lymphocytes

The ??????????????• Located in mediastinum• Deteriorates after puberty:

– diminishing effectiveness of immune system

The Thymus• Located in mediastinum• Deteriorates after puberty:

– diminishing effectiveness of immune system

Figure 22–8

The Thymus

Thymus Hormones • ?????????????? • Promote development of

lymphocytes

Thymus Hormones • Thymosins • Promote development of

lymphocytes

Figure 22–9

3 Functions of the Spleen

3 Functions of the Spleen1. Removal of abnormal blood cells

and other blood components by phagocytosis

2. Storage of iron recycled from red blood cells

3 Functions of the Spleen3. Initiation of immune responses by

B cells and T cells:– in response to antigens in circulating

blood

What are the body’s nonspecific defenses and their functions?

SEVEN Nonspecific Defenses• Always work the same way • Against any type of invading agent

• ???????

7 Types of Nonspecific Resistance

1. Physical barriers2. Phagocytic cells3. Immunological surveillance4. Interferons5. Complement6. Inflammation7. Fever

Figure 22–10

The 7 Nonspecific Defenses

Complement (C) Proteins • Form the complement system • Complements action of antibodies

Immunity: ComplementPLAY

What is specific resistance? What are the forms and properties of

immunity?

Figure 22–14

Forms of Immunity

Forms of Immunity• ?????????:

– present at birth• ?????????:

– after birth

Forms of Immunity• Innate:

– present at birth• Acquired

– after birth

Acquired Immunity • ????????:

– antibodies develop after exposure to antigen

• ????????:– antibodies are transferred from

another source

Acquired Immunity • Active:

– antibodies develop after exposure to antigen

• Passive:– antibodies are transferred from

another source

Active Immunity • ??????????? ?????????:

– through environmental exposure to pathogens

• ????????????:– through vaccines containing

pathogens

Active Immunity • Naturally acquired:

– through environmental exposure to pathogens

• Induced:– through vaccines containing

pathogens

Passive Immunity • Naturally acquired:

– antibodies acquired from the mother• Induced:

– by an injection of antibodies

What are the differences between cell-mediated

(cellular) immunity and antibody-mediated (humoral) immunity?

Figure 22–15 (Navigator)

The Immune Response

The Immune Response• 2 main divisions:

– cell mediated immunity (??????? cells)– antibody mediated immunity (??????

cells)

Immunity: Cell-Mediated ImmunityPLAY

The Immune Response• 2 main divisions:

– cell mediated immunity (T cells)– antibody mediated immunity (B cells)

Immunity: Cell-Mediated ImmunityPLAY

What are the types of T cells and their functions

in the immune response?

Antigens and MHC Proteins

Antigens and MHC ProteinsPLAYFigure 22–16a (Navigator)

2 Classes of MHC Proteins• Class ???????:

– found in membranes of all nucleated cells

• Class ???????: – found in membranes of antigen-

presenting cells (APCs)– found in lymphocytes

2 Classes of MHC Proteins• Class I:

– found in membranes of all nucleated cells

• Class II: – found in membranes of antigen-

presenting cells (APCs)– found in lymphocytes

??????????? Cells (APCs)• Responsible for activating T cells

against foreign cells and proteins

Antigen-Presenting Cells (APCs)

• Responsible for activating T cells against foreign cells and proteins

Phagocytic APCs • Free and fixed macrophages:

– in connective tissues• Kupffer cells:

– of the liver• Microglia:

– in the CNS

Pinocytic APCs• Langerhans cells:

– in the skin• Dendritic cells:

– in lymph nodes and spleen

Actions of ??????????? T Cells 1. Release perforin:

– to destroy antigenic cell membrane 2. Secrete poisonous lymphotoxin:

– to destroy target cell3. Activate genes in target cell:

– that cause cell to die

Actions of Cytotoxic T Cells 1. Release perforin:

– to destroy antigenic cell membrane 2. Secrete poisonous lymphotoxin:

– to destroy target cell3. Activate genes in target cell:

– that cause cell to die

4 Functions of ??????????1. Stimulate T cell divisions:

– produce memory T cells– accelerate cytotoxic T cell maturation

2. Attract and stimulate macrophages

3. Attract and stimulate NK cells4. Promote activation of B cells

4 Functions of Cytokines1. Stimulate T cell divisions:

– produce memory T cells– accelerate cytotoxic T cell maturation

2. Attract and stimulate macrophages

3. Attract and stimulate NK cells4. Promote activation of B cells

??????????? Cells • Responsible for antibody-mediated

immunity• Attack antigens by producing

specific antibodies• Millions of populations, each with

different antibody molecules

Immunity: Antibody-Mediated ImmunityPLAY

B Cells • Responsible for antibody-mediated

immunity• Attack antigens by producing

specific antibodies• Millions of populations, each with

different antibody molecules

Immunity: Antibody-Mediated ImmunityPLAY

B Cell ?????????????• Corresponding antigens in

interstitial fluids bind to B cell receptors

• B cell prepares for activation• Preparation process is sensitization

B Cell Sensitization• Corresponding antigens in

interstitial fluids bind to B cell receptors

• B cell prepares for activation• Preparation process is sensitization

Figure 22–20 (Navigator)

B Cell Sensitization and Activation

B Cell Sensitization and ActivationPLAY

B Cell Sensitization• During sensitization, antigens are:

– taken into the B cell– processed– reappear on surface, bound to Class II

MHC protein

What is the structure of an antibody, and what

types of antibodies are found in

body fluids and secretions?

Figure 22–21a, b

Antibody Structure

Antibody Structure• 2 parallel pairs of polypeptide

chains: – 1 pair of heavy chains – 1 pair of light chains

• Each chain contains:– constant segments – variable segments

5 Heavy-Chain Constant Segments

• Determine 5 types of antibodies:– ??????????????????????

5 Heavy-Chain Constant Segments

• Determine 5 types of antibodies:– IgG– IgE– IgD– IgM– IgA

Figure 22–21c, d

Antibody Function

A ???????????? • Also called partial antigen • Must attach to a carrier molecule

to act as a complete antigen

A Hapten • Also called partial antigen • Must attach to a carrier molecule

to act as a complete antigen

Dangers of Haptens• Antibodies produced attack both

hapten and carrier molecule• If carrier is “normal”:

– antibody attacks normal cells– e.g., penicillin allergy

What are the functions of antibodies and how are they performed?

7 Functions of Antigen–Antibody Complexes

7 Functions of Antigen–Antibody Complexes 1. Neutralization of antigen binding

sites2. Precipitation and agglutination:

– formation of immune complex

7 Functions of Antigen–Antibody Complexes 3. Activation of complement4. Attraction of phagocytes5. Opsonization:

– increasing phagocyte efficiency

7 Functions of Antigen–Antibody Complexes 6. Stimulation of inflammation7. Prevention of bacterial and viral

adhesion

What are the primary and secondary responses

to antigen exposure?

Figure 22–22

Primary and Secondary Responses

• Occur in both cell-mediated and antibody-mediated immunity

The Primary Response • Peak response:

– can take 2 weeks to develop– declines rapidly

• IgM:– is produced faster than IgG– is less effective

The Secondary Response• Activates memory B cells:

– at lower antigen concentrations than original B cells

– secrete antibodies in massive qualities

Figure 22–24

Body Responses to Bacterial Infection

Figure 22–25

Combined

Immune System

Responses

Table 22–3

Hormones of the Immune System

???????????? Disorders • A malfunction of system that

recognizes and ignores “normal” antigens

• Activated B cells make autoantibodies against body cells

Autoimmune Disorders • A malfunction of system that

recognizes and ignores “normal” antigens

• Activated B cells make autoantibodies against body cells

Autoimmune Disorders • Thyroiditis• Rheumatoid arthritis• Insulin-dependent diabetes

mellitus

Immunodeficiency Diseases 3 examples (categories):

Immunodeficiency Diseases 1. Problems with embryological

development of lymphoid tissues:– can result in severe combined

immunodeficiency disease (SCID)

Immunodeficiency Diseases 2. Viral infections such as HIV:

– can result in AIDS

Immunodeficiency Diseases 3. Immunosuppressive drugs or

radiation treatments:– can lead to complete immunological

failure

?????????????? • Inappropriate or excessive immune

responses to antigens• Allergens:

– antigens that trigger allergic reactions

Allergies • Inappropriate or excessive immune

responses to antigens• Allergens:

– antigens that trigger allergic reactions

4 Categories of Allergic Reactions

• ????

4 Categories of Allergic Reactions

• Type I:– immediate hypersensitivity

• Type II:– cytotoxic reactions

4 Categories of Allergic Reactions

• Type III:– immune complex disorders

• Type IV:– delayed hypersensitivity

Type I Allergy (1 of 3)• Also called immediate

hypersensitivity• A rapid and severe response to the

presence of an antigen• Most commonly recognized type of

allergy• Includes allergic rhinitis

(environmental allergies)

Type I Allergy (2 of 3)• Sensitization leads to:

– production of large quantities of IgE antibodies

– distributed throughout the body • Second exposure leads to:

– massive inflammation of affected tissues

Type I Allergy (3 of 3)• Severity of reaction depends on:

– individual sensitivity– locations involved

• Allergens in blood stream may cause anaphylaxis

Anaphylaxis (1 of 2)• Can be fatal• Affects cells throughout body• Changes capillary permeability:

– produce swelling (hives) on skin

Anaphylaxis (2 of 2)• Smooth muscles of respiratory

system contract:– make breathing difficult

• Peripheral vasodilatation:– can cause circulatory collapse

(anaphylactic shock)

What are the effects of stress on immune

function?

Stress and the Immune Response

• ???????????????????:– secreted to limit immune response – long-term secretion (chronic stress):

• inhibits immune response• lowers resistance to disease

Stress and the Immune Response

• Glucocorticoids:– secreted to limit immune response – long-term secretion (chronic stress):

• inhibits immune response• lowers resistance to disease

Functions of Glucocorticoids • Depression of the inflammatory

response • Reduction in abundance and

activity of phagocytes• Inhibition of interleukin secretion