Lesson 1.1 Basic physiology immune system

Question 1

What are the two general means of protection the body uses against infection

Answer 1

1. Physical barriers: skin, epithelial surfaces, cilia

2. Chemical barriers: acids, mucous, lysozymes

Question 2

What are the two components of immunity

Answer 2

Innate immunity and adaptive immunity

Question 3

What are the primary lymphoid tissues

Answer 3

Bone marrow and thymus

Question 4

What are the secondary lymphoid tissues?

Answer 4

Lymph nodes, lymph nodules, lymph vessels, spleen

Question 5

What are the primary (central) lymphoid tissues “organs” where immune cells mature

Answer 5

Red bone marrow: Pluripotent stem cells give rise to all of the different types of blood cells, including all immune cells (“leukocytes” or white blood cells)
Thymus gland above the heart in the thorax, site of T lymphocyte maturation

Question 6

The site where T lymphocytes mature and develop “self-tolerance” before participating in immune reactions

Answer 6

Thymus

Question 7

Purpose is to promote efficient interactions between antigens and immune cells and a controlled environment in order to maximize the rapid development of immune responses

Answer 7

Secondary Lymphoid tissue

Question 8

along lymphatic vessels, to process antigens found in interstitial fluid

Answer 8

Lymph nodes

Question 9

Process antigens found on mucosal surface. Include tonsils and adenoids in pharynx, Peyer’s patches )
Lymphoid aggregates in the appendix, and other diffuse lymphoid aggregates in the esophagus, on other mucosal surfaces

Answer 9

Lymph nodules

Question 10

Process antigens found in the blood

Answer 10

Spleen

Question 11

Large numbers of lymphocytes and macrophages are exposed to antigens as they flow around the WBC contained in the lymph nodes / lymph nodules / spleen

Answer 11

Secondary lymphoid tissues

Question 12

Drains tissue fluid, cells and antigens from most tissues, through lymph nodes and back into blood via thoracic duct

Answer 12

The lymphatic vasculature

Question 13

Lymphoid tissue associated with mucosal surfaces (MALT)

Answer 13

Associated with gastrointestinal tract, respiratory tract, breast, urogenital tract (i.e., all mucosal tissues)

Question 14

Has epithelial covering with specialized phagocytic epithelial cells (M cells) that transfer antigen into the lymphoid tissue. Secrete IgA onto mucosal surface – initiates inflammatory reaction and prevents microbial binding to surface

Answer 14

Lymph nodules

Question 15

Functions as a filter for antigens in the blood, a site for immune reactions, location where old or damaged RBC and platelets are removed, and as a storage organ for erythrocytes

Answer 15

Spleen

Question 16

what happens if the connective tissue capsule surrounds the spleen rupture?

Answer 16

“Ruptured spleen” and significant abdominal bleeding

Question 17

what are the two distinct components of the spleen

Answer 17

Red pulp and white pulp

Question 18

Red pulp

Answer 18

Contains large numbers of blood-filled small diameter sinusoids (causes lysis of old RBCs), site for removal of old and damaged RBC by macrophages

Question 19

White pulp

Answer 19

Contains WBC necessary for immune response (lymphocytes, macrophages). Responsible for the immunological function against antigens carried in blood. It enlarges with immune reaction (e.g., results in splenomegaly with infectious mononucleosis)

Question 20

Lymphocytes

Answer 20

T and B lymphocytes
Natural killer (NK)

Question 21

Granulocytes

Answer 21

Basophils / mast cells
Neutrophils
Eosinophils

Question 22

Give rise to “plasma cells” which secrete immunoglobulins (antibodies – “Humoral” ) and leave the bone marrow fully mature

Answer 22

B lymphocytes

Question 23

Secrete cytokines which act on other immune cells (CD4+, helper). Cause lysis of infected cells (CD8+, cytotoxic) “cell mediated”. Release by bone marrow and must undergo further maturation in the thymus gland

Answer 23

T lymphocytes

Question 24

Lymphocytes (T and B cells) Make up ______of blood leukocytes
(WBC)

Answer 24

20-35%

Question 25

Antigen presenting cells

Answer 25

variety of cell types including: Monocyte / macrophages/ dendritic cells. Make up 1 – 6% of WBC in blood Specialized names: Langerhans cells / dendritic cells (skin). Microglia (CNS). Kupffer cells (liver

Question 26

Serve a variety of functions in the immune response: Phagocytosis to eliminate microbes, inanimate “particles” Secretion of cytokines (IL-1, IL-6, TNF) to communicate with other WBC
“Antigen presentation” necessary for lymphocyte reaction to specific antigens (adaptive immunity)

Answer 26

Antigen presenting cells

Question 27

Circulate in blood for ~1 day (2-8% of WBC) and are the largest leukocyte and mature into macrophages when they migrate into the tissues and acquire greater phagocytic ability

Answer 27

Monocytes

Question 28

Engulf and kill invading microorganisms and infected cells, clean up dead cells and cellular debris. Help induce/maintain inflammation by secreting signaling proteins (cytokines) to activate and recruit other immune cells

Answer 28

Macrophages

Question 29

Primary role is phagocytosis of bacterial invaders/destroyed or removed innert materails. Most abundant leukocytes (50-70% of WBC). 1st to arrive at the site of acute inflammation- can form pseudopods and are highly mobile

Answer 29

Neutrophils

Question 30

Engulf & destroy bacterial invaders using degradative enzymes (lysozymes) and antimicrobial substances in their cytoplasmic granules, including H2O2 and NO

Answer 30

Neutrophils

Question 31

1-3% of WBC. Kills parasitic worms. Recruited to sites of acute inflammation. Longer life span than neutrophils. Involved in chronic inflammation. Granules contain digestive enzymes, lysozyme, peroxidase, & inflammatory chemicals. Key component of allergic asthma & other allergic reactions

Answer 31

Eosinophils

Question 32

Certain uncommon “eosinophilic” inflammatory conditions, e.g., eosinophilic esophagitis, eosinophilic neuritis

Answer 32

Neutrophils

Question 33

Found in blood (rarely seen, < 1% of blood WBC)
Mast cells are very similar to basophils, fixed in tissues
Both are non-phagocytic cells which, when activated, release compounds from cytoplasmic granules (including histamine)
They play a major role in allergic responses, particularly type I hypersensitivity reactions (classic allergy)

Answer 33

Basophils

Question 34

Both are non-phagocytic cells which, when activated, release compounds from cytoplasmic granules (including histamine) and play a major role in allergic responses, particularly type I hypersensitivity reactions (classic allergy)

Answer 34

basophils and mast cells

Question 35

Very similar to basophils, fixed in tissue first line of defense along mucosal surfaces

Answer 35

Mast cells

Question 36

Antigen

Answer 36

large proteins with high molecular weight (~10,000 or 65 AA) Substance that can be recognized by an immune system as foreign (“non-self”) and provoke an immune reaction (virulence)

Question 37

Autoantigen

Answer 37

Self”-molecules that inappropriately provoke an immune reaction

Question 38

Allergens

Answer 38

Are antigens that provoke a hypersensitivity response (allergic response) to otherwise non-harmful antigens

Question 39

Epitope

Answer 39

Small part of an antigen that interacts with a specific immune antigen receptor (antibody, cell surface receptor). Any antigenic protein may have multiple epitopes in its structure. Each epitope is recognized by a different, specific antibody or immune cell antigen receptor

Question 40

highly conserved throughout nature as they are molecular patterns essential to the normal function and effectivity of microbes

Answer 40

Pathogen-Associated Molecular Patterns (PAMPs)

Question 41

Cannot evade immunologic detection (> 103 patterns recognized)
Examples include: Nucleic Acids: ssRNA, dsRNA (virus); CpG islands (virus, bacteria)
Proteins: pilin and flagellin (bacteria).
Cell wall lipids: lipopolysaccharide (gram-neg. bacteria); lipoteichoic acid (gram-pos. bacteria). Carbohydrates: mannan (fungi, bacteria); dectin glucans (fungi)

Answer 41

PAMPs (pathogen associated molecular patterns)

Question 42

Molecular patterns expressed on the surface of stressed, diseased, injured cells that serve as markers to signal destruction

Answer 42

Danger (Damage)-Associated Molecular Patterns (DAMPs)

Question 43

Examples of DAMPs

Answer 43

Heat shock protein, HSP; alterations in phospholipid structure; nuclear tags

Question 44

Are recognized by Pattern Recognition Receptors (PRR): on phagocytes (Toll-like receptors) – leads directly to phagocytosis and in serum (opsonins) – lead to complementation and signaled for phagocytosis

Answer 44

PAMPs and DAMPs

Question 45

Initiate the innate immune system

Answer 45

Pathogen-Associated Molecular Patterns (PAMPs) and Danger (Damage)-Associated Molecular Patterns (DAMPs)

Question 46

Diverse group of small soluble signaling molecules secreted by cells of the immune system.
Either fight the microbe directly or mobilize the immune system against the microbe
Promote inflammation, target cell growth/survivability/maturation or it’s activation/suppression

Answer 46

Cytokines

Question 47

Most act in a paracrine fashion; some are autocrine (T/B-cell differentiation) or even endocrine (IL-1 and TNF⍺ induce fever)

Answer 47

Cytokines