8. Immune System

Question 1

Where are all leukocytes produced? Where do B and T cells mature? T cell maturation facilitated by what?

Answer 1

Bone marrow via hematopoiesis; bone marrow and thymus. Thymosin (peptide hormone secreted by thymin cells) facilitates T cell maturation

Question 2

What is the spleen for?

Answer 2

Blood storage and activation of B cells that later turn into plasma cells for adaptive immunity and destruction of damaged B cells, destruction of damaged or old RBCs, filters blood to help immune system

Question 3

What is GALT? List examples

Answer 3

Gut-associated lymphoid tissue. Ex: tonsils, adenoids, Peyer’s patches, appendix

Question 4

Which cells are part of humoral immunity and cell-mediated immunity?

Answer 4

B cells and ab for humoral, T cells for cell-mediated

Question 5

Name different barriers of nonspecific/innate immunity

Answer 5

Skin (defensins), GI tract (stomach acid), mucous membranes, complement system (classical and alternative pathway)

Question 6

What is the complement system?

Answer 6

innate immunity where proteins in blood act as nonspecific defense against bacteria –> punch holes in bacteria cell walls to make them osmotically unstable; activated thru 2 pathways: classical: Requires ab binding to ag, and alternative: doesn’t require ab

Question 7

What are interferons?

Answer 7

Proteins that prevent viral replication

Question 8

Functions of neutrophils`

Answer 8

Detects opsonized bacteria; most abundant; found in bloodstream

Question 9

Functions of eosinophils`

Answer 9

Allergies and parasites; release histamines –> vasodilation and inflammation

Question 10

Functions of basophils and mast cells

Answer 10

Allergies; release histamines; least abundant

Question 11

Know the structure of ab

Answer 11

light chain, heavy chain, variable region binds to epitope, constant region, disulfide bond. Constant heavy chain is diff for each isotype

Question 12

Primary response vs secondary response

Answer 12

1st new response against pathogen vs 2nd repeated response against same pathogen

Question 13

Positive selection vs negative selection vs clonal selection

Answer 13

Allow maturation of cells that can respond to ag on MHC correctly vs not allowing maturation of cells that are self-reactive –> so they undergo apoptosis vs B and T cells cloning themselves to generate specificity of ab against ag

Question 14

What are the 3 types of T cells?

Answer 14

helper T cells, regulatory/suppressor T cells, cytotoxic T cells
Suppressor T cells tone down immune system after infection and promote self tolerance

Question 15

Which MHC do Th and Tc cells respond to?

Answer 15

Th respond to exogenous ag presented on MHC II; Tc cells react directly to endogenous ag on MHC I

Question 16

What are the 5 types of infectious pathogens?

Answer 16

bacteria, viruses, fungi, parasites, prions (infectious MISFOLDED proteins)

Question 17

Describe the structure of the lymphatic system

Answer 17

A bunch of vessels that carry lymph (fluid) and join together to make a thoracic duct; along the lymphatic vessels are lymph nodes (bean shaped structure) that give a place for immune cells to be exposed to pathogens
Lymphatic systems helps reduce edema by taking in excess fluid from interstitial spaces, can also carry proteins, dissolved solutes, and water from periphery to blood (in a way this filters blood); they also have one way valves like veins, and is actively pumped by skel muscle contraction

Question 18

What are lacteals? What is chyle?

Answer 18

Small lymphatic vessels located in center of villus in small intestines that transport fats that are packaged in chylomicrons. Chyle = lymphatic fluid carrying a lot of chylomicrons –> milky white appearance

Question 19

What are germinal centers in lymph nodes?

Answer 19

Where B cells can undergo somatic hypermutation (inc chance of mutation after ab binds to its specific ag) and affinity maturation (ab w/ greater affinity to its ag via somatic hypermutation are selected for; if weaker affinity –> apop) and proliferate

Question 20

Active vs passive immunity. Give examples of natural and artificial of each

Answer 20

Ab made during immune response vs ab passed down. Actually getting dz; vaccines vs mom passing ab to fetus via placenta; getting IV ab

Question 21

What is opsonization? What’s the order for ab-mediated ag disposal?

Answer 21

Marking of pathogens for destruction by WBCs. Neutralization, agglutination (gathering multiple pathogens), opsonization

Question 22

Where are MHC I vs MHC II found and what do they do?

Answer 22

All nucleated cells; presents endogenous proteins for CD8+ cells => “endogenous pathway”; primarily responsible for presenting viral ag vs APCs: B cells, macrophages and dendritic cells, present exogenous antigens for CD4+ cells => “exogenous pathway”, primarily responsible for presenting bacterial ag

Question 23

T cells are most effective at fighting which pathogen?

Answer 23

Virus. T cells in general are the only specific defense against intracellular pathogens

Question 24

(Somatic) Hypermutation vs affinity maturation vs clonal selection

Answer 24

Process in which B cells undergo mutations to find the best matching ag-binding region for the ab vs ab w/ greater affinity to its ag via somatic hypermutation are selected for; if weaker affinity –> apop vs B and T cells cloning themselves to generate specificity of ab against ag

Question 25

Where are dendritic cells and mast cells found?

Answer 25

Area where there’s contact between tissue and external environment like the skin, lining of nose, stomach, lungs and intestines

Question 26

Which cells or lymphocytes produce ab?

Answer 26

ONLY B CELLS

Question 27

Virus shielding from the immune system can be caused by what post translational modification?

Answer 27

Glycosylation

Question 28

What are cytokines?

Answer 28

signaling molec that induce inflam during immune response, released by macrophages

Question 29

STAT

Answer 29

transcpxn factors that can bind to DNA (this is its defining characteristic) and dimerize w/ other proteins => heterodimers

Question 30

Lysosomes have a single membrane and help w/ digestion. Their function is directed by immune system

Answer 30

immune system ahh