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GI Flashcards

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1
Q

Mucosal sites, containing specialised lymphoid tissues

A

Appendix, large intestine, peyer’s patch in small intestine, adenoid and tonsils

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2
Q

Function of GI tract

A
  1. food digestion and absoprtion

2. immune regulation

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3
Q

GI tract: regards to immune functions

A
  1. portals of entry for non pathogenic antigens thus requires highly selective defense mechanisms
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4
Q

Polarised columner momolayer separating microbiota from lamina propria consists of? 5 things

A
  1. enteroabsorptive cells
  2. Goblet cells
  3. neuroendocrine cells
  4. Paneth cells
  5. M cells
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5
Q

Small intestine includes…

A 
villi and crypts 
goblet cells-mucus
Paneth cells-defensins
peyer's patches
Nutrient absoprtion
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6
Q

What do peyer’s patches do?

A 
antigen sampling (capture) and immune activation
contain immune cells
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7
Q

Large intestine includes…

A 
higher bacterial load
only crypts, no villi
No paneth cells
Enterocytes do defense
lots of goblet cells
No peyer's patches
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8
Q

Where are paneth cells found?

A

in base of crypts

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9
Q

Intestinal epithelial associated

A

innate immunity, antigen capture and effector function

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10
Q

Antigen capturing: where can it occur?

A

peyer’s patches and directly across the epithelial layer (by dendritic cells)

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11
Q

Peyers patches are covered by what?

A

An epithelial layer containing M cells (which have characteristic membrane ruffles)

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12
Q

three steps to M cell taking up antigen

A

M cell takes up antigen by endocytosis and phagocytosis
antigen transported across the M cell in vesicles and released at the basal surface
Antigen bound to dendritic cell –> activates T cell

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13
Q

where do microorganisms and particles get drained to in the gut

A

mesenteric lymoh nodes

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14
Q

lymphoid tissue in gut contains large numbers of?

A

B cell follicles

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15
Q

How do T cells enter peyers patches from blood vessel

A

homing receptors: CCR7 and L-selectin

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16
Q

Once activates in gut associated lymphoid tissue the niave T cell loses….

A

CCR7 (thus can not longer recirculate)

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17
Q

Most common antibody in the lamina propria of gut…

A

IgA

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18
Q

How does T cell get from blood vessel to Small or large intestine?

A
  1. T cell binds to MAdCAM-1 on endothelium

2. Gut epithelium express chemokines specific for gut-homing T cells

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19
Q

if small intestine is point of entry T cell contains…

A

CCR9

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20
Q

if large intestine is point of entry T cell contains…

A

CCR10

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21
Q

Order of Ig in intestine: from most to least

A

IgA, IgM and IgG

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22
Q

Intraepithelial lymphocytes are?

A

90% T cells –> 80% CD8

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23
Q

Two different recognition mechanisms in intraepithelial if intestine

A
  1. Virus specific - TCR/CD8

2. Stress specific recognition- NK cells

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24
Q

Special T cells in gut?

A

intra-epithelial lymphocytes (lie within lining of gut)

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25
Proposed mechanisms of mucosal hyporesponsiveness
Deletion of antigen specific T cells Generation of T cells ie. CD4 b cell --> IgA commensal organisms
26
Maintaining the balance between protective immunity and homeostasis
1. means of discriminating between pathogen and innocuous antigens 2. oral tolerance
27
how does commensal organisms lead to hyporesponsiveness?
Dendritic cell doesnt mature , gives weak co-stimulation signals ans induce CD4 cell to diff into regulatory Th3 or Treg cells, instead of effector Th1 or Th2 cells
28
Mucosal response to infection. 3 points
1. NFkB pathway activated by PRR (intracellular sensors in epithelial cells) 2. Gene transcription and production of cytokines, chemokines and defensins 3. Activate underlying immune response
29
What kind of disorder is coeliac?
Autoimmune disorder
30
What does coeliac disease do?
Damages small intestine --> malnutrition not allergy incurable
31
What does the presents of gluten cause the mucosal epithelial cells to express?
MIC molecules (activates the intraepithelial lymphocytes to kill the epithelial cells)
32
Digestion of peptides, bound to gluten. 3 steps.
1. enzyme, tissue transglutaminase (tTG) modifies peptides so they can bind to MHC II 2. bound peptide activates gluten-specific CD4 T cells 3. kill mucosal epithelial cells by binding Fas. And. Secrete IFN-y- activates epithelial cells
33
How to diagnosis coeliac disease
Biopsy (gold standard) Serology - IgA anti-tissue transglutaminase autoantibodies - dependant on dietary state of patient
34
IBD: is imbalance of what?
improper development of the intestinal immune system and unable to prevent the invasion of harmful pathogens
35
Ulcerative colitis features: where, type of inflammation, cytokine profile, smoking?
Colon, mucosal, Th2, IL-5/13, smoking is protective
36
Crohns disease features: where, type of inflammation, cytokine profile, smoking?
Any part of GI tract (discontinuous), Transmural/granulomatous, Th1, IL23 and y-IFN, smoking increases risk
37
Most common gene found if CD
NOD2
38
What can you also get from UC?
arthritis/uveitis, skin lesions
39
Where is UC most common?
Urbanised western societies
40
Both UC and CD produce large amount of inflammatory....
cytokinesm IL-1, IL-6 and TNF alpha
41
Biochemistry of liver metabolism
.
42
Job of liver (6)
1. first destination of most nutrients and xenobiotics absorbed from the gut 2. Bile production 3. Elimination of unwanted molecules -into biliary tree and faecal excretion 4. Secretion of plasma proteins (albumin) 5. Storage of important molecules (iron, vits etc) 6. regulation of metabolism
43
What allows the separation of proteins by size?
electrophoresis
44
Examples of plasma proteins separated in electrophoresis
albumin, alpha, beta and gamma globulins
45
Main functions of plasma proteins (5)
1. Maintenance of oncotic and colloid osmotic pressure 2. Transport of hydrophobic substances- steroid hormones, free fatty acids, bilirubin, cholesterol 3. pH buffering- AA side chains can carry net charges 4. Enzymatic - blood clotting 5. immunity
46
What does the maintenance of oncotic and colliod osmotic pressure ensure?
ensures they do no exit into interstitial fluid and prevents loss of plasma proteins
47
What does alpha globulins do?
transport lipoproteins, lipids, hormones and bilirubin. | it is a retinol binding protein- transports vit A
48
Example of alpha globulin
ceruloplasmin
49
What is retinal binding protein?
lipid soluble alcohol, converted to retinaldehyde, part of rhodopsin, a visual pigment Deficiency = visual impair
50
Two types of B-globulins
transferrin and fibrinogen
51
what does tranferrin do?
Transports Fe3+ | indicator of iron deficiency
52
What does fibrinogen do?
inactive for on fibrin, which is involved in the clotting of the blood
53
what is the most abundant plasma protein?
Albumin
54
what is albumin?
small, negatively charged, water-soluble 50% of plasma protein main determinant of plasma oncotic pressure
55
where is albumin made?
liver (14g per day)
56
what stimulates the production?
insulin
57
in albumin levels high or low in liver disease
low (starvation or low protein diet also causes decrease of levels)
58
Transport functions of albumin
multiple binding sites for hydrophobic molecules . Hydrophobic clefts in globular domains. Low affinity, but high copacity due to high conc.
59
What does albumin transport?
Fatty acids, bilirubin, thyroid hormones, exogenous substances (drugs, e.g. aspirin)
60
where is iron stored?
in cells bound to ferritin
61
why is iron important?
component of haem, myoglobin and cytochromes
62
what is copper bound to for transport in blood?
ceruloplasmin
63
why is copper needed?
regulation of redox reactions, transport and use of iron
64
Deficiency in copper?
wilson's disease
65
Where are steroid hormones derived from?
cholesterol
66
steroid hormones and T3/T4 thyroid hormones are hydrophilic or hydrophobic
hydrophobic
67
lipoproteins have a hydrophilic shell and hydrophobic core. what is in core and shell?
Core: cholesterol esters and triglycerides Shell: polar lipids and apoproteins
68
Lipoproteins is involved in fat transport between organs and tissues
yes

medicine (8 decks)

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