DLA 11 + lecture 15+16 Flashcards

1
Q

source of NADPH for fatty acid synthesis?

A
  1. PPP
  2. malic enzyme

NADPH is needed for FA synthesis

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2
Q

citrate lyase

A

uses citrate to form acetyl Co-A and oxaloacetate in the cytosol

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3
Q

mechanism of FA synthesis

A
  1. formation of malonyl CoA by acetyl CoA carboxylase
  2. synthesis of palmitate by FAS
  3. elongation of palmitate by elongases
  4. desaturation by desaturases
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4
Q

rate limiting step of FA synthesis

A

ACC or acetyl Co-A carboxylase

contains biotin

requires 1 ATP

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5
Q

FAS is regulated by….

A

insulin upregulates the amount of enzyme present

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6
Q

key intermediate between fat and carbohydrate metabolism?

A

acetyl Co-A

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7
Q

activator and inhibitor of FA synthesis

A

activator: citrate
inhibitor: long-chain fatty acyl CoA (inhibits acetyl CoA carboxylase)

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8
Q

activator of hepatic synthesis of FA’s and cholesterol?

A

insulin!!

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9
Q

what pathways does insulin favor?

A

glycolysis
glycogen synthesis
fatty acid synthesis
cholesterol synthesis

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10
Q

where does FA chain elongation occur?

A

ER by elongases

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11
Q

fatty acid desaturation system?

A

desaturases introduce double bonds at positions 5,6, or 9 in humans

is an electron transport system in the ER
involves cytochrome b5 desaturase and NADPH cytochrome b5 reductase

double bonds beyond position 9 are essential fatty acids

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12
Q

dietary essential fatty acids

A

linoleate and alpha linolenate

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13
Q

how is acetyl CoA carboxylase regulated

A

allosteric:
activated by citrate and inhibited by palmitoyl CoA

covalent:
activated by dephosphorylation
inhibited by phosphorylation

enzyme:
activated by insulin

polymer is inactive and protomer is inactive

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14
Q

short term allosteric regulation of FA synthesis

A

citrate shifts toward polymer formation using protomers (activation)

palmitoyl CoA shifts toward protomers formation by depolymerization (inhibitor)

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15
Q

Role of AMP activated protein kinase (AMPK)

how is AMPK activated?

A

acetyl CoA carboxylase is inhibited when phosphorylated by this enzyme

activated:
allosterically by AMP
covalent by phosphorylation (glucagon, epi, and norepi trigger phosphorylation)

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16
Q

Role of CPT I?

A

malonyl CoA which is formed in the cytosol during FA synthesis inhibits CPT I

CPT I: moves long chain fatty acids into the mito for beta oxidation

this ensures that during FA synthesis, beta oxidation is inhibited

17
Q

histology of the gastro-duodenal junction

A

mucosa:
appearance of finger-shaped villi

submucosa:
appearance of Brunner’s glands for mucus

muscle:
2 typical layers of muscle.. no oblique layer

18
Q

peptic ulcers

A

crater-like lesion in areas exposed to gastric juices

common cause: 
infection by H. Pylori (breaks down mucus and creates alkaline environment; leads to more acid production) 
smoking 
NSAID
zollinger-Ellison syndrome: gastrinoma 

loss of mucosal protection and thus inflammation

19
Q

complication of chronic peptic ulceration

A

ulcers may extend deeper if left untreated

can lead to bleeding, perforation, peritonitis, pernicious anemia

20
Q

mucosa and submucosa of the small intestine?

A
mucosa: 
simple columnar 
contains GALT 
2 muscular layers 
have villi
have crypts of lieberkuhn 

submucosa:
DCT
contains Meissner’s plexus
circular folds of plicae circularis

21
Q

crypts of lieberkuhn (SI)

A

invagination of epithelium into the LP

simple columnar epithelium

simple tubular glands

22
Q

enterocytes (SI)

A

simple columnar cells for absorption

can produce digestive enzymes and secrete water

23
Q

goblet cells (SI)

A

unicellular mucus secreting cells

increase in number from small intestine to large intestine

24
Q

Paneth cells

A

found at the base of intestinal glands

secrete lysozyme: antibacterial enzyme and digests certain bacteria

Alpha defensins: microbicidal peptides

regulates normal bacterial flora of the small intestine

25
Q

enteroendocrine cells in SI

A

similar to those seen in stomach
found at the base of the crypts

releases CCK, secretin, GIP, Motilin
(peptide hormones)

26
Q

M cells in the SI

ATC cells in SI

A

M cells:
epithelial cells that cover peyer’s patches and large lymphatic nodes

ATC:
take up microorgansims and macromolecules from lumen

27
Q

distinguishing characteristic of the duodenum?

A

The presents of Brunner glands

these glands secrete an alkaline mucus that neutralizes acidic chime

28
Q

distinguishing characteristics of the jejunum

A

plicae circularis- have a feathery appearance

long prominent villi

29
Q

distinguishing features of the ileum

A

absorption of vitamin B12 occurs here
increase in paneth and goblet cells
lumen is smaller

has peyer’s patches

30
Q

celiac disease

A

gluten sensitivity

autoimmune mediated intolerance to gliadin

inflammation in distal duodenum and proximal jejunum

mucosa will appear flattened due to atrophy of villi and hyperplasia of crypts

31
Q

Crohn’s disease

A

ulcer formation of mainly the SI (def the ileum)

malabsorption and crampy abdominal pain
cobblestone appearance due to inflammation
can see giant cells
can have fibrosis

32
Q

distinguishing features of the large intestine

A

Taenia coli
haustra
omental appendices

33
Q

Colonic Adenomatous Polyps - Adenomas

A

slow growing intraepithelial neoplasm
usually no symptoms; sometimes bleeding

three types:
tubular - most common; less likely to become cancer
villous - rare; fingerlike appearance
tubulovillous - intermediate features

34
Q

three zones of the anal canal

A
  1. colorectal zone
    upper 1/3; simple columnar
  2. anal transitional zone
    middle 1/3
    transition between simple columnar to strat. squamous
  3. squamous zone
    lower 1/3
    keratinized strat. squamous