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
enteroendocrine cells in SI
similar to those seen in stomach found at the base of the crypts releases CCK, secretin, GIP, Motilin (peptide hormones)
26
M cells in the SI ATC cells in SI
M cells: epithelial cells that cover peyer's patches and large lymphatic nodes ATC: take up microorgansims and macromolecules from lumen
27
distinguishing characteristic of the duodenum?
The presents of Brunner glands these glands secrete an alkaline mucus that neutralizes acidic chime
28
distinguishing characteristics of the jejunum
plicae circularis- have a feathery appearance long prominent villi
29
distinguishing features of the ileum
absorption of vitamin B12 occurs here increase in paneth and goblet cells lumen is smaller has peyer's patches
30
celiac disease
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
Crohn's disease
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
distinguishing features of the large intestine
Taenia coli haustra omental appendices
33
Colonic Adenomatous Polyps - Adenomas
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
three zones of the anal canal
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