Phys 2 Flashcards
Overall function of the large intestine
- absorb water
- compact undigested material
- form and release stool
Regions of the large intestine
- cecum
- appendix
- colon: ascending, transverse, descending, sigmoid
- rectum
- anal canal
- anus
Cell histology type in large intestine mucosa
simple columnar epithelium
cell types contained within the large intestine mucosa
- colonocytes (absorption)
- goblet cells (mucus)
- stem cells
(no plica or villi b/c don’t need digestive enzymes anymore)
What is the muscularis layer in the large intestine?
-taenia coli
taenia coli
longitudinal layer reduced to 3 bands of muscle
haustra
puckers of intestinal wall created by tone of taenia coli
What is the function of the normal flora in the large intestine?
- to ferment undigested sugars releasing acids and gases
- release B vitamins, vitamin K and short chain FA
types of normal flora in the large intestine
- 500 species of bacteria and candida
- many of genus bacteroides (anaerobic gram positive cocci)
What are the functions of the pancrease?
- endocrine
- digestive
endocrine cells of the pancreas
- alpha islet cells (20%)
- beta islet cells (70%)
- delta islet cells (10%)
(all scattered in the acini)
alpha islet cells release:
glucagon
beta islet cells release:
insulin
delta islet cells release:
somatostatin
anatomical components of the pancreas
- acini: cluster of cells
- interlobar duct which drains into the:
- pancreatic duct
- sphincter of Oddi
acinar cells
- clusters of granulated secretory cells
- secrete enzymes
centroacinar cells
- form interlobar duct
- secrete watery bicarb solution
pancreatic juice
- how much produced
- pH
- 1.2-1.5 L qd
- pH: 8
digestive enzymes of the pancreas
- usually secreted in inactive form
- trypsin and chymotrypsin proteases
- amylase
- lipase
- nucleases
what do amylase and lipase enzyme digest?
- amylase: carbs
- lipase: lipids
General regulation of secretion from pancreas
- PSNS
- 2 intestinal hormones: secretin and CCK
PSNS regulation of secretion of the pancreas
vagal stimulation causes release of pancreatic secretions during gastric and cephalic phases
secretins function in pancreatic regulation of secretion
- secretin is released in response to Hcl in the duodenum
- target duct cell to release watery alkaline juice
CCK function in pancreatic regulation of secretion
- released in response to proteinaceous content in duodenum
- targets acini to release enzyme rich pancreatic juice
liver anatomy - 3 main parts of the functional unit
- hepatic lobule
- hepatic sinusoid
- bile canaliculi
blood flow to the hepatic sinusoid
- a central vein is fed by a branch of the hepatic portal vein
- the hepatic a. also feeds into it
- so oxygen rich and nutrient rich blood meet at the sinusoids
bile canaliculi
- the liver processes material and makes bile
- it secretes bile via the bile canaliculi to the bile duct
hepatocytes
- large, cube, often binucleate
- arranged in sheets of tissue - bathed in mixed blood of sinusoids
functions of hepatocytes
- bile production
- glycogen metabolism
- lipid metabolism
- production of plasma proteins
- detox
- urea production
- iron storage
Kupffer cells
- macrophages that eat:
- debris, aged cells, RBCs, foreign cells
- line the sinusoid space
- help protect from stuff coming in from the small intestine
hepatic stellate cells
- regulate the Kupffer cells via cytokines
- line the perisinusoidal space
- lipid droplets
hepatic portal circulation review
- splenic v. and superior mesenteric v. drain to hepatic portal v.
- hepatic portal v. to liver
- from liver, through hepatic veins to IVC
- IVC to heart
- heart through abdominal aorta to proper hepatic a.
- back to liver
What are the various carb metabolism functions of the liver?
- glycogenesis
- glycogenolysis
- lipogenesis
glycogenesis
- production of glycogen
- stimulated by insulin
- glycogen synthase, glycogen branching enzyme
glycogenolysis
- break down of glycogen
- stimulated by glucagon
- glycogen phospohorylase
lipogenesis
-TG formation from glucose
What are the various amino acid metabolism functions of the liver?
- gluconeogenesis (from aa)
- urea production: deamination of aa produces ammonia - urea cycle
- aa production
lipolysis by liver
- lipid metabolism in the liver stimulated by glucagon, NE/E, ghrelin
- release of FA and glycerol from TG
- FFA enter circulation
glycerol that is released in lipolysis is used where?
- glycolysis
- gluconeogenesis
ketogenesis of liver
- stimulated by low blood sugar and glucagon
- occurs in mitochondriion
- ketones release by beta oxidation of FA
- forms acetyl-CoA and enters TCA
ketone bodies formed in ketogenesis enter the circulation as what?
- acetoacetate
- acetone
- beta-hydroxybuterate
fat storage function of the liver
- liver stores lipids and fat-soluble vitamins
- if excessive = fatty liver
liver cholesterol metabolism
- the manufacture of cholesterol
- used in bile, lipoproteins, plasma membranes and steroid hormone synthesis
liver phospholipid synthesis
- membranes, blood clotting, supply of arachadonic acid for prostaglandin synthesis
- synthesized from phosphatidic acid (intermediates in the production of triacylglycerols)
What types of protein does the liver produce?
- albumin (mainly)
- carrier proteins
- coagulation proteins
- complement
- CRP
- apolipoprotein
- hormones
Describe the detox process of the liver
- Kupffer cell phagocytosis
- enzymatic detox: phase 1 and phase 2
- metabolites of detox eliminated in bile or urine
phase 1 of enzymatic liver detox
- Cytochrome P450
- lg group of enzymes
- oxidize molecules to less toxic metabolites
phase 2 of enzymatic liver detox
- esterification
- often steroid compounds
