BSC Metabolism Flashcards
(46 cards)
what are the 3 sections of the small intestine, their lengths, and characteristic features
1- duodenum, 10-12 inches, pyloric valve, arcs around head of pancreas, ends at duodenojejunal flexure/ junction
2- jejunum, 8ft, from duodenum to ileum
3- ileum, 12 ft, joins large intestine at ileocecal valve
what are the roles of the duodenum and ileum
d- receives stomach contents, pancreatic juice, and bile
i- regulates flow of contents
what do plicae circulares/ villi/ microvilli do
absorbs nutrients, electrolytes, and water in small intestine, NEEDS TO BE MAXIMAL SURFACE AREA
what happens to diet glucose
- most of it is absorbed into bloodstream as glucose formed by hydrolysis of dietary starch and disaccharides
- others are converted into glucose in the liver
what are carbohydrates/ sugars/ saccharides the precursor for
1- glycogen for storage
2- ribose & deoxyribose in nucleic acids
3- galactose for synth of lactose in milk
what are the 3 major carbohydrates and list examples for each category
1) monosaccharides, glucose, galactose, fructose
2) disaccharides, sucrose (gl & fr), lactose (ga &gl), and maltose (2xgl)
3) polysaccharides, glycogen stored in skeletal muscle (meat), starch, fiber (cellulose)
how do you regress from polysaccharide to disaccharide? from disaccharide to monosaccharide?
- poly to di: salivary amylase and pancreatic amylase
- di to mono: disaccharidases in small intestine and brush border enzyme near microvilli
how are glucose, galactose, and fructose absorbed into cells? how do they leave?
- glucose and galactose: SGLT1, secondary active transport thru Na+ dependent cotransporter, high luminal [ ] against gradient
- fructose: GLUT5, facilitated diffusion via glucose transporter
- all leave through GLUT2 into capillaries
what happens when lactose is tolerated vs not tolerated
tolerated: lactase breaks down lactose to glucose and galactose -> normal poopie
not tolerated: lactase not present, only water, bacteria results and ferments -> gas, organic acids, osmotically active molecules irritation and motility -> back to more bacteria
what do insulin and glucagon do
insulin: stores fuel
glucagon: creates fuel by breaking down
what are the 4 fates of glucose
1) metabolized into pyruvate/ lactate via glycolysis
2) metabolized in the pentose phosphate pathway
3) stored as glycogen in the liver and skeletal muscle
4) stored as triglyceride in adipose tissue
what are the processes involved with metabolizing glucose into pyruvate/ lactate
glycolysis, krebs/tca/citric acid cycle, etc
what are the processes involved with metabolizing using the pentose phosphate pathway
glycolysis- alternate route: HMP -> glutathione
what are the processes involved with storing glycogen in the liver and skeletal muscle
glycogenesis
what are the processes involved with storing triglyceride in adipose tissue
fatty acid synthesis
what are the important features of glycolysis
- 10 enzymatic rxns
- occurs in cytosol
- anaerobic (but w/ O2 can make 5 ATP in ETC)
- aerobic, undergoes oxidative degradation in mitochondria to acetyl CoA
- result sin 2 ATP and 2 NADH
- 1 glucose = 2 pyruvate
what happens if glycolysis takes place in an anaerobic setting? what is another situation where this would occur
- converts to lactate
- w/ cells that have no mitochondria like RBCs
what is the process of pyruvate undergoing oxidative degradation during glycolysis
1) carboxyl group removed from pyruvate, releases CO2
2) NAD+ reduced to NADH
3) acetyl group transferred to coenzyme A -> acetyl CoA
what are the important features of krebs cycle? alternate names for this process?
- occurs in mitochondria
- doesn’t use O2 but will stop w/o it
- forms: NADHx6, FADH2x2, GTPx2, waste- CO2
- needs B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid)
- TCA (tricarboxylic acid), citric acid cycle
describe the important features of ETC
- inner mitochondrial membrane
- requires lots of O2
- converts NADH to NAD+ : generates 2.5 ATP& FADH2 to FADH generates 1.5 ATP
- ATP synthase enzyme is key and what creates the H+ gradient to produce ATP
- 4 complexes
what are the important features of the alternate route of glycolysis
- HMP
- not ATP instead NADPH and pentoses important for ribose (RNA, DNA, and making proteins)
- instead of glucose becoming pyruvate
- occurs in cytosol, thus all cells
- key enzyme: G6DP NEEDED
what is NADPH used for
- donates electrons (reducing agent) in anabolic rxns to make fatty acids and cholest. in liver and adipose tissue/ mammary glands/ synth steroids
- indirectly eliminates toxic oxygen radicals
what is glutathione and what are its states
major endogenous antioxidant produced by all cells
- participates directly in neutralizing free radicals
- maintains vitamin c& e in reduced forms
- reduced state- GSH, oxidized state- GSSG
what are important features about glycogenesis
stores glucose in liver/ skeletal muscle for a rainy day