Physio 2 - Metabolism 1

drraythe's version from 2015-06-09 01:48

Small intro + CARBS

Question Answer
Three main places of storage of food molecules?fat, glycogen, protein pool
direction of metabolism is dependent on what? three paths it can take?depends on FUEL AVAILABILITY, main directions are (1) storage of energy (anabolic) (2) mobilization of energy (catabolic) (3) conversions
how does she draw out the "metabolic players/directions" into one very simple picture?(DRAW/LOOK AT 1.1.2) carbs are coming off of C6 (this is usually glucose). C6 is attached to C3, which has lipids and proteins branching off of it. C3 is then attached to C2, which has ENERGY branching off of it. what is left is C1, the waste product (usually CO2)
what is anabolic metabolism?store energy
what is catabolic metabolism?mobilization of energy
how are fuel stores interconnected?interconnected through a "spinal column" of carbon compounds by a mult of pathways
directions of metabolic pathways controlled by? (4)hormones, nervous system, ATP/ADP ratios, accumulation of intermediates/end products
what is the preferred fuel in all tissues?GLUCOSE
What are the glucose-dependent tissues? (7)NERVOUS SYSTEM, RBCs, retina, renal medulla, gonads, fetus, lactation
what is the adequate blood glucose level that is absolutely essential to maintain?~80-120mg glc/dl
glucose level which could cause irritability? seizures? coma? death?irrit= <80mg. seizures= <50. coma=<20, then after slip into coma, death
how does one maintain blood glucose levels? (3)(1) eat/digest/absorb glucose (2) storing (glycogenesis) and releasing stores (glycogenolysis) (3) synth of new glucose from precursors (gluconeogenesis)
if you get excess glucose levels, what hormone is released?insulin
if you get hypoglycemic, what hormone(s) is released?glucogon....if very severe, cortisol/epi/norepi also
how does glucose enter cell? what is it dependent on? what does it require?via facilitate diffusion. dependent on concentration of glucose. Requires GLC XPORTERS (GLUTs)
glucose uptake in glucose dependent tissues+liver is... (where are the GLUTs? what's going on with their facilitated diffusion?)built in! GLUTs are part of their cell membranes, facilitated diffusion is always active
glucose uptake in glucose independent tissues (mm,fat) is... (where is GLUT? whats going on with facilitated diffusion?)GLUTs are stored intra-cellularly. need insulin stim to allow GLUTs to fuse with cell membranes (therefore facilitated diffusion ONLY when INSULIN present)...GLUTs detach if no insulin present
so if you have a hyperglycemic state (in reference to glc uptake)ALL cells have access to blood glucose
if you have a hypoglycemic state ( in reference to glc uptake)only glc-dependent cells have access to blood glc (glc independent use alternate fuels)
what is glucose trapping?upon cell entry, glucose is phosphorylated to Glc-6-P, so glucose cant diffuse out of cells. this is irreversible except in liver, kidney, and GI cells (since they are designed to release it back into the blood)
fate (direction) of glucose depends on what?body's energy situation
energy ATP production (aerobic)? (basic jist)glycolysis--> acetyl CoA--> krebs cycle--> ETC
energy ATP production (anaerobic)? (basic jist)glycolysis and lactic acid formation
energy storage? (basic jist-2 things)glycogen, conversion of Glc into fatty acids
where does glycolysis take place? (in the cell)cytoplasm
what happens during glycolysis?C6 split into 2 C3s= PYRUVATES
purpose of glycolysis? (3)(1) glc prepared to enter mitochondria (as pyruvate) (2) some ATP (2 per glc) is generated (3) some of glc's energy is xfered/stored via H in form of NADH/H+ for entry into ETC
what happens when pyruvate (C3) ENTERS the mitochondrion (2 things, and result?)Is decarboxylated to acetyl group=C2 ---> acetyl group attaches to coenzyme A.== ACETYL CoA---> ready to enter KREBS CYCLE
what IS the krebs cycle? (where is this taking place? products?)in MITOCHONDRION. It is a SEQUENCE of rxns in which acetyl group is degraded into 2 CO2, 1ATP, and 8 Hydrogen atoms (NADH/H+)
describe the process of krebs in like...2-3 steps (starts with Acetyl CoA...)acetyl CoA (C2) combines with OXALOACETATE (OAA) (C4) ---> forms citric acid (C6), citric acid undergoes sequence of decarboxylations and dehydrations---> ends in OAA. (it's a circle, lol)
what does krebs start and end with?OAA (oxaloacetate)
what is the most important outcome of glucose oxidation in the krebs cycle?making energy-rich hydrogen bonds available for subsequent oxidation in the ELECTRON TRANSPORT CHAIN (ETC)
what is ETC stand for?electron transport chain
aside from making energy-rich H-bonds, what else can krebs synthesize?fatty acid, glucose, amino acids, and combustion of fatty acids and amino acids
what is the ETC doing?series of electron carriers integrated into inner mitochondrial membrane, in which the energy stored in NADH/H+ is transferred to ATP = OXIDATIVE PHOSPHORYLATION
what does the oxidative phosphorylation of the ETC lead to? (3 things)generation of ATP, regeneration of NAD, formation of water out of the remaining protons and oxygen
in an anaerobic environment, oxidative phosphorylation of ETC can't happen. if there was no alternate, what would happen?no O2, so NADH/H+ would pile up, reduce krebs activity, pyruvate would pile up and would inhibit glycolysis, ATP production would seize to a stop
what happens in an anaerobic enviro since ETC can't happen?need to keep glycolysis open so-- remove pyruvate and regenerate NAD via LACTATE PATH.
what happens in the lactate path?pyruvate reduced to lactic acid by lactate dehydrogenase (LDH) which regenerates NAD (some ATP still generated by glycolysis)
what is the main enzyme in the lactate (anaerobic) path? what does it do? where is it? (5 places)LDH (lactate dehydrogenase). intercovert lactate and pyruvate. can be in mm, liver, RBCs, GI, kidneys
what is the main metabolic pathway in RBCs? why?Lactate path (anaerobic path) because they DON'T HAVE MITOCHONDRIA
what happens to the lactate that builds up from the anaerobic path? (apprx 3 steps)it diffuses into circulation, then is utilized by tissues where O2 is available (heart muscle) where LHD converts lactate back to pyruvate (aerobic path), it then enters gluconeogenesis in the liver to make new glucose
what does LDH in the plasma indicate?(lactate dehydrogenase) tissue damage of tissues where LDH is present! (mm, liver, RBCs, GI, kidneys)
what do you want to do FIRST with glucose? (when it is first absorbed, etc)produce ATP
what happens if there is excess glucose available?glycogenesis
is glucose osmotically active?highly
what is glycogenesis?storing excess glucose in the liver and mm as glycogen (a glucose polymer)
what are the advantages of glycogen?glycogen precipitates and is not osmotically active
MAIN glycogen storing organs (and % max storage)liver= max 6% (of its weight). mm= max 1%
how is a branched carb formed? (explain linkages, etc)first have alpha 1-4 linkages of glc in a chain...but when too long, a BRANCHING ENZYME cleaves off 6 glc units and attaches in a branching manner in ALPHA 1-6 LINKAGES (so has 1-4 and 1-6 linkages) (and you got glycogen)
what hormone stimulates glycogenesis?insulin
what happens if you have glycogen and you need glucose? (process, enzyme, product)GLYCOGENOLYSIS with a DE-BRANCHING enzyme and glycogen is broken into glucose-6-phosphate
what hormone for glycogenolysis ?glucagon
how to release free glucose from glc-6-P (cant diffuse and usually this bond is irreversible, if you remember)?need PHOSPHATASE which is in LIVER, KIDNEY (AND GI)
what happens with hepatic glycogenolysis?inc blood sugar
what happens in mm glycogenolysis?inc mm energy supply
if hepatic glycogenolysis is happening, where does the broken down sugar go(tissue-wise, once already in the blood)?GLUCAGON is active so only glc dependant tissues get the glucose.
how long does a full liver store of glycogen last you?a few hours
what is gluconeogenesis?body makes its own glucose, this happens when glycogenolysis is happening
where can gluconeogenesis occur?liver, kidney can a little
what are the gluconeogenic precursors? (4)many amino acids, lactate, propionate out of fermentation, glycerol (from triglyceride breakdown)
where do ingredients of gluconeogenesis go to, what happens to them?precursors enter krebs and are pulled into cytoplasm as OAA/malate and enter gluconeogenesis
which precursor of gluconeogenesis doesn't come from krebs?glycerol
can an acetyl group add to gluconeogenesis?no-- the carbons from acetyl group are lost in krebs.
put in _________ Carbons into krebs in gluconeogenesis?at least 4 or 5
how much glucose from gluconeogenesis is done by liver? kidney? (of 100% gluconeogenesis)80%, 20%
product of gluconeogenesis?glucose-6-phosphate.


Question Answer
dietary fats consist of mostlytriglycerides, phospholipids, cholesterol
fat is essentially a...carbon chain...usually around 18-20
utilization of lipids for...(5 things)energy gain, energy storage, building blocks (membranes), hormones and bile acids
how can you make lipids soluble for transport?make it a LIPOPROTEIN
what is a lipoprotein? (specific components)aggregations of lipids surrounded by a shell of hydrophilic proteins, phospholipids,and specific receptor proteins (APOPROTEINS)
what is an apoprotein?organ-specific receptor protein in lipoproteins (on outside of chylomicron)
what makes chylomicros? what do they do?enterocytes make them. chylos formed after absorption of dietary lipids
what are the two classes of lipoproteins?chylomicrons and VLDL (very low density lipoprotein)
what makes VLDLs? when?formed by liver after production of new (endogenous) fats
how does a tissue uptake lipids from lipoproteins? (specifics)apoprotein bind to cell's endothelial receptors, ACTIVATE endothelial lipo-protein-lipases (LPLs) ---> LPLs dissolve part of lipoprotein shell ---> hydrolyze triglycerides ---> FFAs+glycerol diffuse into tissues
What is an LPL?enzyme, lipo-protein-lipases, they nibble open a lipoprotein so a cell can access the lipids inside
after lipids are freed by LPLs, they diffuse into tissues for... (uses) (2)(1) storage in fat tissues (2) energy use in most tissues
what happens to the remnants of lipoproteins after they've been worked on by LPLs?detach from LPLs and are handled by the liver
How is fat stored in fat tissue?after LPL allows lipids (FFAs) out of lipoprotein to diffuse into cell, the FFAs re-condense into triglycerides
what is the release of stored fat called?lipolysis
when is lipolysis initiated?when circulating fuel levels are low and energy is needed
what enzyme is involved in lipolysis? what does it do? products?HSL (hormone sensitive lipase), it hydrolyzes stored triglycerides into FFAs+glycerol
how do the products of lipolysis (FFAs and glycerol) get out of the cell, and get to the tissues that need them? (not liver or GI)they DIFFUSE out of the adipocyte and then bind to PLASMA ALBUMIN which forms NEFAs (non-esterified fatty acids) which can deliver FFAs+glycerol to active tissues
what is a NEFA? what is it made of, what does it do?Non-esterified fatty acid, it is plasma albumin+FFA+glycerol, it is used to transport the FFA and glycerol to a tissue that needs them (necessary b/c FFA+glycerol are non-soluble)
How does a tissue utilize FFAs for energy? (the name of the process)BETA-OXIDATION (beta meaning "second linkage")
where can FFAs used for energy come from? (3)NEFAs, VLDLs, and Chylomicrons
what is involved in beta-oxidation? (where, products, what happens to products)FFAs enter MITOCHONDRIA and undergo progressive release of C2 segments (beta) as Acetyl CoA. The A-CoA enter Krebs for complete oxidation and then ETC for ATP production
Summary statement for Beta-oxidation would beFFAs are utilized for energy gain by entering beta-oxidation which releases acetyl groups for use in the krebs cycle/ETC (FFA-->Acetyl CoA)
Does the glycerol undergo beta-oxidation?no
What happens to the glycerol which is released in lipolysis? (2)it diffuses into active tissues and (1) enters glycolysis--> krebs--> ETC when ATP is needed (2) enters GLUCONEOGENESIS when glucose is needed
what is it called when the body makes needed FFAs?lipogenesis
what are the precursors for lipogenesis?excess glucose and amino acids
where does lipogenesis take place?fat tissue, mammary gland, and liver
when is lipogenesis activated?when stores of ATP, glycogen, and labile (easily altered) protein are full and there is still glc and AA available
in lipogenesis, after the FFAs are formed, what happens to them (and in what 2 locations)FFAs are condensed with glycerol into TGs in (1) fat tissue (storage form) (2) mammary gland (secreted into milk)
is the liver a fat storage site?no
how is the liver involved with fat storage?NOT a storage site. It packs the newly made TGs into lipoproteins (VLDLs), then theres exocytosis into circulation, the adipose LPLs hydrolyze the VLDLs, and they are then in fat storage.
what does the LIVER do during a LIPOLYTIC phase?It acts as a "fat sponge" (readily takes up FFAs and NEFAs without using them) and makes them avail for OTHER tissues as VLDLs and Ketone bodies (the liver is the good momma)
What is the advantage to the liver making VLDLs?The albumin-binding capacity for FFA is limited, so liver is able to increase lipid xport via VLDLs
summary of VLDL formation/workingFFAs re-synthesized into TGs (lipogenesis in the liver) and packed into VLDLs. VLDLs released into circulation and taken up in tissues via LPLs for energy gain via Beta-oxidation
What prompts ketone body formation in the liver? (2)many FFAs enter B-oxidation and Acetyl CoA accumulates b/c (1) as liver ATP stores fill up, krebs declines activity (2) OAA/malate are withdrawn from Krebs for gluconeogenesis (loss of substrate)
what are ketone bodies (ketoacids) made of? (3)the accumulating acetyl groups condense into (1) acetoacetic acid (2) acetone (3) Beta-Hydroxybutyrate
how do you reverse hepatic ketone body formation?you can't, it's irreversible
what happens to KBs once they're formed?they are released into the blood, taken up by other tissues, hydrolyzed back into Acetyl CoA, and enter krebs/etc for energy
what is the advantage of hepatic ketone body formation?liver beta-oxidizes FFA for other tissues and supplies an easily usable hydrophilic substrate for energy gain, eg, to neurons and mm
why are KBs important?SOURCE OF ENERGY for many tissues when GLUCOSE LEVELS ARE LOW (b/c they are made of FFAs)
what organ makes fatty acids?liver