anaerobic metabolism Flashcards
what are other names for the glycolytic system
glycogenolysis
glycolysis
lactate production
what are the characteristics of carbs
only macro that can generate ATP both anaerobically and aerobically
where are carbs stored the most
muscle - readily available
where can carbs be found in the body
blood
muscle - most available for exercise
liver - transport to muscle via blood
ingested - from digestion to muscle via blood
how does glucose enter a muscle cell
glucose transporter 4 (GLUT4)
what is GLUT4
- transport protein to get glucose inside the cell (uses facilitated diffusion)
- specific to muscle cells
- in cell membrane
what is GLUT4 sensitive to
insulin
- insulin sends GLUT4 to the cell membrane from the vesicles inside the cell to get glucose inside the cell
when is pyruvate converted to lactate
high intensity exercise
- otherwise pyruvate enters the cell
how many pyruvate or lactate are produced from 1 glucose
2 pyruvate OR lactate per 1 glucose molecule
(everything after fructose in the chain is doubled)
what is the ATP consumption vs production from anaerobic metabolism using GLUCOSE
uses 2 ATP
creates 4 ATP
NET = 2 ATP
what is the ATP consumption vs production from anaerobic metabolism using GLYCOGEN
uses 1 ATP
creates 4 ATP
NET = 3 ATP
what is the function of hexokinase (HK)
converts glucose to glucose 6 phosphate (G6P)
how is G6P produced
ATP is hydrolysed to ADP + Pi + H+
Pi will be attached to glucose to produce G6P
- G6P can’t leave the cell
irreversible reaction
what are the 2 fates of G6P
- undergoes glycolysis
- stored as glycogen
how is G6P stored as glycogen
- phosphoglucomutase converts G6P to G1P
- glycogen synthase converts G1P to glycogen
what is the process to convert back to G6P from glycogen
- glycogen phosphorylase (PHOS) breaks down glycogen to G1P
- phosphoglucomutase converts G1P back to G6P (bi directional pathway)
what is the function of phosphofructokinase
rate limiting enzyme in the process of converting G6P to pyruvate
what is PFK activated and inhibited by
activated
- ADP, AMP, Pi, G6P (substrate)
inhibited
- ATP, H+
what is the difference between glycolysis and glycogenolysis
glycolysis = glucose breakdown
glycogenolysis = glycogen break down
what is the yield from glycolysis
2 ATP
- requires 2, produces 4
2 NADH + H+
how does NADH get back to NAD+
oxidised by lactate dehydrogenase
redox reaction of NADH and NAD+ happens consistently
where does glycogenolysis occur
sarcoplasm - outside mito
what catalyses glycogenolysis
glycogen phosphorylase (PHOS)
- convert glycogen to G1P
what is PHOS
rate limiting enzyme
what is PHOS activated and inhibited by
activated (break down more glycogen)
- Ca2+, AMP, Pi, epi
inhibited (don’t need more glycogen)
- H+, ATP, G6P
what is the yield from glycogenolysis
3 ATP
- requires 1, produces 4
where does pyruvate go
always into the cell
- amount depends on how fast you need ATP
what happens to pyruvate when ATP is needed fast
pyruvate builds up
cant be taken in by mito fast enough
- converted to lactate
what happens to pyruvate when ATP is needed slower
pyruvate can go into the mito more smoothly
- less build up outside
what are the two types of glycolysis
anaerobic and aerobic
what is the use of oxygen, speed, ATP production and product of anaerobic glycolysis
oxygen = no
speed = fast
ATP production = low
product = LACTATE
what is the use of oxygen, speed, ATP production and product of aerobic glycolysis
oxygen = yes
speed = slow
ATP production = high
product = PYRUVATE
what is the function of lactate dehydrogenase
helps converts pyruvate to lactate
NADH + H+ –> NAD+
(can convert back to pyruvate)
when is lactate formed
when pyruvate and NADH + H+ accumulate
(mismatch between glycolytic rate and capacity of mito to accept pyruvate)
how / when is lactate removed
- can be converted back to pyruvate during low intensity exercise
- can go out of the cell to the bloodstream and travel to other organs (liver, heart, etc) as a source of fuel
what is the relation between lactate production and exercise intensity
as exercise intensity increases, lactate generation increases
does lactate cause fatigue
NO
- causes pain but not fatigue
when does lactate cause pain
when ATP demand > aerobic metabolism ATP supply
- cellular pH drops
- impairs enzyme activity and cross bridge cycling
which system contributes the most to ATP production in the first few seconds of exercise
PCr
- gradually reduces
which system contributes the most to ATP production in between 5 and 30 seconds of exercise
glycolysis
- takes over from PCr and then gradully decreases
when does oxidative phosphorylation increase
around 30 seconds
(all systems work together even at the highest intensity)
