week 5: The muscular system: Integrated responses to exercise: Flashcards
why does performance rely on cardiac performance
it determines oxygen transport to active tissue which then used to generate energy
what does cardiac function rely on
HR max
SV max ( affected by training and genetics)
what determines how well you then use the ox delivered to tissue
(CaO2-CvO2)
-FIBRE TYPE
mitochondrial and capillary density (this can be affected by training)
genetics
-FlO2 (inspired)
-[Hb]
-PO2
ATPase reaction
ATP > ADP + Pi + αH+
during rest, skeletal muscle ATP storage
low
5-8mmol.kg-1 wet weight
enough for 8 maximal contractions/ 2seconds
ATP supply during sprint exercise
stored ATP
PCr breakdown
glycolysis
PCr breakdown
sits inside muscles
phosphate bounds to creatine
can liberate phosphate and transfer it to ATP quickly
glycolysis
breakdown of glucose to make immediate ATP
produces pyruvate
glucose/ glycogen
glucose 6-P (requires 2 ATP)
fructose 1,6-DP
phosphorylated pyruvate
2x pyruvate
(4 ATP, 2 NADH produced)
what is temporarily buffered by two reactions during severe intensity exercise
cystsolic ATP conc
adenylate kinase (AK) reaction:
2 ADP <-> ATP + AMP
what type of reaction is AK reaction
reversible buffer reaction
what does AMP accumulation play an important role in
stimulating glycogen phosphorylase and phosphofructokinase (PFK)
phosphofructokinase
enzyme for regulation of glycolysis
catalyses the formation of fructose-1,6-bisphosphate
(unstable two-phosphate sugar molecule)
AMP hydrolysis
AMP deaminase (AD) reaction
AMP + H2O + H+ > IMP + NH4+
IMP
inosine monophosphate
when in AMP deaminase inhibited
when ATP conc is high
why is AMP deaminase useful
can prevent acidosis by using up H+ ions
what is IMP an activator for
glycogen phosphorylase
inorganic phosphate
activates glycolysis
CA2+ effect on glycogen
breakdown of glycogen stored in muscle liberating glucose within the muscle
do not need to wait for it from liver
breakdown PCr reaction
PCr + βH+ <> Pi + Cr
what does PCr breakdwon buffer
ADP accumulation
Pi
substrate in glycolysis
activator of glycogen phosphorylase (GP), hexokinase (HK), and PFK in glycolysis
why is it important Pi produced during PCr breakdown is turned back into ATP quickly
Pi is thought to be a major cause of muscle fatigue as it interferes with contractions
during sprints conc of PCR, ADP, Pi….
PCr: decrease
ADP: increase
Pi: increase
beginning of exercise ATP production and as exercise goes on
initially ATP production due to PCR breakdown (CK reaction)
As exercise goes on glycolysis activated by rising Pi and presence of ADP and AMP (after 5 seconds)
CK isoform: mechanical machinery CK (MMCK)
highly expressed in cytosol
CK isoform: mitochondrial CK (MiCK)
co-localised at mitochondria transfer structures
PCr as a temporal buffer
provides rapid ATP provision during sprint exercise
Pcr as a spatial buffer
a signalling molecule to communicate with other cellular compartments the requirements for increased ATP production
net reaction of glycolysis
glucose + 2Pi + 2ADP + 2NAD+ > 2 pyruvate + 2ATP + 2NADH + 2H+ + 2H2O
net yield of glycolsysis
2 ATP if started with glucose
3 ATP if started with glycogen
pyruvate > lactate allows repsiration to occur with no oxygen present as
revers NADH back to NAD+
it can then be used in glycolysis
enzyme which converts pyruvate to lactate
lactate dehydrogenase
lactic acid + sodium bicarbonate >
sodium lactate
sodium lactate + carbonic acid >
carbon dioxide
H20
reason for VCO2 increase during anaerobic exercise
carbonic acid produced> H2O + CO2
where does sodium bicarbonate come from
blood- main buffer for H+ to maintain blood pH
where are cytochromes located
inner membrane of mitochondria
main function of cytochrome
electron transport
how do mitochondria produce energy
use energy stored in NADH and FADH to liberate electrons
how do metabolic processes transport electrons
in the form of hydride ions H-
using NADH and FADH
electron transport chain
series of electron transport proteins located in the inner membrane of the mitochondria
how are H+ pumped from mitochondrial matrix to intermembrane space
redox reactions, redox-active proteins pump protons
four protein complexes that make up ETC
NADH dehydrogenase
succinate dehydrogenase
cytochrome bc1
cytochrome c oxidase
how does ATP synthase use proton gradient
H+ from intermembrane space travels to mitochondrial matrix through ATP synthase channels
ADP+Pi> ATP
how many H+ needed to generate 1ATP
4
3H+ to generate 1ATP
1H+ used to translocate Pi (and ADP)
electron transfer from NADH and FADH2 translocates
NADH: 10H+
FADH2: 6H+
