Muscle Biochmistry 2012, International University of Africa, Atif Hassan Khirelsied

8/3/2019 Muscle Biochmistry 2012, International University of Africa, Atif Hassan Khirelsied

1/46

MuscleMetabolism

AtifHassanKhirelsied,B.Sc.,M.Sc.,Ph.D.

DepartmentofBiochemistry

InternationalUniversityofAfrica,Khartoum,Sudan


2/46

Aprimarymuscletypes:

skeletal musclecardiac muscle

smooth muscle


3/46

1. Movement

2. Supportsoft

tissues

3. Guardbodyopenings

.


4/46

1. Fastfibers

2. Slowfibers

3. Intermediatefibers


5/46

Whitemusclefibers

1. Fast twitch

. , .

3. Depends on the phosphagensystem and on glycolysis-lactic acid.

4. Stores glycogen for conversion to glucose.

. .

6. Little or no myoglobin.


6/46

Redmusclefibers

1. Slow twitch.

. , .

3. Depends on aerobic metabolism.

4. Utilize fats as well as glucose.

. e gycogen s orage.

6. Many blood vessels and much myoglobingive this muscle its

reddish appearance.


7/46


8/46


9/46

=

s e mme ae source o energy or musce conrac on.

1/10/2012 Atif H.Khirelsied9


10/46

Muscle Metabolism

s necessary or musc e con rac on an

relaxation. yos n ase,

Ca2+ ATPase in the SR membrane,

a ase n e sarco emma


11/46

Muscle Metabolism

usc es yp ca ys ore;

Limitedamounts ofATP.

Ceatine phosphate).

Glycogen.


12/46

Production of ATP durin muscles contraction


13/46

Fuel utilization durin exercise

evera actors nterp ayto eterm new at ue s

utilized:. ;

2. theamountoffuelstored(glycogen);

.

4. theavailability

of

oxygen

for

the

muscle;

5. the intensit of the exercise

6. thedurationoftheexercise.


14/46

Fuel utilization during exercise


15/46

Phosphocreatine

DuringexerciseATPcanbeusedfasterthancangenerated

byrespiration.

Phosphocreatine:toregenerateATPfromADP

Phosphocreatinelevels

are

3X

ATP


16/46

Allfibretypescanusephosphocreatine,particularly

typeIIB

fibres

which

also

convert

glycogen

to

lactic

aci .

Intype

Iand

IIA

fibres,

most

of

the

glycogen

is

completelyoxidizedbutthereisstillalargecapacityto

convertglycogentolacticacidtogenerateextraATP,if

itis

required.


17/46

Glycogenolysis andanaerobicglycolysis

The fate of the l co en will de end however on theintensityoftheexerciseandthesupplyofoxygen.

Duringstrenuousexercise, ATPisderivedfromanaerobic.

ATP,thecapacityofthisprocessislimitedbytheactivityof

.


18/46

Glycogenolysisandanaerobicglycolysis


19/46

Trans ortofthefueltothemuscle

Bloodbornefuelsareglucose,whichisderivedfromliverglycogen,andfattyacidsderivedfromadiposetissue.

Uptakeoffuelsdependson:

1. theflowofbloodthrou hthemuscle

2. theconcentration

of

the

fuel

in

the

blood

. .

u u x e owo oo an ueutilizationincreaseupto50fold.


20/46

Ox ensu l tothemuscle

Theavailabilityofoxygeniscruciallyimportantfor

generation

of

ATP.

ATPmoleculesgeneratedfromaerobicoxidationof

glucoseis

tenfold

greater

than

that

from

anaerobic

glycogenolysis andglycolysis.

Oxygenavailability

is

the

major

factor

limiting

performanceinathleticevents.


21/46

Oxygensupplytothemuscle

Oxygensupplytothemusclesdependsonthefollowing

1. Theflowofbloodthroughthemuscle

3. Theconcentration(partialpressure)ofoxygenintheblood.

4. The u take of ox en from the air in the alveoli of the lun

thiscan

be

reduced

by

altitude,

pollution

and

in

patients

(e.g.

emphysema).

5. Thenumberoferythrocytesintheblood.

6. The

volume

of

the

blood.

Blood

doping7. Theconcentrationintheerythrocytesof2,3

bisphosphoglycerate


22/46

Durationofexercise

Asthedurationoflowintensityexerciseincreases,the

contributionoffatoxidationtoATPgenerationrisesand

parallelsthe

reduced

contribution

of

glycogen

Forver rolon edactivities whenallthemuscleandliver

glycogenhas

been

used,

fatty

acids

become

the

only

fuel

available.


23/46

Estimatesof

percentage

contribution

of

glucose,

glycogen

and

fattyacidstoATPgenerationoverfourhoursofphysicalactivity


24/46

Intensityofexercise

Asintensityincreases,thecontributionsofbloodglucose

andglycogentoATPgenerationincrease.

Aboveabout50%ofmaximumpoweroutput,therateof

l co enutilizationincreasesalmostex onentiall

(glycogenis

converted

to

lactic

acid

at

an

increasing

rate)


25/46

Coriscycle(Glucoselactate)cycle

Laurence A. Moran. Some of the text is from Principles of Biochemistry4th ed. Pearson/Prentice Hal


26/46


27/46

Fuelsforvariousathleticeventsandgames

Sprinting

andphosphocreatine.

Asthedistanceextendsto400m,aerobicoxidationoccurs,.

ispresentinthemuscle


28/46


Themarathon

A u marat on 42.2 m requirest eoxi ationo a out700gofglycogen.

Onlyabout500gcanbestoredinthebody,thereforefatty

acid

are

oxidized

to

supplement.

Slowpaceattheearlypartoftherun,enableuseofboth

glycogen

and

fatty

acids

by

the

muscle

(avoid

glycogen

depletion).


29/46


Themarathon

Afterseveralhours,glycogenisexhaustedandfattyacids

arethe

only

fuel

used.

Asfattyacidoxidationcannotprovidemorethanabout

60%of

the

ATP

required

for

maximum

power

output

(i.e.

thepace)mustslow.

Hencethe

rate

of

oxygen

consumption

(VO )

falls

to

about

60%ofmaximum.


30/46


31/46

Muscle fatigue

Physiologicalinabilitytocontract.

ATP.

Othercontributingfactorsincludethe

decreaseinsarcoplasmic pH?,increased

,

.


32/46

Oxygen debt

e ers o epos exerc se rea ngra e>>>res ng

breathingrate

Servesmanytasks:

Replenishthe

glycogen

stores

Convertlacticacidbacktoglucose

.


33/46

Oxygen debt


34/46


35/46

DopinginSport

AtifHassanKhirelsied,B.Sc.,M.Sc.,Ph.D.

DepartmentofBiochemistry

InternationalUniversityofAfrica,Khartoum,Sudan


36/46

Do in

B definition do in is the use o an rohibitedcompoundormethodinordertogainacompetitiveadvantage.

Thetypeofcompoundchosendependsonthetypeof

activity.


37/46

Do in

Therearemanyethicalwaystogainacompetitive

advantagein

sport.

Waysofimprovingperformanceinclude:. super ortra n ng,

2. improveddiet,

. ,

4. betterrest,physicaltherapy,

. ,

6. andahostofsportspsychologytechniques.


38/46

The am hetamines do in

s ngar c a s mu an s,suc asamp e am nes, oallowhimtoridelonger,higher,andfaster.

,

createan

oxygen

debt

that

they

cannot

repay.


39/46

Am hetaminesallowhumanstodosomethin thathorses

candorunthemselvestodeath


40/46

The anabolic steroid do in

Drugsthatmimictheeffectsoftestosterone and

dihydrotestosterone inthe

body.

Theyincreaseproteinsynthesiswithincells,whichresu ts nt e u upo musc es.

,

suchaspowerliftingandsprinting.


41/46

Do in

Canadiansprinter

Ben

Johnsonwasdisqualified

forsteroiduseafter1988

meterdash.


42/46

The most common do in ractices

Testosterone isalsousedtohelprecoveryafterexercise.

Extratestosteronehelpssuchathletesbereadyto.

Astestosteroneisanaturalhormone,detectingits

useis

difficult.


43/46

The blood doping practices

.

moreredbloodcells.

Blooddoping: removingsomeoftheathletesbloodandstoringtheRBCs. Then,justbeforethecompetition,theathletehashis

orher

own

stored

RBCs

reinjected


44/46

The blood doping practices

, .

bythickblood.

Inthe

late

1980s,

another

technique

was

the

use

of

recombinanterythropoietin (EPO).

Morethan20athletesdiedwhileusingEPO


45/46


46/46

Date post:	06-Apr-2018
Category:	Documents
Upload:	dr-atif-hassan-khirelsied
View:	214 times
Download:	0 times

Muscle Biochmistry 2012, International University of Africa, Atif Hassan Khirelsied

Documents