K 19 20 Metabolism Regulation

8/18/2019 K 19 20 Metabolism Regulation

1/29

Metabolism Regulation

Sry Suryani W

Biochemistry Department


2/29

• Metabolic pathways fall into three categories:

– Anabolic pathways : involved in the synthesis ofcompounds such as protein.hey are endergonic.

–

!atabolic pathways : involved in the brea"down oflarger molecules# commonly involving o$idativereactions # they are e$ergonic# producing reducinge%uivalents and mainly via the respiratorychain#A&.

– Amphibolic pathways : occur at the ' crossroads 'of metabolism# acting as lin"s between theanabolic and catabolic pathways# eg the citric acidcycle.


3/29

• (ndergonic reaction )also called anunfavorable reaction or anonspontaneous reaction* is achemical reaction in which thestandard change in free energy ispositive# and energy is absorbed.

http://en.wikipedia.org/wiki/Thermodynamic_free_energyhttp://en.wikipedia.org/wiki/Thermodynamic_free_energy


4/29

• ($ergonic reactions are ones thatrelease energy+ these reactions willusually occur spontaneously since they

do not re%uire energy to occur.• ,n the other hand# endergonic

reactions absorb energy to form bonds#

so they do not occur spontaneously.-nstead# they occur only if energy isavailable to be used in the reaction.


5/29

. ormal metabolism includes :adaptation to periods of starvation#e$ercise# pregnancy# and lactation.

• Abnormal metabolism may resultfrom nutritional de/ciency# en0ymede/ciency# abnormal secretion of

hormones# or the actions of drugsand to$ins# e$p : diabetes mellitus.


6/29

&athways that process thema1or products of digestion

• All the products of digestion aremetaboli0ed to a common product :acetyl !o2A# which is then o$idi0ed by

the citric acid cycle.• !arbohydrate metabolism is centered on

the provision 3 fate of glucose

• 4ipid metabolism is concerned mainly

with fatty acids and cholesterol.• Amino acid metabolism involves

transamination.


7/29


8/29

Metabolism carbohydrate


9/29

4ipid Metabolism


10/29

Metabolism Amino Acid


11/29

• Metabolic pathways :

– at tissue and organ level.

–

At subcellular level.• At tissue and organ level:

– 4iver:

• 5lucose : glycogenesis

• 6at : lipogenesis

• Between meal : glycogenolysis

• With "idney : gluconeogenesis ) converting noncarbohydrate metabolites such as lactate#glycerol

and amino acids to glucose.• Synthesi0es ma1or plasma proteins ) albumin*

and deaminates amino acids# forming urea#whichis transported to "idney.


12/29


13/29


14/29

• At Subcellular level:

– 5lycolysis occurs in cytosol and citricacid cycle in mitochondria.

– &entoses phosphate pathway

– 6atty acid synthesis.


15/29


16/29

Starve2feed cycle


17/29

-n the well2fed state# diet supplies theenergy re%uirements.


18/29

-n the early fasting state hepaticglycogenolysis is an important source

of blood glucose.


19/29

6asting state re%uires gluconeogenesisfrom amino acids and glycerol


20/29

-n early refed state# fat is metaboli0ednormally and normal glucose metabolism is

slowly reestablished


21/29

5lucose 7omeostasis

• &hase - : well fed state# in which glucoseis provided by dietary carbohydrate.

• &hase -- : once the supply is e$hausted#

hepatic glycogenolysis is used tomaintain blood glucose.

• ,nce the supply of glucose starts to

decreased#hepatic gluconeogenesisfrom lactate#glycerol and alanin ta"esplace.


22/29

• &hase --- : gluconeogenesis is the ma1orsource of blood glucose. ) these changeshappen within 89 hours of fasting*

• &hase - : Dependence ongluconeogenesis decrease. ;etonebodies high enough concentration to

enter the brain and meet some of itsenergy needs.

• Renal gluconeogenesis ta"es place.


23/29

• &hase : energy needs of almostevery tissue were supply by eitherfatty acids or "eton body o$idation.

) after long starvation of e$tremlyobese patient*


24/29


25/29

4iver metabolism in the well2fed and starvedstates

• -n a well2fed liver process engaged is :glycogenic# glycolytic and lipogenic.

• he fasting liver :

glycogenolytic#gluconeogenic#"etogenicand proteolytic.


26/29

• Metabolic interrelationships of tissues invarious nutritional and hormonal states :

– Staying in the well2fed state results : obesity

and insulin resistance. – ype 8 Diabetes Mellitus

– ype < Diabetes Mellitus.


27/29

Glucose

Blood glucose is important

–

Normal [glucose]: 70-110 mg/dl –High [glucose] (>140 mg/dl

–o! [glucose] ("#0 mg/dl$


28/29

54=!,S=R-A

• he e$cess passes into the urine to

produce 5lucosuria• ormal individual : glucosuria occurs when

the venous blood glucose concentration :

> ?#@


29/29

K 19 20 Metabolism Regulation

Documents

Transcript of K 19 20 Metabolism Regulation