integration of metabolism

Question 1

describe metabolism pathways?

Answer 1

pathways and cycles and reactions occur in integrated manner to fulfil cell requiement

Question 2

what is unique about brain metabolism ?

Answer 2

Require glucose

and can use keton bodies under CERTAIN CONDITIONS

SOLELY GLUCOSE AND KETON BODIES

Question 3

Unique metabolism of muscles?

Answer 3

Use glucose

Fatty acids

Ketone bodies

Question 4

metabolism of liver?

Answer 4

Provide fuel to brain and muscles

Question 5

metabolism of adipose tissue?

Answer 5

Provide fuel

Question 6

RBCs?

Answer 6

ONLY GLUCOSE cuz theres no mitochondria

Question 7

what are 2 types of metabolism ?

Answer 7

Anabolism –> BUILDING

Catabolism —> Breaking down to produce energy

Anabolism reactions will happen in other places than catabolic reaction

if they occur at the same place = wont occur at the same time /phase

Question 8

what regulates metabolism?

Answer 8

Enzyme levels –> ALLOSTERIC INERACTION and covalent modification and transcription ( like phosphorylation for example)

Compartmentalization —> like how glycolysis in cytosols and TCA in mito

Specialization of organs

Question 9

what are central themes of metabolism ?

Answer 9

ATP

Reducing molecules ( NADH, FADH, NADPH )

Biomolecules

Biosynthetic and degradation pathways are distinct

Question 10

describe ATP?

Answer 10

Universal energy carrier

Atp is generated by oxidation of metabolic fuels —> Glucose , fatty acids or AA

substrative phosphorylation where molecules with higher energy levels are able to phosphrylate ADP into ATP

Question 11

describe reducing molecules?

Answer 11

Redox agent for reductive biosynthesis

Question 12

describe biomolecules ?

Answer 12

Constructed from a small set of building blocks

Question 13

what are 3 metabolic key crossroads ?

Answer 13

Glucose 6 phosphate

Pyruvate

Acetyl- COA

Question 14

what are key junctions between Glucose 6 phosphate 6 pathways?

Answer 14

When glucose is transported into cells it rapidly become GLUCOSE 6 P

1- G6P can become pyruvate ( most common and main )

2- G6P can be converted to G1P and become glycogen ( in liver)

3- Converted to ribose 5 phosphate by the pentose phosphate pathways

4- Glucose 6 phosphate can e generated from glycogen stores or by gluconeogenesis

Question 15

junctions between pathways of PYUVATE ?

Answer 15

Pyruvate is generated from :

1- G6P by glycolysis

Pyruvate is REDUCED into LACTATE under ANEROBIC CONDITION

Lactate produced must be subsequently oxidized back into pyruvate

2- Pyruvate is also TRANSAMINATED to form alanine
- Several AA are gedraded into pyruvate

3- Pyruvate maybe CARBOXYLATED to form Oxaloacetate in the matrix of the mitochondria —> FIRST STEP OF GLUCONEOGENSIS

4- OXIDATION of pyruvate into Acetyl COA by pyruvate dehydrogenases complex ( for citric acid cycle )–IRREVERSIBLE–> this is between Carbohydrate and fatty acid metabolism

Question 16

what are the junctions between pathways Acetyl Coa pathways?

Answer 16

Acetyl Coa is generated from :

1- Oxidation decarboxylation of PYRUVATE

2-from B oxidation of fatty acids

3- Acetyl Coa is produced from degradation of KETOGENIC AA

4- Acetyl Coa may be completely OXIDIZED into CO2 via the citric acid cycle

5- Converted to HMG COA —> cholesterol or ketone bodies

6- Acetyl Coa may be exported into cytosol and converted to FATTY ACIDS

Question 17

what are 2 types of AA?

Answer 17

Ketogenic –> converted to acetyl Coa directly

Glucogenic –> Converted to pyruvate which then to Acetyl Coa

Question 18

what is the metabolic profile of brain?

Answer 18

Glucose is fuel for the brain

Consumes 120 g/day of glucose

60-70% of utilization of glucose

DURING STARVATION = KETONE BODIES

Question 19

describe metabolic prolife of muscles?

Answer 19

Major fuels —>

WELL FED = GLUCOSE

Fasting/starvation = FATTY ACIDS, KETONE BODIES ( while brain and RBC will use glucose )

Storage of glycogen –> 3/4 of all glycogen

Highly affected by physical activity

Glycogen in the muscle is degraded into glucose 1-P –> Glucose 6 P –> Glycolysis –> Energy

Glycogen in the muscle is not intended to provide blood glucose cuz of LACK of enzyme GLUCOSE 6 PHOSPHATE ( BUT LIVER CAN DONATE GLUCOSE TO BLOOD cuz it has the enzyme )

Glucose is for burst activity —> Produce lactate ( anerobic )

Question 20

what is the source of ATP in burst activity ?

Answer 20

Phosphocreatine

Question 21

describe adipose tissue metabolic prolife ?

Answer 21

Triacylglycerols –> Stored in adipose tissue

Enormous reservoir of metabolic fuel

Synthesis of TAG needs glucose

Glucose lvl determines if FA are released into blood or not

Well fed —> High insulin –> activate synthesis of Triglycerides and thus FA synthesis

Glucose will get into glycolysis -> reach intermediate DHP –>Glycerol phosphate –> add to fatty acyl Coa = triacylglycerols to be stored

Fasting —> Glucagon –> ACTIVATE HSL = break down stored TAGS –> glycerol will be used for gluconeogenesis and FFA will be sued for energy and Acetyl Coa will be used for keton energies

Question 22

Describe metabolic prolife of kidney ?

Answer 22

Excretion of urine

Excretion of waste products

Blood plasma is filtered

Water and glucose REABSORBED

during starvation –> IMP SITE FOR GLUCONEOGENSIS

Question 23

Liver prolife in carbohydrate metabolism ?

Answer 23

Essential for providing fuel to brain ,muscles and other organs :

Glycogenolysis
Gluconeogenesis
Ketogenesis

Most compounds is absorbed from diet —> PASS THROUGH LIVER

Regulate metabolites in blood

Pentose phosphate pathway –> produces NADPH –> REDUCING AGENTS FOR CHOLESTEROL SYNTHESIS AND FATTY ACID

G6P –> liver glycogen or sent outside to blood or pyruvate

pyruvate –> Acetyl Coa

ACETYLCOA–> fatty acids

or Cholesterol or ketone bodies or TCA

Question 24

Liver prolife of FATTY ACIDS?

Answer 24

Synthesize :

Fatty acids

Lipoproteins

Cholesterol

Ketone bodies

TaGS

Fatty acids will converted to triglycerides and wont be stored here instead = exported as VLDL if this is disrupted = FATTY LIVER

Acetyl Coa –> Cholesterol = bile sites

or Acetyl Coa –> KETONE BODIES then to blood

or Acetyl Coa –> TCA cycle

Question 25

liver prolife of AA?

Answer 25

Liver cells will: Synthesis proteins like albumin ( all plasma prorteins are from liver except immuno) AA are broken down in the liver by UREA CYCLE Gluconeogenesis --> Glucogenic AA will be converted to pyruvate (ALANINE ) We cant store AA so we convert them to pyruvate ESPECIALLY ALANINE

Question 26

what is the function of insulin on metabolism ?

Answer 26

released in well fed state ( 2 hours of last meal )--> WILL START FED STATE : 1- Stimulate storage of fuels --> Synthesis of TAGs in adipose tissue and muscles 2- Accelerate uptake of blood glucose 3- Stimulates Glycogen synthesis in muscle and liver 4 Accelerate glycolysis in liver 5- Increase synthesis of fatty acids 6- Stimulates the synthesis of proteins 7- SUPPRES gluconeogenesis of liver

Question 27

what is the function of glucagon in short starvation?

Answer 27

Main target organ is liver 1- Mobilizes Glycogen stores ( breakdown ) 2- Inhibit glycogen synthesis 3- Inhibit fatty acid synthesis 4- Stimulates gluconeogenesis in LIVER --> large amount of glucose in liver is released in blood stream to maintain the lvl 5- Promotes muscles + Liver use FATTY ACIDS as fuel when blood glucose lvl drop FATTY ACIS ARE NOT GLUCOGENIC SUBSTRATE it cannot be used in gluconeogenesis like Pyruvate , glycerol , lactate, AA, WHY? cuz fats will break down to ACETYL COA but ACETYL COA CANNOT BE CONVERTED BACK TO PYRUVATE so not useful

Question 28

what is the first priority in prolonged starvation ?

Answer 28

Provide sufficient glucose to brain and other tissues thar are dependent on it

Question 29

what is the second priority in prolonged starvation ?

Answer 29

PRESERVE PROTEIN by shifting from utilization of glucose to utilization of fatty acids + KETONE BODIES Mobilization of TAGS in adipose tissue + GLUCONEOGENESIS by liver ---> MUSCLE SHIFT FROM GLUCOSE TO FATTY ACID AS FUEL

Question 30

what happens after 3 days of starvation ?

Answer 30

Liver form large amount of : Keton bodies will released to blood--> BRAIN and HEART uses them as fuel

Question 31

what happens after several weeks of starvation ?

Answer 31

Ketone bodies are major fuel of brain After depletion of TAG stores ( glycerol will be used for gluconeogenesis and FFA for energy ) The proteins degradation is stimulated --> death due to loss of heart, liver and kidney function ( CUZ we get AA from protein for energy and AA --> PYRUVATE --> GLUCOSE ) Excessive triglyceride breakdown will cause keton bodies to slowly raise ( cuz end product is Acetyl Coa and can be used for ketone bodies ) and once it does it will make brain favor the use of keton bodies over glucose ( shifting utilization of glucose to fatty acids and ketone bodies )