Skip to main content

Renin Angiotensin Mechanism.

HMP Shunt.

 

Definition:

It is an alternative minor pathway for glucose oxidation.

  • Does not produce ATP nor utilize it. 

  • Producing NADPH+H+, (Biosyn Lipids) and Ribose (Synthesis of NA).

  • Also called,

    • PPP (Pentose Phosphate Pathway)

    • HMP Shunt (Hexose Monophosphate Shunt)

Intracellular site and tissue distribution:

  • Cytosolic in tissues namely: liver, Adipose tissues, Lactating mammary gland, RBCs, Suprarenal cortex, Thyroid and testis. 

  • Not active in non-lactating mammary gland, and in skeletal muscles. 

Steps of HMP Shunt:

  • The pathway are divided into two phases:

    • 1. Phase I : Oxidative irreversible phase 

    • 2. Phase II : Non-oxidative reversible phase.

Regulation of HMP shunt: -

  • The key regulatory enzymes are G-6-PD and 6-phospho-gluconate dehydrogenase.

  • They are activated by fed state, glucose, insulin, thyroxine and NADP. 

  • But….

    • They are inhibited during starvation, diabetes mellitus and with high NADPH.H+/NADP ratio.

Significance of HMP Shunt:

  • I- Production of pentoses:

  • Tissues must satisfy their own requirement of pentoses since dietary pentoses are not utilizable and ribose is not a significant constituent of systemic blood. 

  • Pentoses are used for:

    • 1. Nucleic acids, Ribose for RNA and Deoxyribose for DNA.

    • 2. Coenzymes synthesis, e.g., NAD+, FAD, CoASH.

    • 3. Free nucleotide Coenzymes, e.g., ATP, GTP, 

    • 4. Synthesis of certain vitamins, e.g., B2 and B12.

  • II-HMP pathway is the major human source for production of NADPH.H+ required for:

    • 1. Fatty acid synthesis (lipogenesis) and fatty acid 

    • desaturation.

    • 2. Cholesterol and other steroid synthesis.

    • 3. Synthesis of sphingosine and cerebrosides. 

    • 4. Synthesis of non-essential amino acids, e.g., 

    • glutamate and tyrosine from phenylalanine.

    • 5. Regeneration of reduced glutathione (G-S-H).

    • 6. Metabolic hydroxylation with cyp450.

Commonly Asked Questions.

  1. Write in detail about HMP Shunt and its significance..

  2. Write significance of HMP Shunt.
Labels:

Popular posts from this blog

Heat Exchangers and Heat Interchangers.

  In pharmaceutical industries many types of equipments are used for transfer of heat, they can be classified as follows, Heat Exchangers. Heat Interchangers. Heat Exchangers: These devices are used for transferring heat from a fluid (Hot Gas or Steam) to another fluid (Liquid) through a metal wall. Heat Interchangers: These devices are used for transferring heat from a One liquid to another liquid or one gas to another gas through a metal wall. HEAT EXCHANGERS; The equipment used for heat transferring are known as heat exchangers. Some of the processes that involves heat transfer in pharmaceutical industries are: Preparation of starch paste (in steam jacketed kettle). Crystallization. Evaporation. Distillation.  Classification of heat exchangers On the basis of transfer of heat, heat exchangers are classified as: Direct transfer type:  The hot and cold fluids are separated by a metal wall through which the heat is transferred from hot fluid to cold fluid. E.g. shell and ...
Read more

Glycogenesis.

  Definition: Biosynthesis of Glycogen from Glucose is called Glycogenesis. Glycogen is synthesized  Depending on the demand for glucose and ATP (energy), insulin promotes the glucose conversion into glycogen. Glycogen is the major storage form of carbohydrate in animals similar to starch in plants. It is a homopolymer made up of repeated units of α- D glucose and each molecule is linked to another by 1→4 glycosidic bonds . Once there is a chain consisting of 8 to 10 glycosidic residues in the glycogen fragment, branching begins by 1→6 linkages . Glycogen is stored in liver and skeletal muscles. Location: Cytoplasm of cells in the muscle, liver, and adipose tissue. Steps Involved in Glycogenesis: Glucose is converted into glucose-6-phosphate by the action of glucokinase or hexokinase  with conversion of ATP to ADP. Glucose-6-phosphate is converted into glucose-1-phosphate by the action of phosphoglucomutase. Glucose-1-phosphate is converted into UDP-glucose by the actio...
Read more

Rate of Drying Curve.

  Definition Drying is defined as the removal of liquid from a product usually with application of heat. Rate of Drying Curve. Drying process can be divided into three periods Initial Adjustment Period. Constant drying rate period. First falling drying rate period. Second falling rate period. Initial Adjustment Period (A-B): Also called the “ Heating up” period . In this period the substance gets heat and increases in temperature. Drying has not yet started. Constant drying rate period (B-C): During this period the temperature of the solid and the rate of drying remain constant. The moisture evaporating from the surface is replaced by water diffusing from the interior of the solid at a rate equal t o the rate of evaporation.  The moisture content at the end of constant rate (point C) is referred to as the critical moisture content (CMC).  At CMC, dry spots start appearing and drying rate starts falling . First falling drying rate period (C-D): This period is also called ...
Read more