Hormones of metabolic homeostasis at a glance

1.                   Insulin; which decrease blood glucose concentration

2.                   Glucagon; increase blood glucose concentration

3.                   Catecholamines ; increase blood glucose concentration

4.                   Cortisol ; increase blood glucose concentration

5.                   Growth hormone ; increase blood glucose concentration

Urea cycle at a glance

Substrate—NH₃

Product--Urea

Site--Liver,

Compartment—Mitochondria & Cytoplasm

Nature--anabolic

Rate limiting enzyme—Carbamoylphosphate  synthase 1

Energy needed—03 ATP

Regulator—N-acetyl glutamate

Importance:

1.      Conversion of toxic NH₃ into no toxic urea

2.      Disposal of two waste products; NH₃ and Co₂

3.      Synthesis of argentine

4.      Synthesis of proline

5.      Interaction of TCA cycle

·         TCA cycle  Co₂ and ATP for urea cycle

·         Urea cycle provides fumerate for TCA cycle

Hexose Monophosphate Shunt /PPP /HMP shunt At a glance

Another name—Pentose phosphate pathway

Substrate--Glucose 6 phosphate

Product--Ribose sugar or NADPH₂

Site--Liver, Adipose tissue, RBC, Gonads, Adrenal cortex, Macrophage, lactating breast

Compartment--Cytoplasm

Nature--Catabolic

Rate limiting enzyme-- Glucose 6 phosphate dehydrogenase

Co enzyme--NADP, TPP (derived from Thiamine)

ATP production—No ATP is directly produced or consumed

Unique specialty--alternative pathway of glucose oxidation

Importance:

1.      Provide ribose sugar for synthesis of nucleotide and nucleic acid

2.      Provide NADPH₂ to-               

·         Help in reductive synthesis of fatty acid ,steroid , cholesterol etc

·         Help detoxifying functions of liver to convert toxic substance in to nontoxic form

·         Prevent hemolaysis by facilitating antioxidant activity in RBC

·         Facilitate superoxide and free radical production in phagocytes through oxygen dependent myeloperoxidase system to kill bacteria and other pathogens

·         Help in reduction of H₂O₂

·         Help in synthesis of nitric oxide or endothelial derived relaxing factors

3.      It’s an alternative pathway of glucose oxidation. 

Glycolysis At a glance

Another name--Embden Meyerhof pathway

Substrate--Glucose

Product--Pyruvate(in aerobic state) or Lactate(in anaerobic state)

Site--All cell & tissue

Compartment--Cytoplasm

Nature--Catabolic

Rate limiting enzyme--Phosphofructokinase

Co enzyme--NAD (from niacin)

ATP production--08 (in aerobic state) or 02 (in anaerobic state)

Unique specialty--Can occur in both aerobic and anaerobic conditions

Regulation—

Stimulated by- Insulin, ADP, ANP.

Inhibited by- Glucagon, ATP, Citrate