Gaurav (CORI CYCLE) - Powerpoint presentation

This presentation explains the CORI CYCLE.

1. PT. RAVISHANKAR SHUKLA UNIVERSITY CORI CYCLE CENTER FOR BASIC SCIENCES Guided by:- Dr. L. Shivlata Presented by :- Gaurav Dhruw Semester - VI

2. Introduction:- The cori cycle refers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles move via the blood stream to the liver where it is converted into glucose. First discovered by Carl and Gerty Cori. It is a cycle in which ........... glycogen in the muscle is degraded to produce lactic acid → blood → liver where it is changed back into glucose . When needed the glycogen is broken down into glucose and the blood carries the glucose to the muscle.

3. Cori Cycle During the muscle activity, muscle requires moderate amount of glucose. Which can be supplied by the blood glucose or breakdown of glycogen reservoir present in the muscle tissue. During time of great excertion , muscle tissue uses oxygen faster than it can be supplied by the blood stream so the muscle must operate anaerobically . Under these condition the glucose breakdown stops at the 3 carbon acid lactate. Lactate enters into bloodstream and picked up by the liver. Liver convert lactate back into the glucose. Glucose further returned to the muscle for further glycolysis . The cycling of glucose and lactate between skeletal muscle and liver known as the cori cycle.

4. Vigorous exercise can lead to oxygen shortage ( anaerobic conditions), and energy requirements must be meet by increased levels of glycolysis . Under such conditions, glycolysis converts NAD to NADH, yet O2 is unavailable for regeneration of NAD via cellular respiration. Instead, large amounts of NADH are reoxidized by the reduction of pyruvate to lactate. The lactate thus produced can be transported to the liver, where it is reoxidized by liver lactate dehydrogenase to yield pyruvate , which is converted eventually to glucose. In this way, the liver shares in the metabolic stress created b vigorous exercise. It exports glucose to muscle, which produces lactate, and lactate from muscle can be processed by the liver into new glucose.

5. Liver, with a typically high NAD/NADH ratio, readily produces more glucose than it can use. Muscle that is vigorously exercising will enter anaerobiosis and show a decreasing NAD/NADH ratio, which favors reduction of pyruvate to lactate.

6. The Cori cycle involves several steps: Anaerobic Glycolysis in Muscles: During intense exercise, when oxygen availability is limited, muscles produce lactate as a byproduct of anaerobic glycolysis. This process breaks down glucose into pyruvate, which is then converted into lactate. Transport of Lactate to the Liver: Lactate is transported via the bloodstream from the muscles to the liver. Conversion of Lactate to Pyruvate: In the liver, lactate is converted back into pyruvate by the enzyme lactate dehydrogenase.

7. Gluconeogenesis: Pyruvate generated from lactate in the liver undergoes gluconeogenesis, a process where glucose is synthesized from non-carbohydrate precursors. This newly synthesized glucose is released into the bloodstream. Transport of Glucose to Muscles: Glucose produced in the liver is transported back to the muscles through the bloodstream. Glycolysis in Muscles: Once glucose reaches the muscles, it can be used as a substrate for glycolysis to produce energy (ATP) for muscle contraction.

8. Oxygen Debth In the Cori cycle, the term "oxygen debt" refers to the oxygen required to metabolize lactate produced during anaerobic glycolysis in muscles. When muscles undergo intense activity, they rely on anaerobic metabolism to produce energy, leading to the accumulation of lactate. During recovery, oxygen is needed to convert the accumulated lactate back into pyruvate in the liver, which can then enter aerobic metabolism and generate ATP with the help of oxygen. This process requires additional oxygen consumption, hence the term "oxygen debt."

9. The Cori cycle helps to repay this oxygen debt by recycling lactate produced in muscles back into glucose in the liver, which can then be used as a substrate for aerobic metabolism. By replenishing glucose and oxygen levels, the Cori cycle contributes to restoring energy balance and facilitating recovery after intense exercise.

10. Referencess wikipedia.org sciencedirect.com study.com uh.edu

11. THANK YOU