3.2 Energy Systems

metabolism

all the biochemical reactions that occur within an organism, including anabolic and catabolic reactions

anabolism

**energy requiring reactions whereby small molecules are built up into larger ones**

catabolism

**chemical reactions that break down complex organic compounds into simpler ones, with the net release of energy.**   

* **Aerobic catabolism → requires oxygen**
* **Anaerobic catabolism → independent of the presence of oxygen.**

glycogen & its storage sites

* glycogen comes from the greek word glyko meaning sweet
* animals store polysaccharides as glycogen in the liver and muscle
* when the diet provides more glucose that the tissue requires, your body stores glucose as glycogen

triglyceride storage sites

adipose tissue (fat) and skeletal muscle

the role of insulin in the formation of glycogen and the accumulation of body fat

the main job of insulin is to keep the level of glucose in the bloodstream within a normal range

* after you eat, carbohydrates break down into glucose and enter the bloodstream. this increases the glucose concentration in the blood
* the pancreas responds by producing insulin
* when insulin levels are high, excess glucose enters the liver and the muscles and is synthesized into glycogen
* after we eat, triglycerides (fats) are broken down into monoglycerides and free fatty acids, which enter the bloodstream
* high levels of insulin the blood also cause fatty acids in the blood to be synthesized into triglycerides and stored as fat in adipose tissue
* the higher the level of insulin in the blood, the higher the amount of fat stored

the role of insulin in the formation of glycogen and the accumulation of body fat (simple terms)

* Insulin is a hormone that informs the body’s cells that the animal is well fed


* Causes liver and muscle cells to take in glucose and store it in the form of glycogen


*  Causes fat cells to take in blood lipids and turn them into triglycerides
* Ingest carbohydrates 
* increase in blood glucose 
* insulin is released by pancreas


* After a meal, insulin concentrations rise and cells uptake glucose thereby decreasing the level of glucose in the blood

exercise and insulin

in response to exercise, we need muscle to use glycogen and not store it into muscle and the liver. when you exercise the insulin contrentation goes down.

glycogenolysis

@@the breakdown of glycogen to glucose.@@ when the body needs more glucose than is ingested (eaten) glycogen in the liver and muscles is broken down to glucose and is then used for energy. @@occurs as a result of of the hormone glucagon@@.

glycogenolysis (in the liver)

breakdown of glycogen results in elevated blood glucose.

glycogenolysis (in the muscle)

* breakdown of glycogen is used by the muscle for energy. 
* there is NO release of glucose into the bloodstream from the muscle.

lipolysis

the process of releasing triglycerides from the body’s fat stores. the stored fat provides energy when energy supply is not available from glycogen stores

functions of glucagon and adrenaline during fasting and exercise

* during fasting and exercise the blood glucose level drops and therefore the release of glucagon and adrenaline will result in an increase of blood glucose


* glucagon and adrenaline stimulate the breakdown of glycogen in the liver to increase blood glucose levels during long periods of exercise and times of fasting

role of insulin and muscle contraction on glucose uptake during exercise

* insulin will result in an increased uptake of blood glucose into the liver and muscle


* muscle contraction will also result in an increase of blood glucose uptake from the blood due to higher energy demands