Christine2
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Educational Purposes
Resource:
Nutritional Sciences Textbook
From Fundamentals To Foods
Regulation Of Blood Glucose.. &.. Energy Storage
The concentration of glucose within the blood stream fluctuates .. throughout your day.. every day..
After going several hours .. without eating .. your blood glucose levels will decrease.. &... conversely.. those blood glucose levels .. increase .. after eating a meal rich in carbohydrates..
Because .. our cells need energy 24 hours a day.. The pancreatic hormones .. insulin.. &.. glucagon work rather hard.. to maintain those blood glucose levels.. within a acceptable range .. at all times..
The pancreas ... which is partially .. made up of hormone secreting cells ... playing a major role .. in glucose homeostasis... meaning balance ...
Those endocrine cells ... are collectively known as ... The Islets of Langerhans ... consisting .. mainly .. of the beta cells that produce.. the hormone Insulin.. &.. the alpha cells that produce the hormone Glucagon ...
The Pancreas ... releases these hormones directly into the circulating blood.. to deal with .. the fluctuations in blood glucose levels..
The hormones .. insulin .. &.. glucagon are assisting in that blood glucose regulation.. &.. energy storage..
The pancreas takes on the action of releasing .. more .. insulin.. in response.. to those increasing levels of blood glucose ..
The insulin in turn .. lowers .. the blood glucose levels .. by facilitating the uptake of the glucose into cells .. for cellular use..
However.. when meals are providing .. more glucose.. then the cells require for use .. insulin stimulates .. now.. storage as glycogen..
What ... is glycogen.. well .. it is a polysaccharide .. consisting of a highly branched arrangement of glucose molecules... glucose.. is a monosaccharide ... meaning consisting of one molecule of sugar... a polysaccharide .. well.. is a complex carbohydrate... made of many monosaccharides... in the case of glycogen .. it is a polymer of repeating glucose molecules.. as they.. meaning the glucose molecules.. had to be De-activated for the .. now.. storage process ..
However.. The story .. does not end here.. once.. the muscles.. &.. the liver .. reach .. their glycogen-storage-capacity.. The body has .. no other choice.. but .. to convert those unnecessary glucose molecules to fat.. which is stored in the adipose-tissue..
Glucose.. enters our cells through facilitated diffusion controlled by carrier proteins .. known as glucose transporters..
&.. if you remember from previous articles.. some .. glucose-transporters.. require.. insulin to transport the glucose across .. the Cellular membrane.. where as .. others do not..
In fact.. it is the type of glucose-transporter within a cell .. that is determining.. if insulin is needed .. for the uptake of the glucose..
Examples .. of tissues that require insulin for the glucose transporters .. are the skeletal-muscle.. &.. adipose tissue.. while.. the liver.. &.. the brain tissue.. have glucose transporters that .. do not require .. insulin for the uptake of glucose..
After eating a carbohydrate containing meal.. the blood glucose levels... quickly rise .. causing the pancreas to increase the release.. of the hormone insulin..
Insulin travels through the bloodstream... encountering cells ... with the insulin-responsive-glucose-transporters..
Which allows .. for the binding .. of insulin to the cellular membrane.. taking place on the insulin receptor .. which is on the cellular membrane..
This binding.. that the Insulin does to the receptor site.. actually signals .. for the glucose-transported.. to relocate itself... from the cytoplasm of that particular cell .. to the cellular membrane ... allowing for the glucose to.. enter into the cell..
ATTENTION .. everyone .. this is my favorite part..
During exercise.. skeletal-muscle-cells ... can temporarily take up glucose...WithOut .. the use of insulin..
Why.. well.. muscle contraction.. actually stimulates the movement of glucose transporters .. from the cytoplasm of the cell ... to the cellular membrane .. activating them.. allowing for glucose to be up-taken into the cell.. for use.. without the use of Insulin ..
&.. The insulin responsive glucose transporters ... can stay .. activated in this manner.. meaning... without the requirement of insulin.. for up to 3-hours .. after exercise stops..
So ... moving on..
The hormone insulin .. also..promotes energy storage...
Cells require .. readily available source of glucose .. however after a meal .. more glucose may be available.. then is necessary.. when this occurs the body .. stores the excess amount of glucose for later use.. in addition .. Insulin also stimulates.. protein synthesis..while.. inhibiting the break down of muscle..
Before excess energy from glucose .. can be stored.. it must first .. be converted into glycogen .. or.. fat ..
Insulin controls .. the synthesis of glycogen .. through a process called glycogenesis ..
Which occurs .. mainly in the liver .. &.. skeletal muscle..
However .. the body can only store a limited amount.. of glycogen.. once the limit has been reached ... insulin promotes the uptake of excess glucose by the adipose tissue .. where the glucose is converted to fatty-acids ...
Unlike glycogen-storage... the body has a.. seemingly endless capacity ... to store excess energy from glucose as body fat ...
In fact.. that the conversion of glucose into a fatty acid is irreversible...
That is .. once glucose is transformed into a fatty acid .. the fatty acid .. cannot .. be converted back into glucose ... this is very different from the reversible .. metabolic transformation between glucose ..&.. glycogen ..
The body also requires .. another hormone for during periods of low blood glucose... this is when the hormone glucagon comes in to plays its important role ...
Several hours after one has eaten... the blood glucose levels begin the fall ... unless .. the glucose is replenished by food ...
So.. if not replenished.. the body must .. begin to break down liver-glycogen .. to maintain adequate blood glucose levels for the rest of the body ... the Hormone glucagon... provides the signal for this to occur..
Maintaining blood glucose levels.. is especially important for the bodily tissues.. such as the brain .. which relies heavily on glucose .. as their main .. energy source ..
Because the brain.. &.. other components of the nervous system cannot store glucose.. they are totally dependent on the circulating glucose.. & .. ketones.. which .. are a organic compound .. used as a alternative energy source .. during times of starvation.. fasting...low-carb-diets.. or.. uncontrolled diabetes for their energy source ..
The brain .. is very sensitive to low blood glucose levels .. &.. even a relatively small decrease.. a condition known as hypoglycemia .. to make some people .. feel nauseated .. dizzy .. anxious .. lethargic.. &.. irritable .. this is a perfect example of concentration issues.. when one has not eaten for a long time..
Resource:
Nutritional Sciences Textbook
From Fundamentals To Foods
Regulation Of Blood Glucose.. &.. Energy Storage
The concentration of glucose within the blood stream fluctuates .. throughout your day.. every day..
After going several hours .. without eating .. your blood glucose levels will decrease.. &... conversely.. those blood glucose levels .. increase .. after eating a meal rich in carbohydrates..
Because .. our cells need energy 24 hours a day.. The pancreatic hormones .. insulin.. &.. glucagon work rather hard.. to maintain those blood glucose levels.. within a acceptable range .. at all times..
The pancreas ... which is partially .. made up of hormone secreting cells ... playing a major role .. in glucose homeostasis... meaning balance ...
Those endocrine cells ... are collectively known as ... The Islets of Langerhans ... consisting .. mainly .. of the beta cells that produce.. the hormone Insulin.. &.. the alpha cells that produce the hormone Glucagon ...
The Pancreas ... releases these hormones directly into the circulating blood.. to deal with .. the fluctuations in blood glucose levels..
The hormones .. insulin .. &.. glucagon are assisting in that blood glucose regulation.. &.. energy storage..
The pancreas takes on the action of releasing .. more .. insulin.. in response.. to those increasing levels of blood glucose ..
The insulin in turn .. lowers .. the blood glucose levels .. by facilitating the uptake of the glucose into cells .. for cellular use..
However.. when meals are providing .. more glucose.. then the cells require for use .. insulin stimulates .. now.. storage as glycogen..
What ... is glycogen.. well .. it is a polysaccharide .. consisting of a highly branched arrangement of glucose molecules... glucose.. is a monosaccharide ... meaning consisting of one molecule of sugar... a polysaccharide .. well.. is a complex carbohydrate... made of many monosaccharides... in the case of glycogen .. it is a polymer of repeating glucose molecules.. as they.. meaning the glucose molecules.. had to be De-activated for the .. now.. storage process .. However.. The story .. does not end here.. once.. the muscles.. &.. the liver .. reach .. their glycogen-storage-capacity.. The body has .. no other choice.. but .. to convert those unnecessary glucose molecules to fat.. which is stored in the adipose-tissue..
Glucose.. enters our cells through facilitated diffusion controlled by carrier proteins .. known as glucose transporters..
&.. if you remember from previous articles.. some .. glucose-transporters.. require.. insulin to transport the glucose across .. the Cellular membrane.. where as .. others do not..
In fact.. it is the type of glucose-transporter within a cell .. that is determining.. if insulin is needed .. for the uptake of the glucose..
Examples .. of tissues that require insulin for the glucose transporters .. are the skeletal-muscle.. &.. adipose tissue.. while.. the liver.. &.. the brain tissue.. have glucose transporters that .. do not require .. insulin for the uptake of glucose..
After eating a carbohydrate containing meal.. the blood glucose levels... quickly rise .. causing the pancreas to increase the release.. of the hormone insulin..
Insulin travels through the bloodstream... encountering cells ... with the insulin-responsive-glucose-transporters..
Which allows .. for the binding .. of insulin to the cellular membrane.. taking place on the insulin receptor .. which is on the cellular membrane..
This binding.. that the Insulin does to the receptor site.. actually signals .. for the glucose-transported.. to relocate itself... from the cytoplasm of that particular cell .. to the cellular membrane ... allowing for the glucose to.. enter into the cell..
ATTENTION .. everyone .. this is my favorite part.. During exercise.. skeletal-muscle-cells ... can temporarily take up glucose...
WithOut .. the use of insulin.. Why
.. well.. muscle contraction.. actually stimulates the movement of glucose transporters .. from the cytoplasm of the cell ... to the cellular membrane .. activating them.. allowing for glucose to be up-taken into the cell.. for use.. without the use of Insulin .. &.. The insulin responsive glucose transporters ... can stay .. activated in this manner.. meaning... without the requirement of insulin.. for up to 3-hours .. after exercise stops.. So ... moving on..
The hormone insulin .. also..promotes energy storage...
Cells require .. readily available source of glucose .. however after a meal .. more glucose may be available.. then is necessary.. when this occurs the body .. stores the excess amount of glucose for later use.. in addition .. Insulin also stimulates.. protein synthesis..while.. inhibiting the break down of muscle..
Before excess energy from glucose .. can be stored.. it must first .. be converted into glycogen .. or.. fat ..
Insulin controls .. the synthesis of glycogen .. through a process called glycogenesis ..
Which occurs .. mainly in the liver .. &.. skeletal muscle..
However .. the body can only store a limited amount.. of glycogen.. once the limit has been reached ... insulin promotes the uptake of excess glucose by the adipose tissue .. where the glucose is converted to fatty-acids ...
Unlike glycogen-storage... the body has a.. seemingly endless capacity ... to store excess energy from glucose as body fat ...
In fact.. that the conversion of glucose into a fatty acid is irreversible...
That is .. once glucose is transformed into a fatty acid .. the fatty acid .. cannot .. be converted back into glucose ... this is very different from the reversible .. metabolic transformation between glucose ..&.. glycogen ..
The body also requires .. another hormone for during periods of low blood glucose... this is when the hormone glucagon comes in to plays its important role ...
Several hours after one has eaten... the blood glucose levels begin the fall ... unless .. the glucose is replenished by food ...
So.. if not replenished.. the body must .. begin to break down liver-glycogen .. to maintain adequate blood glucose levels for the rest of the body ... the Hormone glucagon... provides the signal for this to occur..
Maintaining blood glucose levels.. is especially important for the bodily tissues.. such as the brain .. which relies heavily on glucose .. as their main .. energy source ..
Because the brain.. &.. other components of the nervous system cannot store glucose.. they are totally dependent on the circulating glucose.. & .. ketones.. which .. are a organic compound .. used as a alternative energy source .. during times of starvation.. fasting...low-carb-diets.. or.. uncontrolled diabetes for their energy source ..
The brain .. is very sensitive to low blood glucose levels .. &.. even a relatively small decrease.. a condition known as hypoglycemia .. to make some people .. feel nauseated .. dizzy .. anxious .. lethargic.. &.. irritable .. this is a perfect example of concentration issues.. when one has not eaten for a long time..
