Introduction reminder:
Homeostasis is all about controlling conditions in the human body.
Homeostasis is a word that is
sometimes used to describe your bodily functions that try to maintain a
stable constant internal environment including the factors listed above.
Therefore you need to know
internal conditions controlled include blood sugar (usually
glucose) level.
The blood sugar levels must be
adequate to provide the
cells with a constant supply of energy to meet their needs, but not to high
to cause problems, some health issues are described below.
Having too much glucose in your blood for long
periods of time can cause serious health problems if it's not
treated. This condition is called hyperglycemia and can damage the
vessels that supply blood to vital organs, in turn this can increase
the risk of heart disease and stroke, kidney disease, vision
problems, and nerve problems.
When sugary or carbohydrate
foods are digested in the small intestine, the blood sugar levels rise as the sugar is absorbed from
the gut into the bloodstream.
Your normal cell metabolism uses
and removes the sugar in your normal energy releasing chemistry -
respiration.
If you are not doing much
physical work your blood sugar level will tend to rise.
Insulin reduces the
concentration of glucose in your blood.
Lack of insulin can lead
to dangerously high glucose levels in your blood.
Excess glucose can be to
glycogen and stored in the liver and in your muscles, the glycogen
which can be converted back to glucose for use during exercise.
When the glycogen stores are
'full', the excess glucose is converted to, and stored as, lipid fats.
If you are doing some demanding
physical exercise your blood sugar level tends to fall as the sugar is
consumed.
During exercise a number of
changes take place e.g. the heart rate increases and the rate and depth of
breathing increases.
These changes increase
the blood flow to the muscles and so increase the supply of sugar and oxygen
for energy from respiration and also increase the rate of removal of carbon dioxide
- the waste product.
Glycogen is produced and stored and
released for conversion to glucose on a supply and demand basis.
If there is surplus glucose and
physical activity is low, more glycogen is produced.
The more you physically
exercise, the greater the glucose demand, if this exceeds what is available
in the blood stream, then the glycogen reserves are called upon to fill the
energy gap.
The blood glucose level is
monitored and controlled by the pancreas which produces the hormone
insulin.
The pancreas secretes enzymes
that digest carbohydrates, proteins and lipid fats.
It can be dangerous if your
blood sugar levels become too high or too low, so your blood sugar level is
regulated by the hormone insulin made in the pancreas, which enables your body to have a regular
supply of sugar for energy from respiration.
Changes in the blood
glucose level are monitored by the
pancreas, which produces the hormone insulin, which allows the glucose to move from
the blood into the cells and stored as glycogen.
A second hormone, glucagon, is produced in
the pancreas when blood glucose levels fall.
Glucagon causes glycogen to be converted
back into glucose and released into the blood for
respiration.
So, the level of glucose in the blood must be kept steady and your
automatic monitoring systems keeps a check on any changes.
This is done by the pancreas using the hormones insulin and
glycogen
in a negative feedback cycle.
Note that the metabolism of glucose is
controlled by three hormones, here it is insulin and glucagon
maintaining the balanced level of glucose in the blood, but there is
also the action of
adrenaline on the liver in our
body's 'fight or flight' response.
