Insulin, a hormone, is used to regulate carbohydrate and fat
metabolism in the body. Insulin causes cells to take up glucose from the
blood and store it as glycogen in the liver and muscle.
This hormone
stops the body from using fat as an energy source by inhibiting the
release of glucagons.
Without insulin the body fails to take glucose
into the bodies cells and in turns uses fat as an energy source. It also
has several other anabolic effects throughout the body.
Diabetes mellitus results from insulin level control fails. That is
why insulin is used to control diabetes. Type 1 diabetes patients need
external insulin to survive because their bodies no longer produce it.
Type 2 are resistant to insulin and can suffer from relative insulin
deficiency.
Insulin also influences other body functions like the
vascular compliance and cognition and enhancing learning and memory as
well as benefiting the verbal memory.
It is also suggested that central
nervous insulin contributes to the control of whole-body energy
homeostasis in humans.
Composed of 51 amino acids, Insulin is a peptide hormone that has a
molecular weight of 5808 Da. The Insulin’s structure varies slightly
between each species of animal. Due to this variation insulin from
animal sources differ somewhat in “strength” in humans.
Porcine insulin
is, however, close to the human version. Even insulin from some fish
species is close enough to human to be clinically effective in humans.
The C-peptide of proinsulin; however, differs much more amongst species.
There are several regulatory sequences in the promoter region of the
human insulin gene, which transcription factors bind. There are also
silencers that inhibit transcription.
Insulin, stored in the body as a hexamer, is active as a monomer. The
hexamer has long-term stability which keeps the insulin protected, yet
readily available. This hexamer-monomer conversion is a central aspect
of insulin formulation for injection.
The hexamer is more stable but the
monomer is a faster reacting drug because diffusion rate is inversely
related to particle size. Since the drugs can react quickly the
injections don’t have to precede mealtimes by hours which allow
diabetics to have more flexibility with their schedule.
The pancreas produces insulin that is released when certain stimuli
including ingested protein and glucose in the blood produced from
digested food. In carbohydrates there is a possibility to include
glucose which will be absorbed into the bloodstream and the blood
glucose level will begin to rise.
Insulin initiates a signal
transduction that increases glucose uptake and storage. Eventually the
insulin is degraded and the response is terminated.
The pancreas is primarily an exocrine gland with one to three million
islets of Langerhans that form the endocrine part. Only 2% of the total
mass of the pancreas accounts for the endocrine portion.
Within the
islets of Langerhans the beta cells constitute 60-80% of all the cells.
Within the beta cells insulin is synthesized from the proinsulin
precursor molecule by the action of proteolytic enzymes known as
prohormone convertases.
Insulin and its related proteins can also be produced inside the
brain and when these protein levels are low there is a link to
Alzheimer’s disease.
The Beta cells in the islets of Langerhans release insulin in phase
one rapidly by a triggered response to increased blood glucose levels.
The second phase is a steady, slow release of newly formed vesicles that
are triggered independently of sugar.
Some insulin release takes place with food intake and the beta cells
that release insulin can also be affected somewhat by the autonomic
nervous system. However these signals are not fully understood.
Amino acids, acetylcholine, and gastrointestinal hormones are other
substances that can stimulate insulin release. Three amino acids act
similarly to glucose by altering the beta cell’s membrane potential.
Adrenaline can also active the beta cells triggering insulin release.
Whenever glucose levels drop into normal physiologic value, the insulin
release from the beta cells slows or stops.
However, if blood glucose
levels drop much lower than this the release of hyperglycemic hormones
forces cellular stores to release glucose into the blood primarily from
liver cell stores. The release of these hyperglycemic hormones prevents
life-threatening hypoglycemia.
Stress can be a major problem because it
inhibits insulin release resulting in increased blood glucose levels
during stress.
They are special transporter proteins in cell membranes through which
glucose from the blood can enter a cell. Low levels of insulin prevent
glucose from entering those cells.
Muscle cells and fat cells are most strongly influenced by insulin as
far as stimulation of glucose uptake is concerned. They are important
due to the muscle cells central role in movement, breathing, and
circulation while the fat cells are important because they accumulate
excess food energy against future needs. Together these cells make up
about two-thirds of all cells in the human body.
The liver and kidney are responsible for the clearance of any used
insulin. The liver does the primary work by clearing most insulin during
first-pass transit while the kidney does the clearing primarily in the
systemic circulation.
Lack of glucose can dramatically make itself manifest by impairing
the central nervous system, causing dizziness, speech problems, and even
loss of consciousness. This low glucose is known as hypoglycemia. There
have actually been a few cases of murder and attempted murder by use of
insulin overdose.
Synthetic “human” insulin is now manufactured for widespread clinical
use. Researchers have even put the insulin gene into plants. Many of
these are modified versions that have somewhat different absorption or
duration of action characteristics. Insulin is taken through injections
by needle or an insulin pump.
How I Was Raped By A Police Officer
-
A Woman identified as Gladys in one of the town in Lagos state, has shared
a sad experience on how she was allegedly raped by a Nigerian security
officer...
0 comments:
Post a Comment