Gastrointestinal Hormones in Digestion Nursing Article (Article Sample)

NAME:MOTATIRO CHACHA EMMANUEL
REGISTRATION NUMBER: I411/1305/2013
COURSE:BIOCHEMISTRY AND MOLECULAR BIOLOGY
UNIT:BIOCHEMICAL ENDOCRINOLOGY
A)DISCUSS THE BIOSYNTHESIS, SECRETION AND ROLES OF GASTROINTESTINAL HORMONES IN DIGESTION. (15 Marks)
Introduction
Gastrointestinal hormones constitutes a group of hormones secreted by enteroendocrine cells in the stomach, pancreas and small intestine that controls various functions of the digestive organs. Enteroendocrine cells do not form glands but are spread throughout the digestive tract. They exert their autocrine and paracrine actions that integrate gastrointestinal function.
Discussion
1 Gherin
It is secreted when the stomach is empty. It enters the bloodstream and affects a part of the brain known as the hypothalamus which governs appetite. Gherin is a peptide hormone releasesd from the stomach and liver and is often called “hunger hormone” since high levels of it are found in individuals who are fasting. Gherin agonistic treatment can be used to treat illness such as loss of appetite in cancer patients. It is also used in the treatment of obesity.
2 Pancreozymin
This hormone is secreted and released by the enteroendocrine cells in the duodenum, the first segment of the small intestine. Its presence causes the release of digestive enzymes and bile from the pancreas and gall bladder and also acts as a hunger suppressant, it also catalyses the digestion of fats, protein and carbohydrates.
3 Cholecystokinin
This hormone is synthesized and secreted by enteroendocrine cells in the mucosal lining of the small intestine found in the duodenum and jejunum called I cells. Cholecystokinin plays a major role in induction of the gall bladder contraction, stimulates secretion of pancreatic enzymes, insulin, glucagon and pancreatic polypeptides. It also plays a role in indicating satiety. The C-terminal 8 amino acid peptide cholecystokinin-8 retains full activity.
4 Secretin glucagon family
Are families of evolutionary related peptide hormones that regulates activity of G- protein coupled protein receptors from secretin receptor family. Glucagon belongs to the family and is secreted in the alpha cells of pancreatic islets. It affects glucose metabolism in the liver by inhibiting glycogen synthesis, stimulating glycogenolysis and enhancing gluconeogenesis. It also increases mobilization of glucose, free fatty acids and ketone bodies.
5 Glucose dependent insulinotropic hormone.
It is derived from a 153 amino acid proprotein encoded by the glucose dependent insulinotropic gene and circulates as a biologically active 42-amino acid peptide. It is synthesized by k cells found in the mucosa of the duodenum and jejunum of gastrointestinal tract. Its roles includes; stimulation of insulin release, reduces gastric and intestinal motility and increases fluid and electrolyte secretion from the ileum.
B)DISCUSS THE ROLES OF HORMONES IN GROWTH AND DEVELOPMENT OF INSECTS.
Introduction
Both molting and metamorphosis are controlled by hormones. Molting is initiated when sensory receptors in the body wall detect that the internal soft tissues have filled the old exoskeleton and trigger production of a hormone from neurosecretory cells in the brain.
Discussion
Two hormones are mostly involved in the molting and metamorphosis of an insect. The hormone triggered from the neurosecretory cells in the brain by the exoskeleton, acts upon the prothoracic gland, which in turn secretes the molting hormone, a steroid known as ecdysone.Ecdysone then act...