digestion and hepatic systems Flashcards
• The major function of the digestive system is to:
Covert food eaten into a form utilised by the cells for energy
-rid the body of waste material
• The major function of the digestive system is to:
Covert food eaten into a form utilised by the cells for energy
-rid the body of waste material
why does SI need such a large SA?
• The small intestine needs a large surface area a sit is the main site for chemical digestion and absorption- the total surface area is the size of a tennis court.
WHY AND HOW DOES THE STOMACH PROTECT ITSELF FROM ITSELF?
• The stomach must protect itself from itself. 2L of hydrochloric acid is secreted into the stomach every day to kill bacteria and aid digestion. The stomach has a thick coating of mucus to protect itself and this is renewed every 2 weeks.
what is digestion?
• Necessary to breakdown food we eat from large, complex molecules to simple molecules which can be absorbed and used up by the body.
• Several organs make up this system and each have their own role.
-The GI tract also harbours diverse microorganisms which are essential to health and well-being- these are known as the microbiome, a unique and balanced ecosystem of billions of bacteria and other microbes that live on in us.
what is digestion?
• Necessary to breakdown food we eat from large, complex molecules to simple molecules which can be absorbed and used up by the body.
• Several organs make up this system and each have their own role.
-The GI tract also harbours diverse microorganisms which are essential to health and well-being- these are known as the microbiome, a unique and balanced ecosystem of billions of bacteria and other microbes that live on in us.
describe the route food passes during digestion?
- The teeth and tongue chew and begin the first phase of digestion during the process “mastication”.
- Salivary glands open to the mouth. Food passes from the oesophagus to the stomach via a muscular opening known as the cardiac sphincter. The stomach secretes enzymes and acid that digests food. Ridges of muscle called rugae line the stomach. The stomach muscles contract periodically, churning food to assist with digestion. The pyloric sphincter is a muscular valve that opens to allow digested food to pass into the first section of the small intestine- THE DUODENUM.
describe the route food passes during digestion?
- The teeth and tongue chew and begin the first phase of digestion during the process “mastication”.
- Salivary glands open to the mouth. Food passes from the oesophagus to the stomach via a muscular opening known as the cardiac sphincter. The stomach secretes enzymes and acid that digests food. Ridges of muscle called rugae line the stomach. The stomach muscles contract periodically, churning food to assist with digestion. The pyloric sphincter is a muscular valve that opens to allow digested food to pass into the first section of the small intestine- THE DUODENUM.
what is a common misconception about the stomach?
• Common misconception that stomach is at the centre of the DS. The stomach plays a large role in “mechanical digestion”, p[physically breaking up the food and converting it to a thick paste called “chyme”.
-There is a little chemical digestion in the stomach- necessary for nutrients to pass into the blood stream.
what are the causes for gastric and duodenal ulcers?
The main cause of gastric and duodenal ulcers is infection with H. pylori bacteria, especially in low-income countries and settings.
Another cause of gastric ulcers, and less so duodenal ulcers, are nonsteroidal anti-inflammatory drugs, or NSAIDS, like ibuprofen.
A rare cause of peptic ulcer disease is Zollinger Ellison syndrome, which is
Causes of gastric and duodenal ulcers
1)The main cause of gastric and duodenal ulcers is infection with H. pylori bacteria, especially in low-income countries and settings.
what?
o What?
-H. pylori are gram-negative bacteria that colonize the gastric mucosa and release adhesins that help them adhere to gastric foveolar cells as well as proteases that cause damage to mucosal cells.
o Most individuals with H. pylori don’t develop any problems, but sometimes it causes a patchy pattern of damage that starts in the antrum, and then spreads to the rest of the stomach and eventually into the duodenum.
o Over time the damage erodes deeper and deeper into the mucosa, eventually causing ulcers.
Causes of gastric and duodenal ulcers
2)Another cause of gastric ulcers, and less so duodenal ulcers, are nonsteroidal anti-inflammatory drugs, or NSAIDS, like ibuprofen
Why?
o Why?
- NSAIDs inhibit the enzyme cyclooxygenase which is involved in the synthesis of inflammatory prostaglandins.
- Reducing the level of prostaglandins over a prolonged period of time, though, leaves the gastric mucosa susceptible to damage, and over time ulcers can start to develop.
Causes of gastric and duodenal ulcers
3)A rare cause of peptic ulcer disease is Zollinger Ellison syndrome, which is due to a tumour called a gastrinoma
o A gastrinoma is a neuroendocrine tumour that is typically located in the duodenal wall or pancreas and secretes abnormal amounts of gastrin.
-Excess gastrin stimulates parietal cells to release excess hydrochloric acid, which overwhelms normal defence mechanisms and allows ulcers to develop in the first portion of the duodenum or even in the distal duodenum or jejunum.
-Peptic ulcers that result from any of these mucosa-damaging-mechanisms are usually small, round “punched out” holes in the mucosa.
o Gastric ulcers typically form in the lesser curvature of the antrum.
o Duodenal ulcers on the other hand usually develop right after the pyloric sphincter and there’s usually Brunner gland hypertrophy - which is a consequence of the body trying to produce more mucus to protect the damaged area.
o Very deep ulcers can erode into underlying blood vessels and can cause bleeding, which is a problem that is extremely dangerous when there’s a nearby artery.
o That’s because haemorrhage into the gastrointestinal tract can happen and this rapid loss of a lot of blood can ultimately lead to shock.
o Two well-known dangerous spots are when there’s a gastric ulcer on the lesser curvature of the stomach eroding into the left gastric artery, and a duodenal ulcer on the posterior wall of the duodenum eroding into the gastroduodenal artery.
o Another complication is perforation, which is when an ulcer erodes all the way through the wall of the stomach or duodenum, allowing gastrointestinal contents -like undigested food and gastric secretions to get into the peritoneal space - which is usually sterile.
o Perforation is a well-known complication of duodenal ulcers on the anterior wall of the duodenum.
o When they perforate, air starts to collect under the diaphragm, irritating the phrenic nerve, and sending referred pain up to the shoulder.
o Finally, and very rarely, long-standing duodenal ulcers near the pyloric sphincter, can sometimes have so much edema or scarring that they obstruct the normal passage of gastric contents into the intestines resulting in gastric outlet obstruction, this can quickly lead to nausea
o or vomiting since the food literally can’t get by.
what’s the main symptoms for gastric duodenal ulcer ulcers?
o The main symptom of gastric and duodenal ulcers is epigastric pain, which is an aching or burning in the upper abdomen.
o Other symptoms are bloating, belching, and vomiting.
o Classically, gastric ulcer pain increases while eating a meal due to the physical presence of the food, as well as the hydrochloric acid production stimulated by the process of eating.
o On the other hand duodenal ulcer pain decreases while eating a meal.
o This may be why gastric ulcers are associated with weight loss, while duodenal ulcers are associated with weight gain.
what’s the main symptoms for gastric duodenal ulcer ulcers?
o The main symptom of gastric and duodenal ulcers is epigastric pain, which is an aching or burning in the upper abdomen.
o Other symptoms are bloating, belching, and vomiting.
o Classically, gastric ulcer pain increases while eating a meal due to the physical presence of the food, as well as the hydrochloric acid production stimulated by the process of eating.
o On the other hand duodenal ulcer pain decreases while eating a meal.
o This may be why gastric ulcers are associated with weight loss, while duodenal ulcers are associated with weight gain.
