Gastrointestinal Flashcards
revision of GI tract digestion (start at mouth)
- Mouth: teeth masticate the food and salivary glands secrete saliva containing enzymes
- food then passes by the pharynx to the oesophagus
- then to the stomach which mechanically and chemically breaks down the food.
- chyme then goes to the small intestine which signals enzyme release (produced from accessory glands- liver, pancreas, gallbladder)
- most nutrients absorbed in small intestine and then it goes to large intestine where water is absorbed
- waste then leaves via the rectum/anus.
what is the role of the digestive system?
- reduces particle size
- helps absorb macronutrients and trace elements
- sets physical and immunological barrier
- breaks down: fats, carbs, proteins
- moves food via peristalsis
What are some clinical signs and symptoms in patients with altered digestive function?
nausea vomiting diarrhoea constipation gastrointestinal bleeding anorexia and abdominal pain
Describe Nausea
a subjective sensation of the need to vomit, can be short lived or ongoing.
When physical it can be caused by problems in the brain or organs in upper GI.
Causes: anything that slows down GI motility, sympathetic NS, pain, motion, disease
Describe vomiting and physical alterations that lead to vomiting.
the forceful emptying of the stomach contents.
Vomiting centre is stimulated in the brain.
Stimuli known to cause vomiting include: pain, distension of the stomach, trauma to organs, copper salts in duodenum.
- the stimuli such as pain activates sympathetic response= noradrenaline/adrenaline coursing through the body that decreases motility leading to vomiting.
Describe Diarrhoea
increase in the frequency of defecation and fluidity.
Patients may also experience fever, pain and bloody stools.
can be mild or severe.
2 types: osmotic (when substance cant be absorbed) and secretory (excessive mucous secretion or inhibition of salt)
Describe Constipation
when defecation becomes difficult or infrequent.
Causes: may be neurogenic, mechanical problems, low fibre diets, sedentary lifestyle
Describe Anorexia
lack of desire to eat despite physiological stimuli that would normally produce hunger. It is often non specific symptom that is associated with nausea, pain and diarrhoea.
Disorders can accompany anorexia: cancer, heart disease, kidney failure.
Define Abdominal pain
may be mechanical or chemical pain.
or visceral : caused by inflammatory injury to the abdominal organs, where pain is poorly localised.
or referred: pain felt distance away from affected organ, usually well localised and felt in skin or deeper tissue that share a central afferent pathway
What are some disorders of motility?
Dysphagia, GORD and Intestinal obstruction
Describe Dysphagia.
it is the difficulty to swallow caused by mechanical obstruction or functional obstruction.
Mechanical: can be intrinsic (in all of the oesophagus) or extrinsic (outside the oesophagus lumen pressing inward)
Functional: is neural or muscular disorder such as Parkinson’s.
Describe GORD or GURD
Gastro-oesophageal reflux disease (GORD) occurs when stomach acid leaks from the stomach and moves up into the oesophagus (food pipe).
There are different types: physiological (no symptoms) or oesophagitis (inflammation)
Causes: coughing, vomiting, gastric ulcers, hiatal hernia
Describe Intestinal Obstruction
Failure of normal motility or prevention of low flow of chyme.
Causes: mechanical obstruction (tumour) or Functional (obstruction)
Increase in fluid and gas may accumulate, leading to inflammation and oedema which can result in shock.
What are some inflammatory disorders and ulceration of the gastro-intestine?
Gastritis, peptic ulcer disease, appendicitis, peritonitis and diverticulitis.
What is gastritis?
Acute or chronic inflammation of gastric mucosa.
May be caused by infection, NSAIDS which inhibit protective prostaglandin> decreasing mucous production, alcohol etc.
Chronic may be more in elderly
What is Peptic ulcer disease ?
It derives from the breakdown of the protective mucosal lining. It occurs due to an imbalance between gastric acid production and mucosal barrier. May occur in the oesophagus, stomach or duodenum. Duodenal are most common.
Peptic ulcer disease occurs due to an imbalance of acid production and mucosal barrier. What factors affect these?
(what increases gastric acid and decreases mucous)
Factors that Increase in gastric acid production:
- increase in the number of chief cells
- decrease in the inhibition of gastric secretion
- increased sensitivity to food
Factors that impair mucosal barrier production:
- Ischemia
- sympathetic stimulation = decreases
- impaired mucous secretion
- protective prostaglandin
- alcohol consumption
What is Diverticular disease?
Small herniations that occur through the muscle layer of the colon wall. Many patients are asymptomatic.
Diverticulitis is the inflammatory stage.
Causes: low fibre diets= leads to reduced faecal bulk, reduced colon diameter> increasing pressure > outpouchings at weak points in the wall.
Describe Vermiform appendicitis?
Pathophysiology is controversial: thought to be obstruction of the lumen of faecal, or an increase oedema due to inflammation which increases pressure within appendix.
What is Peritonitis:
Inflammation of the peritoneum: results from contamination of the space between parietal and visceral layer which is normally sterile. Often the result of bacteria, and may lead to shock or septicaemia.
What is the definition of Maldigestion?
failure of the chemical process in digestion
What is the definition of Malabsorption?
failure of the intestinal mucosa to absorb the nutrients
What are some examples that result in malabsorption and maldigestion?
Bile salt deficiency, pancreatic insufficiency, vitamin deficiencies (D, K,E, A), Lactase deficiency, inflammatory bowel disease, Crohn’s disease, anorexia, Coeliac disease
What is irritable Bowel syndrome?
Structural changes of the bowel does not occur rather the afflicted
person experiences abdominal pain and discomfort and altered bowel habits.
Describe the pathophysiology of Crohn’s disease.
Inflammatory disorder that affects the small
and large intestine.
– Neutrophils and macrophages promote the inflammatory reaction.
– Genetic predisposition and alterations in
normal bowel flora is suspected.Causes ‘skip lesions’
– Ulcerations can produce longitudinal and transverse inflammatory fissures
– Anaemia may result from malabsorption of vitamin B12 and folic acid
Describe the pathophysiology of Diverticular Disease
Diverticula are sac like out pouching or herniations that occur in the mucosae and protrude through the muscle layers of the
large intestine.
– Most common in the sigmoid colon.
– Regular consumption of a low fibre
diet reduces faecal bulk – thus
reducing the diameter of the colon
– diverticula can rupture under increased pressure
What nutritional disorders occur as the result of alterations in digestive physiology?
- intolerance – due to a deficiency in the elnzyme lactase which breaks down lactose into its smaller components glucose and galactose.
– Coeliac disease – results in the loss of the mature intestinal villi caused by a hypersensitivity to gluten. This results in malabsorption of nutrients.
Why does lactose intolerance cause diarrhoea and abdominal pain?
Bacterial fermentation of undigested lactose leads to increased gas production which stretches the intestines causing pain.
– The undigested lactose also changes the osmotic gradient in the intestines causing fluid to be drawn into the intestines, thus causing diarrhoea.
Discuss pathophysiology of colorectal cancer
Carcinoma starts in the glands of the mucosal lining. – Genetics and a diet high in fat, low in fibre and low in calcium my promote colorectal cancer development. – Bleeding may be evident, pain may be present and a palpable mass can sometimes be felt. – Faeces may decrease in size or an obstruction may develop.
Outline the clinical manifestations that you may observe in a patient who has experienced severe vomiting for several days.
deep inspirations inability for maldigestion and malabsorption stomach/abdominal pains electrolyte imbalance dehydration fatigue burning of the oesophagus weight loss anaemia muscle cramps tend to bruise and bleed easily
Discuss possible causes and the complications that can result from upper gastrointestinal bleeding.
causes: may be from a range of areas in the Gi tract ( upper or lower). may be due to ulcers, inflammation, diverticulitis, Chron’s disease, cancer.
Severe bleeding may cause hypovolemic shock.
Clinical manifestations:
- Haematemesis (vomiting blood)
- Melena (black foul smelling)
-Haematochezia (bright red)
Complications:
- Diarhea due to irritating nature of blood
- Anemia
- elevated BUN due to digestion of blood proteins
Discuss the treatments that could be used to alleviate symptoms observed in celiac disease
and lactose intolerance
- Treatment of lactose intolerance= reducing milk consumption and other diary products may need to be consumed to ensure adequate calcium (some people can tolerate fermented lactose such as cheese and yogurt or soy) Oral lactase supplements may be taken.
- Coeliac disease treatment = diet free of cereal grains immediately. Patient education, lactose intolerance may accompany this disease due to villi destruction. Infants and adults need vitamin D, iron and folic acid supplements to treat deficiencies
Explain how the stomach protects itself from its gastric acid
Stomach epithelial cells are protected from gastric juice by a layer 1-3mm thick of alkaline mucous secreted by the surface mucous cells and mucous neck cells.
Compare and contrast the causes and pathophysiology of osmotic and secretory diarrhoea.
Osmotic diarrhoea:
- a non-absorbable substance in the intestine draws excess water in the intestine and increases stool weight and volume= producing large volume of diarrhoea. It causes lactase and pancreatic enzyme deficiency and excessive ingestion of artificial sugars.
Secretory Diarrhoea:
- excessive mucosal secretion of fluid and electrolytes produces large volume diarrhoea. Causes bacterial enterotoxins, neoplasms, exotoxins. Elderly and immunocompromised are at risk.
