Digestive System Diseases

Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones. 

When food enters the mouth, its digestion starts by the action of mastication, a form of mechanical digestion, and the contact of saliva. Saliva, which is secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will now be in the form of a small, round mass, called a bolus. It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which are waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes. After some time (typically an hour or two in humans, 4–6 hours in dogs, somewhat shorter duration in house cats), the resulting thick liquid is called chyme. When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine. Water and minerals are reabsorbed back into the blood in the colon (large intestine)

Gastritis

Gastritis is the inflammation of the lining of the stomach. This condition can be an acute (with rapid onset, short period, and usually severe intensity) or a chronic condition.

The two most common forms of gastritis:

• Erosive gastritis
• Non-erosive gastritis

Gastritis Symptoms

The symptoms of gastritis are:

• Pain or burning sensation in the stomach, especially between meals or at night
• Upset stomach
• Blood in stool

In some people, gastritis does not have any symptoms.

How is Gastritis Diagnosed?

Your doctor may perform the following tests to diagnose this condition:

• Upper endoscopy
  Here, an endoscope or a flexible tube with a camera is carefully threaded into the stomach to see the signs of gastritis.
  
  In erosive gastritis, there are visible tiny, superficial abrasions, erosions or holes in the stomach lining.
  
  In non-erosive gastritis, the stomach lining may be red or inflamed but there are no erosions. In some people, the lining may appear completely normal and a biopsy or tissue sample need to be taken, and further tests need to be performed.
  
  
• Blood test
  For non-erosive gastritis, blood test may be done to see the presence of Heliobacter pylori (H. pylori) infection. Vitamin B12 level can also be tested, to confirm or rule out pernicious anemia as one of the cause.

Causes of Gastritis

The causes of gastritis include:

• H. pylori infection
  
  
• Non-steroidal anti-inflammatory drugs (NSAIDs)
  These are painkillers that can reduce the protective nature of the stomach lining against the digestive acids and enzymes in the stomach.
  
  
• Drinking alcoholic beverages
  Alcohol stimulates the production of stomach acid and large doses of alcohol can damage and inflame the stomach.
  
  
• Autoimmune disorder
  Here, the body’s immune system mistakenly attack the stomach lining. In this form of gastritis, the body is no longer able to absorb vitamin B12 thus resulting in a condition called pernicious anemia.
  
  
• Immune response to other diseases
  Gastritis may also be caused by improper immune responses to other diseases such as Crohn’s disease and syphilis.

Treatment for Gastritis

Gastritis is treated with:

• Antibiotics
  If H. pylori is present, antibiotics are prescribed to eliminate this bacteria.
  
  
• Medications to reduce stomach acid
  These include:
  
  
  • Histamine or H2 blockers, which prevents the histamine receptors from stimulating the production of stomach acids
    
    
  • Proton pump inhibitors, which stop stomach acid production.
    

  Abdominal examination

  The abdominal exam, in medicine, is performed as part of a physical examination, or when a patient presents with abdominal pain or a history that suggests an abdominal pathology.
  
  The exam includes several parts:
  
      Setting and preparation
      Inspection
      Auscultation
      Percussion
      Palpation  

  
  

  Special maneuvers

  Suspected cholecystitis

  •     Murphy's sign

  
  Suspected appendicitis or peritonitis

  
  •     Rebound tenderness - pain elicited by the release of palpation by the examiner
  •     Psoas sign - pain when tensing the psoas muscle
  •     Obturator sign - pain when tensing the obturator muscle
  •     Rovsing's sign - pain in the right iliac fossa on palpation of the left side of the abdomen
  •     Carnett's sign - pain when tensing the abdominal wall muscles
  •     Patafio's sign - pain when the patient is asked to cough whilst tensing the psoas muscle
  •     Cough test - pain when the patient is asked to cough

  
  Suspected Pyelonephritis

  •     Murphy's punch sign

  
  Hepatomegaly
  
  

  •     Liver scratch test

  
  Examination for ascites

  •     bulging flanks