Journey Through the GI System Trivia Quiz

Answer: amylase

Digestion begins in the mouth with both mechanical and chemical processes. Mechanical digestion refers to the teeth chewing and breaking food down into smaller pieces and, at the same time, the tongue mixing food with saliva, which begins the process of chemical digestion. Saliva contains the enzyme amylase which breaks down starchy foods, such as bread, pasta and potatoes, into simple sugars.

Amylase is also made by the pancreas. The name amylase is derived from the Greek "amylon" meaning starch and the suffix -ase, which is used to denote enzymes.

Answer: peristalsis

Movement through the gastrointestinal tract involves two primary types of contraction - peristalsis and segmentation. Peristalsis is a series of involuntary, co-ordinated wave-like motions that move food, fluids, gases and waste through the digestive tract. It begins in the oesophagus and continues through the stomach, intestines and rectum. It involves the co-ordinated contraction of circular muscles (narrowing the GI tract) and longitudinal muscles (shortening the GI tract).

Segmentation, on the other hand, involves localized, rhythmic contractions of circular smooth muscles within the small and large intestines. These contractions move food back and forth rather than in one direction.

Myoclonus is the name given to involuntary muscle movements that are sudden, brief, jerks or twitches, commonly affecting the limbs, face, neck, or torso, not the digestive system.

Sometimes you can hear peristalsis as gurgling noises, commonly known as stomach or "tummy" rumbling. The medical term for this is borborygmus (singular) or borborygmi (plural). While peristalsis is usually quiet, these sounds can become loud enough to hear without a stethoscope, especially when someone is hungry.

Answer: pituitary

As the name implies, the salivary glands make saliva which is essential for the process of digestion. Saliva contains enzymes such as amylase to facilitate the chemical breakdown of food. Saliva also helps the tongue to taste food, acts as a lubricant to assist swallowing and contains proteins to help fight bacteria to prevent cavities and infections.

There are six salivary glands, two parotids (located on the sides of the cheeks, between the ears and the jaw), two submandibular (located under the jaw, in the floor of the mouth) and two sublingual (located under the tongue). The parotid glands are the largest salivary glands. They are the ones usually affected in the disease known as mumps (also known as parotitis), a viral illness which results in painful facial swelling, although the submandibular and sublingual glands may also be affected.

The pituitary gland is a pea-sized organ located at the base of the brain which regulates other hormones and body processes. It is not a salivary gland.

Answer: varices

Varices are abnormally enlarged or swollen veins, most commonly found in the lining of the lower oesophagus or stomach. They usually occur when there is high pressure (known as portal hypertension) in the veins that lead to the liver, often caused by liver disease (such as cirrhosis) or blood clots.

They are serious because they can rupture and bleed. If they rupture, symptoms can include vomiting blood, passing black or bloody stools, feeling dizzy or fainting, and shock. The mortality (death) rate for this is 15-20%.

Cirrhosis of the liver can also lead to ascites, an abnormal build-up of fluid, but this occurs in the abdominal or peritoneal cavity, between the lining of the abdomen and the organs, not in the oesophagus.

Answer: pyloric sphincter

A sphincter is a ring-like or circular muscle. In the gastrointestinal tract, they control the passage of food through the various segments.

The cardiac sphincter (also known as the lower oesophageal or gastro-oesophageal sphincter) controls food entering the stomach. The pyloric sphincter is the one that controls food leaving the stomach and entering the duodenum, which is the first segment of the small intestine.

The sphincter of Oddi regulates the flow of bile and pancreatic juices into the small intestine and the urethral sphincter controls the flow of urine out of the bladder.

Answer: fats

Lipase is primarily produced in the pancreas but is also produced, to a much lesser extent, in the salivary glands, stomach, small intestine and liver. It is an enzyme which works with bile to break down fats or lipids into fatty acids and glycerol.

Answer: gallbladder

The accessory organs of the gastrointestinal tract are those which assist in some way with the digestion of food but the food does not actually pass through them. The major accessory organs are the salivary glands, liver, pancreas and gall bladder.

The pancreas produces insulin and glucagon to regulate blood sugar as well as a number of enzymes including lipase (breaks down fats), amylase (breaks down carbohydrates), and protease (breaks down proteins). The liver has many functions, one of which is to produce bile to aid fat digestion. The primary storage organ for bile is the gallbladder.

The small intestine is not an accessory organ.

Answer: caecum

The small intestine is a long, coiled tube about 6-7 metres (20-22 feet) in length in an adult human. It consists of three segments. The first segment is the duodenum (about 25-30 cm or 10-12 inches long). Its function is to receive food from the stomach and mix the food with bile and pancreatic enzymes to break it down. The second segment is the jejunum (about 2.5 metres or 8 feet long). Its main function is to absorb the nutrients released as products of digestion. The third segment is the ileum (about 2-4 metres or 6.5-13 feet long). Its function is to absorb nutrients, particularly vitamin B12, minerals and bile salts.

The caecum is a pouch that forms the first part of the colon or large intestine. It removes water and electrolytes (salts) from the food and mixes the food with mucus to facilitate its movement through the large intestine.

Answer: microvilli

For maximum absorption of nutrients, the digestive system requires a very large surface area. This is achieved with three main structures in the small intestines - the circular folds (plicae circulares), the villi and the microvilli.

The circular folds increase the absorptive surface area approximately 3-fold. The villi (plural) are fingerlike projections which increase the surface area approximately 10-fold. Each villus (singular) is in turn covered with even smaller fingerlike projections called microvilli, which add another 10 to 20-fold increase on top of that. The combination of all three structures increases the surface area of the small intestine up to 600-fold.

Another way of expressing this concept is to say that these three structures increase the surface area of the small intestine to an estimated 200-250 square metres (2,150-2,700 square feet). This is roughly equivalent to the size of a tennis court. If the small intestine was a smooth tube lacking these structures, its surface area would only be approximately 0.3-0.5 square metres (3.2-5.4 square feet), which is about the size of a doormat.

Answer: cholelithiasis

Cholelithiasis is the condition of having stones in the gall bladder. The word is derived from the Greek word elements "chole" (bile), "lith" (stone) and "iasis" (process or condition of). The gall bladder stores bile which is made by the liver. If bile contains too much bilirubin or cholesterol, or lacks enough bile salts, then the bile becomes too concentrated and these substances may crystallize and solidify into stones.

Achlorhydria is a lack of hydrochloric acid production in the stomach. Dysphagia is difficulty in swallowing. Dysentery is an intestinal infection, primarily caused by bacteria or parasites, which results in severe diarrhoea accompanied by blood and mucus.