Stomach ulcers

Question 1

Peptic ulcer

Answer 1

Any ulcer in the mucosa (e.g. stomach or upper duodenum) that is covered in hydrochloric acid and gastric juices.

Question 2

How do drugs help heal ulcers?

Answer 2

Effective drugs either reduce gastric acid secretion or increase mucosal resistance to the acid.

Question 3

Where is acid and mucus secreted?

Answer 3

Acid- parietal cells

Mucus- Goblet cells

Question 4

Helicobacter pylori

Answer 4

Spiral shaped and gram negative bacteria. It grows at an optimum pH of 7. Bacteria is a prokaryotic singled celled organism. It divides by binary fission leaving two identical daughter cells. A septum forms in the middle of the bacteria once the DNA plasmids have copied. This new wall then separates to two new bacteria.

Question 5

How does helicobacter pylori survive the stomach acid?

Answer 5

H. pylori secretes an enzyme called urease, which converts the chemical urea to ammonia. The production of ammonia around H. pylori neutralizes the acidity of the stomach, making it more hospitable for the bacterium.

Question 6

How does a helicobacter pylori breath test work?

Answer 6

H. pylori produces an enzyme called urease, which breaks urea down into ammonia and carbon dioxide. During the test, a tablet containing urea is swallowed and the amount of exhaled carbon dioxide is measured. This indicates the presence of H. pylori in the stomach.

Question 7

Normal function of stomach acid

Answer 7

Creates an optimum environment for protein to be broken down into shorter chain polypeptides. Pepsinogen a proenzyme that breaks down protein is activated to pepsin by the hydrochloric acid in the stomach. The acid helps to kill pathogens. HCL is secreted by the mucosa layer.

Question 8

Peptic ulcer symptoms

Answer 8

Abdominal pain, vomiting and a change in appetite.

Question 9

Risk factors of a stomach ulcer

Answer 9

Smoking- Interfere with GI tract secretion. Can lead to increase acid secretion, less sodium bicarbonate secretion by the pancreas which neutralises the stomach acid as it leaves the stomach and less mucus.

Aspirin- An non-steroid anti-inflammatory (stop pain signal reaching the brain) that can damage the stomach lining if too much is taken over time. Should be taken with food to prevent damage.

Question 10

Untreated stomach ulcers can lead to…

Answer 10

Eroded blood vessel walls (internal bleeding) or damage to the stomach and duodenum.

Question 11

What drugs treat stomach ulcers?

Answer 11

Proton pump inhibitors (e.g. omeprazole or lansoprazole) - Hydrogen ions are transported by proton pumps in the stomach across the cell wall which stimulates the secretion of acid. Proton pump inhibitors block the transport of hydrogen ions, therefore stopping or reducing the secretion of stomach acid.

Antacids (e.g. aluminium hydroxide or calcium carbonate) - Raises the pH of the stomach and increases the rate of emptying. only a short term relief. Combines with the stomach acid to reduce acidity of the gastric juices so the stomach lining can heal.

Antibiotics (e.g. amoxicillin) - Stops the division (bacteriostatic) or kills (bactericidal) the bacteria.

Question 12

Gram positive bacteria

Answer 12

A thick layer of peptidoglycan and a single membrane. Easy to penetrate.

Question 13

Gram negative bacteria

Answer 13

A thin layer of peptidoglycan enclosed by a double membrane making it harder to penetrate.

Question 14

Gram staining

Answer 14

A differential staining process that stains some bacteria one way and other another way. First heat the slide with the bacteria on it so that the bacteria sticks to the slide. This stops it getting washed away by dye (fixation). Add crystal violet leading to the bacteria turning purple. This tries to penetrate the peptidoglycan. Next add iodine solution which acts as a mordant leading to crystal violet binding to the peptidoglycan more if it can penetrate. Decolourise the bacteria with ethanol which washes away any dye that hasn’t penetrated the peptidoglycan. Add counter stain, safranin, which stains anything that hasn’t been stained already turning it prink.
Gram positive - purple
Gram negative - pink

Question 15

Faecal antigen test

Answer 15

RIA (radioimmunoassay) - Uses antibodies to detect and quantitate the amount of antigen present in a sample. Radioactive antigens (known as tracers) compete with a non-radioactive antigen (sample) for a fixed number of antibody or receptor binding site. The displacement in then measured to work out the amount in the sample.

Elisa (Enzyme linked immuno-sorbent assay) - Uses enzymes and colour change to identify a substance (e.g. metabolite (disease) ). Antibodies are used to detect whether a specific protein is present and its quantity.

Question 16

Full blood count

Answer 16

Full blood count also known as a haematology profile examines the components of the blood. Often highly automated and uses special equipment in a lab. It involves measuring: erythrocyte, leukocyte and thrombocyte count per mm of blood. The size of the erythrocyte, mean size in a sample, the proportion of the blood made up by erythrocytes (haematocrit) and the amount of haemoglobin in erythrocytes. The amount of different types of leukocytes can be calculated to look at the bodies ability to fight infection. Thrombocyte count can show the bodies ability to clot blood.

Question 17

Gastroscopy

Answer 17

A gastroscopy is a procedure where a thin, flexible tube called an endoscope is used to look inside the oesophagus (gullet), stomach and first part of the small intestine (duodenum). The endoscope has a light and a camera at one end. The camera sends images of the inside of your oesophagus, stomach and duodenum to a monitor.

Question 18

How does neutralising the stomach acid effect the body negatively?

Answer 18

More prone to infection due to the acid cannot kill microorganisms entering the gut.
Can cause protease to work at a slower rate or denature so protein is not broken down as efficiently. Protein is used for growth and repair and our body needs 20 different amino acids to function. This can lead to a slower healing process, weight loss and stunt growth.

Question 19

What would a full blood count show on a stomach ulcer patient?

Answer 19

High leukocyte count because of the stimulation of the immune response. Low erythrocyte count due to internal bleeding and potentially blood in the faeces.

Question 20

Gut layers

Answer 20

Mucosa - Inner most layer. Often has villi and goblet cells which secretes mucin which builds up to a mucus layer.
Sub-mucosa - Made up of smooth and dense connective tissue supporting the mucosa.
Serosa - Secretes lubricant to reduce friction.
Gut epithelial - One cell thick lining across organs.

Question 21

Smooth muscle

Answer 21

Makes up the walls of organs by long and thin connective tissue. It is an involuntary movement so cant be controlled and is self stimulant. The muscle does not fatigue and can keep doing regular contractions. Made up of actin and myosin. For the muscle to contract myosin pulls in the thick actin leading to one filament to contract and get shorter. If many filaments contract the whole muscle will contract. The myosin will release the actin and then they slide over each other as the muscle relaxes.

Question 22

Antibiotic resistance

Answer 22

Antibiotic resistance is a natural process but the misuse of it in humans and animals is accelerating the process. Bacteria can produce enzymes which neutralise the antibiotic leading to the antibiotic breaking down. Antibiotic resistance can develop in someone using treatment for a prolonged period when the drug has failed to eliminate the bacterial infection quickly. The weakest bacteria is killed first because they are easiest to penetrate. This may lead to patient feeling a bit better. If they stopped taking the course early, bacteria is likely to recur and will undergo mitosis (genetically identical cell division) creating resistant strains of bacteria. These resistant strains may also spread between people. Efflux pumps can develop in the cell wall of the bacteria, leading to ejection of antibiotics out of a cell. Resistant traits can be inherited between generation of bacteria. For example, plasmid (small rings of DNA) can be removed from the bacteria in small sections and transmit between bacteria creating more resistant traits.

Question 23

Amino acid structure

Answer 23

Amine group NH2
Central carbon
Above hydrogen 
Below Variable group 
Carboxylic acid COOH

Question 24

Primary structure of a protein

Answer 24

A sequence of coded amino acids joined by peptide bonds through condensation reaction to form a polypeptide of different shapes.

Question 25

Secondary structure of a protein

Answer 25

The polypeptide forms a 3D structure of alpha helix or beta pleated sheets. Held together by hydrogen bonds or/and amino acid residue.

Question 26

Tertiary structure of a protein

Answer 26

The 3D structure is folded and has a different bond between each amino acid (hydrogen, disulphide, covalent or ionic). if disturbed the protein could denature because this structure determines the function.

Question 27

Quaternary structure of a protein

Answer 27

The forming of more than one polypeptide. The way they combine shows the quaternary structure and contains the same bonds as tertiary structure.

Question 28

Biochemical test for protein

Answer 28

Add biuret to the sample. This is made up of an alkaline solution containing sodium hydroxide and copper sulphate (cuII). If a protein is present the ions form complexes with peptides, changing the solution from blue to purple.

Question 29

Digestion of protein

Answer 29

Mechanical digestion - teeth in the mouth (buccal cavity) + stomach churning (muscular bag)
Chemical digestion - Optimum levels in the stomach for protease (acidic). Secreted as a proenzyme to stop self digestion. Pepsinogen is converted to pepsin by HCL. This hydrolyses the polypeptides to smaller polypeptides. Endo/exopeptidase hydrolyses protein into dipeptides (e.g. trypsinogen to trypsin by adding a phosphate). Then in the duodenum exocrine cells secrete pancreatic juices contain dipeptidase that hydrolyses the dipeptides to amino acids to be absorbed in the ileum and processed by the liver.