Digestive System Disorders

Esophagus -transfers food to stomach by peristalsis Cardiac sphincter -opens to allow food esophagus stomach -heartburn –acid escapes stomach esophagus

Stomach Short term storage reservoir (1L for up to 4h) Digestion = chemical (HCl and enzymes) - proteins = mechanical - liquefication of food Slowly releases food into intestine chyme Cardiac sphincter Pyloric sphincter

Acid (HCl) – parietal cells Hormone (gastrin) – G cells Mucous – goblet cells -- Enzymes (pepsinogen) – chief cells Stomach epithelial cells are some of the fastest growing cells in the body, typically replacing themselves about every 3 days Stomach Epithelium Ulcers (stomach, duodenum) – peptic ulcers. Most commonly caused by H. pylori prevents self-digestion pH 1-2 Kills bacteria Loosens fibrous foods Activates pepsinogen Denatures salivary amylase Activated to pepsin by HCl Converts proteins peptides Controls gastric motility and acid secretion

ULCERS An ulcer forms when the mucus layer that protects the stomach lining erodes due to the HCl in the stomach An acid-resistant bacteria: Helicobacter pylori attaches to the stomach wall causing the site of attachment to stop producing mucus

ULCERS FACTORS SUCH AS: o Smoking o Caffeine o Alcohol o Stress can all contribute to the formation of ulcers TREATMENTS o acid-reducing medicines o antibiotics o lifestyle adjustments (lower stress levels)

Small Intestine Around 6m in an adult Food takes 1-6 h to pass through 2 main tasks = digestion, absorption 3 parts Duodenum Jejenum Ileum

Pancreas –pancreatic juice= NaHCO3, enzymes (insulin, glucagon) pH of duodenum = 7-8 Amylase, lipase, trypsinogen, chymotrypsinogen Liver – bile made in liver, stored in gall bladder = Water, salts, bile salts Neutralise HCl Digestion and absorption of fats and fat soluble vitamins (emulsification) Waste products eliminated by secretion into bile and elimination in feces (e.g. bilirubin, biliverdin) Duodenum = 25cm long - the duodenum is mainly responsible for the digestion of nutrients

Liver Weighs about 1.5kg Holds about 13% of total blood Liver cell = hepatocyte Unique ability to regenerate – average life = 150 days Right lobe Left lobe Blood rich in food from ileum The liver performs over 500 jobs. Some of these are: Makes bile (600mls/day) Detoxifies body (alcohol, drugs etc) Breaks down excess amino acids urea (deamination) kidney Converts glucose glycogen for storage (source of quick energy) Converts excess carbohydrates fat Stores vitamins - A, D, E and K Stores minerals – Fe, Cu, Zn Makes plasma proteins e.g. fibrinogen – blood clotting Makes cholesterol – needed to form many hormones Produces heat to warm blood Clears blood of particles, including bacteria Fights infections –half the body’s macrophages -destroy bacteria Produces hormones, including the sex hormones

LIVER DISEASES HEPATITIS an inflammation of the liver 3 types: HEPATITIS A: from drinking contaminated water HEPATITIS B: sexual contact (more contagious than AIDS) HEPATITIS C: infected blood (no vaccine currently) SYMPTOMS Fever Appetite loss, nausea Abdominal pain Jaundice (yellow skin, eyeballs) TREATMENTS Drugs Vaccination (prevention)

HEPATITIS

CIRRHOSIS WHAT IS IT? Scar tissue and fat replace healthy liver tissue – making the liver virtually useless CAUSES: Alcoholism Hepatitis C TREATMENT: Liver transplant

GALLSTONES Cholesterol in the bile can precipitate out and form crystals The crystals grow in size and become stuck in the gall bladder and duct leading to the duodenum

GALLSTONES con’t CAUSES: Obesity Alcohol intake Heredity TREATMENT: Medications Ultrasound (disintegrate the stones) Surgery to remove gallbladder

Jejenum – digestion/ absorption. 2.5m long Ileum – absorption. 4m long Walls only one cell thick Villi, microvilli – increase surface area for absorption Rich blood supply – capillaries absorb water and soluble nutrients (glucose, amino acids, vitamins, minerals) and the blood carries the nutrients to the liver, which stores nutrients and releases them as required Lacteal – contains lymph. Fatty acids and glycerol are absorbed by the epithelial cells where they reform into fats. They become coated in protein (chylomicrons) and pass into the lymph in the lacteals. It takes around 18h for lymph to rejoin the blood, the protein coat dissolves and fats are absorbed into cells Small Intestine cont.

Large Intestine 1.5m long, 6cm diameter – much THICKER than small intestine Food stays 10h to a few days -More fat in diet – longer duration -More roughage – less duration Large intestine (also called colon) Reabsorbs water – so waste is converted to semi-solid = feces – eliminated Diarrhea, constipation (fibre helps stimulate peristalsis of GI tract) Caecum the start of the lg I Appendix Function unknown – in herbivores they contain bacteria that help digest cellulose

Bacteria 1-2kg of bacteria in your gut = 4000 species Good – symbiotic bacteria. These live in close harmony with the body without causing harm, and have additional health benefits. Probiotics are live micro-organisms that, when consumed in adequate amounts, confer a health benefit to the host. e.g. bifidobacteria, lactobacillus (found in yogurt) Bad - bacteria that can cause illness e.g. H pylori (ulcers), Salmonella, E. coli, Listeria (food poisoning) Aid digestion Break down toxins Produce vitamins B12 and K Stimulate the immune system Help prevent growth of cancers

INFLAMMATORY BOWEL DISEASE CROHN’S DISEASE – inflammation of the intestinal lining (usually the ileum) COLITIS - inflammation and ulceration of the lining of the colon

WHAT’S THE DIFFERENCE BETWEEN CROHN’S & COLITIS? CROHN’S DISEASE It can affect any part of the digestive tract, but usually only affects the ileum Inflammation extends deep into the lining of the intestine Surgery not usually an option COLITIS It affects the colon The inflammation is usually restricted to the inner lining of the colon only Surgery can be used to remove parts or all of the colon

CROHN’S DISEASE SYMPTOMS: Abdominal pain Cramping Diarrhea Rectal bleeding Weight loss Skin problems TREATMENT Drugs to control inflammation Dietary adjustments

COLITIS SYMPTOMS: Diarrhea Abdominal cramps Weight loss TREATMENTS: Drugs to reduce inflammation Surgery

Celiac Disease Celiac disease is a medical condition in which the absorptive surface of the small intestine is damaged by a substance called gluten. This results in an inability of the body to absorb nutrients: protein, fat, carbohydrates, vitamins and minerals, which are necessary for good health. Although statistics are not readily available, it is estimated that 1 in 133 persons in Canada are affected by celiac disease. SYMPTOMS diarrhea bloating, cramps headaches weight loss fatigue dermatitis herpatiformis (an itchy, bumpy rash that forms all over the body) - From the Canadian Celiac Association

Celiac Disease CAUSES unknown, although genetics does play a role TREATMENT life-long elimination of gluten from diet some medications can be used to treat skin conditions no cure

Normal small intestinal villi compared to Celiac small intestinal villi

Celiac Disease What is gluten? a specific protein found in wheat, barley and rye in people with celiac disease, gluten attacks the villi of the small intestine and breaks them down Without properly functioning villi, nutrients can’t be absorbed properly What is gluten-free food? corn, rice, potatoes, beans all fruit and veggies in their natural forms (ie not processed) Look for this symbol:

Celiac Disease

Treatment for Celiac Disease

OBESITY

CAUSES??CURES??

OBESITY INFO >50% of Canadians are classified as either overweight or obese CAUSES: Lifestyle Genetics Hormones Social factors Biological? TREATMENT: Lifestyle changes – diet/exercise Surgery – stomach stapling, liposuction,etc

OBESITY PREVENTION? HEALTHY DIET REGULAR EXERCISE v=dLMoFST_Lmc

HOW IS OBESITY DEFINED? – BY USING A BMI (BODY MASS INDEX)