THE DIGESTIVE SYSTEM

DIGESTIVE SYSTEM ASSIGNMENT In a group of 3 or 4 you are to create an information handout of a particular structure of the digestive system and present their information to the class. Your handout must include: description and picture of the structure, function of structure, and how the structure works to achieve its contribution to digestion. Your choices are: the oral cavity esophagous stomach small intestine large intestine salivary glands liver and gallbladder pancreas rectum & anus Each group must have a different topic (NO OVERLAP). Handouts must be complete by the end of the period. Copy and paste into my hand-in file. Presentations will be done on Wednesday.

DIGESTIVE SYSTEM FUN FACTS We each eat about 250 kg (1/4 ton) of food per year. False: we eat about 500 kg (1/2 ton) of food each year We each produce 1.7 litres of saliva every year. True Muscles contract in waves to move the food down the oesophagus. This means that food would get to a person’s stomach even if they were standing on their head.

An adult stomach can hold approximately 1.5 litres of material. True The digestive system of an adult human is about 5 m long. False: its about 8 m long Every day 11.5 litres of digested food, liquids and digestive juices flow through the digestive system, but only 100 mLs is lost in faeces (poo)

Salivary glands Mouth/teeth eosophagus trachea Gall bladder stomach liver pancreas duodenum Small intestine Large intestine appendix Rectum/anus

Digestion presentations

Handouts: the digestive organs : distinguishing b/w mechanical and chemical digestion Article: the Bacteria in my gut

DIGESTIVE SYSTEM DISORDERS/ DIAGNOSIS TECHNIQUES For this group (2-3 people) assignment you are to prepare a summary of the information you gather. The summary should include the following: If you are doing a disorder: include cause, symptoms, complications, diagnosis and treatment, If you are doing diagnosis techniques: include a description of the technique and any complications. DISORDER DIAGNOSIS TECHNIQUES heartburn Upper GI series Gall stones Upper endoscopy Lactose intolerance Flexible sigmoidoscopy Cirrhosis of the liver Lower GI series Inflammatory bowel disease colonoscopy ulcers Endoscopic retrograde cholangiopancreatography (ERCP) Diverticular disease Irritable bowel syndrome

DIGESTIVE ENZYMES Biological catalysts Proteins Breakdown nutrients through process of hydrolysis

Human enzymes of Digestion ENZYME GROUP AMYLASE PROTEASE LIPASE Example of this enzyme Source Substrate Products Optimum pH Salivary amylase Pancreatic lipase pepsin Salivary glands Wall of stomach pancreas starch proteins Triglycerides (fats or oils/ maltose Small polypeptides Fatty acids and glycerol pH 7 pH 1.5 pH 7

DIGESTION OFCARBOHYDRATES

Insert pic of digestion of fats THE DIGESTION OF FATS Insert pic of digestion of fats

Insert pic of digestion of proteins

Lab: how enzymes are affected by temperature?

REGULATING BLOOD SUGAR An example of Homeostasis

HOMEOSTASIS: the process by which an organism maintains a constant internal environment Includes the control of constant temperature, blood pressure and blood sugar levels

HOW DOES HOMEOSTASIS OCCUR? All of the body’s organ systems are involved in this work. They use a negative feedback system. i.e. The body has a set of conditions under which it operates. If one of these conditions is broken, receptors send signals to other organs in the body. When organs receive these signals, they respond in such a way that counteracts the change to the system.

BLOOD SUGAR CONTROL AS AN EXAMPLE OF HOMEOSTASIS Pancreas is the primary organ involved in regulating blood sugar. Cells in the Islets of Langerhans, alpha and beta cells, monitor and control blood sugar levels. The set level of blood sugar in the body is 4-6 mmol/L

After you eat, blood sugar levels rise After you eat, blood sugar levels rise. Receptors signal the pancreas to release insulin (via beta cells) into the blood stream. When receptor cells sense a return to the set level of blood sugar, they signal the pancreas to stop releasing insulin, and stimulate storage of extra glucose as glycogen in the liver When blood sugar levels bet below set point, alpha cells release a hormone classed glucagon that induces the release of glucose from the liver by changing glycogen back into glucose

Diabetes clip? Tw: p 274 # 5, 6, 7