TOPIC 6.1 Digestion

Series of events in order: Ingestion- eat the food Digestion- series of chemical rxs to convert food to smaller molecules Absorption- small molecules are absorbed through the cells of your digestive system into blood or lymphatic vessels Transport- circulatory system delivers the small molecular nutrients to body cells

DIGESTION process of making food absorbable it must be changed into simpler chemical compounds nutrients can't be used by the body until they are absorbed into the cells & tissues They can't be absorbed unless they are small & soluble

Before & After Digestion Molecular Form Ingested Form After Digestion Protein Triglycerides poly, di and monosaccharides DNA and RNA Amino acids Glycerol and fatty acids Monosaccharides Nucleotides

Breaking food into smallest components HYDROLYSIS Breaking food into smallest components ex. albumin in egg whites contain the amino acid serine needed in pancreas to produce insulin

Organs of the Digestive System You can think of the digestive system as two sets of structures First set called the alimentary canal: consists of organs that food passes through directly it’s a one-way tube with two openings

The Second Set accessory organs outside of but connected to the alimentary canal these organs produce digestive enzymes Liver, pancreas, gall bladder, salivary glands, etc.

Enzyme-catalysed rxs Increase rate of rx at lower T° (37°C) Lower energy of activation Amylase in salivary glands of mouth Pepsin (a protease) in stomach cells Lipase in pancreas cells

Proteins (polypeptides) Salivary Amylase Pepsin (a protease) Lipase Source Salivary glands Stomach cells Pancreas cells Substrate Amylose (starch) Proteins (polypeptides) Lipids Products Maltose & glucose Amino acids Glycerol & fatty acids Optimum pH Neutral (pH 7) Acidic (pH 3) TOPIC 6.1.3

Be able to draw and label!!!!!!!!!! 6.1.4

Complete Biozone page 269

ALIMENTARY CANAL

Mouth- amylase (in saliva) mechanical digestion of all food (teeth chewing & grinding) chemical digestion of carbohydrates begins esophagus- passageway to stomach smooth muscle- peristalsis

http://www.youtube.com/watch?v=Q- n_Q0qKXzg&safe=active

Stomach Gastric Juices: Pepsin – protease enzyme HCl – creates optimium pH for pepsin to be active & helps degrade and breakdown food Mucus – lines and protects stomach from HCl mechanical digestion of food (churning of stomach walls)

Small Intestines 1st portion called duodenum Accessory organs secrete juices: Bile – produced in liver, stored in gall bladder (emulsifies fats) Trypsin (protease), lipase, amylase and bicarbonate from pancreas absorption: small soluble nutrients (sugars, amino acids, fatty acids)

Villi of Small Intestines - greatly increase surface area for absorption Contain capillaries and lacteals (small vessel of the lymph system) lacteal Small molecules taken into capillaries, except fatty acids which are absorbed into lacteals

Inside the Villi inside are two types of vessels, capillaries & lacteal the capillaries web around the lacteal protein & carbohydrates (amino acids & simple sugars) are absorbed by capillaries lipids (fatty acids & glycerol) are absorbed in the lacteal

Circulatory System delivers absorbed molecules to body cells Nutrient molecules used by cells: For energy (e.g. glucose) For buiding larger molecules (e.g. amino acids) Assimilation= the process of bringing nutrients to a body cell and using it to build larger molecules

Large Intestines Contains undigested and unabsorbed food and water water is absorbed from indigestible wastes (feces) Also contains naturally occurring bacteria (including E. coli) Mutualistic relationship-we supply nutrients, water and warm environment and they synthesize vitamin K and maintain a healthy environment in our large intestines Faeces or solid waste is egested from our body

Complete Biozone pages270-275

http://www.youtube.com/watch?v=nM 5kMSjBrmw http://www.youtube.com/watch?v=s06 XzaKqELk http://www.youtube.com/watch?v=fiR KW0W51Pg

Complete Biozone page 276 Write the answer beside the clue

Two Questions for You: 1. A single sandwich is likely to contain carbohydrates, lipids and proteins. From a biochemical viewpoint, what will happen to each type of molecule on digestion?

2. You ingest a glucose. molecule in the starch of a. breakfast cereal 2. You ingest a glucose molecule in the starch of a breakfast cereal. State as many specific locations as you can for this single glucose molecule from the time it is in your mouth to the time it enters a muscle cell of your right forearm.