Animal Nutrition WJEC Biology Module 2 ( ) © Teachable and Carol Lekkas. Some rights reserved.

Learning outcomes Know that proteins, carbohydrates and fats are insoluble Know the constituent parts derived from enzyme activity for absorption across the small intestine into the blood Label a diagram of the human digestive system Know the five stages of digestion © Teachable and Carol Lekkas. Some rights reserved.

Food Food is required for growth and energy release to maintain all the life processes. What are the 7 necessary elements in a healthy diet? 1.Carbohydrates 2.Proteins 3.Fats 4.Minerals 5.Vitamins 6.Roughage 7.Water © Teachable and Carol Lekkas. Some rights reserved.

Main food groups Carbohydrates, proteins and fats are all insoluble For the body to make use of them they need to be broken down into smaller, soluble molecules These molecules can then be absorbed into the blood to be used. (give out bread to put + keep in mouth!) © Teachable and Carol Lekkas. Some rights reserved.

Digestive Enzymes Different enzymes break down the three main food groups: CarbohydraseCarbohydrates  Sugars ProteasesProteins  Amino Acids LipaseFats  Fatty Acids + Glycerol © Teachable and Carol Lekkas. Some rights reserved.

Amylase is produced in; Salivary GlandsSalivary Glands PancreasPancreas Small IntestineSmall Intestine NextBack Amylase (a carbohydrase) Give out diagram to annotate © Teachable and Carol Lekkas. Some rights reserved.

Amylase will break down starch into sugars. Large Insoluble STARCH (complex carbohydrate) Small Soluble GLUCOSE (simple carbohydrate) AMYLASE Products of carbohydrate digestion needed as an energy supply for respiration. © Teachable and Carol Lekkas. Some rights reserved.

Proteases (a group of protein enzymes) Protease is produced in; StomachStomach PancreasPancreas Small IntestineSmall Intestine Annotate diagram © Teachable and Carol Lekkas. Some rights reserved.

Proteases will break down Protein into Amino Acids. Large insoluble PROTEIN Small soluble AMINO ACIDS PROTEASE Products of protein digestion needed to build proteins in the body. © Teachable and Carol Lekkas. Some rights reserved.

Lipase Lipase is produced in; PancreasPancreas Small IntestineSmall Intestine Annotate diagram © Teachable and Carol Lekkas. Some rights reserved.

Lipase will break down fats (lipids) into Fatty Acids and Glycerol. Large insoluble FATS Small soluble FATTY ACIDS and GLYCEROL LIPASE Products of fat digestion needed as an energy supply for respiration. © Teachable and Carol Lekkas. Some rights reserved.

Questions 1. Where in the digestive system do the following molecules get broken down and by what enzyme? CarbohydratesFatsProteins 2. Why does bread taste sweet if you chew it for long enough? 3. Starch is a form of carbohydrate. Where in the body is it going to be broken down? © Teachable and Carol Lekkas. Some rights reserved.

The Digestive Tract or Alimentary Canal © Teachable and Carol Lekkas. Some rights reserved.

The molecules in our diet are too large to be absorbed into our bodies. The job of the digestive system is to break down these large insoluble molecules into smaller more soluble molecules which can be more easily absorbed. © Teachable and Carol Lekkas. Some rights reserved.

The Human Alimentary Canal © Teachable and Carol Lekkas. Some rights reserved.

The human digestive system comprises of a number of different organs working together. These include: Oesophagus, Stomach, Liver, Pancreas, Small Intestine and Large Intestine.

Stages of digestion 1.Ingestion Food enters the mouth a)is broken into smaller pieces by chewing (mechanical digestion) b)saliva is secreted into the mouth by salivary glands (starts chemical digestion) Saliva contains amylase Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

The gullet is called the oesophagus. It is a muscular tube which contracts and relaxes to push the food to the stomach = peristalsis At the entrance to the stomach, a special valve called a sphincter, opens to let food in. Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

2. Digestion The stomach stores, mixes, dissolves and begins to digest food: Chemical – pepsin secreted to digest proteins Mechanical - muscles churn food in stomach juices around **Stomach secretes hydrochloric acid pH2 (optimum conditions for pepsin) ** Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

The liver produces bile, which helps break down fats. Bile is stored and released by a small organ called the gallbladder. Bile emulsifies the fat (makes the fat droplets very small – ↑SA) The liver also processes and detoxifies the products of digestion after they have been absorbed. Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

The pancreas is connected to the small intestine. The pancreas makes and secretes digestive enzymes into the small intestine to break down carbohydrates, proteins (trypsin) and fats. The pancreas also makes a hormone called insulin which helps balance blood sugar levels (not digestion!). Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

3. Absorption Chemical digestion continues in the first section of the small intestine, with the help of enzymes from the pancreas and bile from the liver. The lower part of the small intestine is lined with tiny bumps called villi which absorb nutrients into the bloodstream. Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

Villi The small intestine is lined with villi. They increase the SA for absorption of nutrients into the blood stream. Cross section of the small intestine A villus © Teachable and Carol Lekkas. Some rights reserved.

4. Assimilation Blood then transports the digested, soluble food to all parts of the body. It is transformed into substances to aid metabolism. © Teachable and Carol Lekkas. Some rights reserved.

The large intestine is where waste products of digestion are collected and processed into faeces. Some vitamins are absorbed in the large intestine. Excess water is also reabsorbed. Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

Anything that is not digested, such as fibre, is stored in the rectum before being expelled. Label the diagram © Teachable and Carol Lekkas. Some rights reserved.

Label the diagram 5. Egestion The anus is the opening through which faeces are expelled. The anus is surrounded by strong sphincter muscles. These normally keep the anus closed, but open to release faeces. © Teachable and Carol Lekkas. Some rights reserved.

Model gut experiment © Teachable and Carol Lekkas. Some rights reserved.