animal nutrition wjec biology module 2 (2010-2012) © teachable and carol lekkas. some rights...

Animal Nutrition

WJEC Biology Module 2 (2010-2012)

© Teachable and Carol Lekkas. Some rights reserved. http://teachable.net/res.asp?r=8714

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


FoodFood is required for growth and energy release to maintain all the life processes.

What are the 7 necessary elements in a healthy diet?1. Carbohydrates2. Proteins3. Fats4. Minerals5. Vitamins6. Roughage7. Water


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!)


Digestive Enzymes

Different enzymes break down the three main food groups:

• Carbohydrase Carbohydrates Sugars

• Proteases Proteins Amino Acids

• Lipase Fats Fatty Acids + Glycerol


Amylase is produced in;

•Salivary Glands•Pancreas•Small Intestine

NextBack

Amylase (a carbohydrase)

Give out diagram to annotate


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.


Proteases (a group of protein enzymes)

Protease is produced in;

•Stomach•Pancreas•Small Intestine

Annotate diagram


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.


Lipase

Lipase is produced in;

•Pancreas•Small Intestine

Annotate diagram


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.


Questions

1. Where in the digestive system do the following molecules get broken down and by what enzyme?Carbohydrates Fats Proteins2. 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?


The Digestive TractorAlimentary Canal


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.


The Human Alimentary

Canal


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 digestion1. IngestionFood 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 amylaseLabel the diagram


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


2. DigestionThe stomach stores, mixes, dissolves and begins to digest food:Chemical – pepsin secreted to digest proteinsMechanical - muscles churn food in stomach juices around

**Stomach secretes hydrochloric acid pH2 (optimum conditions for pepsin)**

Label the diagram


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


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


3. AbsorptionChemical 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


VilliThe 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


4. Assimilation

Blood then transports the digested, soluble food to all parts of the body.

It is transformed into substances to aid metabolism.


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


Anything that is not digested, such as fibre, is stored in the rectum before being expelled.

Label the diagram


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.


Model gut experiment

http://practicalbiology.org/


http://practicalbiology.org/

animal nutrition wjec biology module 2 (2010-2012) © teachable and carol lekkas. some rights...

Documents

carol lekkas

diagram teachable

water teachable

stages of digestion

food food

lipase lipase

soluble molecules

fats lipids