unit3 nutritionalprocessdigestive_illnesses

Unit 3 The Nutritional Process

Index

1. Introduction

2. Digestive system

3. Respiratory system

4. Circulatory system

5. Excretory system

1. Introduction

There are 4 system involved in nutrition:Digestive system:

- digestive tract-associated glands

Respiratory system:-respiratory paths-lungs

Circulatory system:-heart-blood-blood vessels

Excretory system:-kidneys-urinary tracts

Products expelled Organ

Carbon dioxide Lungs

Urea, water and salts Kidneys

Faeces Intestin

Substances which enter the organism:

• air• water• foods

Products expelled by the organism (waste products)

2. Digestive system

2.1 Main parts

Gut (digestive tube)

• mouth•pharynx• oesophagus• stomach• small intestine• large intestine

Glands

• salivary glands• liver• pancreas

(it contains amylase)

(it does not contain any enzyme)

(It contains lipase, pancreatic amylase, protease)

SALIVA

BILE

PANCREATIC JUICE

2.2 The digestive processThere are three phases in food processing:

-Digestion (mouth, stomach and small intestine) separation of substances (nutrients) that can be used from the food

-Absorption (small intestine) nutrients pass into thebloodstream

-Expulsion of waste (large intestine) unusable substancesare expelled

PERISTALTIC MOVEMENTS = Movement of food through the digestive tract. It consistson the narrowing of the tube through the contraction of the muscles of the walls,what pushes the food.

2.3 Digestion

A. Types of digestion

Mechanical digestion cutting, crushing food(physical changes)

Chemical digesion substances attack the food and break it down into smaller chemical compounds (nutrients)

B. Stages of digestion

In the mouthmastication and salivation take place

The salivary glands produce saliva, a liquid containing digestive enzymes (which actchemically on the food)

Chemical digestion in the mouth amylase breaks down the starch into maltose

DIGESTION

starch maltoses

DIGESTION

Physical digestionChemical digestion

In the stomach begins gastric digestion(both physical and chemical digestion take place

simultaneously)

Movement of the walls of the stomach Food is mixed with the gastric juices,which contain HCl and enzymes

http://www.youtube.com/watch?v=URHBBE3RKEs = gastric digestion

As a result of gastric digestion, a pulp known as chyme leaves the stomach via the pylorus

First section of the small intestine(duodenum)

Chemical digestion the chyme is mixed with

intestinal juices. They come from

• the walls of the duodenum

• the liver produces bile

• the pancreas produces pancreatic juice

The result is called chyle

2.4 Absorption (in the jejunum and illeon)

The digested food (nutrients) passes into the

bloodstream through the intestine’s walls.

The walls of the intestine are filled with intestinal hairs (deep folds in the wall and manyblood vessels) this increases the efficiency of absorption considerably.

• Functions

• water and some ions pass into the bloodstream (absorption ofwater and ions)

• faeces are released through the anus

2.5 Large intestine

Leftovers and water arrive to the largeintestine.

Page 65, activities 1 and 3

http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related = digestion and absorption

2.6 Some illnesses

Cavities destruction of teeth due to attacks from the bacteria which live in the mouth

Gastritis inflammation of the walls of the stomach. It makes digestion difficult.

Gastroenteritis caused by a virus or bacteria, producing vomits, fever or diarrhoea.