Lesson 1 - Structure and Function of Digestive System PDF Slides

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Nutrition for Healthy Living

Lesson 1: Structure and Function of the Digestive System

Unit 1

Food Groups and Digestion

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Lesson 1 Learning Objectives

• Understand the structure and functions of the digestive system

• Outline the roles of the digestive organs

• Describe movement through the digestive system

• Describe the role of digestive enzymes

• Describe digestion of carbohydrates, fats and proteins

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Functions of Digestive System

• Breakdown of foods

• Extraction of nutrients for use around the body

• Extraction of water for use around the body

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Structure of Digestive System

• Mouth

• Oesophagus

• Stomach

• Duodenum

• Small intestine

• Large intestine (including colon and rectum)

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Role of Digestive Organs - Mouth

• Teeth and saliva work to breakdown food

• Saliva contains the ENZYME SALIVARY AMYLASE

• Breaks starch in to sugars

• Passes easier along the oesophagus

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Role of Digestive Organs –

Oesophagus

STRUCTURE

• Muscular tube

• Leads the pharynx to the stomach

• First key organ in the digestion process

FUNCTION

• Carry food to stomach

• Moves via muscular contraction

• Known as peristalsis

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Role of Digestive Organs – Stomach

STRUCTURE

• Rounded and hollow

• Innermost layer (mucosa – mucous membrane)

• Elastic – expanding and relaxing

• Sphincters at top and bottom prevent back flow and ensure control

• Food enters from oesophagus and leaves into the duodenum (1st part of the small intestine)

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Role of Digestive Organs – Stomach

FUNCTION

• Digests proteins and fats through enzymatic reactions

• Gastric juices breaks down food further

• Absorbs alcohol

• When food is partly digested, the mass is known as chyme

• Chyme moves from stomach to small intestine

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Role of Digestive Organs – Small

Intestine

STRUCTURE

• 7 metres long

• 3 sections (duodenum, jejunum and ileum)

• Inner wall covered in villi, tiny finger like projections which increase area for absorption

FUNCTION

• Completes the chemical digestion process

• Absorption of nutrients take place here

• Absorbed through the villi into blood

• Site for water absorption too

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Role of Digestive Organs - Pancreas

STRUCTURE & FUNCTION

• Behind the stomach

• Works with digestive and endocrine system to produce enzymes

• Pancreatic enzymes break down CHO, protein and fat

• Break down food, stores insulin and glucagon

(glycogen back to glucose)

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Role of Digestive Organs – Gall

Bladder

STRUCTURE

• Pear shaped

• Stores bile made from the liver

• Bile used to digest food

• Bile emulsifies fat and allows for absorption of fats

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Role of Digestive Organs –

Duodenum

• Monitors content of chyme via sensors

• Proteins and fats cause hormone to released bile from gall bladder

• Bile reaches duodenum where is breaks fats down by enzyme pancreatic lipase

• Absorption of vitamins, minerals and nutrients takes place here

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Role of Digestive Organs – Jejunum

• Section where the villi line the walls

• The majority of absorption is carried out in this section

• Simple sugars, water soluble vitamins and amino acids

Role of Digestive Organs – Ileum

• Final stages of absorption occur

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Duodenum

Role of Digestive Organs

Jejunum

Ileum

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Role of Digestive Organs – Large

Intestine

STRUCTURE

• 1.5m long

• Four sections: caecum, appendix, colon and rectum

• Deals with waste

FUNCTIONS

• Formation of Vit B and K

• Reabsorb remaining water

• Eliminate waste and undigested foods

• Results in faeces – passed to colon

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Peristalsis

• Term used for the movement of food through digestive system

• A series of smooth muscular contractions

Contraction

Muscular Wall

Chyme

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Organ

Mouth

Salivary Glands

Digestive Enzymes

Secretion

Salivary amylase

Action

Converts starch into sugars

Pancreas and

Duodenum Lipase

Coverts fats into fatty acids

Stomach Pepsin Digestion of proteins

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Summary Video

External Video available in Resources Section https://www.youtube.com/watch?v=b20VRR9C37Q

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Summary

• Identified the structure of the digestive system

• Determined the route which food takes in order to be digested

• Identified that the small intestine has 3 sections and each are important for the absorption of nutrients

• Highlighted the key enzymes responsible for digestion

• Described the process of digestion of carbohydrates, proteins and fats.

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ANY QUESTIONS?

If you need any support please do not hesitate to get in contact with your mentor.

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Activities

• Complete the Quiz

‘Quiz Yourself from Lesson 1’

• Label the blank Digestive System

Diagram

• Download/Print any resources you need for Lesson 2

• Take a 15 minute break

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End of Lesson 1

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