Chapter 17 – Part I

• Alimentary canal• Mouth• Pharynx• Esophagus

Can you sort out the statements into True and False?

Carbohydrates, proteins and fats are all made up of carbon, hydrogen, nitrogen and oxygen.

Fats are made up of smaller units called amino acids

Starch is a large carbohydrate molecule

Starch molecules can be broken down by amylase.

Proteins are made up of one or more glucose molecules

Proteins are important for the growth and repair of cells

How do we break down the food we eat?

1. Mastication/Mechanical

2. Chemical Digestion

teeth

bile

stomach acid

enzymes

The Alimentary CanalThe alimentary canal (or gut) is the tube within the body through which food passes and is processed in various ways

1.  Mucosa - protects tissues and carries absorption

2.  Submucosa - glands, blood vessels, nerves

3.  Muscular Layer - smooth muscle tissue, circular & longitudinal fibers, pushes food  (PERISTALSIS)

4.  Serosa (serous layer) - visceral perineum, outer covering of the tube, lubricates surfaces (serous fluid)

Layers of the Alimentary Canal

The Mouth

TeethEnamel is the hardest substance in the human body.

 Incisors –cutting and chopping food

Cuspid (canine) – sharp and pointed for cutting and tearing food

Bicuspids – cutting and chopping

Premolars – crushing and grinding food

Molars - grinding and mashing food

• Get a mirror and look at a partner’s teeth. Identify each type of tooth – count them

• A dentist would write your dental records as:

I: 2/2 C:1/1 PM: 2/2 M: 3/3.What do you think this means?

Dental Caries

What causes tooth decay?Saliva is slightly alkaline – it’s not that!

When we eat, bacteria in your mouth feeds on the sugar and turns it to acid. The acids wear away the enamel.

Decay has started in the

enamel

NO PAIN

Decay has reached the

dentine

SLIGHTTOOTHACHE

Decay reaches the

pulp

SEVERETOOTHACHE

Decay has spread down to the nerve

rootEXCRUCIATING

PAIN!!

Meth Mouth

Dry mouth –xerostomia (no neutralization of acids)

Shrinking blood vessels

Erosive chemicalCompulsive grindingDesire for sugar

Wisdom teeth

Digestion ‘the breakdown of large insoluble molecules into soluble molecules’

Absorption – only small particles can pass through cells, but large molecules can be broken down into smaller ones

TASK: Copy and complete this diagram into your notes:

starchstarch

starch

starchG

G

G

GUT INSIDE THE BODY (BLOOD)

G

G

G

BEFORE ABSORPTION

GUT INSIDE THE BODY (BLOOD)

AFTER ABSORPTION

Digestive Enzymes There are 3 main types of digestive

enzymes:Amylase breaks starch down into

glucose.Protease breaks protein down into

amino acids.Lipase breaks fats down into fatty

acids and glycerol

Salivary Glands

Saliva is mixed with food during chewing

Teeth assist the mechanical breakdown of food

Saliva contains the enzyme amylase which starts the digestion of food

Saliva contains mucus that keeps the mouth moist and lubricates food for easier swallowing

Digestive Enzymes

Amylase

StarchGlucose

Protease

ProteinAmino Acids

Glycerol

Fatty Acid

Fatty Acid

Fatty Acid

Glycerol

Fatty Acid

Fatty Acid

Lipase

Fat Fatty Acids and Glycerol

Digestive Juices SALIVA

•Salivary amylase

GASTRIC JUICE•Hydrochloric acid•Pepsin (protease)

LIVER •bile

PANCREATIC JUICE•Pancreatic lipase•Proteases (trypsin)

INTESTINAL JUICE•Mucus, various enzymes

Peristalsis

http://nutrition.jbpub.com/resources/animations.cfm?id=1&debug=0

Pharynx  nasopharynxoropharynxlaryngopharynx  

  

Esophagusesophageal hiatus is where it penetrates the diaphragm cardiac sphincter at entrance to stomach