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Digestion
Digestion – when complex foods are broken down into small water soluble molecules that can
be absorbed into the body
2 phases

Mechanical Digestion– When food is mechanically broken into smaller pieces by the chewing
action of the teeth and the surface area of the food is increased for phase 2
Chemical Digestion – Protein enzymes are secreted from the glands of the digestive system
and symbiotic microorganisms complete the breakdown of the food
Micro Fauna – Responsible for the digestion of food and the production of vitamins in the
intestine
Probiotic Bacteria- Bacteria that survive the digestion process and then colonize your
intestine
2 glands that secrete enzymes

-Organs of the alimentary canal “food tube” (stomach, etc)

-Ducted Glands which deliver chemicals to the digestion system through tubes or ducts (liver,
pancreas)
Alimentary Canal - The whole passage along which food passes through the body from mouth
to anus
...

Muscular Pharynx- a cone shaped passageway leading from the oral and nasal cavities to the
esophagus, it serves both respiratory and digestive functions

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Salivary glands in the cheeks

Parotid – located in the cheeks in front of the ears
Submandibular – located under the lower jaw
Sublingular – located under the tongue
All 3 produce saliva carried by ducts that emerge behind the lower front teeth
Saliva - a calcium rich substance that when mixed with bacteria forms plaque on the teeth
...

5 different functions of the tongue
Taste – There are 4 sets of chemical sensors called taste buds that screen food for nutrients
and poisons
...

Bitter – detects chemical bases which are often poisonous

Sour –detects acids like ascorbic acid (vitamin C)

Salt - important to maintain body chemistry

Sweet- detects carbohydrates which are important sources of
energy
Helps you chew - it holds your food against your teeth

Helps you swallow

Cleans the inner surface of your teeth

It is essential for speech

Teeth – each mammal has a set of differentiated teeth where each tooth has a specific job
...
Pockets of gas in your teeth can indicated
where a person has lived
Deciduous – baby teeth that fall out to be replaces by your adult set when you are about 6
years old
Incisors – Sharp edged nipping or cutting teeth
...

Premolars / bicuspids – grinding teeth that specialize in foods of medium hardness
Molars / tricuspids - grinding teeth that specialize in foods of greater hardness
Third Molar/ wisdom tooth – comes in, in early adulthood (17-21) to replace worn out teeth
but are not needed due to modern dentistry
Human Dental Formula - 2 1 2 2/3

2 1 2 2/3

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Esophagus and Stomach

food passes from the pharynx into the esophagus
Esophagus - A muscular tube about 30 cm long that connects the pharynx to the cardiac
valve
...
Gastric Juice consists of:
Pepsin - an enzyme that begins protein digestions
Hydrochloric Acid - activates pepsin, dissolves minerals, and helps destroy invading
microorganisms
...

Mucous – protects the stomach wall from acid and pepsin in order to prevent gastric
ulcers
*Gastric juices are unable to digest carbohydrates
Stimulation of Gastric Juices 

-swallowing food

-sight of food

-smell of food

-taste of food
Gastric Ulcers - are often associated with Helicobacter Pylori bacteria as well as stress
...
It is produced in
the liver, stored in the gall bladed and transported through the common bile duct
Pancreatic Fluid- is produced in the pancreas and enters the duodenum through the common
bile duct
...
Secretes insulin
...
The common bile duct is formed by the
junction of the cystic duct that comes from the gallbladder and the common hepatic duct
that comes from the liver
...
Most nutrients are
absorbed in the first metre
Ileum - consists of the last 4
...
Very little nutrients are absorbed
here
...

leading

Ileitis – an autoimmune disease where the immune system attacks section of the ileum
to parts of it needing to be removed
...

Caecum- a small extension of the colon, it stores symbiotic microorganisms
Appendix - located at the end of the Caecum, it is a vestigial organ
Appendicitis –Inflammation of the appendix, usually leading to removal of the appendix
Colon – responsible for reclamation of water and forming feces
...
Wastes are
released through a sphincter muscle in the anus
...

Autoimmune disease – a disease in which your immune system targets a part of your own
body not normally harmful and attacks it

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