1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

1

January 06, 2016

The Human Digestive System

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

2

January 06, 2016

The Human Digestive System

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

3

January 06, 2016

You are a tube inside a tube…

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

4

January 06, 2016

The Four Stages of Food Processing 1. Ingestion ­ the taking in or eating of food

2. Digestion ­ the breakdown of food by mechanical and chemical processes into molecules small enough for cells of the body to absorb

Mechanical Digestion • chewing, chopping, and grinding of food into smaller pieces, increasing its surface area•done by teeth, beak or other similar structures, and by contractions and churning motions in the stomach

The Digestive System

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

5

January 06, 2016

Chemical Digestion • the chemical breakdown of nutrient molecules into smaller molecules by enzyme action; called hydrolysis

Carbohydrates simple sugars

Lipids glycerol + fatty acids

Proteins amino acids

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

6

January 06, 2016

Chemical Digestion • the chemical breakdown of nutrient molecules into smaller molecules by enzyme action; called hydrolysis

Carbohydrates simple sugars

Lipids glycerol + fatty acids

Proteins amino acids

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

7

January 06, 2016

3.Absorption ­ the transport of the products of digestion from the digestive system into the circulatory system­ the molecules are transported in the blood to the body cells­ in the cells they are joined to make bigger molecules or broken down to provide energy

4. Elimination ­ the removal of undigested solid waste matter from the body

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

8

January 06, 2016

• to break up food particles ­ mechanical digestion • to lubricate food particles ­ saliva• begin digestion of complex carbohydrates (starches and glycogen) ­ chemical digestion

Oral Cavity (The Mouth)

The primary functions of the oral cavity (mouth) is to ...

The mouth is also used for tasting food (using the tongue) to help determine if it should be ingested or not.

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

9

January 06, 2016

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

10

January 06, 2016

Mechanical Digestion:

Mechanical digestion in the oral cavity (mouth) involves ...

Oral Cavity (The Mouth)

Teeth ­ to break up food particles (mastication)Tongue ­ position food particles Salivary Glands ­ lubricate food particles

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

11

January 06, 2016

Tooth Decay

What do you think causes tooth decay?

­ Saliva is normally slightly alkaline. ­ When we eat, bacteria in our mouth feed on sugar and turn it into acid. ­ The acid starts to attack the enamel and wear it away.

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

12

January 06, 2016

Oral Cavity (The Mouth)

Chemical Digestion:

Chemical digestion in the mouth involves the enzyme amylase.

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

13

January 06, 2016

Oral Cavity (The Mouth)

https://www.youtube.com/watch?v=pNcV6yAfq­g

The Process of Swallowing1. The tongue forces the food to the back of the throat. This is a voluntary movement.

2. The food goes from the pharynx into the esophagus using involuntary movement. The soft palate (uvula), rises to block the nasal cavity. The epiglottis closes over the respiratory passage (trachea). Muscles of the esophagus alternatively relax and contract causing a wave motion called peristalsis, that pushes the food through the canal. Peristalsis continues to move food and waste through the entire alimentary canal.

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

14

January 06, 2016

The Esophagus

This is done using a powerful, synchronized set of muscle contractions called Peristalsis.

FUNCTION:The primary function of the esophagus is to transport food from the mouth to the stomach by the process of swallowing.

mouth

stomach

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

15

January 06, 2016

The Movement of Food:Peristalsis is a distinctive pattern of smooth muscle contractions (longitudinal and circular) that propels foodstuffs distally through the esophagus and intestines.

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

16

January 06, 2016

The Esophagus

Between swallows, the esophagus usually does not contract.

­ sphincter muscle separating the esophagus from the stomach (esophageal sphincter/cardiac sphincter) normally stays tightly closed to prevent acid in the stomach from washing up into the esophagus.

­ when we swallow, this sphincter muscle opens up (relaxes) so that the food we swallow can enter the stomach.

sphincter

What happens if acid travels back up to the esophagus?

1 ­ ANIMALS Digestive System Oral Cavity and Esophagus.notebook

17

January 06, 2016

Acid Reflux

Heartburn (acid reflux)­ is caused when acid washes up into the esophagus repeatedly (gastroesophageal reflux or GERD) and irritates the lining of the esophagus.

­ the esophageal sphincter separating does not work properly; the function of this sphincter is to prevent reflux from occurring when the stomach contracts.