The Human Digestive System - Ms. Teng's...
Transcript of The Human Digestive System - Ms. Teng's...
1 ANIMALS Digestive System Oral Cavity and Esophagus.notebook
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The Human Digestive System
1 ANIMALS Digestive System Oral Cavity and Esophagus.notebook
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The Human Digestive System
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You are a tube inside a tube…
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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
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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
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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
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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
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• 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.
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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
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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.
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Oral Cavity (The Mouth)
Chemical Digestion:
Chemical digestion in the mouth involves the enzyme amylase.
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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.
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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
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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.
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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?
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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.