GI 4 Flashcards
What are the three functions of the mouth?
- Mechanical breakdown of food
- Preparation for swallowing
- Onset of digestion
How does the mouth mechanically breakdown food?
By mastication (chewing)
Which facilitates the mastication in the mouth?
Teeth and facial muscle
How does the mouth prepare food for swallowing?
By moistening of the food bolus using saliva
How does the mouth begin the onset of digestion?
Through enzymatic breakdown of carbohydrates with salivary amylase
What is a muscle that helps with mastication?
The masseter
What does Salivary amylase breakdown?
Carbohydrates
What is the breakdown due to Amylase more to do with?
Taste rather than digestion and absorption
What is the swallowing reflex under the control of?
The autonomic nervous system
What is swallowing initiated by?
The voluntary collection of the food bolus into the pharynx by the tongue
What is the Oral Phase of swallowing?
The voluntary collection of the food bolus into the pharynx by the tongue
What are the three phases of swallowing?
- Oral Phase
- Pharyngeal Phase
- Esophageal Phase
What occurs in the Pharyngeal phase of Swallowing?
Involuntary contraction of the pharyngeal muscles that push the bolus into the esophagus
What occurs during the esophageal phase?
The bolus driven down by the esophagus by peristaltic contraction
Aside from swallowing, what does the swallowing reflex include?
The closure of the Glottis and inhibition of respiration
What occurs in the closure of the glottis?
The trachea raises up
What prevents food from entering the nasal passage?
The soft palate elevates
What prevents food from entering the nasal passage?
The elevation of the soft palate
Which sphincter relaxes during swallowing?
The upper esophageal sphincter
What did Horace Fletcher beleive?
That chewing your food hundreds of times would increase nutrient absorption. This was false.
What are the functions of the stomach?
- Store ingested material
- Continue digestion
- Regulate emptying into the small intestine
Which sphincter opens when food enters the esophagus?
The lower esophageal sphincter
What two types of digestion occur in the stomach?
Mechanical and Chemical
What is mechanical digestion in the stomach facilitated by?
Rugae and peristaltic waves
What facilitates chemical digestion in the stomach?
HCl and Pepsin
What does HCl in the stomach do?
- Denatures proteins
* Cleaves pepsinogen to pepsin
What does Pepsin in the stomach do?
Breaks down proteins
What is the inactive precursor of pepsin?
Pepsinogen
What converts pepsinogen to pepsin?
HCl
