PHIS 206 Lecture Notes - Lecture 24: Alpha-Amylase, Vocal Folds, Classical Conditioning
Lecture 24: Mouth to Stomach
Oral Cavity (Mouth)
• Secretion
o Secretion Saliva contains:
▪ Mucus for lubrication
▪ Electrolytes for salt balance
▪ HCO− 3 to neutralize pH
▪ Enzymes
o Chewing (mastication) begins mechanical breakdown of food and aids in
incorporation of oral secretions → increases surface area of what’s there
(increases surface area of food that you eat)
• Digestion
o Secretion of two enzymes begins digestion
▪ Ptyalin (salivary amylase) → break down carbohydrates
▪ Lingual Lipase → break down fats
• Absorption
o No designed mechanisms for absorption
o Thin mucosa and shallow vasculature does allow for non-digestive absorption
(some drugs)
• Motility
o In conjunction with esophagus (and stomach) → Swallowing
o Three phases to swallowing
▪ Oral phase
▪ Pharyngeal (or oropharyngeal) phase
▪ Esophageal phase
Salivary Control
• Many control mechanisms are reflex-based
• Reflexes can be local, or transmit extensively
• Simple reflex vs conditioned reflex (pavlov’s dogs)
Oral Phase of Swallowing
• Oral Phase
o Food in mouth
Pharyngeal Phase of Swallowing
• Epiglottis covers entrance to larynx, and vocal cords close, preventing aspiration
Peristalsis
• Think Toothpaste Tube
o Coordinated squeezing behind whatever needs to move forward
Peristaltic Wave
• Involves all layers of muscle working in unison (only innermost circular muscle layer
shown here)
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Document Summary
In conjunction with esophagus (and stomach) swallowing: three phases to swallowing, oral phase, pharyngeal (or oropharyngeal) phase, esophageal phase. Salivary control: many control mechanisms are reflex-based, reflexes can be local, or transmit extensively, simple reflex vs conditioned reflex (pavlov"s dogs) Oral phase of swallowing: oral phase, food in mouth. Pharyngeal phase of swallowing: epiglottis covers entrance to larynx, and vocal cords close, preventing aspiration. Peristalsis: think toothpaste tube, coordinated squeezing behind whatever needs to move forward. Esophageal phase of swallowing: food moves to stomach via esophageal peristalsis, swallowing reflex has two forms, 1. Primary peristalsis (all phases) - mouth throat esophagus: 2. Secondary peristalsis (esophageal only) - if swallowing is interrupted, reflex begins again in esophagus if it"s not starting in mouth, then it is secondary peristalsis. Esophagus: no secretion, or absorption, digestion can occur within bolus of food due to salivary enzymes, motility two forms of peristalsis, les (lower esophageal sphincter) controls passage into stomach.