Final answer:
The cephalic phase of digestion begins with sensory stimulation (sight, smell, thought of food), leading to increased saliva production from the salivary glands and gastric juice release from the stomach lining. Saliva contains enzymes like amylase for carbohydrate digestion, while gastric juice has hydrochloric acid and enzymes for overall digestion preparation. The CNS coordinates this phase, getting the stomach and digestive muscles ready for food.
Step-by-step explanation:
Cephalic Phase of Digestion
The cephalic phase of digestion is an early stage in the digestive process that begins when the senses trigger a neural response to the anticipation of food. When we see, smell, or even think about food, our digestive system starts preparing for the meal to come. The main secretions during this phase are saliva from the salivary glands and gastric juices from the stomach.
- Salivation: Triggered by the autonomic nervous system, the salivary glands produce more saliva in response to the anticipation of food. Saliva contains enzymes like amylase that begin the digestion of carbohydrates right in the mouth.
- Gastric Juice Secretion: The stomach begins to secrete gastric juice, which contains hydrochloric acid and digestive enzymes. This secretion is stimulated by the brain's response to the senses associated with food and helps to prepare the stomach for digestion.
The gland of origin for saliva is the salivary glands, while gastric juices originate from the stomach lining. The stimulation for their release is the neural response to sensory interactions with food such as sight, smell, and thought.
The brain exerts control over this phase, preparing the muscles of the digestive tract, including the esophagus, for peristaltic movements. Additionally, the central nervous system (CNS) plays a role in the preparation of the stomach by signaling the release of these digestive secretions.