Deglutition or swallowing is probably a reflex phenomenon. Higher centres facilitate this reflex. Once aroused, the swallowing centre in the medulla evokes the complete act of swallowing by discharge through six nuclei and the motor neurones. This reflex act occurs in three stages: (1) First or oral, (2) Second or pharyngeal, and (3) Third or oesophageal (Fig. 9.46). (1) First [...]
The various humoral (chemical) factors controlling the different secretions in the gastro-intestinal tract may be summarised as follows: 1. For Gastric Secretion: i. Gastrin- Responsible for gastric phase. ii. A chemical substance may be a hormone or secretagogue - Responsible for intestinal phase. iii. Enterogastrone- Inhibits gastric secretion. 2. For Pancreatic Secretion: i. Secretin- Main chemical stimulus. ii. Pancreozymin. iii. [...]
The following types of movements are found in the human small intestine: 1. Rhythmic segmentation or Ludwig's pendulum 2. Peristalsis. Type # 1. Rhythmic Segmentation: Nature: These are rings of contraction occurring at regular space of intervals in which a portion of the intestine is divided into segments. The contraction is followed by relaxation. The contraction takes place at the [...]