• List the main functions of Gastrointestinal Tract motility

main functions are to propel digested food forward through the GIT where it can be absorbed and mixed, nutrients are absorbed in the small intestine and water is absorbed in the proximal part of the large intestine. mixing functions also prevent backflow of chyme form the rectum direction towards oral which is pathological and would cause vomiting

• Summarise the physiological mechanism of swallowing

there are 3 stages of the swallowing mechanism

stage 1 - Voluntary/Oral stage

it is the only voluntary part of the swallowing mechanism, it involves the tongue pushing food to the back of the mouth into the pharynx

stage 2 - Pharyngeal phase (involuntary)

the trachea closes and oesophagus opens

this phase carries on from phase 1, this phase occurs when the food is in the pharynx, nerves are stimulated to cause a singular peristalsis type contraction which is propelled from the pharynx to the end of the oesophagus and food is pushed down this (if the food gets stuck a further movement will be stimulated known as secondary peristalsis but usually only primary peristalsis is needed 1x)

stage 3 - Oesophageal phase (involuntary)

the food is pushed down the oesophagus coupled with the movement which is initiated in the stage 2 pharyngeal phase of the peristaltic movement, Receptive Relaxation also precedes this peristaltic. movement allowing for a better flow of food into the stomach form the lower oesophageal sphincter.

Receptive relaxation is when the muscles are relaxed in front of the peristalsis occurring to make it easier for the food to travel through, this also means the stomach becomes slightly relaxed when food enters.

• Describe the motor functions of the stomach and the processes by which they occur