Chapter+19

=**p. 205. Data-based question: The wall of the Oesophagus**=

Question 2:

 * Oesophagus transport food to the stomach.
 * This food whilst moist from mucus added in the mouth is largely insoluble and will create friction with the walls of the oesophagus.
 * Since there is no absorption in the oesophagus it can protect itself with mutiple layers much like the skin.
 * The Intestine and Stomach either have a secretory function or one of absorption for which a short distance (diffusion times) would be an advantage, hence one layer.

**Question 3.**

 * X is the circular, fibres running around the circumferance of the oesophagus
 * Y are the longitudinal, fibre running perpendicular to the circumferance of the image.

**Question 4:**

 * Mucus
 * To lubricate the movement of the food to the stomach

**Question 5:**

 * Blood supply to the muscles providing oxygen and nutrient for respiration
 * Blood supply to the dividing cells of the lining of the oesophagus to support growth of the tissue.

**Question 6:**

 * Smooth muscle under control of the autonomic nervous system. Concerned with peristalsis.
 * Striated muscle under voluntery (somatic) nervous system. Concerned with swallowing.