A student wrongly stated that an enterocyte has many cilia on its apical surface. Explain the difference between a cilium and a microvillus.
Suggest one role of the mucus secreted by the goblet cells of the villus.
In Fig. 1.1, blood vessel X carries blood to the capillary network of the villus, where tissue fluid is formed. Some of this fluid returns to the capillaries and then enters the venule. Blood vessel X gets blood from an artery. Name the type of blood vessel represented by X.
Describe the formation of tissue fluid in the capillary network of the villus.
In response to compounds in the gut lumen, enteroendocrine cells make and release peptides (short chains of amino acids) that act as cell-signalling molecules. One such cell-signalling molecule is GLP-1. GLP-1 brings about several responses in different body cells. These include: an increase in the release of insulin from cells in the pancreas; a decrease in the release of acid from cells in the stomach. Outline, in sequence, the main stages involved in cell signalling by GLP-1.
Paneth cells are produced after the mitotic division of an intestinal stem cell during a cell cycle. Complete the cell cycle shown in Fig. 1.3 by naming, in sequence, the stages of mitosis.
One function of a Paneth cell is to synthesise and secrete peptides and proteins that act against pathogens in the gut lumen. State and explain the evidence, visible in Fig. 1.2, which suggests that a Paneth cell: • is a secretory cell • synthesises many peptides and proteins.
Explain why a Paneth cell has a very different appearance to an intestinal stem cell.