Video Transcript
What type of specialized cells line the stomach and small intestine? Option (A) nervous cells, option (B) epithelial cells, option (C) connective cells, option (D) alveoli, or option (E) stem cells.
To answer this question, let’s first consider the meaning of the term specialized cells. Neurons, which are nerve cells, are good examples of specialized cells. They have a number of features that make them good at their job of transmitting electrical impulses around the body, firstly their shape. They have a long axon so they can carry impulses over long distances. They have projections, called dendrites, which extend out from the cell body and receive signals from other neurons. The axon is surrounded by Schwann cells, which wrap around it forming the myelin sheath. This provides electrical insulation and increases the speed of transmission of impulses.
In contrast, stem cells are unspecialized cells. They have the ability to differentiate into different types of specialized cell, for example, a neuron. In humans, stem cells are found in both embryos and adults. Embryonic stem cells found in early-stage embryos are pluripotent. This means they have the capability to develop into any type of specialized cell. In contrast, adult stem cells are multipotent. These cells found in the bone marrow, heart, and a variety of other tissues and organs are able to differentiate into a limited number of cell types.
We now have enough information to eliminate two of our answer options. We have seen how nervous cells, or neurons, are specialized to transmit electrical impulses around the body. We can therefore eliminate option (A) nervous cells. We have also seen how stem cells are in fact unspecialized cells, so we can also eliminate option (E).
The question is asking us about specialized cells that line the stomach and small intestine. Cells that line the inside and outside of structures in our body are called epithelial cells. There are many different types of epithelial cells, each specialized for their particular role. A group of epithelial cells that work together to carry out a particular function are called epithelial tissues.
The prefix epi- means upon or around. So these epithelial tissues are found around the internal and external surfaces of our organs. The cells of an epithelium are closely joined together with little material between them. This tight packing enables epithelial tissue to work effectively as a barrier protecting the organs it lines. The stomach and small intestine are lined by simple columnar epithelium. As shown in the diagram, the cells are taller than they are wide.
We now have enough information to answer our question. “What type of specialized cells line the stomach and small intestine?” The answer is (B) epithelial cells.
