Question

All cells maintain a polarized plasma membrane. What role does polarization play in the function of neurons? You viewed your own cheek cells. What term best describes their shape? What is the function of the small projections (cilia) observed on the pseudostratified columnar slide? Skin cells, like those you observed in the section of scalp, produce keratin, a fibrous and water resistant protein. What role does keratin serve? What is the unifying feature of all the forms of connective tissue? What kind of cells produce the collagen found in tendon? How does smooth muscle differ from skeletal muscle? What is the purpose of the intercalated discs found in cardiac muscle? What are the three parts of a neuron? What function does the myelin sheath serve for neurons?

Answer 1

1. Polarization of membrane is meant for maintaining two different chrged molecules or ions on either side of the membrane. For example, a neuron contains Na⁺ ions outside the cell and K⁺ ions inside the cell. The cell when not transmitting electrical charges to other cells, it may contain 30 times more Na⁺ ions out side than K⁺ ions inside the cell. When the cell is electrically charged it contains more K⁺ ions inside than Na⁺ ions outside. Therefore, polarized membrane selectively allow the chraged ions and molecules to pass into cells through the membrane.

2. Cheek cells occur in circular to irregular in shape. The cells may contain very thin cell membrane.

3. Pseudostratified columnar epithelium is simlar simple stratified columnar epithelim but appears in multiple layers of cells. Pseudostratified columnar epithelium is found in trachea, small bronchi and uterine tubes. The main function of Pseudostratified columnar epithelium is to secrete mucus. The cilia present in Pseudostratified columnar epithelium are useful to propulsion of mucus.

4. Keratin is a fibrous and water resistant protein that maintains structural integrity. It acts like a protective barrier. It is tough and insoluble. Keatin is dissolved in only certain chemical substances. Keratin provides smoothness to hair cells.