Cancer cells are cells that basically bypass any sort of regulatory processes in the cell cycle (and mitosis - the splitting of the cell). This leads to uncontrollable cell growth/duplication which hence leads to more and more cancerous cells. Cancer itself is so hard to cure for a couple of different reasons. If the cells are in the form of a benign tumor, that is a tumor that does not spread from its original infected tissue, it should be "easy" to remove with surgery. However, if it metastasizes, or spreads into surrounding tissues through the lymph or blood systems, then it becomes even harder to remove because of its far reach and complex structure. Also, cancer cells can be simply described as normal body cells that have gone rogue. That being said, things such as antibiotics, that are designed to get rid of foreign bodies, cannot get rid of cancerous cells without getting rid of most of your regular body cells as well simply because they cannot tell the difference.
Hope this helps :)
First it is a kind of protein that is capable of pumping out compounds. For example, sodium potassium ATPhase is a transmembrane pump that pumps out 3 Na+ ions for the cell.
It is prevented by heat capacity
Answer:
In our respiratory system, there is a pair of external nostril situated above the upper lip that receives atmospheric air and passed to the pharynx (a common passage for air and food). The pharynx passed this air to the trachea via larynx (known as the soundbox). The trachea is an extended part which is divided into left and right primary bronchi. Bronchi divide into secondary bronchi, tertiary bronchi, and bronchioles that ending up in thin terminal bronchioles. Each terminal bronchiole constitutes a number of irregular-walled, thin and vascularised bag-like structures called alveoli which are the primary sites of gases exchange.
