When you smoke a cigarette, the components; e.g. nicotine and carbon monoxide enter the lungs and are absorbed into the bloodstream. They are carried by the Red Blood Cells to the blood-brain barrier, here, nicotine binds to nicotinic acetylcholine receptors (nAChRs), resulting to a cascade that results to release of dopamine (good-feeling neurotransmitter).
Answer:
The nucleus, cell membrane and cytoplasm.
Explanation:
The nucleus, cell membrane and cytoplasm are three elements that cannot be absent in a cell because they are necessary for the survival of the cell. The nucleus controls and regulates the activities happening inside the cell e.g. growth and metabolism etc. Cell membrane acts as a wall to protect the inner part of the cell from the external environment as well as allows nutrients and gases inside and outside the cell. Cytoplasm serves as a medium for the conduction of nutrients and waste from on place to another and also for the medium for organelles in which they floats.
Answer:
The first line of defense involves skin.
