How does the nicotine from cigarette smoking disrupt oxygen distribution to the cells?

 

1. It restricts air flow through the bronchi.
2. It reduces the surface area of the alveolar sacs.
3. It binds to hemoglobin in red blood cells.
4. It affects the nerve signals that regulate breathing.

 

4.It affects the nerve signals that regulate breathing.

Step-by-step explanation

Nicotine, a strong alkaloid, in its pure form is a clear liquid with a characteristic odor. It turns brown on exposure to air. It is water soluble and separates preferentially from organic solvents. It is an amine composed of pyridine and pyrrolidine rings.

Nicotine absorption can occur through oral mucosa, lungs, skin or gut. The increase in pH of a solution causes an increase in concentrations of uncharged lipophilic nicotine, in this form it can actively pass through all biological membranes. Nicotine once ingested, is absorbed and metabolized by the liver. The metabolic process can be categorized into two phases.

Nicotine acts via 3 major mechanisms, producing physiological and pathological effects on a variety of organ systems.

1. Ganglionic transmission.
2. Nicotinic acetylcholine receptors (nAChRs) on chromaffin cells via catecholamines.
3. Central nervous system (CNS) stimulation of nAChRs.

The effects of nicotine on respiratory system are twofold. One, directly by a local exposure of lungs to nicotine through smoking or inhaled nicotine, and second via a central nervous system mechanism. Nicotine plays a role in the development of emphysema in smokers, by decreasing elastin in the lung parenchyma and increasing the alveolar volume. Nicotine stimulates vagal reflex and parasympathetic ganglia and causes an increased airway resistance by causing bronchoconstriction. Nicotine alters respiration through its effects on the CNS. The simultaneous effect of bronchoconstriction and apnea increases the tracheal tension and causes several respiratory disorders. In a study microinjection of nicotine were administered to the prebotzinger complex and adjacent nuclei in the brain. The firing pattern of the brain signals and breathing pattern were monitored. There was an increased frequency of bursts and decreased amplitude and a shallow and rapid rhythm of respiration.