The Use and Abuse of Drugs


Biology - 5090

The Use and Abuse of Drugs

The Use and Abuse of Drugs
A drug is any externally administered substance that changes the chemical reactions in the body

Medical Use of Antibiotics

Medicinal drugs, like antibiotics, are taken in to correct the body’s metabolism. Antibiotics only cure bacterial infections, as they are made from fungi that produce chemicals that kill the bacteria. When they are taken in, they puncture the cell wall of the bacteria causing them to burst. At times, they even stop the enzyme production or protein synthesis of the bacteria. 

Some bacteria are resistant to antibiotics which reduces the effectiveness of the antibiotic. Those bacteria have an extra coat, known as the resistant coat. If the medicine is stopped before the resistant bacteria are dead, the bacteria will reproduce. MRSA is an extremely dangerous bacteria as it is resistant to most antibiotics. To slow down and stop the development of other strains of resistant bacteria, we should:

Avoid unnecessary use of antibiotics 
Ensure a full course of treatment is completed

Antibiotics only kill bacteria, and they do not affect other cells, like viruses. This is because antibiotics kill the bacteria by damaging their cell walls. Viruses don’t have cell walls, so they remain unharmed by antibiotics. Viruses are not living cells; They are simple protein structures with no metabolism so antibiotics have no effect on them. The chemical properties of antibiotics are specific to the bacterial cell whereas viruses are much smaller in different shapes.


Heroin is a powerful depressant drug obtained from opium. It increases reaction time e.g. thinking and blinking. When a person stops the intake of heroin, they suffer from severe physiological and physical symptoms like severe body pain, nausea, headache etc. It reduces pain and slows down breathing.


Increases reaction time.
Causes inflammation of the gums
Weakens the immune system
Can lead to depression 
Can cause insomnia


Heroin abuse may increase criminal activity as addicts turn to crime, like robbery, to finance their addiction, so more opportunity to become drug dealers.
Injecting heroin can cause infections, such as HIV since a lot of these needles are not sterile and are shared amongst many people. This causes widespread disease.

Effect of Heroin On the Nervous System

There are many neurotransmitters present in the brain. One of its groups is endorphins which help reduce the sensation of pain and reduce thirst and hunger. When heroin enters the brain, it is metabolized to morphine (endorphin receptors). Morphine fits into the receptors, which makes you feel good. Intake of heroin reduces the production of endorphins. If you stop the intake of heroin, you will suffer from unpleasant withdrawal symptoms.

Withdrawal Symptoms 

Muscle cramps

Effects of Excessive Consumption of Alcohol

Alcohol is a powerful depressant drug. 

It affects the medulla of the brain which is the life-support center of the body. It can cause a halt in breathing, causing brain damage and death. Its consumption in excess decreases a person’s self-control, nervous control, and muscular control. It also affects the brain by reducing the levels of ‘calming agents’ in the brain, therefore disturbing the sleep pattern. 

Alcohol is addictive, so when you once start taking it, your body starts being dependent on it. The natural chemicals get replaced by the drugs. If you don’t take the same amount from time to time, you will suffer from severe body pain, nausea, vomiting, blurred vision, headaches etc. It will lead to the body being unfit. It can even lead to financial problems, and higher chances of the addict committing crimes. 

Excessive alcohol consumption leads to liver cirrhosis. The main function of the liver is to detoxify drugs, so when it becomes overloaded with alcohol, it will definitely get damaged. The normal liver cells which line blood vessels change to fibrous mass of cells, causing the malfunctioning of the liver. 

Long Term Effects of Excessive Alcohol

Brain damage
Mouth cancer, pancreatic cancer, liver cancer
Heart diseases
High blood pressure 
Loss in body weight
Stomach ulcers

Effects of Tobacco Smoke

Many chemicals are present in cigarettes like nicotine, tar and carbon monoxide. These harmful irritants enter the body, and cause a lot of damage. 

Carbon monoxide 

Due to the burning of tobacco, carbon monoxide is obtained. This is a highly toxic gas. When it enters the body, it combines with hemoglobin as the hemoglobin has more affinity for carbon monoxide than oxygen. As a result of this, carboxyhemoglobin is formed. This will cause a decrease in oxygen levels of our bodies. The carboxyhemoglobin will lead to anaerobic respiration as it does not allow oxygen to reach our body cells. Therefore, more levels of lactic acid will be formed in the body causing the cells to become fatigued, leading to myocardial infarction.


It is a stimulant and an addictive drug. It mimics the natural neurotransmitters in the brain which are concerned with heartbeat and blood pressure. Nicotine causes an increase in the heartbeat rate, narrowing the blood vessels which causes an increase in blood pressure. Due to the increased heartbeat, there is a higher demand for oxygen, but the presence of carbon monoxide reduces its availability, causing damage to the heart muscles.

Due to nicotine, the body fats are accumulated and deposited in the coronary arteries. This makes the lumen shorter, and oxygen will not be able to reach the heart, causing the heart muscles to be fatigued. Another effect of the fat deposition is that the coronary artery wall will break, becoming uneven. This causes blood clots to accumulate which results in cardiac arrest.


Tar is the black, sticky substance present in tobacco smoke. It is a carcinogen which mutates the cells of the respiratory tract, causing cancer. The most common ones are lung cancer, mouth cancer, and throat cancer. 

As it enters the trachea, it sticks the cilia together. This blocks the air passages and prevents mucus, secreted from the goblet cells, to enter the esophagus. Thus, the mucus will stay in the respiratory tract. This will increase the chances of bacterial infection as the bacteria are trapped in the mucus. Due to throat inflammation, the gaseous exchange passage will be narrow, and the person will face difficulties while breathing. This leads to spontaneous coughing and inflammation of the trachea. A lot of carbon dioxide will accumulate in the cells, blocking the small bronchioles with mucus. The alveoli will eventually burst, and the surface area for gas exchange decreases. This is known as Chronic Obstructive Pulmonary Disease (COPD). It includes chronic bronchitis and emphysema. Chronic bronchitis refers to spontaneous coughing, while emphysema refers to the bursting of alveoli.

Smoking and Lung Cancer

Due to the carcinogens present in tobacco smoke, the respiratory cells get affected causing uncontrollable division. The cells divide over and over again and form a tumor. If cells break away from the first tumor, cancer may spread throughout the body.

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