Drugs
A drug is any substance taken into the body that modifies or affects chemical reactions in the body.
There are two types of drugs: Medicinal Drugs(to reduce symptoms like headaches, bacterial infections) and Misused Drugs(taken to provide stimulation, induce sleep and create hallucinations(recreational drugs), often illegally)
Medicinal drugs:
Antibiotics-
This has to be a chemical that destroys the pathogen without harming the tissues of the host.
Eg: Penicillin, produced by mould fungus Penicillium
How do antibiotics act on the pathogen without harming the host cell?
- They act by destroying the cell wall. Since animal/human cells do not contain a cell wall, the hosts cells are not affect and the pathogens are targeted and removed.
- They can also act on 70S ribosomes, since human/animal cells produce 80S ribosomes. Thus, they do not affect the host cell.
ANTIBIOTICS DO NOT ACT ON VIRUSES
This is because they viruses make use if the host cell to survive.
It is also important not to use antibiotics in a diluted form, for too short a period or for a trivial complaints. It is also crucial to finish the course of the antibiotic as some of the bacteria that is being used to destroy will not be killed, but will become resistant to the antibiotic. This causes the antibiotic to become less effective. Eg:- MRSA(methicillin-resistant Staphylococcus aureus)
Misused Drugs
Narcotics
Heroin, morphine(depressants), codeine- made from Opium
Once gotten addicted to, it gives temporary “high” feelings. When tried to give up, these drugs cause severe withdrawal symptoms.
Alcohol
Alcohol acts as a depressant of The Central Nervous system. Small amounts give a sense of well being and release from anxiety. However, it causes a fall-down in any activity requiring skill
It also gives a misleading sense of confidence(drunken drivers think they are driving extremely well)
Even a small amount in our blood increases our reaction time(the interval between receiving a stimulus and making a response)(DON’T DRINK AND DRIVE)
It causes vasodilation in the skin, giving a sensation of warmth but in fact leading to a greater loss in body heat.
Different amounts can lead to unconsciousness and even to death.
The liver treats alcohol as a toxin and 90% of the alcohol is detoxified in the liver———— the oxidation of alcohol to carbon dioxide and water. Only 10% is excreted by the kidneys
When the level of alcohol in the blood builds up to toxic proportions, it is called intoxication
Some ppl build up a tolerance and dependence to alcohol, called alcoholism.
High doses of alcohol can cause the liver cells to form too many fat droplets, leading to the disease cirrhosis.(A cirrhotic liver is less able to stop poisonous substances in the intestinal blood from reaching the general circulation.
Pregnancy
Drinking alcohol during pregnancy can present a major risk to the developing fetus(Fetal Alcohol Syndrome(FAS))
Behaviour
Alcohol reduces inhibitions because it depresses the part of the brain that causes shyness. It can lead to being outroverted but can also lead to irresponsible behaviour like vandalism and aggression.
Moderate Drinking
A moderate intake of alcohol is ok
Upper limits of alcohol for men: 21-28 units ——————over a one week period
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Upper limits of alcohol for women: 14-21 units ——————————
Pregnant women should avoid alcohol together
Smoking
The short- term effects of smoking cause the bronchioles to constrict and the cilia lining the air passages to stop beating
The smoke also makes the lining to produce more mucus
Nicotine, the addictive component of tobacco smoke, produces an increase in the rate of the heartbeat and a rise in blood pressure
It may, in some cases cause an erratic or irregular heartbeat and a rise in blood pressure.
Tar in cigarettes causes lung cancer.
Carbon monoxide permanency binds with haemoglobin in RBC , reducing the smokers ability to provide oxygen to respiring cells. This results in the smoker getting out of breath easily and reduces physical fitness
The long term effects can be severe, disabling and often lethal
Lung Cancer
Cancer is a term used for diseases in which cells become abnormal and divide out of control. Tar , a carcinogen(cancer causing substance, increases the risk of the lungs becoming cancerous.
This causes tumours to develop(balls of abnormal cells which do not allow gaseous exchange like normal cells)
The higher the no o cigarettes soaked, the greater the risk of cancer.
Chronic Obstructive Pulmonary Disorder(COPD)
Eg:- Chronic Bronchitis, Emphysema and Chronic Obstructive Airways Disease.
Symptoms are breathing difficulties (because of the narrowing of the airways(bronchi and bronchioles)), breathlessness when active, frequent chest infections and a persistent cough with phlegm
Emphysema
Emphysema is a breakdown of the alveoli. The action of one or more substances in tobacco smoke weakens the walls of the alveoli. This results in smoker’s cough which may burst some of the weakend alveoli. In time, the absorbing surface of the lungs is greatly reduced. Then the smoker cannot oxygenate his or her blood properly and the least exertion makes one breathless and exhausted.
Chronic Bronchitis
The smoke stops the cilia from beating in the air passages and so the irritant substances in the smoke and excess mucus collect in the bronchi. This leads to an inflammation called bronchitis
Heart Diseases
Coronary Heart disease is the leading cause of death in most developed countries. It results from the blockage of the coronary artery by fatty deposits. This reduces the supply of oxygenated blood to the hear and may lead to heart failures. High BP, diets with too much animal fat and lack of exercise also may cause it, but mostly it is caused by smoking.
The nicotine and carbon monoxide from cigarette smoke increase the tendency for the blood to clot and so block the coronary arteries, already partially blocked by the fatty deposits. The carbon monoxide increases the rate at which the fatty material is deposited at the arteries.
Other risks
Leg amputations
Strokes
Cancer of the bladder
Babies born to smokers are smaller in average
Twice the frequency of miscarriages
50% higher still- birth rate for babies
26% higher death rate for babies
Passive Smoking
It is not only the smokers who re affected but even the non- smokers in the same room are affected
Reducing the Risks
By giving up smoking, a person who smokes unto 20 cigarettes a day will, after 10 years, be at no greater risk than a non- smoker of he same age. A pipe or cigar smoker, provided he or she doesn’t inhale, is at a less risk than a cigarette smoker but greater risk than a non- smoker
prepIGCSE 