the use of some fertility drugs can increase the probability of having fraternal twins to 1in 5. The probability of having identical twins is unaffected. How might these drugs affect the body? Explain

Drugs affect your body's central nervous system. They affect how you think, feel and behave. The three main types are depressants, hallucinogens and stimulants:

Depressants slow or 'depress' the function of the central nervous system. They slow the messages going to and from your brain. In small quantities depressants can cause a person to feel relaxed and less inhibited. In large amounts they may cause vomiting, unconsciousness and death. Depressants affect your concentration and coordination, and slow your ability to respond to situations. It is important to not operate heavy machinery while taking depressants. Alcohol, cannabis, GHB, opiates (heroin, morphine, codeine) and benzodiazepines (minor tranquillisers) are examples of depressants.

Hallucinogens distort your sense of reality. You may see or hear things that are not really there, or see things in a distorted way. Other effects can include emotional and psychological euphoria, jaw clenching, panic, paranoia, gastric upset and nausea. Ketamine, LSD, PCP, 'magic mushrooms' and cannabis are examples of hallucinogens.

Stimulants speed or 'stimulate' the central nervous system. They speed up messaging to and from the brain, making you feel more alert and confident. This can cause increased heart rate, blood pressure and body temperature, reduced appetite, agitation and sleeplessness. In large amounts stimulants may cause anxiety, panic, seizures, stomach cramps and paranoia. Caffeine, nicotine, amphetamines (speed and Ice), cocaine and ecstasy (MDMA) are examples of stimulants.

Explanation:

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