CLASSIFICATION AND EFFECTS OF DRUGS ON HUMAN HEALTH

The psychotropic drugs act on the mind in various ways. Depending on how they act, they have been classified into four major groups given below.

(i) Sedatives and tranquillizers, e.g. valium, etc.
(ii) Opiate narcotics, e.g. opium, morphine, heroin, etc.
(iii) Stimulants, e.g. caffeine, cocaine, amphetamines, etc.
(iv) Hallucinogens, e.g. LSD, mescaline, charas, bhang, hashish, marijuana, etc.
Effects of the drugs according to classification are given below:

1 Sedatives and tranquillizers (depressant)

a. Valium, Calmpose, Trytanol
They depress the activity of central nervous system and produce a feeling of calmness and relaxation. They decrease anxiety temporarily and reduce the sensitivity to the world around the user. They bring drowsiness and in higher doses induce deep sleep. They help to relieve pain. So they are used by doctors to relieve pain, induce sleep and to reduce emotional anxiety. Tranquillizers are the drugs that reduce tension and anxiety, bring calmness without inducing sleep.

b. Barbiturates
Barbiturates are synthetic drugs commonly called as sleeping pills. They are used to decrease anxiety and induce sleep. As such they are not addictive but a person may develop emotional dependence on them. In such cases it is difficult to withdraw from them as the person suffers from withdrawal symptoms when deprived of the drug. Barbiturates have two more severe hazards in the society: They are frequently used in higher doses for suicide. They are lethal for the body when taken with alcohol, can lead to tragic death.

2 Opiate narcotics or narcotic drugs

a. Opium
It can be taken orally in powder form, or inhaled (smoked) or taken in the form of injections. Opium is extracted from the juice of white poppy capsule Papaver somniferum. It is reddish brown, has strong smell and is bitter in taste. It is eaten or smoked. People addicted to opium, show loss of weight, sterility and total loss of interest in work. They show severe withdrawal symptoms if drug is not made available thus they degrade the human health. An overdose may stop respiration and lead to death.

b. Morphine and Codeine
Morphine is the active ingredient of opium and is used to relieve pain. It is valuable as an analgesic. It leads to addiction. Codeine is a mild analgesic. In small doses it does not cause addiction. It is an ingredient of certain medicines like cough syrups.

c. Heroin
Heroin is highly addictive and so dangerous to human health that its use in medicine is also illegal. It is taken orally, inhaled or injected. It is often diluted with harmful substances before injected into the human body. Also the needles or syringes used are not sterile. Hence these drugs addicts often suffer from secondary illness like blood poisoning, formation of abscess, serum hepatitis and AIDS. As heroin addicts are dependent on the drug, failure to get it causes severe withdrawal symptoms like vomiting, diarrhea, shivering, twitching, perspiration, abdominal cramps and muscle cramps.

3 Stimulants

a. Caffeine
Caffeine is a mild stimulant and is found in the leaves of tea plant, seeds of coffee and cocoa plant. It is commonly taken in the form of beverages like tea, coffee, cocoa and cold drinks. It increases alertness and thought. Excessive use of caffeine causes addiction.

b. Cocaine
Cocaine is extracted from the leaves of the South American cocoa plant. (It is different from the beverage cocoa). Cocaine causes a feeling of excitement and increases self-confidence. It causes temporary stimulation of nervous system and feeling of enlightment. Later person gets a feeling of fear and turns violent. It is also used as local anesthesia by doctors.

c. Amphetemines
Amphetemines are synthetic drugs often used as pep pills. These are often taken by truck drivers and night workers to keep themselves awake, without realizing that these also cause blurred vision and impair judgement. Higher doses can cause hallucinations. Weight watchers use them to reduce their appetite.

4 Hallucinogens
Hallucinogens are also known as psychedelic, or mind expanding drugs. LSD, mescaline, psilocybin and products of hemp plants like charas, bhang, marijuana, hashish. Hallucinogens alter a person's thoughts, feeling and perceptions. The person claims to see sounds, and hear things that do not exist.

a. LSD (Lysergic acid diethylamide)
LSD is the most dangerous hallucinogen. It is obtained from the argot fungus. An LSD drug even in very small amounts like 1 µg per kg of body weight induces psychedelic trips. The user sees bright lights, strange shapes and a feeling of outside their bodies. It causes severe damage to the nervous system.

b. Mescaline
Mescaline is extracted from the spineless cactus that grows in south – west America. The drug is used to get kicks and has similar effects like other hallucinogens.
c. Psilocybin
Psilocybin is extracted from certain mushrooms. It is also taken to get kick and causes hallucinations.
d. Products of hemp plant charas, bhang and ganja, marijuana and hashish
All these are obtained from the dried leaves and flowers parts of the hemp plant Cannabis sativa. These drugs are commonly taken by drug users in India. The reaction depends upon the amount and strength of drug used. The user feels relaxed, elated and high. However may become moody and violent. They lose the sense of timing and judgement and see and hear objects. These drugs have dangerous often fatal effects when taken along with other drugs like heroin and when taken in combination with alcohol.

Introduction to Drugs

Drugs
Definition: By the definition, the term drug can be defined as any substance used in the composition of a medicine. In medical terms a drug is defined as any chemical substance which taken into the body, alters the way the body functions. It means a drug may modify one or more of the body's physical or mental functions.

Uses of Drugs
Drugs are used in a number of ways.
Drugs are prescribed as medicines to prevent or cure a variety of disease. Some drugs help to fight against infections.
Drugs may be used to promote better physical and mental health.
A number of drugs are used to alleviate anxiety, reduce pain or insomnia.
Drugs may be used to alter the mood. Such drugs are termed as mood – altering drugs.

The drugs should be used under medical advice only. Self – medication may be very harmful because drugs do have harmful side – effects. Some drugs like mood – altering drugs have a particular risk of a patient becoming totally dependent on them called drug dependence. They are habit forming drugs, also called as psychotropic drugs.
In this topic we will only come to know about the habit forming drugs in detail.

Psychotropic Drugs
(i) Psychotropic drugs act on the brain and affect its normal functioning. They slow down and interfere in the functioning of the nervous system.
(ii) Psychotropic drugs alter behavior, consciousness and powers of perception. They alter the mood of a person, hence are called as mood – altering drugs.
(iii) Psychotropic drugs have a visible effect on the behaviour of a person.
(iv) Psychotropic drugs impair the person's judgments.
(v) Psychotropic drugs make a person increasingly dependent on them. Therefore they are called as habit forming or addictive drugs. They lead to both physical and mental addiction.
Certain Terms Related to Habit Forming Drugs
Given below are certain terms to drug addiction which will often used in this topic.

Tolerance: - Tolerance to a drug means less response to a specific dose with repeated use. That means body has developed resistance to the effect of the drug. Now the person needs more of the drug to get the desired effect. For example, when a person takes 1 microgram of a drug for the first time, the response he gets is far more than when he takes it the hundredth time. Now he needs to take much more the amount for the same effect.

Drug Addiction: - Drug addiction means that after a drug has been taken for some time, it is very hard to give up its use. It is state of periodic and persistent urge, deterimental to the health of individual and society. The person who becomes addicted is known as addict.
An addict shows the following characteristics:
(i) A strong urge to continue taking the drug.
(ii) Progressive tolerance to the drug, that is increasing the dose of drug to get desired effects.
(iii) Physical and mental dependence on the drug.

Withdrawal Symptoms: When a drug is taken regularly for sometime, two types of addiction may occur – physical and emotional or psychological.
In physical addiction the body develops a need for the drug. When drug supply is cut off, the body reacts violently and a number of withdrawal symptoms starts appearing. These include:
(i) Severe abdominal pain or severe body ache
(ii) Muscular cramps
(iii) Headache
(iv) Fever
(v) Watering of eyes and nose
(vi) Vomiting and pain in stomach
(vii) Sleeplessness, difficulty in breathing, irregular heartbeat, etc. Such a person gets relief only when he gets more of the drugs.

Emotional or Psychological addiction: It means a person has a strong craving or urge for the drug either for pleasure r to avoid the intense physical disturbance. If the drug is not given, the addict faces severe depression and derangement. If a person is not physically addicted to a drug, he may overcome his addiction without suffering from withdrawal sickness. But usually people are addicted to a drug physically as well as emotionally. They need proper medical care to overcome their addiction.

Psychological Drug Dependence: It refers to the state of mind of a person who is so dependent on the drug that his life or activities are centered around in ensuring the supply of drug. The drug itself may or may not be addictive but the person wants to take it continuously just to enjoy its effects or to avoid the discomfort caused by its absence. Repeated use of the drug makes a patient totally dependent on them. World Health Organization (WHO) suggested the use of the term drug dependence to include the terms drug addiction or drug abuse. The drugs that cause drug dependence are called as psychotropic drugs as they act on the brain and alter behavior, consciousness power of perception.

LEVELS OF ORGANIZATION – SPECIES AND POPULATION

Levels of Organization

The living organism is a system of interwoven and overlapping hierarchies of organization. Starting from atom, each level makes the base for the next higher level and thus forms different levels of organization. The properties of those levels of organization are unique and are different from any levels of organization, e.g. water is a molecule of hydrogen and oxygen. It has its own properties which are different from hydrogen and oxygen, both. Each level of organization is more complex and has fewer units than the previous one i.e. there are lesser tissues than cells. The molecules of life are packed into highly organized, self enclosed units called cells. Each cell has a complex structure that gives it the capability of self-reproduction a unique characteristic of living things. Cell is the lowest level among the levels of organization that is considered to be alive. The structural hierarchy represents how matter has become more and more organized with each levels of organization. At every shift of organizational level, energy is required. This new level of organization has its own properties. Energy is necessary to maintain that level of organization. There is an intimate relationship between organism and environment in every levels of organization. Levels of organization are the basis of evolution. Levels of organization has determined the kind of life that existed in past and is existing today however, the activities of an organism also produce changes in environment so the relationship is in both ways.

A living organism – the most observable unit can be studied at various levels as given:

Genes → Cells → Tissues → Organs → Organisms → Populations → Biotic Community → Ecosystem

In this part headed "Levels of Organization" we will study the living organisms at the species and population level.

The Individual Organism

A living organism is able to carry out its life processes within its body independently. The individuals can be counted, measured and studied as they are the most concrete objects. The individual organism is always derived from the pre – existing ones through vegetative, asexual or sexual reproduction. An individual always has a life span with a definite beginning and a definite end. An individual is able to transmit its characters to the offspring. The aggregation of individuals of one kind forms the population.

Population
Population is a geographically isolated group of the same kind (so called species). It is a group of organisms of same species that occupy a specific area. The population may be closer or widely dispersed geographically. The number of population distributed over a large geographical area may form one species.

Species
Species is supposed to be the basis unit of taxonomy. A species may be defined in number of ways in various biological aspects.

Genetically – A species having group of organisms that show a distinct similarity in the genetic karyotype.
Morphologically – A species is a distinct and recognizable group of organisms.
Ecological – A species having group of organisms that share the same ecological niche. (No two species can have the same niche)
Interbreeding – A species having group of organisms that can interbreed and produce a fertile offspring in nature. The criteria is too simple to understand a species. There are number of species where the organisms may look different and yet they belong to the same species.

Amazing Biology

Biotic Community

Characteristics of a Biotic Community

In any natural environment of only one species cannot exist by themselves. It is always a group of population that live together in the same area. An association of a number of different inter-related populations of different species in a common environment in a nature forms a Biotic Community. The members of a biotic community can be producers, consumers or decomposers. The members of a biotic community are all interdependent. A biotic community may be small or large e.g. pond community occupies a limited area while the desert or grass land communities could spread to miles. A biotic community may primarily be of plants or animals and generally includes both. As different species share a common environment, number of direct or indirect interactions exists between them inside a biotic community. A biotic community interacts with the abiotic factors and forms an ecosystem.

Cells – Tissues – Organs – Organisms – Population = Biotic Community

Every biotic community needs abiotic factors for survival. At times the dominance of one factor determines the predominance of particular kind of population in a biotic community. For example: In a biotic community of fruit bearing trees the frugivorous bats and insects would be in plenty. A grass land biotic community has seed eating birds, mice and predatory birds living on small insects. A damp marsh has frogs, toads, fish, water insects and water birds that feed on small creatures. Aquatic plants of different kinds adapted for different intensities of light at the surface or at different depths would be present in a biotic community.

Interspecific Interact

ions in a Biotic Community

When various species live together in a biotic community, numbers of interactions take place according to specific needs of food, shelter and habits. We will discuss some of these in this chapter.

1. Predation 2. Scavenging 3. Parasitism 4. Commensalism 5. Symbiosis 6. Competition

1. Predation

Predation is a direct and often complex interaction of two species in a biotic community. The stronger animal called predator captures and feeds on the weak animal called prey. The decline in number of predators leads to a increase in number of the prey. An increase in the predator population leads to decrease in the prey population in a biotic community. These fluctuations play an important part in regulating natural population. Examples: Tiger feeds on deer, owls on rats etc. At times an animal could be a predator as well as a prey.

2. Scavenging

Scavenging is a direct food relationship where animals called scavengers feed on other dead animals which have either died naturally or have been killed by another animal in a biotic community. They play an important role in a biotic community as food is not wasted and also is disposed off. Examples: - Vulture feeds on dead bodies. Hyenas and jackals feed on left over killed animals by lion. They may feed on big animals like zebra and giraffe killed by other animals.

3. Parasitism

Parasitism is a negative interaction in a biotic community where one not only derives nourishment but also lives a part or the whole of life on another organism. The parasite is an organism that lives on another organism, the host from which it obtains food as well as shelter in a biotic community. It could be between animals between plants or between animals and plants in a biotic community. In the host – parasite relationship the weak attacks the stronger. It is beneficial to parasite and harmful to host. Generally a parasite may cause an illness but not kill the host except in severe cases. There may be number of parasites on one host.

4. Commensalism

In Commensalism one organism or a population is benefited while the other is neither benefited nor harmed. In some cases the host may be able to derive some minor benefit. There is no physiological exchange of any kind. The association may be temporary or permanent in a biotic community. Example

: Remora – a small fish attaches itself to the lower side of a shark. Remora feeds on scraps of shark's food and is not harmed.

5. Symbiosis

Symbiosis is an association of two populations in a biotic community where both the populations are benefited. There is often a close or permanent association. In some cases both are so interdependent that neither can live alone in that biotic community.

6. Competition

The two species in a biotic community interact in such a way that it affects their growth and survival. Both the species share the same resources like water, nutrients, space, sunlight, food, etc of a biotic community. Members of both species compete to survive in that respective biotic community. There is a direct inhibition of one by another. Many a times there is no set pattern as any one can succeed. Examples:- Carnivorous animals like tiger and lion compete for the prey. Trees, herbs and shrubs compete for sunlight and nutrients in a biotic community.

7. Some Passive Interactions

There are many interactions that exist in nature of a biotic community in between the animals, or between animals and the surrounding, which also help an organism to survive in that biotic community. Camouflaging – The blending of an animal with its surrounding is called camouflaging. It is also known as protective coloration. They camouflage their body shape and colour to suit the environment. Examples:- Stick insect Carausius morosus resembles a thin dry branch. Dead Leaf butterfly Kalima parolecta resembles a dry leaf. Praying mantis Mantis religiosa resembles the green foliage. Mimicry – Mimicry is also a type of protective resemblance in a biotic community. In this an animal mimics another animal so as to avoid predation. The viceroy butterfly mimics the common Monarch butterfly which is avoided by birds for its unpleasant taste.

Other Interactions

There may be many other interactions which may not be apparent. The association of birds and animals bringing about seed dispersal and pollination. The birds feeding on ticks – the parasites on the body of cattle. The red billed and yellow billed ox peckers perch on the black rhinoceros of Africa and feed on ticks and thus make the animal rid of the parasites to survive in a biotic community. They also warn the animal of the approaching danger. The rufus woodpecker makes a nest in a hole in the ball shaped nest of the ants. The ferocious ants do not harm the eggs or young ones but the birds feed on these ants and keep a check on their population to continue their generation in a biotic community.

Biotic Stability

A biotic community is a naturally occurring assemblage of plants and animals living in the same environment. They all interact to make the

community stable. It has been seen that more the number of species, more stable is the community. For example a biotic community containing a large population of Eucalyptus or any other plant may be totally wiped out by a fungal disease or insect infestation. But if a biotic community contains many species and kinds of plants, only one would wiped out at a time and the rest would survive. Example – In Serengeti plains of Africa, 20 species of antelope graze in the same area. Each species eats on a different kind of grass or shrubs. Some that feed on the same species, feed at different stages of grass. This makes the biotic community rich and stable.

Changes in a Biotic Community – Ecological Succession

A community is built up over a period of time. As the time passes, communities change. In a biotic community there are interactions among the organisms (biotic factors) and between the biotic and abiotic factors (climate, light, soil, etc) All these bring about changes in a biotic community. A biotic community is a dynamic unit where tropic levels exist, there is

a flow of energy and cycling of nutrients. It is a living part of an ecosystem. The wind, fire, volcanic activity or any other event in nature or man may destroy the organisms living in a biotic community. Now if this area is left alone, a succession would start and ultimately a permanent biotic community would take shape. This process from the beginning to the climax may take many years. During this time there will be an orderly and progressive replacement of one biotic community by another till a relatively stable biotic community is established. This is called as ecological succession. A complete succession is called as Sere. A Sere is made up of a number of seral stages. A climax community is the final or the seral stage.

Kinds of Ecological Succession

(1) Primary Succession (2) Secondary Succession.

1. Primary Succession

Primary Succession occurs where no biotic community has previously existed like sand dunes, volcanic islands, lava flows, etc. The area is devoid of any organisms. It may take upto 1000 years before climax community gets established.

Various stages in a Primary Succession – Let us take an example of a bare rock or volcanic islands. Trees, herbs or shrubs can not grow because of absence of good soil. The first organisms often called pioneer organisms are lichens that invade the rocky area. The fungal component holds and the algae provides food. The usually rode the rock surface and tiny crevices or fissures open in the rock in a biotic community. The erosion of rock, sand, dead and decayed lichens provide sufficient soil for larger plant species to invade. Next mosses, ferns and grasses grow on the rocky surface. Certain insects and small animals are also seen. Then the herbs, shrubs and trees replace the earlier vegetation and new animals continue to invade. Ultimately these plants will be succeeded by large seed bearing plants, tall grasses. This would also support number of different kinds of animals populations in a biotic community. This final stable self growing community is called as climax community. The animals also show a succession but these are governed by the plant succession.

Climax Community

It may take hundreds of years for a climax forest community to be established on a sand dune. A climax community is in equilibrium with the environment. A climax community often has one or more dominant species. It is generally referred to those species which collectively form a greater biomass and are generally larger in size. Climax community supports large number of species. Climax community has a high bio mass and rich organic soil. Climax community provides a wide range of food material. Climax community has a diverse variety of niches for animals.

2. Secondary Succession

It occurs when a biotic community has been disrupted and the surface is completely or largely devoid of vegetation. It may be due to earthquake, fire or even clearing of forest by man. As the spores, seeds, rhizomes the organs of vegetative reproduction are present beneath the soil, often grasses, shrubs, weeds are first to appear. The same principle of primary succession applies but it occurs at a much faster pace. It has been observed that a destroyed grass

land may take 50 – 100 years and a destroyed forest about 200 years. Overgrazing of grasslands is like reversion of the community succession. The introduction of exotic weeds in a cleared forest seriously affects the succession and it may become impossible to regenerate the same old type of forest in a biotic community.

Dominance of Species

Each sere has one or more dominant species which are a part of climax community. These could be Pine, Oak, Sal or Teak depending on the area and climatic conditions in that biotic community. The dominant species are the most numerous plants. They are generally large in size and have the greatest biomass. They influence the local environment. The species may be fewer in number in temperate forests – 90% of trees may be pines and oaks of a biotic community. The species may be more in tropical rain forests like Andaman group of islands where there are about 12 dominant species.

Evidences from Palaeontology and Comparative Cytology

Evidences from Paleontology

Paleontology is the study of past life based on fossil and fossilization record. The fossils are the petrified remains or impressions or imprints of the hard parts of the ancient organisms. They are preserved in the sedimentary rocks (gradual deposition of soil particles in layer after layer) or other media like volcanic ash, ice, sand, mud, etc. to study about evidences from Paleontology. Examples: Archaeopteryx left bones and feathers in the form of impression.

Note:

Dinosaurs left foot print on the hard rocks called Imprints.

Leonardo da Vinci (1452-1519) is called father of Paleontology.

Georges Cuvier (1800) is called father of modern Paleontology.

Paleozoology is the branch of Paleontology which deals about the study of animal fossils.

Four general types of Fossils

They are Unaltered, Petrified, Moulds and Casts and Prints

Unaltered

Whole bodies of extinct organisms have been found frozen in ice at the poles (fossilized resin of confers). Example: Elephant like Wooly mammoths were found buried in ice in Siberia.

Petrified

According to evidences from Paleontology the fossil includes the hard parts of extinct organisms such as bones, shell, teeth, etc. Sometimes these hard parts are found unchanged but mostly they are found with their organic parts or completely replaced by deposition by minerals. Replacement of organic parts by minerals deposition is called petrification.

Moulds and Casts

Evidences from Paleontology suggests that moulds of hardened and fossilized mud that surrounds an extinct organisms have retained true copies of their shapes. During moulding buried organisms are completely replaced by minerals.

Prints

It includes print of print of foot, wings, bone, skin, etc. in soft mud.

Evidences from Comparative Cytology

According to evidences from comparative cytology all forms of life come from cellular level. The cell is structural and functional unit of life. This indicates basic relationship among living forms. All cells contain cell membrane made up of double layered lipo proteins. They have DNA - RNA protein information and communication system. All the cells utilize the glycolytic pathway and have a Krebs cycle and an electron transport system as pointed by the evidences from comparative cytology.

Evidences from Embryology

Embryology is the study of development of an egg into the adult. Evidences from Embryology based on comparative developmental studies of embryos of various organisms. Some examples are: All multicellular start their life as a Zygote. Zygote is a single celled and comparable to Protozoa. Zygote undergoes a series of events like morula, blastula and gastrula. Cell of blastula organize to differentiate into two germ layers i.e. Ectoderm and Endoderm (in diploblastic animals). Blastula changes into gastrula. During gastrula stage (in triploblastic) the third germ layers mesoderm originates. According to Evidences from Embryology the developmental stages upto gastrula stage in all metazoans are similar i.e. Monophyltic origin. The development of heart in embryos of fish is two chambered and same condition of the heart retained in adult stage. The development of heart starts as two chambered in amphibia, reptiles, birds and mammals but become three chambered in adult amphibia, three and half in reptile (in crocodile 4 chambered), in aves and mammals four chambered. The presence of gills slits is one of salient characters of chordates; which remains as such in primitive characters (protochordata). The gill pouch and gill slits develops into gills in fish for aquatic respiration. But in adult amphibia, reptiles, aves and mammals replaced by lungs for Aerial respiration.

Von Baer (1828)
Von Baer suggests basic principles of Evidences from Embryology development, which are as follows: During development general characters appear before special characters. From more general, the less general and finally the special characters appear. During development, an animal develops progressively from the form of other animals. Young stages are like young stage of ancestors or embryonic stages of lower animal, but not like adults of those animals.

Biogenetic Law
Biogenetic Law was proposed by Ernest Haeckel (1866), also called Recapitulation Theory. He studied a lot about Evidences from Embryology. It states that ontogeny repeats phylogeny. It means all organisms during their development receives ancestral characters (ontogeny). This historical evolution is called phylogeny. Ontogeny: It means development of organs, Phylogeny: It means ancestral characters. Example: Gills, gill slits, tail, tail fin, lateral line, sense organs, etc. in the tadpole larva of frog.