Human Health & Disease

CLASS - XII
HUMAN
HEALTH &
DISEASES
AJAY KUMAR GAUTAM

HEALTH & DISEASE
■ The term health is very frequently used by everybody. How do we define it?
Health does not simply mean ‘absence of disease’ or ‘physical fitness’.
■ It could be defined as a state of complete physical, mental and social well-being.
When people are healthy, they are more efficient at work. This increases
productivity and brings economic prosperity.
■ Health also increases longevity of people and reduces infant and maternal
mortality.
■ Balanced diet, personal hygiene and regular exercise are very important to
maintain good health. Yoga has been practised since time immemorial to achieve
physical and mental health.
■ When the functioning of one or more organs or systems of the body is adversely
affected, characterised by appearance of various signs and symptoms, we say that
we are not healthy, i.e., we have a disease.
■ Diseases can be broadly grouped into infectious and non-infectious. Diseases
which are easily transmitted from one person to another, are called infectious
diseases.
■ Infectious diseases are very common and every one of us suffers from these at
sometime or other. Some of the infectious diseases like AIDS are fatal.

DISEASE
CLASSIFICATION
Congenital
Diseases
Non -Infectious
Diseases
Infectious
Diseases

COMMON DISEASES IN HUMANS
BACTERI
AL
DISEASE
S
VIRAL
DISEASE
S
PROTOZOA
NS
DISEASES
HELMINTH
ES
DISEASES
FUNGAL
DISEASES
Examples of
Bacterial
Disease :
i. Typhoid
ii. Pneumonia
iii. Plague
iv. Tuberculosis
v. Leprosy
vi. Cholera
Examples of
Viral Disease :
i. Common
Cold
ii. Mumps
iii. Rabies
iv. Dengue
v. Chikungunya
Examples of
Protozoan
Disease:
i. Malaria
ii. Amoebiasi
s
Examples of
Helminthes
Disease:
i. Ascariasis
ii. Filariasis
Examples of
Fungal
Disease:
i. Ringworm

TYPHOID : (Enteric Fever)
Pathogen : Salmonella typhi (A Gram negative bacterium)
Mode of Transmission : These pathogens generally enter the small intestine
through contaminated food & water and migrate to other organs through blood.
Symptoms : Sustained high fever ( 39° to 40°C), weakness, stomach pain,
constipation, headache, and loss of appetite are some of the common symptoms
of this disease.
■ Intestinal perforation and death may occur in severe cases.
Diagnosis Test : Typhoid fever could be confirmed by Widal Test.

■ Pathogen : Bacteria like Streptococcus pneumoniae and Haemophilus
influenzae.
■ Mode of Transmission : A healthy person acquires the infection by
inhaling the droplets/ aerosols released by an infected person or even by
sharing glasses and utensils with an infected person.
■ Symptoms : In pneumonia, infection occurs in alveoli of the lungs. As a
result of the infection, the alveoli get filled with fluid leading to severe
problems in respiration.
❖ The symptoms of pneumonia are fever, chills, cough and headache.
❖ In severe cases, the lips and finger nails may turn gray to bluish in
colour.
PNEUMONIA

PLAGUE / BUBONIC PLAGUE
■ Also known as “ Black Death ”
■ Pathogen : Yersinia pestis
■ Mode of Infection : It is primarily a disease of rodents but can
accidently affect man/ It spreads from rat to rat through rat flea
(Xenopsyla), But when the infected rats die, the fleas leave their body
and can even bite man and inject plague germs into his blood.
■ Symptoms : It is characterised by high fever and a bubo (lump) in
the groin or the armpit.
❖ Red patches appear on skin which turn black and ultimately leads
to death (black death).

TUBERCULOSIS (TB)
⮚ It is also called “Koch’s Disease”.
■ Pathogen : Mycobacterium tuberculosis
■ Mode of Infection : The bacteria damage the tissues and
release a toxin named tuberculin which produces the
disease. It affects the lungs, lymph nodes, bones and
joints.
Incubation period is quite variable.
■ Symptoms : Symptoms of pulmonary (lungs)
tuberculosis are fever, cough, sputum containing blood,
pain in the chest and loss of weight excessive fatigue, loss
of appetite, rise of temperature in the evening, hoarseness
of throat, night sweating and rapid pulse
■ Treatment : BCG vaccine gives considerable protection
against tuberculosis.
■ BCG 🡪 bacille Calmette-Guerin

LEPROSY DISEASE
■ Also known as “Hansen’s Disease”.
■ Pathogen : Mycobacterium leprae
■ Symptoms : Appearance or light coloured patches on the skin,
thickening of the nerves, partial or total loss of sensation in the
affected parts of the body.
⮚ These are accompanied by fever, pain, ulcers and skin
eruptions.
⮚ Deformities of toes and fingers may also develop.
⮚ The bacilli leave the body in nasal discharge, from the
throat during coughing, sneezing and even speaking and
through broken skin lesions.
■ Treatment : The patient is treated with DDS ( Diamino
diphenyl sulphone).

CHOLERA
■ Pathogen : Vibrio cholerae
■ Symptoms : These may get into a healthy person with contaminated food and
water. The patient starts passing stools frequently, which are white like rice-water,
and gets repeated vomiting.
■ Treatment : Since, a large quantity of fluid and salts are rapidly lost through
stools and vomit, therefore, the most important treatment is to replace the lost fluid
and salts equally by oral rehydration-therapy (ORS).
⮚ To allay thirst, water, soda water or green coconut water should be given for
sipping although this may be thrown out by vomiting. Therefore, only small
quantities of water should be given repeatedly, as these may remain for
sometime within the stomach and stay of every one minutes means some
absorption.
⮚ Ice may be given for sucking. This will reduce internal temperature and
restrict the tendency to vomit. Intravenous infusions of saline solution
should be given to compensate for the loss of fluids and salts from the body.
The patient may require five litres or more a day.
⮚ Ice may be given for sucking. This will reduce internal temperature and
restrict the tendency to vomit. Intravenous infusions of saline solution
should be given to compensate for the loss of fluids and salts from the body.
The patient may require five litres or more a day.

BACTERIAL
DISEASES COMMON COLD
■ Pathogen : Rhino virus
■ Mode of Transmission : It is one of the most
infectious human diseases, transmitted through
droplets resulting from cough or sneezes of an
infected person, either inhaled directly or transmitted
through contaminated objects such as pens, books,
cups, door knob etc.
■ Symptoms : Rhino virus infects the nose and
respiratory passage but not the lungs.
⮚ It is characterized by nasal congestion and
discharge, sore throat, hoarseness, cough,
headache and tiredness, etc which usually last
for 3-7 days.

MUMPS ( Infectious Parotitis )
■ Pathogen : Paramyxovirus (RNA virus)
■ Symptoms : Disease causes Fever, Difficulty in
opening the mouth and painful swelling of the parotid
glands which lie just below the lobe of the ears.
■ Prevention : The virus comes out in the saliva of the
infected person. The patient should take complete bed
rest till the swelling subsides in order to avoid
complications.
■ Usually, there are no complications, but in some cases
there may be pain and swelling of the testes (orchitis)
or pain in the abdomen.

RABIES (Hydrophobia)
■ Pathogen : Rhabdo virus
■ Mode of Infection : It is introduced in the body by the bite of
rabid (mad) dogs usually. It can be injected by the bites of
Jackals, Cats, Wolves etc.
■ Incubation Period : Incubation period is about 10 days to 1
Year.
■ Symptoms : Fear of water is the most important characteristic
of this disease.
⮚ Other symptoms include excess salivation, severe headache,
high fever, alternating periods of excitement and depression,
inability to swallow even fluid due to choked throat.
⮚ The virus destroys the brain and spinal cord.
❖ Rabies is 100% fatal.
■ Prevention : There should be separate immunization of dogs
and cat population.

DENGUE FEVER
▪ Pathogen : Dengue fever is caused by a RNA containing Arbovirus ( Arthopod borne virus ) of
flavivirus group which also causes yellow fever (not found in India). Thus, the virus which causes dengue
fever is a mosquito borne flavi–ribo virus.
▪ Mode of Infection : The virus of dengue fever is transmitted by the bite of female Aedes aegypti (tiger
mosquito).
▪ Incubation Period : Incubation period is 3-8 days.
▪ Types of Dengue Virus : Classical dengue fever and dengue haemorrhagic fever are known to occur.
▪ Symptoms of Classical Dengue Fever are :
• Abrupt onset of high fever
• Severe frontal headache.
• Pain behind the eyes which worsens with eye movement.
• Muscles and joint pain
• Loss of sense of taste and appetite.
• Measles like rash over chest and upper limbs.
• Nausea and vomiting.

■ Symptoms of Dengue Haemorrhagic Fever : Symptoms are similar to classical
dengue fever except the following :
• Bleeding from the nose, mouth, gums and skin bruising.
• Severe and continuous
• Stomach pains.
• Frequent vomiting with or without blood.
• Pale cold or clammy skin.
• Excessive thirst (dry mouth)
• Rapid weak pulse
• Difficulty in breathing.
• Restlessness and constant crying.
▪ Prevention : If there is fever doctor should be consulted at once, paracetamol tablets
should be taken on the advice of doctor Aspirin and Dispirin to be avoided.
✔ Plenty of liquids to be given to the patient.
✔ Cold sponging required if fever is high.
❖ No vaccine for Dengue fever is available.
⮚ Mosquito breeding places to be eliminated by covering small water containers, water
tanks, changing the water of cooler every week, and where Aedes mosquito breed.
⮚ Do not allow children to play in shorts and half sleeved clothes.
⮚ Use mosquito repellents, repellent cream and sleep in mosquito-net.
DENGUE FEVER

Chikunguny
a
■ Pathogen : Chikungunya virus
✔ This virus was first isolated from human patients
and Aedes aegypti mosquitoes from Tanzania in
1952.
⮚ The name 'Chikungunya' is derived from the
native word for the disease in which patient
walks "doubled up" due to severe joint pain.
■ Symptoms : Its symptoms include sudden onset
of fever, crippling joint pain, lymphodenopathy
and conjunctivitis. Some show haemorrhagic
manifestations.
■ No vaccine is available.

■ Pathogen : Plasmodium, a tiny protozoan is responsible for this disease.
Different species of Plasmodium (P. vivax, P. malaria and P. falciparum)
are responsible for different types of malaria.
✔ Of these, malignant malaria caused by Plasmodium falciparum is the most
serious one and can even be fatal.
■ Mode of transmission : Malarial parasite (Plasmodium) requires two
hosts to complete its life cycle: i) Human, ii) Mosquito (female
Anopheles) which is the vector/transmitting agent too.
✔ Plasmodium enters the human body as sporozoites (infectious form)
through the bite of infected female Anopheles.
■ Incubation Period : Incubation period is the duration between the
initial sporozoite infection and the first appearance of malarial symptoms.
✔ It is about 14 days in P. vivax, 30 days in P malariae 14 days in P ovale
and 12 days in P falciparum.
PROTOZOAN
DISEASES
MALARIA

Plasmodium enters the
human body as sporozoites
(infectious form)
When a female Anopheles mosquito bites an
infected person, these parasites enter the
mosquito’s body and undergo further
development.
The parasites multiply within them to form
sporozoites that are stored in their salivary
glands.
The parasites initially multiply within
the liver cells and then attack the red
blood cells (RBCs) resulting in their
rupture.
The rupture of RBCs is associated with release of a
toxic substance, haemozoin, which is responsible for
the chill and high fever recurring every three to four
days.
When these mosquitoes bite a human, the
sporozoites are introduced into his/ her body,
thereby initiating the events mentioned.

■ Pathogen : Entamoeba histolytica
■ Mode of Transmission & Vector : Houseflies act as
mechanical carriers and serve to transmit the parasite from
faeces of infected person to food and food products, thereby
contaminating them.
✔ Drinking water and food contaminated by the faecal
matter are the main source of infection.
■ Symptoms : Symptoms of this disease include
constipation, abdominal pain and cramps, and stools with
excess mucus and blood clots.
AMOEBIASIS

■ Pathogen : It is caused by the common round worm, Ascaris
lumbricoides, an intestinal parasite of small intestine of human
beings.
■ Mode of transmission : A healthy person acquires this
infection through contaminated water, vegetable, fruits, etc.
■ Symptoms : This disease is characterized by internal bleeding,
muscular pain, fever, anaemia and blockage of intestinal
passage. The eggs of the parasite come out along with faeces of
infected persons which contaminate soil, water and plants etc.
HELMINTHAL
DISEASES ASCARIASIS

■ Pathogen : Wuchereria (W. bancrofti and W.
malayi)
■ Mode of Transmission : The pathogen are
transmitted to a healthy person through the bite of
infected female Culex (mosquito)
■ Symptoms : The filarial worms cause a slowly
developing chronic inflammation of the organs in which
they live for many years, usually the lymphatic vessels of
the lower limbs and the disease is called Elephantiasis
or Filariasis.
✔ The genital organs are also often affected,
resulting in gross deformities.
FILARIASI
S

■ Pathogen : Many fungi belonging to genera Microsporum,
Trichophyton and Epidermophyton are responsible for ringworms,
one of the most common infectious diseases in man.
■ Mode of Transmission : Ringworms are generally transmitted
from soil or by using infected individuals.
■ Symptoms : A appearance of fry, scaly lesions on various parts of
the body such as skin, nails, and scalp are the main symptoms of the
disease.
✔ These lesions are accompanied by intense itching. Heat and
moisture help these fungi to grow, which makes them thrive in
skin folds such as those in the groins or between the toes
(athlets foot).
✔ Tinea cruis, the groin and perineum are involved. In tinea
barbae, the beard areas of the face and neck are involved. Tinea
pedis or athlets’s foot affects foot.
FUNGAL
DISEASES
RINGWOR
M

Preventive Measures and Control of
Diseases
⮚ Maintaince of personal and pubic hygiene is very important for prevention
and control of many infectious diseases.
1. Personal hygiene include keeping the body clean, consumption of clean
drinking water, food, vegetables and fruits etc.
2. Public hygiene include proper disposal of waste and excreta, periodic
cleaning and disinfection of water reservoirs, pools and tanks. These
measures are particularly essential where the infectious agents are
transmitted through food and water such as typhoid, amoebiasis and
ascariasis.
3. For air borne diseases such as pneumonia and common cold, close contact
with the infected persons or their belongings should be avoided.
4. The use of vaccines and immunization programmes have enabled us to
completely eradicate a deadly diseases like small pox. Large number of
other infectious diseases like polio, diphtheria, pneumonia, tetanus have
been eradicated to a large extent by the use of vaccines
5. Discovery of antibiotics and various other drugs has also enabled us to
effectively treat infectious diseases.

IMMUNITY
■ Overall ability of the host to fight the disease-causing organisms,
conferred by the immune system is called immunity.
■ Immunity is of two types: (i) Innate Immunity and (ii) Acquired
Immunity
IMMUNITY
Innate
Immunity
Acquired
Immunity

INNATE IMMUNITY
■ Innate immunity is non-specific type of defence, that is
present at the time of birth. This is accomplished by
providing different types of barriers to the entry of the
foreign agents into our body.
■ Innate immunity consist of four types of barriers. These are
—
1. Physical Barriers
2. Physiological Barrier
3. Cellular Barrier
4. Cytokine Barrier

1. Physical barriers : Skin on our body is the main barrier which prevents
entry of the micro-organisms. Mucus coating of the epithelium lining the
respiratory, gastrointestinal and urogenital tracts also help in trapping
microbes entering our body.
2. Physiological barriers : Acid in the stomach, saliva in the mouth, tears
from eyes–all prevent microbial growth.
3. Cellular barriers : Certain types of leukocytes (WBC) of our body like
polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and
natural killer (type of lymphocytes) in the blood as well as macrophages in
tissues can phagocytose and destroy microbes.
4. Cytokine barriers : Virus-infected cells secrete proteins called interferons
which protect non-infected cells from further viral infection.
INNATE
IMMUNITY

■ Acquired immunity, on the other hand is pathogen specific. It is characterised by memory. This means
when our body encounters a pathogen for the first time it produces a response called primary response
which is of low intensity.
■ Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic
response.
■ This is ascribed to the fact that our body appears to have memory of the first encounter.
■ The primary and secondary immune responses are carried out with the help of two special types of
lymphocytes present in our blood, i.e., B-lymphocytes andT-lymphocytes.
■ The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with
them. These proteins are called antibodies.
■ The T-cells themselves do not secrete antibodies but help B cells to produce them.
■ Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy
chains.
■ Hence, an antibody is represented as H2L2. Different types of antibodies are produced in our body. IgA,
IgM, IgE, IgG are some of them.
■ Because these antibodies are found in the blood, the response is also called as humoral immune response.
This is one of the two types of our acquired immune response – antibody mediated.
The second type is called cell-mediated immune response or cell-mediated immunity (CMI). The T-
lymphocytes mediate CMI.
ACQUIRED
IMMUNITY

ACTIVE AND PASSIVE
IMMUNITY
■ When a host is exposed to antigens, which may be in the form of
living or dead microbes or other proteins, antibodies are produced
in the host body. This type of immunity is called Active Immunity.
■ Active immunity is slow and takes time to give its full effective
response.
■ When ready-made antibodies are directly given to protect the body
against foreign agents, it is called Passive Immunity.
■ Do you know why mother’s milk is considered very essential for the
new- born infant?
■ The yellowish fluid colostrum secreted by mother during the initial
days of lactation has abundant antibodies (IgA) to protect the
infant.
■ The foetus also receives some antibodies from their mother,
through the placenta during pregnancy.
■ These are some examples of passive immunity.

VACCINATION &
IMMUNIZATION
■ The principle of immunisation or vaccination is based on the property of
‘memory’ of the immune system.
■ In vaccination, a preparation of antigenic proteins of pathogen or
inactivated/weakened pathogen (vaccine) are introduced into the body.
■ The antibodies produced in the body against these antigens would neutralise
the pathogenic agents during actual infection.
■ The vaccines also generate memory – B and T-cells that recognise the
pathogen quickly on subsequent exposure and overwhelm the invaders with
a massive production of antibodies.
■ If a person is infected with some deadly microbes to which quick immune
response is required as in tetanus, we need to directly inject the preformed
antibodies, or antitoxin (a preparation containing antibodies to the toxin).
■ Even in cases of snakebites, the injection which is given to the patients,
contain preformed antibodies against the snake venom. This type of
immunisation is called Passive Immunisation.
■ Recombinant DNA technology has allowed the production of antigenic
polypeptides of pathogen in bacteria or yeast.
■ Vaccines produced using this approach allow large scale production and
hence greater availability for immunisation, e.g., hepatitis B vaccine

ALLERGY OR
HYPERSENSITIVITY
■ The exaggerated response of the immune system to certain antigens present in the environment is called
allergy.
■ The substances to which such an immune response is produced are called allergens.
■ The antibodies produced to these are of IgE type.
■ Common examples of allergens are mites in dust, pollens, animal dander, etc.
■ Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing.
■ Allergy is due to the release of chemicals like histamine and serotonin from the mast cells. For
determining the cause of allergy, the patient is exposed to or injected with very small doses of possible
allergens, and the reactions studied.
■ The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy

AUTOIMMUNITY
■ Memory-based acquired immunity evolved in higher vertebrates based on
the ability to differentiate foreign organisms (e.g., pathogens) from self-cells.
■ Higher vertebrates can distinguish foreign molecules as well as foreign
organisms. Most of the experimental immunology deals with this aspect.
■ Sometimes, due to genetic and other unknown reasons, the body attacks
self-cells. This results in damage to the body and is called auto-immune
disease.
■ Example : Chronic anaemia, Myasthenia gravis, chronic hepatitis.

AIDS
■ AIDS stand for Acquired Immuno Deficiency Syndrome.
■ It is a deficiency of immune system, acquired during the life time of an individual indicating that is
not a congenital disease.
■ ‘Syndrome’ means a group of symptoms. AIDS was first reported in 1981 and in the last twenty-
five years or so, it has spread all over the world killing more than 25 million persons.
■ Pathogen : AIDS is caused by the Human Immuno deficiency Virus (HIV), a member of a group of
viruses called retrovirus, which have an envelope enclosing the RNA genome.
■ Mode of Transmission : Transmission of HIV-infection generally occurs by :
(a) Sexual contact with infected person,
(b) By transfusion of contaminated blood and blood products,
(c) By sharing infected needles as in the case of intravenous drug abusers and
(d) From infected mother to her child through placenta.
■ So, people who are at high risk of getting this infection includes – individuals who have multiple
sexual partners, drug addicts who take drugs intravenously, individuals who require repeated
blood transfusions and children born to an HIV infected mother.

■ It is important to note that HIV/AIDS is not
spread by mere touch or physical contact; it
spreads only through body fluids.
■ It is, hence, imperative, for the physical and
psychological well-being, that the HIV/AIDS
infected persons are not isolated from family
and society.
■ There is always a time-lag between the
infection and appearance of AIDS symptoms.
This period may vary from a few months to
many years (usually 5-10 years).
AIDS

Mode of Action of AIDS
Virus
■ After the entry of virus into the body through body fluids or blood, the virus
enters into the macrophages where RNA genome of the virus replicates to
form viral DNA with the help of enzyme reverse transcriptase.
■ This viral DNA gets incorporated into host cells DNA and directs the infected
cells to produce virus particles. The macrophages continue to produce virus
and in this way ‘Macrophage acts like an HIV Factory’.
■ Simultaneously, HIV enters into Helper T-lymphocytes below 200/mm3
(Having CD, receptors), replicates and produces progeny viruses which
destruct the helper T-cell.
■ The progeny virus released in the blood attacks the other helper T cells. This is
repeated leading to progressive decrease in the number of helper T-
lymphocytes in the body of the infected person. During this period, the
infected person suffers from fever, diarrhoea and weight loss.

■ Due to decrease in the number of helper T-
lymphocytes below 200/mm3, the person
starts suffering from opportunistic
infections of bacteria especially
Mycobacterium, viruses, fungi and even
parasites like Toxoplasma. The patient
becomes so immunodeficient that he/she is
unable to protect himself/herself against
these infections.
■ Besides Pneumocystis carinii (Pneumonia),
AIDS victims have persistent diarrhoea and
are especially susceptible to Toxoplasma
infections (tuberculosis), leukoplakia (whitish
patches on mucus membranes primarily due
to yeast infections), Cytomegalovirus
(leading to blindness and dementia). Herpes
Simplex, among many other bacterial fungal
infections, and Kaposí’s sarcoma.
Mode of Action of AIDS
Virus

DIAGNOSIS
■ A widely used diagnostic test for AIDS is Enzyme Linked Immuno-
Sorbent Assay (ELISA). Western blotting test is employed for
confirmation of ELISA positive cases.
■ Treatment of AIDS with antiretroviral drugs is only partially effective because it can only
prolong the life of the patient but cannot prevent death. Zidovudin or AZT
(Azidothymidine) was first and still continues to be the drug of choice for the treatment of
AlDS.
■ Drugs with similar action are used to inhibit HIV replicationband slow the progression of
AlDS. Four drugs with similar action are used to inhibit HIV replication and slow
theBprogression of AIDS. They block conversion of retroviral RNA into DNA.
■ The first and still most commonly used drug to treat AIDS is AZT (Azidothymidine) or
Retrovir. Among patients taking AZT, there is a slowing in the progression of symptoms.
The main side effects are red bone marrow damage and anemia. Eventually, the virus
develops resistance to the drug.
■ Other drugs are DDI (dideoxyinosine), DDC (dideoxycytidine), and D4T (stavudine),
which may be used in patients who do not respond to AZT or have become resistant to it.
■ Doctors generally give Zidovudine and Nevirapine to HIV positive pregnant woman to
ensure that their babies do not cary the infection.
TREATMENT

CANCER
❏ It is one of the most dreaded diseases of human
beings and is a major causes of death all over
the worlds. More than a million Indians suffer
from cancer and a large number of them die
annually.
❏ In our body, cell growth and differentiation is
highly controlled and regulated. In cancer cells,
there is breakdown of these regulatory
mechanisms. Normal cells show a property
called contact inhibition by virtue of which
contact with other cells inhibits their
uncontrolled growth.
❏ Cancer cells appears to have lost this property.
As a result of this, cancerous cells just continue
to divide giving rise to masses of cells called
tumors or Neoplasm.

TYPES OF TUMORS
 Tumors are of two types: Benign Tumor and Malignant
Tumor.
■ Benign Tumor : Benign tumors normally remain confined to their
original location and do not spread to other parts of the body and cause
little damage.
■ Malignant Tumor : The malignant tumors, on the other hand are a
mass of proliferating cells called neoplastic or tumor cells.
– These cells grow very rapidly, invading and damaging the
surrounding normal tissues. As these cells actively divide and grow
they also starve the normal cells by competing for vital nutrients.
– Cells sloughed from such tumors reach distant sites through blood,
and wherever they get lodged in the body, they start a new tumor
there.
– This property called metastasis is the most feared property of
malignant tumors.
Example of Benign Tumor

Causes of Cancer/ Carcinogenic
agents
Transformation of normal cells into cancerous neoplastic cells may be induced by physical, chemical or
biological agents. These agents are called carcinogens.
 Physical Agents
 Ionising radiations like X-rays and gamma rays and non-ionizing radiations like UV cause DNA
damage leading to neoplastic transformation.
 Chemical Agents
 The chemical carcinogens present in tobacco smoke have been identified as a major cause of lung
cancer. For instance, asbestos exposure canlead to cancer of lungs while carcinogens like cadmium
oxide is associated with prostate cancer.
 Biological Agents
 Cancer causing viruses called oncogenic viruses have genes called viral oncogenes. Furthermore,
several genes called cellular oncogenes (c-onc) or proto oncogenes have been identified in normal
cells which, when activated under certain conditions, could lead to oncogenic transformation of the
cells.

TYPES OF CANCER
a) Carcinomas are malignant growths of the epithelial (ectodermal) tissues that cover or line the body
organs eg; skin cancer, breast cancer, lung cancer, cancer of stomach and pancreas.
 (About 85% of all tumors are carcinomas)
b) Sarcomas are malignant growths arising in tissues derived from primitive mesoderm. Eg; Bone tumors,
cancer of lymph nodes.
c) Leukaemias result from unchecked proliferation of cell types present in blood and their precursors in the
marrow.
 Others types of cancers are:
 Melanoma – Cancer of pigment cells of the skin
 Adenocarcinoma - Cancer of glands
 Lymphoma – Cancer of lymphatic tissue
 Glioma – Cancer of glial cells of CNS

DETECTION & DIAGNOSIS OF
CANCER
• Early detection of cancers is essential as it allows the disease to be treated successfully in many cases.
 Biopsy & histopathological studies of the suspected tissue : In biopsy, a piece of the suspected tissue cut into thin
sections is stained and examined under microscope (histopathological studies) by a pathologist for detection of
cancerous cells.
 Blood and bone marrow tests for increased cell counts in the case of leukemia.
 Techniques like radiography (use of X-rays), CT (Computed Tomography) and MRI (Magnetic Resonance
Imaging).
 These very useful to detect cancers of the internal organs. Computed tomography uses X-rays to generate a
three-dimensional image of the internals of an object. MRI uses strong magnetic fields and non-ionising
radiations to accurately detect pathological and physiological changes in the living tissue.
 Antibodies against cancer -specific antigens are also used for detection of certain cancers. Techniques of molecular
biology can be applied to detect genes in individuals with inherited susceptibility to certain cancers. Identification of
such genes, which predispose an individual to certain cancers, may be very helpful in prevention of cancers. Such
individuals may be advised to avoid exposure to particular carcinogens to which they are susceptible (e.g., tobacco
smoke in case of lung cancer).

TREATMENT OF
CANCER
 The common approaches for treatment of cancer are :
 Surgery : Generally a tumor is surgically removed wherever possible.
 Radiotherapy/ Radiation Therapy : Tumor cells are irradiated lethally, taking proper care
of the normal tissues surrounding the tumor mass. Eg; I^131 for thyroid cancer.
 Chemotherapy : Several chemotherapeutic drugs are used to kill cancerous cells. Some of
these are specific for particular tumors e.g. two anticancer drugs, vinblastine and vincristine,
used in the treatment of leukaemia are obtained from common weed Cathranthus roseus.
Majority of drugs have side effects like hair loss, anemia, etc.
 Immunotherapy : Tumor cells have been shown to avoid detection and destruction by
immune system. Therefore, the patients are given substances called biological response
modifiers such as α-interferon which activates their immune system and helps in destroying
the tumor.

MAJOR CATEGORIES OF
DRUGS
TRANQUILIZERS
SEDATIVES
&
HYPNOTICS
HALLUCINOGENS STIMULANTS
 DRUG – Any chemical substances/ compounds which changes the
biological actions of the body & causes in the body are called drugs.
 Therapeutics Drugs : Use of any drugs or medication for the diagnose,
cure, treat, or prevent disease.

DRUGS & ALCOHOL
ABUSE
The drugs, which are commonly abused are opioids, cannabinoids and coca alkaloids.
Majority of these are obtained from flowering plants. Some are obtained from fungi.
 Opioids are the drugs, which bind to specific opioid receptors present in our central
nervous system and gastrointestinal tract.
 Heroin, commonly called smack is chemically diacetylmorphine which is a white,
odourless, bitter crystalline compound. This is obtained by acetylation of morphine ,
which is extracted from the latex of poppy plant Papaver somniferum .
 Generally taken by snorting and injection, heroin is a depressant and slows down body
functions.

 Cannabinoids are a group of chemicals , which interact with
cannabinoid receptors present principally in the brain.
 Natural cannabinoids are obtained from the inflorescences of the
plant Cannabis sativa . The flower tops, leaves and the resin of
cannabis plant are used in various combinations to produce
marijuana, hashish, charas and ganja.
 Generally taken by inhalation and oral ingestion, these are known for
their effects on cardiovascular system of the body.
CANNABINOIDS

■ Coca alkaloid or cocaine is obtained from coca plant Erythroxylum coca,
native to South America.
■ It interferes with the transport of the neuro-transmitter dopamine.
■ It has a potent stimulating action on central nervous system, producing a
sense of euphoria and increased energy.
■ Cocaine, commonly called coke or crack is usually snorted.
■ Excessive dosage of cocaine causes hallucinations.
COCAINE

TOBACO ADDICTION
■ Smoking also paves the way to hard drugs. Tobacco has been used by human beings for more than 400 years.
■ It is smoked, chewed or used as a snuff. Tobacco contains a large number of chemical substances including nicotine,
an alkaloid.
■ Nicotine stimulates adrenal gland to release adrenaline and nor-adrenaline into blood circulation, both of which raise
blood pressure and increase heart rate.
■ Tobacco chewing is associated with increased risk of cancer of the oral cavity.
■ Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of haembound oxygen.
This causes oxygen deficiency in the body.
■ Smoking is associated with increased incidence of cancers of lung, urinary bladder and throat, bronchitis,
emphysema, coronary heart disease, gastric ulcer, etc.
■ When one buys packets of cigarettes one cannot miss the statutory warning that is present on the packing which
warns against smoking and says how it is injurious to health. Yet, smoking is very prevalent in society, both among
young and old. Knowing the dangers of smoking and chewing tobacco, and its addictive nature, the youth and old
need to avoid these habits. Any addict requires counselling and medical help to get rid of the habit.

ADOLESCENCE AND DRUG/ALCOHOL
ABUSE
■ Adolescence means both ‘a period’ and ‘a process’ during which a child becomes mature in terms of
his/her attitudes and beliefs for effective participation in society.
■ The period between 12-18 years of age may be thought of as adolescence period.
■ In other words, adolescence is a bridge linking childhood and adulthood. Adolescence is accompanied
by several biological and behavioural changes.
■ Adolescence, thus is a very vulnerable phase of mental and psychological development of an individual.
■ A child’s natural curiosity motivates him/her to experiment. This is complicated further by effects that
might be perceived as benefits, of alcohol or drug use. Thus, the first use of drugs or alcohol may be out
of curiosity or experimentation, but later the child starts using these to escape facing problems.
■ Of late, stress, from pressures to excel in academics or examinations, has played a significant role in
persuading the youngsters to try alcohol and drugs. The perception among youth that it is ‘cool’ or
progressive to smoke, use drugs or alcohol, is also in a way a major cause for youth to start these habits.
■ Television, movies, newspapers, internet also help to promote this perception. Other factors that have
been seen to be associated with drug and alcohol abuse among adolescents are unstable or
unsupportive family structures and peer pressure.

Addiction and Dependence
■ Addiction is a psychological attachment to certain effects –such as euphoria and a
temporary feeling of well-being – associated with drugs and alcohol.
■ These drive people to take them even when these are not needed, or even when their
use becomes self-destructive. With repeated use of drugs, the tolerance level of the
receptors present in our body increases.
■ Consequently the receptors respond only to higher doses of drugs or alcohol leading
to greater intake and addiction.
■ However, it should be clearly borne in mind that use of these drugs even once, can be
a fore-runner to addiction. Thus, the addictive potential of drugs and alcohol, pull the
user into a vicious circle leading to their regular use (abuse) from which he/she may
not be able to get out.
■ Dependence is the tendency of the body to manifest a characteristic and unpleasant
withdrawal syndrome if regular dose of drugs/alcohol is abruptly discontinued.
■ This is characterised by anxiety, shakiness, nausea and sweating, which may be
relieved when use is resumed again. In some cases, withdrawal symptoms can be
severe and even life threatening and the person may need medical supervision.
■ Dependence leads the patient to ignore all social norms in order to get sufficient
funds to satiate his/her needs. These result in many social adjustment problems.

ALCOHOL ABUSE
■ The use of alcohol during adolescence may also have long-term effects. It could lead
to heavy drinking in adulthood. The chronic use of drugs and alcohol damages nervous
system and liver (cirrhosis).
 EFFECTS OF ALCOHOL ON AN INDIVIDUAL
 EFFECT ON LIVER :
Absorbed alcohol is carried directly to the liver, where it becomes the preferred fuel. Use of moderated amounts of alcohol does not
cause liver damages, provided adequate nutrition is maintained. However, chronic alcoholism causes the following diseases:
1. Alcoholic Fatty liver
2. Alcoholic hepatitis
3. Alcoholic cirrhosis
4. Cholestasis
 Effects on Nervous System
 Effects on stomach
 Effects on heart
 Effects on kidneys

Human Health & Disease

More Related Content

What's hot (20)

Similar to Human Health & Disease (20)

More from Ajay Kumar Gautam (13)

Recently uploaded (20)

Human Health & Disease