human health and diseases

Question 1

infectious diseases

Answer 1

Diseases

which are easily transmitted from one person to another, are called infectious diseases.

Question 2

pathogens

Answer 2

A wide range of organisms belonging to bacteria, viruses, fungi, protozoans, helminths, etc., could cause diseases in man

Question 3

Salmonella typhi

Answer 3

Salmonella typhi is a pathogenic bacterium that causes typhoid fever in human beings. These pathogens generally enter the small intestine
through food and water contaminated with them and migrate to other organs through blood. 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
may occur in severe cases

Question 4

typhoid fever confirmation

Answer 4

Widal test

Question 5

Streptococcus pneumoniae and Haemophilus

influenzae

Answer 5

responsible for the disease pneumonia in humans which infects the
alveoli (air-filled sacs) 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 include fever, chills, cough and headache. In severe cases,
the lips and fingernails may turn grey to bluish in colour. 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

Question 6

Rhino viruses

Answer 6

represent one such group of viruses that cause one of the most infectious
human ailments – the common cold. They infect the nose and respiratory
passage but not the lungs. The common cold is characterised by nasal congestion and discharge, sore throat, hoarseness, cough, headache, tiredness, etc., which usually last for 3-7 days. Droplets resulting from cough or sneezes of an infected person are either inhaled directly or transmitted through contaminated objects

Question 7

protozoans

Answer 7

Plasmodium, a tiny protozoan is responsible for malaria. 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

Question 8

life cycle of Plasmodium

Answer 8

Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito. The parasites
initially multiply (asexually) within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. The rupture of RBCs is associated with the release of a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days

Question 9

When a female Anopheles

mosquito bites an infected person

Answer 9

sexual stages develop in the RBC that form gametocytes. the female mosquito takes up the gametocytes with blood meal, fertilization and development take place in the mosquito’s gut, mature infective stages(sporozoites) escape from the gut and migrate to the mosquito salivary glands

Question 10

Entamoeba histolytica

Answer 10

a protozoan parasite in the large intestine of
humans which causes amoebiasis (amoebic dysentery). Symptoms of this disease include constipation, abdominal pain and cramps, stools with excess mucous and blood clots. Houseflies act as mechanical carriers
and serve to transmit the parasite from the faeces of an infected person to food

Question 11

Ascaris

Answer 11

the common round worm,Ascaris, an intestinal
parasite causes ascariasis. Symptoms of these disease include internal bleeding, muscular pain, fever, anaemia and blockage of the intestinal passage. The eggs of the parasite are excreted along with the faeces of infected
persons which contaminate soil, water, plants, etc. A
healthy person acquires this infection through
contaminated water, vegetables, fruits, etc

Question 12

Wuchereria

Answer 12

a (W. bancrofti and W. malayi), 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. The pathogens are transmitted to a healthy
person through the bite by the female mosquito vectors.

Question 13

ringworms

Answer 13

fungi Microsporum, Trichophyton and Epidermophyton are responsible for ringworms.
Appearance of dry, 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 groin or
between the toes. Ringworms are generally
acquired from soil or by using towels, clothes
or even the comb of infected individuals

Question 14

protection from insect vectors that transmit diseases

Answer 14

, introducing fishes like Gambusia

in ponds that feed on mosquito larvae

Question 15

recent widespread diseases in India

Answer 15

the vector-borne (Aedes mosquitoes) diseases

like dengue and chikungunya in many parts of India

Question 16

use of vaccines

Answer 16

A large number of other infectious diseases

like polio, diphtheria, pneumonia and tetanus have been controlled to a the large extent by the use of vaccines

Question 17

immunity

Answer 17

the ability of the host to fight the disease-causing organisms conferred by the immune system

Question 18

2 types of immunity

Answer 18

innate and acquired immunity

Question 19

innate immunity

Answer 19

non-specific type of defence, that is present at the time of birth, gained by providing different types of barriers to the entry of the foreign agents into our body

Question 20

physics barriers

Answer 20

the skin on our body is the main barrier that prevents entry of the microorganisms, the mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital
tracts also help in trapping microbes entering our body

Question 21

Physiological barriers :

Answer 21

Acid in the stomach, saliva in the mouth,

tears from eyes–all prevent microbial growth.

Question 22

Cellular barriers

Answer 22

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.

Question 23

Cytokine barriers

Answer 23

Virus-infected cells secrete proteins called
interferons which protect non-infected cells from further viral
infection

Question 24

Acquired immunity

Answer 24

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 the memory of the
first encounter

Question 25

lymphocytes that help in primary and secondary responses

Answer 25

two special types of lymphocytes present in our blood, i.e., B-lymphocytes and T-lymphocytes

Question 26

The B-lymphocytes

Answer 26

``` produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called antibodies. ```

Question 27

T CELLS

Answer 27

The T-cells themselves do not secrete | antibodies but help B cells to produce them

Question 28

antibody

Answer 28

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

Question 29

types of antibodies

Answer 29

.IgA, IgM, IgE, IgG are some of them

Question 30

antibody-mediated response

Answer 30

humoral immune response

Question 31

cell-mediated immunity

Answer 31

The T-lymphocytes mediate CMI

Question 32

transplant procedure

Answer 32

Grafts from just any source – an animal, another primate, or any human beings cannot be made since the grafts would be rejected sooner or later. Tissue matching, blood group matching are essential before undertaking any graft/transplant and even after this the patient has to take immuno–suppresants all his/her life. The body is able to differentiate ‘self’ and ‘nonself’ and the cell-mediated immune response is responsible for the graft rejection

Question 33

active immunity

Answer 33

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 Active immunity is slow and takes time to give its full effective response. Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity

Question 34

passive immunity

Answer 34

When ready-made antibodies are directly given to protect the body against foreign agents

Question 35

Do you know why mother’s milk is considered very essential for the newborn infant?

Answer 35

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

Question 36

vaccination

Answer 36

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

Question 37

passive immunisation.

Answer 37

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

Question 38

allergy

Answer 38

The exaggerated response of the immune system to certain antigens present in the environment

Question 39

allergens

Answer 39

The substances to which | such an immune response is produced

Question 40

Allergy is due to the release of chemicals like

Answer 40

histamine and serotonin | from the mast cells

Question 41

how to control allergy symptoms

Answer 41

The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy. Somehow, modern-day life style has resulted in lowering of immunity and more sensitivity to allergens

Question 42

auto-immune disease

Answer 42

sometimes, due to genetic and | other unknown reasons, the body attacks self-cells. This results in damage to the body, eg: Rheumatoid arthritis

Question 43

The human immune system consists of

Answer 43

lymphoid organs, tissues, cells | and soluble molecules like antibodies

Question 44

Lymphoid organs

Answer 44

These are the organs where origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes.

Question 45

secondary lymphoid organs

Answer 45

After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix. The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells

Question 46

The bone marrow

Answer 46

the main lymphoid organ where all | blood cells including lymphocytes are produced.

Question 47

thymus

Answer 47

The thymus is a lobed organ located near the heart and beneath the breastbone, The thymus is quite large at the time of birth but keeps reducing in size with age and by the time puberty is attained it reduces to a very small size. Both bone marrow and thymus provide micro-environments for the development and maturation of T-lymphocytes.

Question 48

the spleen

Answer 48

The spleen is a large bean-shaped organ. It mainly contains lymphocytes and phagocytes. It acts as a filter of the blood by trapping blood-borne microorganisms. Spleen also has a large reservoir of erythrocytes.

Question 49

lymph nodes

Answer 49

small solid structures located at different points along the lymphatic system. Lymph nodes serve to trap the micro-organisms or other antigens, which happen to get into the lymph and tissue fluid. Antigens trapped in the lymph nodes are responsible for the activation of lymphocytes present there and cause the immune response.

Question 50

mucosa-associated lymphoid tissue (MALT)

Answer 50

There is lymphoid tissue also located within the lining of the major tracts (respiratory, digestive and urogenital tracts

Question 51

cancer cells

Answer 51

In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of these regulatory mechanisms

Question 52

contact inhibition

Answer 52

Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost this property. As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumours

Question 53

Tumors are of two type

Answer 53

: benign and malignant. Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage. The malignant tumors, on the other hand, are a mass of proliferating cells called neoplastic or tumor cells.

Question 54

The malignant tumor

Answer 54

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

Question 55

carcinogens

Answer 55

Ionising radiations like X-rays and gamma rays and non-ionizing radiations like UV cause DNA damage leading to neoplastic transformation. The chemical carcinogens present in tobacco smoke cause lung cancer. Cancer-causing viruses called oncogenic viruses have genes called viral oncogenes

Question 56

cellular oncogenes | (c-onc) or proto oncogenes

Answer 56

in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells

Question 57

Cancer | detection

Answer 57

n biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts in the case of leukaemias, Antibodies against cancer-specific antigens are also used for detection of certain cancers

Question 58

biopsy

Answer 58

a piece of the suspected tissue cut into thin sections is stained and examined under a microscope (histopathological studies) by a pathologist

Question 59

detect cancers of the internal organs

Answer 59

Techniques like radiography (use of X-rays), CT (computed | tomography) and MRI (magnetic resonance imaging

Question 60

Computed tomography

Answer 60

uses X-rays | to generate a three-dimensional image of the internals of an object

Question 61

MRI

Answer 61

MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue

Question 62

Treatment of cancer

Answer 62

surgery, radiation therapy, chemotherapy and immunotherapy

Question 63

radiotherapy

Answer 63

radiotherapy, | tumour cells are irradiated lethally, taking proper care of the normal tissues surrounding the tumour mass

Question 64

chemotherapy

Answer 64

Several chemotherapeutic drugs are used to kill cancerous cells. Some of these are specific for particular tumors. The majority of drugs have side effects like hair loss, anaemia

Question 65

α-interferon

Answer 65

Tumor cells have been shown to avoid detection and destruction by the 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

Question 66

The drugs

Answer 66

opioids, cannabinoids and coca alkaloids. Majority of these are obtained from flowering plants. Some are obtained from fung

Question 67

opioids

Answer 67

Opioids are the drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal trac

Question 68

heroin

Answer 68

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 (Figure 8.8). Generally taken by snorting and injection, heroin is a depressant and slows down body functions

Question 69

cannabionoids

Answer 69

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

Question 70

cannabis plant

Answer 70

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

Question 71

Coca alkaloid

Answer 71

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

Question 72

plants with | hallucinogenic properties

Answer 72

Atropa belladona and | Datura

Question 73

drugs, that are used as medicines to help patients cope with mental illnesses like depression and insomnia

Answer 73

barbiturates, amphetamines, | benzodiazepines

Question 74

. Morphine

Answer 74

a very effective sedative and painkiller, and is very useful | in patients who have undergone surgery

Question 75

Tobacco

Answer 75

It is smoked, chewed or used as a snuff. Tobacco contains a large number of chemical substances including nicotine, an alkaloid. Nicotine stimulates the adrenal gland to release adrenaline and nor-adrenaline into blood circulation, both of which raise blood pressure and increase heart rate

Question 76

diseases caused due to smoking

Answer 76

increased incidence of cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcer, etc. Tobacco chewing is associated with an increased risk of cancer of the oral cavity. Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of homebound oxygen. This causes oxygen deficiency in the body