Human health and disease

 HUMAN HEALTH AND DISEASES: 

CHAPTER AT A GLANCE

HUMAN INFECTIOUS DISEASES

Bacterial Diseases

Typhoid: 

• Pathogen: Salmonella typhi.
• Widal test: For confirmation of the disease. 
• Transmission: Food & water → small intestine. 
• Symptoms: High fever, weakness, stomach pain, constipation, headache & loss of appetite. Intestinal perforation. 

Pneumonia: 

• Pathogen: Streptococcus pneumoniae & Haemophilus influenzae
• Transmission: Inhaling droplets from patients, Sharing contaminated objects. 
• Symptoms: Respiratory problems, fever, chills, cough, headache. In severe cases, lips and finger nails turn gray to bluish colour.

Viral Diseases

Common cold: 

• Pathogen: Rhinovirus.
• Transmission: Inhaling droplets from cough or sneezes. Contaminated objects. 
• Symptoms: Nasal congestion & discharge, sore throat, cough, hoarseness, headache, tiredness.

Protozoan Diseases

Malaria: 

• Pathogen: Plasmodium sp. 
• Transmission: Female Anopheles mosquito. 
• Symptoms: Haemozoin toxin causes chill and high fever recurring every 3-4 days. 

Amoebiasis (Amoebic dysentery):

• Pathogen: Entamoeba histolytica
• Transmission: Houseflies transmit parasites from faeces to food & water. 
• Symptoms: Constipation, abdominal pain & cramps, stools with mucus and blood clots.

Helminth Diseases

Ascariasis:

• Pathogen: Ascaris 
  
• Transmission: Soil, water, vegetables, fruits etc. contaminated with faeces. 
• Symptoms: Internal bleeding, muscular pain, fever, anaemia, blockage of intestinal passage. 

Filariasis (Elephantiasis):

• Pathogen: Wuchereria (Filarial worms) 
• Transmission: Female Culex mosquito. 
• Symptoms: Chronic inflammation and deformity of limbs & genital organs. 

Fungal Diseases

Ringworm:

• Pathogen: Microsporum, Trichophyton & Epidermophyton 
• Transmission: From soil or towels, cloths, comb etc. 
• Symptoms: Dry, scaly lesions on skin, nails, scalp etc. Itching. 

Summary :

•  Transmitted through food and water — Typhoid,Amoebiasis,Ascariasis
•  Transmitted through air(airborne) —— pneumonia, common cold       
• Transmitted through  vector — Malaria(anopheles-female) ; filariasis(culex) ; dengue and  chikungunya (Aedes)

IMMUNE SYSTEM

LYMPHOID ORGANS 

The organs where origin/ maturation & proliferation of lymphocytes occur. 

2 types: Primary & Secondary. 

1. Primary lymphoid organs: Here, immature lymphocytes differentiate into antigen-sensitive lymphocytes. E.g. Bone marrow & thymus. 
2. Secondary lymphoid organs: The organs, to which matured lymphocytes migrate, interact with antigens and proliferate to effector cells. E.g. Spleen, lymph nodes, tonsils, Peyer’s patches, Mucosa associated lymphoid tissue (MALT) & appendix.

IMMUNITY 

2 types: Innate and Acquired. 

1. Innate immunity 

    Non-specific inborn immunity. 

    It includes 4 types of Barriers: 

• Physical barriers: E.g. Skin, Mucus. 
• Physiological barriers: E.g. gastric HCl, saliva, tear etc. 
• Cellular barriers: Phagocytes like WBC, macrophages etc. 
• Cytokine barriers: Virus infected cells → interferon → protect non-infected cells from viral infection. 

2. Acquired immunity 

    Pathogen specific immunity developed during lifetime. 

    First encounter of a pathogen → primary response in low intensity. 

    Second encounter → strong secondary (anamnestic) response. 

    These responses are carried out by 

• B-lymphocytes (B-cells): Produce antibodies. 
• T-lymphocytes (T-cells): Help B-cells to produce antibodies. 

Types of Acquired immune response 

1. Humoral immune response/ Antibody mediated immunity (AMI): It is mediated by antibodies. 
2. Cell-mediated response / cell-mediated immunity (CMI): It is mediated by T-lymphocytes. 

Structure of antibody 

Types of Acquired immunity 

• Active immunity: Here, antibodies are produced in host body. It is developed during natural infection by microbes or by injecting microbes during immunization. 
• Passive immunity: Here, readymade antibodies are given to the body. E.g. Foetus gets antibodies from mother through Placenta, infants gets antibodies (IgA) in colostrum. 

Types of Immunization 

1. Active Immunization (Vaccination) 

• Vaccine (inactivated pathogen or its antigenic proteins) is introduced into body for the development of antibodies. 
• E.g. Polio vaccine, Hepatitis B vaccine, DPT vaccine etc. 

2. Passive Immunization 

• It is the direct injection of pre-formed antibodies or antitoxin. It requires for quick immune response. 
• E.g. Immunization against Tetanus, snake venom etc. 

Autoimmunity

Due to genetic and other unknown reasons, the body attacks self-cells resulting in damage to the body. It is called auto-immune disease. E.g. Rheumatoid arthritis. 

Allergies

• Exaggerated response of the immune system to some antigens present in the environment. 
• Allergens: E.g. mites in dust, pollens, animal dander etc. 
• Symptoms: Sneezing, watery eyes, running nose, difficult breathing, wheezing etc. 
• Antibodies produced against the allergens are IgE type. 
• Asthma is a respiratory disease due to allergy. 
• Treatment: Drugs like anti-histamine, adrenaline and steroids quickly reduce the symptoms. 
• Modern-day life style & protected environment provided early in life results in low immunity and more sensitivity to allergens. So children in metro cities suffer from allergies and asthma.

AIDS (Acquired Immuno Deficiency Syndrome)

It is caused by HIV (Human Immunodeficiency Virus), a retrovirus having RNA genome. 

Transmission: Sexual contact with infected person, Transfusion of contaminated blood, Sharing of infected needles, From mother to child through placenta. 

Diagnosis: ELISA test (Enzyme-linked immuno-sorbent Assay). 

Treatment: Anti-retroviral drugs. 

Prevention: Educate people about AIDS, Make blood safe from HIV, Use disposable needles and syringes, Condoms, Control drug abuse. 

Replication of retrovirus: 

Life cycle of HIV: 

HIV enters body → To macrophages (acts as HIV factory) → RNA becomes viral DNA in presence of Reverse transcriptase → Viral DNA incorporates into host DNA→ produce virus particles → HIV enters helper T-cells (TH lymphocytes) → Replicates & produce progeny viruses → Attack other TH cells → TH cells decrease → Weaken immunity. 

CANCER

It is an abnormal and uncontrolled multiplication of cells to form tumour. 

Normal cells show contact inhibition (contact with other cells inhibits their uncontrolled growth). Cancer cells do not have this property. 

Types of Tumours: 

• Benign tumours: Confined to the place of its origin. Cause little damage. 
• Malignant tumours: Tumour cells (neoplastic cells) invade and damage surrounding tissues. Cells from tumours reach other sites via blood and form a new tumour. It is called metastasis. 

Causes of cancer (Carcinogens): 

• Physical agents: Radiations like X-rays, gamma rays, UV etc. 
• Chemical agents: Tobacco smoke, vinyl chloride, nicotine, etc. 
• Biological agents: Oncogenic viruses, c-onc (cellular oncogenes or proto oncogenes) etc. 

Cancer detection and diagnosis:

• Biopsy: Histopathological studies of suspected tissue. 
• Imaging techniques: Radiography, CT scan & MRI. 
• Use of antibodies against cancer-specific antigens. 
• Molecular biology technique: To detect cancer related genes. 

Treatment of cancer: 

• Radiotherapy
• Chemotherapy
• Immunotherapy
• Surgery.

DRUGS, SMOKING & ALCOHOL ABUSE

DRUGS 

1. Opioids: 

• E.g. morphine, heroin, brown sugar. 
• Morphine is extracted from latex of Papaver somniferum (poppy plant). It is a sedative & painkiller. Used in surgery. 
• Heroin (smack or diacetylmorphine) is obtained by acetylation of morphine. It is a depressant. 

2. Cannabinoids: 

• Obtained from Cannabis sativa (Hemp plant). 
• Includes marijuana, hashish, charas & ganja. 
• They affect cardiovascular system. 

3. Coca alkaloid or cocaine (coke or crack): 

• It is obtained from coca plant Erythroxylum coca. 
• It interferes with transport of neurotransmitter dopamine. 
• It stimulates CNS producing euphoria & increased energy. 

SMOKING

• Tobacco contains nicotine etc. 
• Smoking causes cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcer etc. Tobacco chewing causes oral cancer. 
• Smoking increases CO content in blood and reduces oxyhaemoglobin. This causes O2 deficiency in the body. 

ADOLESCENCE & DRUG/ALCOHOL ABUSE 

Causes of drug/alcohol use in Adolescence 

• Curiosity and Experimentation. 
• Need for adventure and excitement. 
• To escape facing problems. 
• Stress from pressure to excel in academics or examination. 
• Television, movies, newspapers, internet etc. 
• Unstable or unsupportive family structures & peer pressure. 

Addiction: Psychological attachment with drugs & alcohol. 

Dependence: Body manifests unpleasant withdrawal syndrome if drugs/alcohol is abruptly discontinued. This results in anxiety, shakiness, nausea and sweating. 

Effects of Drug/alcohol abuse

• Reckless behaviour, vandalism and violence. 
• Coma and death. 
• Damage of nervous system and liver cirrhosis. 
• Causes mental and social distress to family and friends. 
• Social problems like stealing and spread of diseases. 
• Misuse of drugs by athletes. 

Warning signs of drug/alcohol abuse in Adolescence period

• Drop in academic performance and absence from school. 
• Lack of interest in personal hygiene. 
• Withdrawal and isolation. 
• Depression, fatigue, aggressive and rebellious behaviour. 
• Loss of interest in hobbies. 
• Deteriorating relationships with family and friends. 

Side effects of anabolic steroid abuse

In males:

• Acne, premature baldness 
• Mood swings & depression, increased aggressiveness. 
• Reduced testicles & decreased sperms. 
• Kidney & liver dysfunction. 
• Enlargement of Breast & prostate gland. 

In females:

• Masculinisation, excessive hair growth 
• Mood swings & depression, increased aggressiveness 
• Abnormal menstrual cycle, deepening of voice 
• Enlargement of clitoris 

Prevention and control 

• Avoid undue peer pressure. 
• Education and counselling. 
• Seeking help from parents and peers. 
• Looking for danger signs. 
• Seeking professional and medical help

Uses — ALKALI METAL

 

Biological classification

 BIOLOGICAL CLASSIFICATION: 

                                                     Chapter at a glance 

Aristotle’s classification: Plants to trees, shrubs & herbs. Animals to those with red blood & without red blood. 

Linnaeus: 2-Kingdom classification (Plantae & Animalia). 

    Drawbacks: 

• Prokaryotes & eukaryotes under Plants. -.
• Unicellular and multicellular organisms in same group. 
• No differentiation between fungi and plants. 

R.H. Whittaker: Five-Kingdom Classification. 

Characteristics of the five kingdoms

Characters	Monera	Protista	Fungi	Plantae	Animalia
Cell type	Prokaryotic	Eukaryotic	Eukaryotic	Eukaryotic	Eukaryotic
Cell wall	Polysaccharide + amino acid	Present in some	Chitin & polysaccharide	Cellulose	Absent
Nuclear membrane	Absent	Present	Present	Present	Present
Body organisation	Cellular	Cellular	Multicellular, loose tissue	Tissue/ organ	Tissue/organ/ organ system
Mode of nutrition	Autotrophic, heterotrophic	Autotrophic, heterotrophic	Heterotrophic	Autotrophic	Heterotrophic

1. KINGDOM MONERA (BACTERIA) 

Most abundant microorganisms. 

4 types: Coccus (Spherical), Bacillus (Rod-shaped), Vibrium (Comma-shaped) & Spirillum (Spiral).

  

I. Archaebacteria:

• Halophiles: Live in salty areas. 
• Thermoacidophiles: In hot springs. 
• Methanogens: In marshy areas and guts of ruminant animals. Produce methane (biogas).

II. Eubacteria (‘true bacteria’):

Rigid cell wall and a flagellum. 

a. Photosynthetic autotrophs (E.g. Cyanobacteria):  

• Have chlorophyll a. 
• Cyanobacteria (blue-green algae) colonies have gelatinous sheath. Some fix nitrogen in heterocysts. E.g. Nostoc & Anabaena. 

b. Chemosynthetic autotrophs: Oxidize inorganic substances and release energy. 

c. Heterotrophic bacteria: Most abundant. Decomposers. 

Reproduction in Bacteria: 

• Mainly by fission. 
• Spore formation: Under unfavourable conditions. 

-

Mycoplasmas are the smallest living cells and no cell wall. 

2. KINGDOM PROTISTA 

Single-celled eukaryotes. 

Some have flagella or cilia. 

Reproduction: Asexual & sexual (cell fusion → zygote). 

I. Chrysophytes: 

• Diatoms & golden algae (desmids). 
• Diatoms have siliceous cell walls. Their cell wall deposit is called diatomaceous earth. 

II. Dinoflagellates: 

• Mostly marine and photosynthetic. 
• Cell wall: stiff cellulose plates. 
• Most have 2 flagella. 
• Red dinoflagellates (E.g. Gonyaulax)- sea appears red (red tides). 

III. Euglenoids: 

• Have a protein rich layer (pellicle) & 2 flagella. 
• Photosynthetic in sunlight. Heterotrophs in darkness. 
• E.g. Euglena. 

IV. Slime Moulds: 

• Saprophytic protists. 
• Suitable condition → form an aggregation (plasmodium). 
• Unfavourable conditions → plasmodium differentiates → fruiting bodies bearing spores. 

V. Protozoans: 

    They are heterotrophs (predators or parasites). 

• Amoeboid protozoans: Move & capture prey by pseudopodia (false feet). E.g. Amoeba, Entamoeba (parasite). 
• Flagellated protozoans: Have flagella. Parasites cause diseases like sleeping sickness. E.g. Trypanosoma. 
• Ciliated protozoans: Move by cilia. E.g. Paramoecium. 
• Sporozoans: Have infectious spore-like stage. E.g. Plasmodium (malarial parasite). 

3. KINGDOM FUNGI 

Except yeasts, fungi are filamentous. 

Saprophytes. Some are parasites. 

Cell wall is made of chitin & polysaccharides. 

Hyphae: Thread-like structures of the body. 

Mycelium: Network of hyphae.  

Hyphae are 2 types: 

• Coenocytic hyphae: Continuous tubes with multinucleated cytoplasm. 
• Septate hyphae: Have septae or cross walls. 

Reproduction: 

• Vegetative propagation: Fragmentation, fission & budding. 
• Asexual: Spores (conidia, sporangiospores & zoospores). 
• Sexual: By oospores, ascospores & basidiospores. They are produced in fruiting bodies. 

Sexual cycle has 3 steps: 

1. Plasmogamy: Fusion of protoplasm between two motile or non-motile gametes. 
2. Karyogamy: Fusion of two nuclei. 
3. Meiosis in zygote to give haploid spores.

In sexual reproduction, 2 haploid hyphae fuse. 

In some fungi, 2 haploid cells fuse → diploid cells (2n). 

In ascomycetes & basidiomycetes, a dikaryotic stage or dikaryophase (2 nuclei) occurs. Such condition is called a dikaryon. Later, parental nuclei fuse → diploid. 

I. Phycomycetes (Lower Fungi) 

• Occur in aquatic habitats and on decaying wood or as obligate parasites on plants. 
• Mycelium is aseptate and coenocytic. 
• Asexual reproduction: By motile zoospores or by non-motile aplanospores. 
• Sexual reproduction: 2 gametes fuse → Zygospores. Gametes are isogamous or anisogamous or oogamous. 
• E.g. Mucor, Rhizopus (bread mould) and Albugo (parasitic fungi on mustard). 

II. Ascomycetes (sac-fungi) 

• Unicellular (e.g. yeast, Saccharomyces) or multicellular (e.g. Penicillium- source of antibiotics). 
• Mycelium is branched and septate. 
• Asexual reproduction: By conidia produced on conidiophores. 
• Sexual reproduction: By ascospores produced in sac like asci. The asci form fruiting bodies (ascocarps). 
• E.g. Aspergillus, Claviceps & Neurospora (used in biochemical & genetic work). 
• Morels & truffles are edible. 

III. Basidiomycetes 

• Includes mushrooms, bracket fungi or puffballs. 
• The mycelium is branched and septate. 
• Vegetative reproduction by fragmentation is common. 
• Plasmogamy by fusion of 2 vegetative or somatic cells → dikaryotic structure → basidium → Karyogamy & meiosis → 4 basidiospores. 
• Basidia are arranged in fruiting bodies (basidiocarps). 
• E.g. Agaricus (mushroom), Ustilago (smut) and Puccinia (rust fungus). 

IV. Deuteromycetes (Imperfect fungi) 

• Only their asexual or vegetative phases are known. 
• They reproduce only by asexual spores (conidia). 
• The mycelium is septate and branched. 
• Some are saprophytes or parasites. Majority is decomposers. 
• E.g. Alternaria, Colletotrichum and Trichoderma. 

VIRUSES, VIROIDS, PRIONS & LICHENS 

Viruses: 

• Non-cellular obligate parasites. So not included in five-kingdom classification. 
• Ivanowsky discovered virus. 
• Louis Pasteur gave the name virus. 
• Beijerinek demonstrated that the extract (Contagium vivum fluidum) of infected tobacco cause infection in healthy plants. 
• W.M. Stanley showed that viruses could be crystallized. 
• A virus is a nucleoprotein, i.e. it has a protein coat (capsid) & genetic material (RNA or DNA). 
• Generally, plant viruses have single stranded RNA. 
• Animal viruses have either single or double stranded RNA or double stranded DNA. 
• Bacteriophages usually have double stranded DNA. 
• The capsid made of small subunits (capsomeres). 

Viroid: 

• An infectious agent with small RNA and no protein coat. 
• Discovered by T.O. Diener. 
• It causes potato spindle tuber disease. 

Prions: 

• Abnormally folded protein. 
• Cause bovine spongiform encephalopathy (BSE) or mad cow disease in cattle and Cr-Jacob disease (CJD) in humans. 

Lichens: 

• Symbiotic association between algae & fungi. 
• Algal component: Phycobiont (autotrophic). Fungal component: Mycobiont (heterotrophic). 
• Lichens are pollution indicators.

Scientist names

 

Organic chemistry

 NAMED REACTION 👻👻👻

Disorders

 Disorders (Human physiology)

BREATHING AND EXCHANGE OF GASES

 BREATHING AND EXCHANGE OF GASES

DIGESTION AND ABSORPTION

 DIGESTION AND ABSORPTION 👻