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Human Health and Disease

Human Health and DiseaseNEET Zoology · Class 12 · NCERT Chapter 7

3 interactive concept widgets for Human Health and Disease. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

Disease-pathogen explorer

Every NEET-tested human disease with its pathogen, transmission and symptoms in one filterable, searchable list.

Diseases

Disease-pathogen explorer

Filter by category or search by disease name, pathogen or symptom. Every NEET-tested human disease, with its pathogen, transmission, and symptoms in one place.

All
Bacterial
Viral
Protozoan
Fungal
Helminthic

Typhoid

Bacterial

Pathogen

Salmonella typhi

Transmission

Contaminated food and water

Symptoms

Sustained high fever, weakness, stomach pain, constipation, headache

NEET note

Diagnosed by the Widal test. "Typhoid Mary" was a famous carrier.

Pneumonia

Bacterial

Pathogen

Streptococcus pneumoniae, Haemophilus influenzae

Transmission

Inhaled droplets from infected person

Symptoms

Fever, chills, cough, headache; lips and fingernails turn grey-bluish in severe cases

NEET note

Alveoli get filled with fluid, blocking gas exchange.

Common cold

Viral

Pathogen

Rhinoviruses

Transmission

Inhaled droplets, contaminated objects

Symptoms

Nasal congestion, sore throat, cough, headache, tiredness

NEET note

Infects nose and upper respiratory tract; not lungs.

Malaria

Protozoan

Pathogen

Plasmodium spp. (P. vivax, P. malariae, P. ovale, P. falciparum)

Transmission

Bite of infected female Anopheles mosquito

Symptoms

High fever with chills, recurring every 48 or 72 hours; anaemia; in severe cases, coma

NEET note

P. falciparum is the most lethal (malignant malaria). NEET favorite.

Amoebiasis (amoebic dysentery)

Protozoan

Pathogen

Entamoeba histolytica

Transmission

Contaminated food and water; housefly is mechanical vector

Symptoms

Constipation, abdominal pain, cramps, stools with mucus and blood

NEET note

Infects the large intestine.

Ringworm

Fungal

Pathogen

Microsporum, Trichophyton, Epidermophyton

Transmission

Contact with infected persons or fomites (towels, combs)

Symptoms

Dry, scaly skin lesions; intense itching, often in groin and between toes

NEET note

A fungal infection, not a worm despite the name.

Ascariasis

Helminthic

Pathogen

Ascaris lumbricoides (roundworm)

Transmission

Ingestion of contaminated food, water or vegetables containing eggs

Symptoms

Stomach pain, fever, anaemia, blockage of intestinal passage

Filariasis (elephantiasis)

Helminthic

Pathogen

Wuchereria bancrofti, W. malayi

Transmission

Bite of infected female mosquito

Symptoms

Chronic lymphatic blockage; gross swelling of limbs and sometimes genitals

NEET note

Adults live in lymphatic vessels and produce microfilariae in the blood.

Try this

  • Filter to "Protozoan". How many diseases? Which one is the most lethal in its category?
  • Search for "mosquito". Two diseases show up. Are they caused by the same kind of pathogen?
  • Search for "Wuchereria". Which disease does it cause and what is the body part it blocks?

Immunity compared

Side-by-side comparison of innate vs acquired and active vs passive immunity. Specificity, memory, speed and the NEET trap (placenta and colostrum are passive, not active).

Immunity

Immunity compared: innate vs acquired, active vs passive

Side-by-side comparison of all four immunity types. Specificity, speed, memory, components and NEET-favorite traps.

Innate vs Acquired Immunity

 

Innate (non-specific)

Acquired (specific)

Specificity

Non-specific. Treats all pathogens the same.

Highly specific. Targets a particular pathogen.

Present from

Birth (present from day 1)

Develops after first exposure to a pathogen

Memory

NEET trap

No memory. Same response every time.

Has memory. Second exposure gives faster, stronger response.

Components

4 barriers: physical (skin, mucus), physiological (HCl, tears, saliva), cellular (macrophages, neutrophils, NK cells), cytokine (interferons)

B lymphocytes (humoral, make antibodies) and T lymphocytes (cell-mediated, attack infected cells)

Speed

Fast (immediate)

Slow on first exposure, fast on second exposure

Active vs Passive Immunity

 

Active (your body makes)

Passive (ready-made from outside)

Antibody source

Your own body makes antibodies

Ready-made antibodies given from outside

How acquired

Natural infection OR vaccination

Placental transfer, colostrum, antiserum injection

Speed of action

Slow (days to weeks to build up)

Fast (immediate protection)

Duration

Long lasting (months, years, sometimes lifelong)

Short lasting (weeks to months)

Examples

Recovery from chickenpox; BCG, hepatitis B, polio vaccines

Antibodies through placenta (IgG); colostrum (IgA); tetanus antiserum, snake-bite antivenom

NEET trap to remember

Babies get passiveimmunity through the placenta (IgG) and colostrum (IgA), even though it's "natural". Active vs passive is about who makes the antibodies, not how it was acquired.

Try this

  • Which immunity type has memory? That is the reason vaccines work for years.
  • Colostrum from mother contains antibodies. Is the baby getting active or passive immunity? (Hint: who is making the antibodies?)
  • BCG vaccination is which type, active or passive? Justify your answer.

Antibody types and structure

Click any of the five isotypes (IgG, IgA, IgM, IgD, IgE) to see shape, abundance, location, function and the NEET facts tested most. Includes a labelled H2L2 schematic.

Antibodies

Antibody types: GAMED (IgG IgA IgM IgD IgE)

Click any isotype to see its shape, abundance, location, function and the NEET facts that get tested most often. Use the mnemonic GAMED to remember all five.

Antibody structure (H2L2)

Heavy chains (2)

Light chains (2)

Antigen-binding tips (paratope)

Variable region = tips (binds antigen). Constant region = base (decides isotype: IgG, IgA, IgM, IgD, IgE).

IgG
IgA
IgM
IgD
IgE

IgG

Monomer (single Y)

Abundance

Most abundant in plasma (~75%)

Where found

Blood, lymph and tissue fluid; crosses placenta

Function

Main antibody of the secondary immune response. Neutralises toxins, activates complement, helps phagocytes.

NEET fact

Only antibody that crosses the placenta. Gives passive immunity to the fetus.

Try this

  • Which antibody appears FIRST in a primary immune response? (Hint: it is also the largest.)
  • Which antibody is most abundant in colostrum and saliva? Now think about how a breastfed baby gets passive immunity.
  • Which antibody binds mast cells and releases histamine? When you have an allergic reaction, that is what is happening.

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