CHSE Biology Health and Disease Chapter Notes
UNIT-3: Biology and Human Welfare
Chapter-1:- Health & Disease
- Health is not only absence of disease.
- WHO has defined health a state of complete physical, mental and social well being.
- Disease can be defined as, "a Condition of the body or its parts in which the functions are disturbed or deranged."
- When one or more organs are not functioning properly.
- Pathogen is an organism which is capable of producing a disease
- A pathogen is an infectious agent that causes a disease or illness to its host.
- Typically, that term pathogen is used to describe, infectious agents such as viruses, bacteria, fungi, prion and parasite of various forms.
- Major classes of pathogens are described below:-
- Vruses- Adenovirus, picorna virus, retro virus, papovavirus, polyoma virus etc.
- Bacteria- Mycobacterium, Streptococcus, Shigella and Salmonella.
- Fungi- Saprophytic Pathogenic Fungi
- Prions- Protein pathogens that don't content nucleic acids.
- Parasites- Protozoon parasites and helminth parasites.
- Pathogenicity is the disease causing property of pathogens. This property is also known as virulence.
- An organism that lives on or in organism of another species, known as the host, from the body of which it obtains nutrients.
- Examples hair and body lice
Disease can be classified into two types
1) Acquired Diseases:-
- Acquired diseases occur only after birth.
- These may be either
- Communicable Or
- Non-Communicable Disease
a) Communicable Disease:-
- These are infectious and spread from infected person to healthy person through pathogens.
- Communicable diseases may be contagious or non-contagious.
Contagious Disease:- Contagious diseases are transmitted through contact example chicken pox, measles, syphilis and leprosy.
- Non-contagious diseases are transmitted through agencies like water, air, food and vector organisms.
=> Communicable diseases can be categorized into several types:-
- Viral diseases
- Bacterial diseases
- Fungal diseases
- Protozoan diseases
- Helminths diseases
b) Non-communicable Diseases
It does not spread from person to person.
These are four types:-
Degenerative disease:- These occur due to degenerative changes in some vital organs. example- Brain disease, arthritis.
Deficiency diseases:- These are caused due to deficiencies in food or nutrients. example- kwashiorkor(Protein deficiency), goitre(Iodine deficiency).
- These are caused by several physical and chemical agents collectively known as cancer causing agents or carcinogens.
- it occurs due to uncontrolled growth of tissue.
Allergy:- These are caused by several allergens (Foreign substances) Example- asthma, hay fever.
2) Congenital Diseases
- These are inherited genetic disorders.
- These diseases are present since birth.
- Example:- Colour blindness, Down's syndrome and Hemophilia.