Question

Define the concepts of pathogen, host, and the basic mechanism of immune system

* Describe different ways of how immunity against pathogens are required

* Identify different types of transmission of pathogens

* Differentiate intoxication and infection

* Identify and differentiate different types of vectors

* Describe the structure of respiratory system

* Differentiate asthma and other allergy for their symptoms and place of occurrence

* Describe how natural disasters can affect public health

Answer 1

1) Pathogen- is any organisms that causes disease.

Host- a living animal or plant on which pathogen acts and infects it.

Immune system- it refers to the host defense system against pathogens. It comprises of many structures like antibodies etc. and many processes too to combat invading pathogen.

2)different types of defenses-

Natural/ innate immunity- it is present by birth and does not require prior interaction with pathogen. It includes the following-

Surface barriers- skin acts as a barrier for all the pathogens. Mucous lining present in oral cavity etc. also prevents entry of foreign agents.

Natural killer cells- these include neutrophils and monocyte which phagocytose pathogens thus providing immunity.

Enzymes- some epithelial and phagocytic cells release various enzymes like lysozyme which kill bacteria etc.

Inflammation related proteins- complement, lectins etc.

Aquired/ adaptive immunity.

this type of immunity works when there is an interaction with pathogen. This elicits an immune response. Primary response is weaker as immune system takes time to develop antibodies. But subsequent response is very high due to memory of 1st attack. It is very specific.

It comprises of two parts-

Humoral immunity- in this type of immunity activated B lymphocytes release antibodies in the blood which fight disease causing organisms.

Cell mediated immunity- in this infection activates T lymphocytes to release cytotoxic t cell which phagocytose pathogens.

3)Different types of transmission of pathogens-

Direct contact- infectious agents can spread through direct contact with infected person like touch, sexual act, mother to foetus or by coughing, sneezing etc

indirect contact- by touching of infected objects like door knobs, table, towel etc.

insect bites- like mosquito bites causes dengue. Many pathogens have an intermediate host like insects.

contaminated food- vegetables are not properly washed, infected water etc.

4)Intoxication occurs when a person eats food which is infected with toxins produced by a pathogen. Viruses don't produce toxins. Only some bacteria do.

infection occurs when a person eats food infected with pathogens like bacteria, viruses etc they cause disease.

5) types of vectors-

arthropods- it is a phylum of animal kingdom which comprises of joint- footed anals. It includes insects, centipedes,millipedes etc.

Eg- mosquito, cockroaches etc

snails- spread diseases like schistosomiasis

rodents- rats spread diseases like plaque.

Above vectors can be of two types-

Biological vector- vector ingests pathogen and pathogen lives a part of its life cycle inside vector.

Mechanical vector- vector just transfers pathogens from infected individual/ food to healthy individual/ food.

6) structure of respiratory system-

respiratory system is concerned with gas exchange.

It consists of -

Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, lungs, alveoli.

Air from external environment enters nose. There it gets filtered and humidified by mucous lining and hairs. Then it enters nasopharynx→ oropharynx→ larynx→ finally into trachea. Larynx is bounded by epiglottis at it's junction with oropharynx. Epiglottis closes opening for larynx during swallowing. Trachea is made up of incomplete cartilaginous rings. It divides into two bronchi which further divide into bronchioles ah finally alveoli.bronchi enters lugs where air is filtered out.

7) Asthma is a condition in which the airways get narrow due to spasm of smooth muscles or mucous. This leads to difficult breathing.

Symptoms- coughing, breathlessness, wheezing, anxiety, chest pressure etc.

other allergy-  a person can be allergic to various things.

Symptoms are present accordingly.

Skin allergy- symptoms- rashes, eczema, atopic dermatitis etc.

Hay fever- running nose, itchy watery eyes.

8)impact of natural disasters on public health-

injuries- natural disasters can injure people like earthquakes collapse the whole building leading to injuries and even deaths of many.

spread of communicable diseases- communicable disease spread during disasters as there is no proper check. People do not have access to clean drinking water during floods.

lack of sanitation sanitation is affected. There is debris everywhere which gives breeding ground for pests and pathogens.

destruction of health care centers- hospitals and clinics are also destroyed so affected individuals do not get proper care.

psychological effects- no affected Individual will be happy. There is depression and lose of hope. People lose their homes, family, and even health.