Question

Your written assignment for this module should be a 1-2 page paper (not including title page and reference page) that describes the following:

• What are the different types of immunities and give an example of each
• Describe how stress impacts the immunity of a person

You should include a minimum of 3 scholarly references. Include a title page, in-text citations, and a reference page in APA format.

Answer 1

IMMUNITY

Immunity means resistance to diseases or the ability of the body to protect against all types of foreign bodies. The immune system of our body defends or fights with pathogens, like bacteria, viruses, fungus, parasites etc. and protects from developing harmful diseases.

The main classification of immunity includes;

1. Innate Immunity (Natural or Nonspecific Immunity) which is inherited by the organism from the parents and protects it from birth throughout life. For example, Distemper is a fatal disease for dogs, but, humans have innate immunity against this disease.

2. Acquired Immunity (Specific or Adaptive Immunity)

Acquired Immunity can be further classified as Active Immunity and Passive Immunity.

Innate immunity or nonspecific immunity is not specific against a particular pathogen or foreign body, but provides barriers to the entry of the pathogens into the body. Innate immunity consists of four types of barriers— physical, physiological, cellular and cytokine barriers.

Examples of physical barriers includes the barriers provided by the skin and mucus membranes. Skin prevents the entry of pathogens to the body. Mucus secreted by mucous membrane traps the pathogens. The cilia in the nose, sweep the mucus and dust particles into the pharynx. From the pharynx it is coughed out or swallowed for elimination with the faeces.

Body temperature, pH of the body fluids and various body secretions are all examples of Physiological barriers. Acid in the stomach kills most of the ingested pathogens. Wax in the ear destroys microorganisms. Bile does not allow growth of pathogens.

Cellular Barriers include macrophages, white blood corpuscles (Neutrophils and monocytes ), immune response like inflammation, fever etc.

Cytokine Barriers play a very important role, both directly (blocking viral replication) and by means of different mechanisms which trigger the inflammatory response, elevation of the body temperature, activation of macrophages etc.

Acquired Immunity:

The immunity that an individual acquires after the birth is called acquired or adaptive or specific immunity. It is specific and mediated by antibodies or lymphocytes or both which make the pathogen or antigen harmless to the body.

Acquired (Adaptive) Immunity is of two types: Active immunity and Passive immunity.

1. Active Immunity:

Here person’s own cells produce antibodies in response to infection or vaccination. It is slow and takes time in the formation of antibodies. It is long lasting and is harmless. Active immunity may be natural or artificial.

Example of Natural Active Immunity - A person who has recovered from an attack of small pox, measles or mumps develops natural active immunity.

Artificial Active Immunity is the resistance induced by vaccines. Examples of vaccines are BCG vaccine against tuberculosis, MMR vaccine against mumps, measles and rubella, Oral Polio Vaccine etc.

2. Passive Immunity:

In passive immunity, ready-made antibodies are directly injected into a person to protect the body against pathogens. It provides immediate relief. It is not long lasting. Passive immunity may be natural or artificial.

(a) Natural passive immunity is the resistance passively transferred from the mother to the baby through placenta. IgG antibodies can cross placental barrier to reach the foetus. Immunoglobulin’s are passed to the new-born through the breast milk. Human colostrum (mother’s first milk) is rich in IgA antibodies. Mother’s milk contains antibodies which protect the infant up to the age of three months.

(b) Artificial passive immunity is the resistance passively transferred to a recipient by administration of antibodies. For example, ATS (Anti Tetanus Serum) is used for passive immunization against tetanus. there is Anti Diphtheric serum (ADS) too.

Stress and Immunity

Stress makes humans susceptible to diseases because the brain sends defense signals to the endocrine system when the person is stressed. This will cause the release of hormones, like adrenaline, that not only gets the body ready for emergency situations, but, severely depresses the immune system. Stress is responsible for many diseases, including cancer and heart disease. Stress triggers chemical reactions and flooding the body with cortisol which decreases inflammation, decreases white blood cells and NK cells (special cells that kill cancer), increases tumor development and growth, and increases the rate of infection and tissue damage. So stress is very harmful for the immune system of the body.