Describe The Importance Of Non Specfic Immunity To Include Natural Barriers And Inflammation

Question 1

What is non specific immunity?

Answer 1

Mechanisms that protect the body against a wide range of dangers.

Usually present from birth

Question 2

Describe specific immunity?

Answer 2

Mechanisms directed against one specific invader

The body learns and remember specific antigens, building a immunological memory

Question 3

What is a non specific defence?
What are the 5 main non-specific defences of the body?

Answer 3

These are non specific first line defences prevent entry of microbes and other foreign material.

1. Epithelial barrier
2. Phagocytosis
3. Natural anti microbial substances
4. The inflammatory response
5. Immunological surveillance

Question 4

Explain the 1st line non specific defence of the epithelial barriers

Answer 4

Epithelial barriers consist of skin and mucous membranes.

Nose hair filter system to stop foreign bodies entering our respiratory tract.

Cilia moves mucus and inhaled foreign materials towards the throat, so it is coughed up or swallowed.

Epithelial secretions e.g oral, vaginal, gastric are anti-bacterial and often acidic, containing antibodies and enzymes.
Sebum and sweat contain antibacterial and anti fungal properties.

One way flow of urine from the bladder minimises the risk of infection ascending (outside to inside) through the urethra into the bladder.

Question 5

Explain 2nd line non specific defence of anti-microbial substances

Answer 5

Saliva washes away food debris to prevent bacterial growth. Contains antibodies, lysozyme and buffers to neutralise bacterial acids that promote dental decay.

Lysozyme is an antibacterial enzyme present in tears

Hydrochloride acid is present in gastric juice

Antibodies are protective proteins inactivate bacteria and are found coating membranes exposed to the external environment e.g respiratory and gastrointestinal tract.

Interferons are chemicals produced by T lymphocytes, macrophages and body cells that have been invaded by viruses. They activate immune cells, including killer T cells, prevent viral replication within infected cells, and reduce the spread of viruses to healthy cells.

Question 6

Explain 2nd line non specific defence of phagocytosis

Answer 6

Phagocytosis is cell eating. Neutrophils and macrophages are examples of phagocytic cells.

Phagocytes migrate to sites of inflammation and infection as they are attracted to chemicals that are released by invading microbes.

Phagocytes attack, digest and destroy foreign cells, damaged cells and debris.

They may also release a chemical which is toxic to invading microbes into the interstitial fluid.

Neutrophils are short lived as they destroy themselves with their toxic chemicals too.

Macrophages live longer, and link the non specific defences with specific immunity.

Question 7

Explain 2nd line non specific defences of inflammatory response

Answer 7

Inflammatory response is a physiological response to tissue damage

Purpose: to isolate, inactivate and remove both the causative agent and damaged tissue, so that healing can take place.

Signs of inflammation are redness, heat, swelling and pain.

Extremes of temperature, pH, trauma, foreign bodies etc trigger an inflammatory response.

Inflammation causes:
increased blood flow : arteriole sodium dilate, capillaries expand. Provide more oxygen and nutrients to the area. Responsible for the increased temperature, swelling and redness. Caused by local release of histamine and serotonin. Capillary walls are more permeable so fluid can move to tissue easier.

accumulation of tissue fluid: fluid leaves blood vessels and moves into interstitial space. Caused by increased blood flow and histamine, serotonin and prostaglandin making capillaries walls more permeable.

migration of leukocytes: loss of fluid from the blood thickens it, slowing flow and allowing the normally fast flowing white blood cells to make contact with, and adhere to, the vessel wall. Neutrophils adhere to the blood vessel lining and enters the tissues for phagocytosis. Macrophages begin phagocytosis after 24 hours.
Less fluid in vessel means flow is slower means the WBC can attach to the wall of vessel means it can enter tissue for phagocytosis.

Increased core temperature: inhibiting the growth and division of microbes while promoting the activity of phagocytes ( helps phagocytosis)

pain: encourages protection. Local swelling compresses sensory nerve endings

suppuration (pus forming): collection of material - dead phagocytes, dead cells, fibrin, inflammatory exudate, and living and dead microbes.

Inflammatory response releases substances such as:
- histamines (from mast cells and basophils)
- serotonin (from platelets, mast cells and basophils)
- prostaglandin [ responsible for pain] (most cells)
- heparin (liver, mast cells)
- bradykinin (tissues and blood)

Question 8

Explain 2nd line non specific defences of immunological surveillance

Answer 8

This is where the body detects abnormal cells and destroys it.

Natural killer (NK) cells: a type of non-selective lymphocyte. They patrol the body , searching for abnormal host cells.
Cells that have been infected with the virus, or mutated cells that might become masking ant, frequent,y display unusual markers on their cell membranes, which are recognised by NK cells.

Having detected an abnormal cell, the NK cell immediately kills it.