U3 KA5 - Non-specific Body Defences

Question 1

Describe the First line of Non-specific body defences

Answer 1

This involves the use of physical barriers (e.g. skin) and chemical barriers (e.g. mucus) to prevent pathogens from entering the bodies systems.

Question 2

Describe the Second line of Non-specific body defences

Answer 2

This involves a cellular and inflammatory responses to dispose of pathogens once they have enter the body

Question 3

What is the surface of the skin composed of

Answer 3

Layers of closely packed epithelial cells which creates a physical barrier against the entry of pathogens into the body.

Question 4

Where, other than skin, can epithelial cells be found?

Answer 4

Epithelial cells are also found in the mucous membranes of the digestive system and respiratory tract form an internal protective barrier.

Question 5

Name some chemical defences in the first line of defence

Answer 5

1. Secretions from the sebaceous glands and sweat glands
2. Tears and saliva
3. Cells in the mucous membranes ​
4. Stomach acid

Question 6

How do tears/saliva destroy pathogens?

Answer 6

They contain the enzyme lysozyme which digest the cell walls of bacteria ​

Question 7

How do Cells in the mucous membranes destroy pathogens?

Answer 7

They secrete sticky mucus that traps microorganisms

Question 8

Describe the stages of the inflammatory response

Answer 8

1. Physical injury occurs
2. Mast Cells activate and release Histmine
3. Histamine stimulated vasodilation of blood vessels/capillaries in injured area
4. Blood vessels become more permeable and leak fluid into neighbouring tissue causing swelling
5. Cytokines Secreted
6. Migration of Phagocytes to injured area
7. Delivery of blood clotting chemicals

Question 9

What are cytokines and what is their role in the inflammatory response?

Answer 9

Cell-signalling proteins which stimulate recruitment of other cell types

Question 10

How do Phagocytes find foreign bodies?

Answer 10

They detect surface antigens found on a foreign body

Question 11

Describe the stages of Phagocytosis

Answer 11

1. Phagocyte detects foreign body
2. phagocyte engulfs pathogen to create a vacuole
3. Lysosomes release enzymes that breakdown and digest pathogen
4. breakdown products are absorbes by pathogen
5. Once digested the phagocytes release cytokines which signal to attract more phagocytes
6. A greater phagocyte presence to continue fighting the pathogens
7. Dead bacteria and phagocytes accumulate at the infected site as pus.

Question 12

Where are Lysosomes found?

Answer 12

Cytoplasm of a phagocyte