22.Innate immunity. Physiological barriers. Cellular defence mechanisms.

Question 1

Immunity - what does it mean?

Answer 1

Means protection and it means the body’s insensitivity to harmful and non harmful agents

Question 2

Types of immunity

Answer 2

• Inate
• Aquired

Question 3

Innate immunity

Answer 3

• 1st line of defense
• ready to act even before the pathogen has entered the body
• activated immediatly after the pathogen has entered the body
  -inate immunity is non-specifc, not directed to all types of pathogen
• rapid response

INNATE IMMUNITY - Barrier defenses
- skin
- mucous membranes
- secretions

INNATE IMMUNITY - Internal defenses
- phagocytic cells
- natural killer cells
- anti microbial proteins
- inflammatory

Question 4

Physiological Barriers

Answer 4

• skin: barrier
• mucous membrane: sectrets mucous to waft and moves pathogen that are found in the digestive, urinary, respiratory along

Question 5

Internal Defenses

Answer 5

• Cellular (direct action of immune cells)
• humoral (via proteins)

Question 6

Cellular Defense Mechanisms

Answer 6

PHAGOCYTOSIS
-2 main types of phagocytic cells in mammalian body:
Neutrophils (microphages)
- Small
- Segmented nucleus (“polymorphonuclear”)
- Circulate in the blood – first barrier in limiting the inflammatory process.
- Migrate through the capillary walls to the sites of tissue damage, where they engulf and destroy the pathogens.
- Short-lived (from a few hours to 4 days)
Macrophages
* Larger
* Unsegmented kidney-shaped nucleus (“mononuclear”)
* Inactive in the blood vessels and stay there very little
* After passing into the connective tissue, they transform into macrophages.
* Long-lived

Question 7

Mechanism of phagocytosis

Answer 7

1. Chemotaxis and adherenceof microbe to phagocyte
2. Ingestion of microbe by phagocyte
3. Formation of a phagosome
4. Fusion of the phagosome with a lysosome to form a phagolysosome
5. Digestion of ingested microbe by enzymes
6. Formation of residual body containing indigestible material
7. Discharge of waste materials

Question 8

Extracellular Killing

Answer 8

• Eosinophillis and NK cells are used when pathogen is too big for phagocytosis

EOSINOPHILLIS CELLS
-pour out content of the granules
- found in blood and submucous tissues
- contain histamine

NK CELLS (NATURAL KILLER CELLS)
- kill by cytolysis
- have large granules called perofins