Chapter 7 Set 5 Flashcards
Non-Specific Defences
What are the 5 methods of Non-Specific Defences?
Natural Killer Cells (NKC)
Phagocytosis
Inflammation
Fever
The Lymphatic System
What are Natural Killer Cells?
A type of white blood cell (leucocyte) that kills everything they encounter by releasing chemicals.
What do NKC’s release?
Cytokines – alert and attract other immune cells
Other chemicals that destroy cell membranes to kill unhealthy cells.
Why don’t Natural Killer Cells kill healthy body cells?
Healthy body cells have proteins on their surface that act as “self” markers so they don’t get attacked.
Virus-infected cells and cancer cells have fewer of these markers, so are more likely to be killed.
What are phagocytes and what do they do? State two types
Cells that can engulf and digest micro-organisms and cell debris.
Macrophages and Neutrophils.
What is inflammation, 3 things it does, and the 4 signs?
Response to any tissue damage
- Reduces spread of pathogens
- Removes damaged tissue and cell debris
- Begins repair of damaged tissue
The 4 signs are:
- Redness
- Heat
- Swelling
- Pain
What is the 1st step of Inflammation?
Tissue damage occurs.
Pathogens may or may not be introduced to continue damage.
What is 2nd step of Inflammation?
Tissue Damage causes Mast cells release
histamine and heparin.
What are the two chemicals released during inflammation and what are their functions?
Histamine causes local capillaries to dilate and become leaky, allowing phagocytes and other leukocytes to enter the area.
This causes heat, redness, swelling and pain.
Heparin prevents clotting in the immediate area.
What is 3rd step of Inflammation?
Complement proteins are activated, and
attract phagocytes.
They are able to enter the area of damage due to the leaky, dilated capillaries from step b.
Phagocytes engulf and digest dead cells and bacteria.
Fun Fact: pus is made from dead and dying cells and bacteria!
What is the 4th step of inflammation?
Once pathogens are cleared, mast cells and
complement stop messaging
Local capillaries return to normal
Phagocytosis ceases
Stage is set for tissue healing.
What is a fever?
Part of the body’s natural immune response to infection. The body raises temperature to combat pathogens such as viruses or bacteria.
What are pyrogens?
After encountering infection, white blood cells release pyrogens (fever causing chemicals) eg: interleukin-1
Pyrogens affect the hypothalamus so that the normal set point of 37oC is temporarily reset to a higher temperature.
Once the infection has been dealt with, the immune system stops producing pyrogens, and the “set point” returns to normal.
What does the hypothalamus do in a fever?
Hypothalamus then initiates warming responses to raise body temperature to the new, temporary set point.
These include normal warming responses such as shivering, vasoconstriction, seeking warmth etc, until the body temperature reaches the new “set point”.
The person then feels hot and cooling responses are activated eg sweating and vasodilation.
Are fevers good?
Fever is beneficial, but only up to a point. Prolonged, high fever can cause harm and even death, if the immune system is unable deal with the infection quickly and effectively.
