1. Cell Death

2. II. Physical Injury Extreme temperatures Trauma Radiant energy
Electrical energy

3. Extreme Temperatures Excessive cold
Blood vessels vasoconstrict and inhibit blood supply to cells
Can lead to frost bite and hypothermia

4. Vasoconstriction What does the word mean?
VASO: vessel COSTRICTION: make small
Vessels can constrict or dilate depending on the situation
Do this by changing the lumen

5. Artery ©http://www. nlm. nih

6. Artery and Vein http://images. google. com/imgres. imgurl=http://www

7. When you are relaxed, lumen are open
Sitting and eating lunch
Fire alarm goes off unexpectedly—what happens?
Lumen becomes smaller, vasoconstriction
Blood is “re-routed” to flow to muscles, etc

8. ©

9. The same events occur when you outside in the cold
In extreme cold, peripheral blood vessels constrict
Why?
Decreases blood flow to skin to persevere heat
Can lead to frostbite, anoxia, amputation

10. Frostbite ©http://www. summitjournal

11. Frostbite

12. Different tissue has different time frames before anoxia occurs
Approximately 6 hours for limbs (when blood supply is decreased with a tourniquet)
4 hours for heart
4.5 minutes for brain

13. Cold puts things in slow motion
Ex. Child falling into frozen lake for a 30 minutes may be revivable
Not good odds for an adult—too much mass
NFL player for Buffalo,Kevin Everett, chilled his blood (2007)

14. Heat Damage High temperatures (burns) can damage tissue
Causes a hyper-metabolic reaction
When a cell’s temperature reaches above 98.6*F, the metabolism of the cell increases
Cells work so fast, there is no way to deliver enough O2 to the tissue

15. Body switches to anaerobic respiration and builds up too much lactic acid
Burns do not “cook” your cells, they work themselves to death

16. Also causes vasodilatation of blood vessels
Body tries to flush away the high temperature and get rid of dead material

17. So why are fevers beneficial?
Bacteria loves 98.6*F
If temperature is raised, pathogens do not reproduce as quickly
Delays potential infection and allows time for wbc to come in