Awesome, thanks for sharing. I would never have thought of factoring in the salt content of the body.Originally Posted by Pete S
Awesome, thanks for sharing. I would never have thought of factoring in the salt content of the body.Originally Posted by Pete S
Steve
Is there really any BAD weather???
I'd also imagine that if we are talking about hands, ears, nose you'd have to be a very sick person for those to freeze even at 30F since our body has a great heat pumping and distribution system.Originally Posted by Pete S
Somewhere back in the confusion of this thread I was trying to get at the frozen tissue-no, tissue damage-yes answer. I think it was lost in the complexity of my response.
I didn't find it confusing. I knew that's what you were saying.Originally Posted by Bill O
Steve
Is there really any BAD weather???
not to barge into your post....but i will add what i have learned and come to know about frostbite and frostnip....
your body works to stay alive first and to stay functioning second....
in conditions of prolonged cold exposure....your body sends signals to the blood vessels in your arms and legs telling them to constrict (narrow)....by slowing blood flow to the skin your body is able to send more blood to the vital organs....supplying them with critical nutrients while also preventing a further decrease in internal body temperature by exposing less blood to the outside cold....as this process continues and your extremities (the parts farthest from your heart) become colder and colder....a condition called the hunter’s response is initiated....your blood vessels are dilated (widened) for a period of time and then constricted again....periods of dilatation are cycled with times of constriction in order to preserve as much function in your extremities as possible....but when your brain senses that you are in danger of hypothermia (when your body temperature drops significantly below 98.6°F) it permanently constricts these blood vessels in order to prevent them from returning cold blood to the internal organs....when this happens frostbite has begun.
frostbite is caused by 2 different means: cell death at the time of exposure and further cell deterioration and death because of a lack of oxygen....
in the first....ice crystals form in the space outside of the cells....water is lost from the cells interior and dehydration promotes the destruction of the cell....in the second....the damaged lining of the blood vessels is the main culprit....as blood flow returns to the extremities upon rewarming....it finds that the blood vessels themselves are injured by the cold as well....holes appear in vessel walls and blood leaks out into the tissues....flow is impeded and turbulent and small clots form in the smallest vessels of the extremities....it is because of these blood flow problems thatcomplicated interactions occur and inflammation causes further tissue damage....this injury is the primary determining factorof the amount of tissue damage you will have in the end....it is rare for the inside of the cells themselves to be frozen....that phenomenon is only seen in very rapid freezing injuries like those that are produced by frozen metals.....
it really comes down to pathophysiology....cold exposure leads to ice crystal formation....cellular dehydration....protein denaturation....inhibition of DNA synthesis....abnormal cell wall permeability with resultant osmotic changes.... damage to capillaries and pH changes....rewarming causes cell swelling.... erythrocyte and platelet aggregation....endothelial cell damage....thrombosis....tissue edema....increased compartment space pressure....bleb formation.....localized ischemia....and tissue death.... underlying responses to these injuries include generation of oxygen free radicals....production of prostaglandins and thromboxane a2....release of proteolytic enzymes and generalized inflammation.....tissue injury is greatest when cooling is slow....cold exposure is prolonged....rate of rewarming is slow and especially when tissue is partially thawed and refreezes.....
frostnip is a nonfreezing injury of the skin tissues....usually of the fingers.... toes....ears....cheeks and chin....numbness and tingling are present but no tissue injury occurs....symptoms develop when blood vessels supplying the affected tissues narrow because of the cold temperature....frostnip occurs at temperatures of about 15°C (59°F)....
a more significant nonfreezing injury from exposure to cold temperatures is chilblains....as tissue temperature drops below 15°C (59°F) tissue injury progresses....the walls of small blood vessels break and the tissues swell....
so....if anyone made it to the end of this post....i hope it helped....and i hope all the dots didnt drive you crazy....its how i tend to type when not working on an official document....
Mary, we thank you! Hopefully your typing fingers are toasty and warm.
Brad (a 6288 club member)
http://bradstreet.zenfolio.com Personal Photo sales site
http://public.fotki.com/bradbradstreet Personal photo web site
http://public.fotki.com/MWO/saved/2012/ MWO image & video archive site 2006-2012
This whole discussion reminds me of a book I got for Xmas a while back called Surviving the Extremes. It was a fascinating read about the enormous variation humans worldwide expose themselves to, both to live and to explore. It contained stories of people on death's door who made inexplicable recoveries, physiological accounts of the body's efforts to save itself, and the types of adaptations made over generations of living in drastic climates.
http://findarticles.com/p/articles/m..._n6100275/pg_1