12 - Cold & Underwater Flashcards
humans are ________, we use behavioural and physiological mechanisms to regulate our core temperature
homeotherms
def: the exchange of electromagnetic energy waves emitted from one object and absorbed by another
radiation
def: occurs whenever two surfaces with differing temperatures are in direct contact
conduction
def: things that do not conduct heat readily
insulator
the rate of conductive heat exchange is ________ related to the thickness of the insulating substance
inversely
def: requires that one of the media be moving as occurs with a fluid or gaseous medium
convection
convective heat loss during swimming is more than ____ that during rest in still water
twice
what are the two primary physiological responses used by humans to defend against cold
- increase in metabolic rate
2. increased tissue insulation
what are the two ways the body increases metabolic rate?
voluntary - exercise
involuntary - shivering
what are 3 factors affecting responses to cold?
- skinfold thickness
- gender
- clothing
who loses heat faster when submerged in water? men or women?
women –> larger surface area to mass
where does your body temp fall when you have hypothermia?
below 35 degrees
where are some critical areas for heat loss
head, neck, sides of chest, groin
when does shivering cease?
when body temp falls below 32-34 degrees
when does death by hypothermia occur?
when body temp drops to 24-28 degrees
what are 5 factors associated with hypothermia?
- immersion in cold water
- wind
- physical exhaustion
- inadequate clothing
- hypoglycemia
def: freezing of superficial tissues which occurs when skin temperature reaches between minus 2 to minus 6 degrees C
frostbite
T or F: you can freeze your lungs when exercising in very cold weather
false
how does throat irritation occur?
- cold air is very dry, cells lining the respiratory passageways become dry
what things are decreased when muscle temperature decreases?
- strength and power
- nerve conduction velocity
- reaction time
- manual dexterity
- flexibility
what two major things does cold affect?
- strength, power & flexibility
2. cardiovascular endurance
def: any material that enters and obstructs a blood vessel
embolus
what percent of embolism victims die?
16%
what should you not do when scuba diving?
never hold your breath while scuba diving
describe pneumothorax(lung collapse)
rupture of alveoli, air pockets form outside the lungs between the chest wall and lung tissue, continued expansion of the trapped air during ascent causes the lung to collapse
describe nitrogen narcosis
- the increased partial pressure and quantity of dissolved nitrogen produces and anesthetic effect on central nervous system
- decreased awareness
def: if the diver ascends to the surface too rapidly after a deep, prolonged dive, dissolved nitrogen moves out of solution and forms bubbles in body tissues and fluids
The Bends or decompression sickness
where is pain first felt with the bends?
around joints within four to six hours after the dive
how can you die from the bends?
if a bubble lodges in an artery
def: occurs when the inspired PO2 exceeds 1520 mm Hg for longer than 30-60 mins
oxygen poisoning
what are the effects of oxygen poisoning?
- irritation of respiratory passages which progresses to pneumonia if exposure continues
- muscle twitching
- confusion, nausea
- convulsions
if mask pressure is not equalized what happens with the mask?
a relative vacuum is created within the mask, blood vessels in and around the eyes rupture as the eyes bulge out of their sockets
don’t dive below __ feet when wearing goggles
8
def: a small membrane lined passage connecting the middle ear cavity and the back of the throat
Eustachian tube
what is the purpose of the eustachian tube?
equilibrate the pressure within the ear cavity with the outside by transferring air to or from lungs
what are the symptoms of middle ear squeeze?
pain in the ears after descending only a few feet, pain rapidly becomes more severe as the descent continues
