Week 13 Flashcards
how does your body respond to a cold environment?
Increase metabolic rate:
Voluntarily: exercise increases heat production 10-20x the basal rate.
Involuntarily: shivering increases heat production 3-4x the basal rate.
Increased tissue insulation: peripheral vasoconstriction and blood shunting to deeper vessels.
What are some non-physiological ways you can respond to an environment?
proper clothes, seeking shelter, starting a fire.
what are factors that affect one’s response to the cold?
Skinfold Thickness: Thicker fat layers = greater insulation.
- Women have more subcutaneous fat but lose heat faster due to higher surface area-to-mass ratio.
- Children have an even higher surface area-to-mass ratio, making them more vulnerable.
Clothing:
- Insulation depends on air layer next to skin, clothing thickness, and air trapped between layers.
- Wind and wet conditions reduce insulation.
Hypothermia
Diagnosed when core body temperature falls below 35°C.
Affects core organs: brain, heart, lungs, blood, liver, kidneys.
Critical areas for heat loss: head, neck, groin, and sides of the chest.
Shivering stops at 32-34°C; death occurs below 24-28°C.
Factors associated with hypothermia?
- immersion in cold water or wet clothing
- wind
-physical exhaustion - not enough clothes
- low percent fat
-hypoglycemia: impaired thermogenesis, reduced shivering- don’t have enough blood sugars so they will be cold. - alcohol consumption: reduced shivering, more blood flow to skin (asian flush) impaired judgement
How does hypothermia affect the oxyhemoglobin dissociation curve?
when you’re cold, it will shift to the left because:
yellow to teal:
higher the saturation, less likely your blood delivers oxygens to tissues. when going to high oxygen to low oxygen, your body will still hold on to it.
results in relative hypoxia (lack of O2 from heart to brain) increased lactic acid output, metabolic acidosis. depressed brain function, cardiac output meaning you’ll have poor control on heart rhythym which will lead to ventricular fibrilation and death.
What about frostbite?
occurs when superficial tissues freeze when skin temp reaches between -2C- to -6C.
- your body wont realixe because the sensory nerves are blocked and become numb
is it better to inhale through your nose or mouth?
it doesnt matter
through nose: filters a bit
through mouth- ppl believe the air doesnt get warmed up (that’s a lie your body will always warm it up to 37C and saturate it with water vapor)
throat irritation due to dry passageways
°**How does cold effect performance?
not good
decrease in strength, power, flexibility due to decrease in:
- nerve conduction time
- reaction time
-manual dexterity
marathon running:
- optimal temp is lower cause when running your body generates a lot of heat so we need less circulation for heat dissipation
- allows more circulation to working muscle.
9:03am
Cold Expose is good or bad?
- can result in dramatic heat loss
water is 25x more conductive than air
-cant survive in water even for a couple hours even if the water is just 10 degrrees celsius
environment physiology (underwater)
pressure changes changes the gradient in gas exchange
What is presure of air at sea level?
1.0 atmospher or 760 mmHg
as a diver goes deeper, the hydrostatic pressure above them increases
What happens to body tissues under pressure?
Body is made of water and water is not very compressable.
- we also have air pockets that ARE compressable.
what is boyle’s law
For every unit of incresase in volume, we get a decrease in pressure.
Valpha1/P
if pressure is doubled volume is halved
*** What is snorkelling?
There are limits to snorkeling due to:
1. pressure effects
- cant have a longer tube cause of the changes in anatomical dead space (tube is dead space so you have to push through cause its too much resistance to try and breathe through)
- diver must inspire air at atmospheric pressure
at 3ft deep, the compressive force of water against chest cavity is much higher than the force the inspiratory muscles (body cant overcome that opressure)
- increase in pulmonary space:
- Va(mL)+Vt-VD
***What is breath holding diving?
remember residual volume (air you can never breathe out)
diving deeper and deeper, pressure is increased. if you compress your lung, it will damage your lung cause they squeexe cause blood might bleed into your lungs (the condition is callwed lung squeeze)
What is breath hold diving?
- diver hyperventilates and hold breath (get as much oxygen as possible so survives under water for longer- not correct)
- when diver gets to a certain depth, pressure will increased a s a reuslt of compression. if my oxygen is increassed and it continues to due so, my volume will decrease.
- okay now i decide to come up so pressure will decrease and it will decreases to an extent
- the pressure decrewszes below critical point that body needs to be alert.
- diver loses consciousness and drowns
What are some potenitial medical problems associated with scuba diving?
7 problems
Why do we wear tanks when scuba diving?
- to overcome pressure exerted on you when youre diving.
- need an opposing pressure when you’re diving. the tank gives additional pressurized air so you can dive.
- open circuit scuba: activated by changes in pressure
