12 - Cold & Underwater

Question 1

humans are ________, we use behavioural and physiological mechanisms to regulate our core temperature

Answer 1

homeotherms

Question 2

def: the exchange of electromagnetic energy waves emitted from one object and absorbed by another

Answer 2

radiation

Question 3

def: occurs whenever two surfaces with differing temperatures are in direct contact

Answer 3

conduction

Question 4

def: things that do not conduct heat readily

Answer 4

insulator

Question 5

the rate of conductive heat exchange is ________ related to the thickness of the insulating substance

Answer 5

inversely

Question 6

def: requires that one of the media be moving as occurs with a fluid or gaseous medium

Answer 6

convection

Question 7

convective heat loss during swimming is more than ____ that during rest in still water

Answer 7

twice

Question 8

what are the two primary physiological responses used by humans to defend against cold

Answer 8

1. increase in metabolic rate

2. increased tissue insulation

Question 9

what are the two ways the body increases metabolic rate?

Answer 9

voluntary - exercise

involuntary - shivering

Question 10

what are 3 factors affecting responses to cold?

Answer 10

1. skinfold thickness
2. gender
3. clothing

Question 11

who loses heat faster when submerged in water? men or women?

Answer 11

women –> larger surface area to mass

Question 12

where does your body temp fall when you have hypothermia?

Answer 12

below 35 degrees

Question 13

where are some critical areas for heat loss

Answer 13

head, neck, sides of chest, groin

Question 14

when does shivering cease?

Answer 14

when body temp falls below 32-34 degrees

Question 15

when does death by hypothermia occur?

Answer 15

when body temp drops to 24-28 degrees

Question 16

what are 5 factors associated with hypothermia?

Answer 16

1. immersion in cold water
2. wind
3. physical exhaustion
4. inadequate clothing
5. hypoglycemia

Question 17

def: freezing of superficial tissues which occurs when skin temperature reaches between minus 2 to minus 6 degrees C

Answer 17

frostbite

Question 18

T or F: you can freeze your lungs when exercising in very cold weather

Answer 18

false

Question 19

how does throat irritation occur?

Answer 19

• cold air is very dry, cells lining the respiratory passageways become dry

Question 20

what things are decreased when muscle temperature decreases?

Answer 20

• strength and power
• nerve conduction velocity
• reaction time
• manual dexterity
• flexibility

Question 21

what two major things does cold affect?

Answer 21

1. strength, power & flexibility

2. cardiovascular endurance

Question 22

def: any material that enters and obstructs a blood vessel

Answer 22

embolus

Question 23

what percent of embolism victims die?

Answer 23

16%

Question 24

what should you not do when scuba diving?

Answer 24

never hold your breath while scuba diving

Question 25

describe pneumothorax(lung collapse)

Answer 25

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

Question 26

describe nitrogen narcosis

Answer 26

• the increased partial pressure and quantity of dissolved nitrogen produces and anesthetic effect on central nervous system
• decreased awareness

Question 27

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

Answer 27

The Bends or decompression sickness

Question 28

where is pain first felt with the bends?

Answer 28

around joints within four to six hours after the dive

Question 29

how can you die from the bends?

Answer 29

if a bubble lodges in an artery

Question 30

def: occurs when the inspired PO2 exceeds 1520 mm Hg for longer than 30-60 mins

Answer 30

oxygen poisoning

Question 31

what are the effects of oxygen poisoning?

Answer 31

• irritation of respiratory passages which progresses to pneumonia if exposure continues
• muscle twitching
• confusion, nausea
• convulsions

Question 32

if mask pressure is not equalized what happens with the mask?

Answer 32

a relative vacuum is created within the mask, blood vessels in and around the eyes rupture as the eyes bulge out of their sockets

Question 33

don’t dive below __ feet when wearing goggles

Answer 33

8

Question 34

def: a small membrane lined passage connecting the middle ear cavity and the back of the throat

Answer 34

Eustachian tube

Question 35

what is the purpose of the eustachian tube?

Answer 35

equilibrate the pressure within the ear cavity with the outside by transferring air to or from lungs

Question 36

what are the symptoms of middle ear squeeze?

Answer 36

pain in the ears after descending only a few feet, pain rapidly becomes more severe as the descent continues