Metabolism Flashcards
1
Q
What is the first law of thermodynamics?
A
Energy can be neither created nor destroyed
2
Q
What is energy input?
A
Ingested food
3
Q
What is energy output?
A
External work = movement of body (use of skeletal muscles)
Internal work
4
Q
What is internal work?
A
- Skeletal muscle used other than external work (e.g. shivering)
- Life sustaining energy requiring processes (e.g. active tpt mechanisms)
5
Q
What is most food energy converted into?
A
Heat
6
Q
What happens in the biochemical processing of nutrients?
A
50% of energy from food transferred to ATP
50% converted to heat
7
Q
How much of ATP generated from food energy is lost?
A
50% is lost as heat
8
Q
What is the net loss of heat?
A
75% of energy from food
50% direct loss from food energy + (50% x 50% of ATP lost as heat) = 75%
9
Q
What is metabolic rate?
A
Rate at which energy is expended by the body during both external & internal work
Metabolic rate = energy expenditure/unit of time
10
Q
What is a calorie?
A
SMALL c
Basic unit of heat energy
- Amt of heat required to raise temperature of 1g of H2O by 1°C
11
Q
When is Kilocalorie or Calorie used?
A
Kilocalorie = kcal
Calorie = BIG c
Used when discussing human body
= 1000 calories (small c)
12
Q
What is the basal metabolic rate (BMR)?
A
Metabolic rate under standardized basal conditions
= Metabolic activity necessary to maintain basic body functions AT REST
13
Q
How is BMR corrected for differences in body size (usually)?
A
Skeletal muscles contribute ~20-30% of basal metabolic rate
Therefore, men usually have greater basal metabolic rate bc more skeletal muscles (65-70 Calories/hr in average 70kg man)
14
Q
What are the standardized conditions required to find the basal metabolic rate?
A
- Subject X eaten for at least 12 hrs
- At physical rest
- No strenuous activity/exercise at least 30 min - 1hr before test
- All mental & physical factors that cause excitement must be eliminated
- Comfortable room temp (no shivering/sweating)
- After a night of restful sleep (8hrs)
15
Q
Why can’t subject eat for at least 12 hours before the basal metabolic rate is taken?
(Standardised basal conditions for BMR)
A
To avoid diet-induced thermogenesis
- ↑ in metabolic rate due to ↑ed metabolism of processing ingested food = stomach & intestines move + secretions = all require energy
16
Q
Why must the subject be at mental rest before basal metabolic rate is taken?
(Standardised basal conditions for BMR)
A
E.g. if stressed = skeletal muscle tone ↑ + adrenaline ↑ = ↑ metabolic rate
17
Q
Why must the subject have enough sleep before basal metabolic rate is taken?
(Standardised basal conditions for BMR)
A
Not enough sleep = some stress hormones might be released
18
Q
What are the methods of measuring metabolic rate?
A
- Direct calorimetry
- Indirect calorimetry
19
Q
What is direct calorimetry?
A
Measure total quantity of heat given out by body per unit time
20
Q
What is indirect calorimetry?
A
Food + O2 → CO2 + H2O + energy (mostly transformed into heat)
Energy equivalent of O2 (4.8 Calories/L energy liberated per litre of O2 consumed)
21
Q
How to calculate estimated BMR (indirect calorimetry)?
A
Estimated BMR = O2 consumption (L/hr) x 4.8 Calories/L
22
Q
What are the factors influencing metabolic rate?
A
- Thyroid hormone = ↑ MR (impt for metabolism, growth, development)
- Testosterone = ↑ MR
- Growth hormone = ↑ MR (stimulates cellular metabolism)
- Fever = ↑ MR
- Sleep = ↓ MR (esp. during slow wave sleep)
- Malnutrition = ↓ MR
23
Q
What is energy balance?
A
Energy input must equal energy output to maintain a neutral energy balance
24
Q
What is a neutral energy balance?
A
Energy intake equals output
25
What is a positive energy balance?
Energy intake exceeds output
- Excess stored as adipose tissue = ↑ weight
26
What is negative energy balance?
Energy intake is less than immediate requirements
27
What are some short-term regulations of food intake?
- Food intake from meal to meal (feeding pattern)
- Appetite signals = sensation of hunger
- Satiety signals = fullness, suppress desire to eat
28
Long-term regulation
Energy balance & body weight
29
What are some regulations of food intake?
1. Short term regulation (meal to meal; feeding pattern)
2. Long-term regulation (energy balance & body wt)
3. Psychosocial/Environmental factors
30
What is food intake controlled by?
Primarily by the hypothalamus
31
What is the role of the arcuate nucleus?
Coordinates the release of Neuropeptide Y (NPY) and melanocortins
- Central role in long-term control of energy balance & body weight & short-term control of food intake from meal to meal
32
What is neuropeptide Y (NPY)?
Potent appetite stimulator
33
What are melanocortins?
Group of hormones shown to play a role in energy homeostasis
34
What are the regulatory inputs to the arcuate nucleus in the long-term maintenance of energy balance?
Leptin & Insulin
35
What is leptin essential for?
Essential for normal body-weight regulation
36
What are adipokines?
Hormones secreted by adipose tissue that play important roles in energy balance & metabolism
- Leptin is a kind of adipokine
- If have a lot of adipose tissues, more adipokines will be secreted
37
What is insulin important for?
Important role in long-term control of body weight
- Indicator of glucose level in blood bc blood glucose high = insulin released
38
What is leptin an indication of?
Indication of amount of triglyceride fat stored in adipose tissue
39
What does leptin do?
Molecular satiety signal = signals fullness
- Suppress appetite = ↓ food consumption = ↑ weight loss
- Long term matching of food intake to energy expenditure
40
How does leptin act on the arcuate nucleus?
↓ Neuropeptide Y (NPY) production
↑ melanocortin release
41
What happens if lectin gene is removed?
Less control in eating behaviour = weight gain
42
What is Ghrelin?
Potent appetite stimulator
43
What does PYY3-36 do?
Inhibits appetite-stimulating NPY secreting neurons
44
What does cholecystokinin do?
Activates the satiety centre in brainstem
- released from duodenum during digestion
45
What does stomach distension activate?
Activates the satiety center in brainstem
46
Steps in the metabolism pathway when a meal is consumed
SLIDE 19
Meal =
(1) ↑ Glucose & other nutrients in blood
(2) ↑ Fat & other nutrients in duodenum
(3) ↑ Ghrelin (from stomach b4 meal)
(4) ↑ PYY3-36 (from intestines during meal)
(5) Stomach distension
(1) ↑ insulin = limits NPY-secreting neurons
47
What is the :
- source of signal
- effect of signal on appetite
of Neuropeptide Y
Source of signal: Arcuate nucleus of hypothalamus
Effect of signal on appetite: ↑
48
What is the :
- source of signal
- effect of signal on appetite
of Melanocortins
Source of signal: Arcuate nucleus of hypothalamus
Effect of signal on appetite: ↓
49
What is the :
- source of signal
- effect of signal on appetite
of Leptin
Source of signal: Adipose tissue
Effect of signal on appetite: ↓
50
What is the:
- source of signal
- effect of signal on appetite
of Insulin
Source of signal: Endocrine pancreas
Effect of signal on appetite: ↓
51
What is the
- source of signal
- effect of signal on appetite
of Orexins
Source of signal: Lateral hypothalamus
Effect of signal on appetite: ↑
52
What is the
- source of signal
- effect of signal on appetite
of Corticotropin-releasing hormone
Source of signal: Paraventricular nucleus of hypothalamus
Effect of signal on appetite: ↓
53
What is the
- source of signal
- effect of signal on appetite
of Ghrelin
Source of signal: stomach
Effect of signal on appetite: ↑
54
What is the
- source of signal
- effect of signal on appetite
of Peptide YY3-36
Source of signal: small & large intestines
Effect of signal on appetite: ↓
55
What is the
- source of signal
- effect of signal on appetite
of Stomach distension
Source of signal: Stomach
Effect of signal on appetite: ↓
56
What is the
- source of signal
- effect of signal on appetite
of Cholecystokinin
Source of signal: Small intestine
Effect of signal on appetite: ↓
57
What regulatory signals increase appetite?
- Neuropeptide Y
- Orexins
- Ghrelins
58
What regulatory signals decrease appetite?
- Melanocortins
- Leptin
- Insulin
- Corticotropin-releasing hormone
- Cholecystokinin
- Stomach distension
- Peptide YY3-36
Male Leopards in Congo Catch Small Penguins
59
Metabolic rate vs Basal metabolic rate
Metabolic rate: Rate at which energy is expanded by body during external & internal work
Basal metabolic rate: Rate at which energy is expanded by body but at rest (like minimum metabolic rate)
60
When does obesity occur?
When more kilocalories are consumed than are burned
61
What is body mass index (BMI)?
Mathematical means of assessing the proportion of body fat (based on est. from population studies)
62
How to calculate BMI?
Weight (kg) / Height² (meters)
63
Difference between Asian BMI vs International BMI
Asian BMI more stringent
+ Asians have higher body fat ratio
64
BMI values??
65
What are the causes of obesity?
Complex ! = involves physiological, lifestyle & env. factors
- Sedentary lifestyle
- Abnormal feeding behaviour
- Genetic factors
- Leptin-signaling pathway dysfunction (leads to overeating)
- Childhood overnutrition (linked to adult obesity bc once fat cells form, they can shrink but won't disappear = remain the same number)
- Hypothyroidism = deficiency of thyroid hormone
66
What are some treatments for obesity?
1. Lifestyle modification
- Inc. energy output (inc activity)
- Dec energy input (dec. food intake)
2. Drugs
- Dec. degree of hunger
- Alter lipid absorption in gut (e.g. Xenical = lipase inhibitor)
3. Surgery
- Gastric bypass surgery
67
What is metabolism?
Chemical processes or reactions in an organism required to sustain life
68
What are the functions of metabolism?
- Metabolic turnover
- Growth & cell division
- Special processes such as secretion, contraction & propagation of action potentials
69
What is catabolism?
Breakdown of organic substrates
- Releases energy used to synthesize high-energy compounds (e.g. ATP)
- Releases energy
70
What is anabolism?
Synthesis of new organic molecules (monomers)
- Uses energy (ATP) produced by mitochondria
71
What happens to excess glucose?
1. Lipogenesis
2. Glycogenesis
72
What is lipogenesis?
Excess glucose is converted to fatty acids and stored as fats
73
What is glycogenesis?
Excess glucose converted to glycogen and stored
74
What are the functions of organic compounds?
- Perform structural maintenance & repairs
- Support growth
- Produces secretions (a lot are protein in nature)
- Store nutrient reserves
75
What is the most abundant form of storage for fats?
Triglycerides
76
What is the most abundant form of storage for carbohydrates?
Glycogen
77
What are proteins mainly used for?
For structural & functional use
78
Which organic compounds mainly contribute to our energy?
Fatty acids & glucose
79
What does carbohydrate metabolism do?
Generates ATP & other high-energy compounds by breaking down carbohydrates
80
What is the equation of carbohydrate metabolism?
Glucose + Oxygen = Carbon dioxide + Water
81
How many molecules of ATP are produced from the processing of one molecule?
30-32 ATP molecules
82
Which form of carbohydrate metabolism produces the majority of energy?
The electron transport chain & citric acid cycle (aerobic)
Produces 30-32 ATP molecules
83
How many ATP molecules does glycolysis produce?
2 ATP molecules (net gain)
bc
- 4 ATP produced during enzymatic rxns in cytosol
- 2 ATP used to initiate glycolysis
= 2 ATP molecules net gain to cell
Anaerobic
84
What is gluconeogenesis?
Synthesis of glucose from noncarbohydrate precursors
- Uses Lactic acid, Glycerol, Amino acids
85
What is glycogenesis?
Formation of glycogen from glucose
- Occurs SLOWLY
86
What is glycogenolysis?
Breakdown of glycogen
- Occurs QUICKLY
87
What happens in lipid catabolism (lipolysis)?
Hydrolysis splits triglyceride into components = one molecule of glycerol & 3 fatty acid molecules
- Enzymes in cytosol convert glycerol to pyruvate
- Different enzymes convert fatty acids to acetyl-CoA (beta oxidation)
88
Which is the most concentrated source of energy reserve out of all the macronutrients?
Lipids = vv effective & efficient source of energy reserve
89
How many ATP molecules does a cell gain for each 2-carbon fragment removed from fatty acid?
12 ATP from acetyl-CoA in citric acid cycle
5 ATP in NADH
90
How many ATP molecules does a cell gain for the breakdown of one 18-carbon fatty acid molecule?
120 ATP molecules
Why not 153?
- Diff in calculation of yield b/w saturated & unsaturated fatty acids = due to enzyme energy requirement
91
How much more efficient is fatty acid breakdown than glucose breakdown?
Fatty acid breakdown yields ~1.3x the energy of glucose breakdown
bc body stores excess energy as fat
92
What are essential fatty acids?
Cannot be produced by the body = must be consumed
- Not for energy
- Linoleic acid (omega-6)
- Linolenic acid (omega-3; unsaturated 18-carbon fatty acid from plants)
93
What is glycerol synthesized from?
Dihydroxyacetone phosphate (intermediate product of glycolysis)
94
What are nonessential fatty acids & steroids synthesized form?
Acetyl-CoA
- Can use almost any organic substrate
95
What do most lipids circulate through bloodstream as?
Lipoproteins
96
What are free fatty acids generally bound to?
Albumin in blood
- Free fatty acids are a small % of total circulating lipids
- Can diffuse easily across plasma mbns
97
What are lipoproteins?
Lipid-protein complexes
- Chylomicrons
- Very low-density lipoproteins (VLDLs)
- Intermediate-density lipoproteins (IDLs)
- Low-density lipoproteins (LDLs)
- High-density lipoproteins (HDLs)
98
How to calculate LDL?
LDL = Total cholesterol - HDL - triglyceride/5
mg/dL
Friedewald formula
99
Steps in lipoprotein transport
1. Liver absorbs chylomicrons & creates low-density lipoproteins (LDLs) & very low density lipoproteins (VLDLs)
- LDL = triglycerides removed from chylomicrons & cholesterol added & surface proteins altered
- VLDLs - contains triglycerides + small amt of phospholipids & cholesterol
2. VLDLs tpt triglycerides from liver to muscle & adipose tissues
3. LDL enter bloodstream & are delivered to peripheral tissues (impt for tpting cholesterol = used in synthesis of membrane hormones)
4. Once in peripheral tissues, LDLs are absorbed
5. Cell extracts the cholesterol & uses it in various ways
6. Cholesterol not used by cells re-enters blood stream = get absorbed by high-density lipoproteins (HDLs) --> can float in bldstream if not absorbed = lead to blockage
7. HDLs return cholesterol to liver --> extracted & packaged in new LDLs/excreted with bile salts in bile
100
What when glucose & lipid reserves are inadequate?
Liver cells break down internal proteins
Absorb additional amino acids from blood
101
What is protein metabolism?
Cellular proteins are recycled in cytosol
- peptide bonds are broken
- free amino acids are used in new proteins
102
What are the factors against protein catabolism?
1. Proteins more difficult to break apart than complex carbs/lipids
2. By-product produced is toxic to cells = ammonium ions
3. Proteins form the most important structural & functional components of cells
(more like a last resort = we don't want this!)
103
Protein synthesis
Body can synthesize half of a.a. neeeded to build proteins
- 11 amino acids made by body on demand (non-essential a.a.)
- 9 essential a.a. = X make/X makae in sufficient quantity = get from diet
104
What are vitamins?
Essential organic nutrient that functions as coenzyme in vital enzymatic reactions (required in micro amounts)
- deficiency in diet can cause metabolic deficits
105
Fat-soluble vitamins
A, D, E, K
- contains significant reserves of fat-soluble vitamins --> stored to a major extent in liver & adipocytes
- absorbed primarily from digestive tract along with lipids of micelles
- normally diffuse into plasma mbns & lipids in liver & adipose tissue
106
Function of Vitamin A?
Structural component of visual pigment retinal
107
Function of Vitamin D
Converted to calcitriol --> inc. rate of intestinal calcium & phosphorous absorption
108
Function of Vitamin E
Stabilizes intracellular mbns
109
Function of vitamin K
Helps synthesis several proteins, incl. 4 clotting factors
110
Water-soluble vitamins
Components of coenzymes
- Relatively less storage (vs fat-soluble vitamins)
- Rapidly exchanged b/w fluid in digestive tract & circulating blood (excesses excreted in urine)
111
Which vitamins have more storage in the body?
Fat-soluble vitamins
= deficiency in water-soluble vitamins more common
112
What does a deficiency of vitamin C cause?
Scurvy
113
Symptoms of scurvy
- Easily bruised
- Tooth & gum disease
- Wounds don't heal
- Malaise (general feeling of discomfort)
- Lethargy
114
What does deficiency of vitamin B3 cause?
Pellagra
(Niacin deficiency)
115
Symptoms of pellagra?
Dementia
Dermatitis
Diarrhoea
116
What is internal core temperature?
Temperature of deep tissues of the body
117
Which sites are more representative of core temperature?
Tympanic (ear) & rectal
- 0.5 - 0.6°C higher than oral temp
118
What causes normal variation in core temperature?
- Normal daily fluctuations = ~1°C during the day
- Women experience monthly rhythm (~0.5°C higher during ovulation)
- Exercise (Inc.)
- Age = older is colder
- Exposure to extremes of temperature (slight variation)
119
What are the mechanisms of heat transfer?
1. Radiation
2. Conduction
3. Convection
4. Evaporation
120
What is radiation?
Transfer of heat energy in the form of electromagnetic waves ("heat waves") = travels through space
121
What is conduction?
Transfer of heat = in direct contact
- Heat transferred through movement of thermal energy from molecule to adjacent molecule
122
What is convection?
Transfer of heat by air currents
- Cool air warmed by body through conduction rises & is replaced by more cool air (enhanced by forced movement of air across the body surface)
- Can also be convection currents in water
123
What is evaporation?
Conversion of liquid (e.g. sweat) into gaseous vapour = requires heat (heat of vaporization)
124
Which mechanisms results in most heat loss from the body?
Radiation heat waves (60%)
Evaporation (22%)
Convection to air (15%)
125
Which mechanism results in the least heat loss from the body?
Conduction to objects (3%)
126
What is sweating?
Regulated evaporative heat-loss process
- Under sympathetic nervous control
- Rate of heat loss can be adjusted
- Sweat MUST BE EVAPORATED for heat loss to occur
127
How does humidity affect sweating?
When humid = sweat stays on skin longer (takes longer to evaporate = reduced heat loss)
128
How is temperature regulated when there is a change in skin temperature?
1. Peripheral thermoreceptors in skin detect the change
2. Signals the hypothalamic centres for thermoregulation
3. Sends signals to:
- Motor neurons
- Sympathetic nerves
- Voluntary changes in behaviour
129
How is temperature regulated when there is a change in core temperature?
1. Central thermoreceptors in hypothalamus, abdominal organs & elsewhere
2. Signals the hypothalamic centres for thermoregulation
3. Sends signals to:
- Motor neurons (skeletal muscles = muscle tone/shivering = adjustments in muscle activity --> metabolic heat prod.)
- Sympathetic nerves (smooth muscle in arterioles in skin = vasoconstriction, vasodilation --> adjustment in loss/conservation of heat)
(sweat glands = sweating --> adjustment in heat loss)
- Voluntary changes in behaviour (e.g. wear jacket; adjustments in heat prod./heat loss)
130
Where are the core thermoreceptors locaated?
- Hypothalamus
- Spinal cord
- Abdominal viscera
- Great veins in upper abdomen & thorax
131
Are there more receptors that detect cold or detect warmth?
Cold
132
Where are peripheral thermoreceptors located and what do they do?
Located in skin
Detect change in skin temperature
- 10x more receptors that detect cold than warmth
133
What are the ways to increase heat production?
- Shivering
- Non-shivering thermogenesis by brown fat
134
What is shivering?
Rhythmic, oscillating skeletal muscle contractions that occur at a rapid rate of 10-20 per second
- Primary involuntary means of increasing heat production (in response to temp. drop)
- Adjustments in heat prod. by skeletal muscles
135
What is non-shivering thermogenesis by brown fat and who is it especially important to?
Increased heat production stimulated by brown adipose tissue = capable of converting chemical energy from food into heat
- Esp impt to newborns (first 6 months) --> bc they lack muscle mass = shivering not as effective
136
How can the magnitude of heat loss be adjusted by flow of blood?
Varying the flow of blood through the skin = vasocontriction (dec. loss of heat)/vasodilation (inc. loss of heat)
- Subject to control --> largely by hypothalamus
137
What coordinates the response to cold exposure?
Posterior hypothalamus
138
What coordinates the response to heat exposure?
Anterior hypothalamus
139
Responses to cold exposure
Inc. heat production:
- Increased muscle tone (sort of like isometric contraction but not the same!)
- Shivering
- Inc. voluntary exercise (behavioural)
- Non-shivering thermogenesis
Dec. heat loss (heat conservation):
- Skin vasoconstriction
- Postural changes = dec. exposed surface area (e.g. hunch shoulders)
- Behavioural adaptations = warm clothing
140
Response to heat exposure
Dec. heat production:
- Dec. muscle tone
- Dec. voluntary exercise (behavioural)
Inc. heat loss:
- Skin vasodilation
- Sweating
- Cool clothing (behaviour)
141
What is the hypothalamic thermoneutral zone?
Core temp can fluctuate within this range w/o triggering thermoregulatory effectors
- basically, don't need to shiver/sweat in this zone
142
What is temperature of the thermoneutral zone?
36.8°C - 37.2°C
143
What is the average set point of temperature?
37.1°C
144
What happens when skin temperature is higher than set point?
- Skin temp can change set point
- If skin temp is higher = start sweating at a lower temp (earlier)
- If skin temp higher = may indicate that you're in a hotter env. (body reacts & anticipates = wants to sweat earlier)
145
What happens when skin temperature is lower than set point?
- If skin temp is lower = start sweating at a higher temp (later)
- If skin temp lower = may indicate that you're in a colder env.
146
The higher the skin temperature, the _________ the set point
The higher the skin temperature, the lower the set point
- Anticipatory mechanism to moderate need for large responses
147
The lower the skin temperature, the _________ the set point
The lower the skin temperature, the higher the set point
- Anticipatory mechanism to moderate need for large responses
148
What is fever?
Regulated increase in body temperature (body inc. temp itself)
- Shifts the hypothalamic set point
149
How does a fever come about?
1. Infection/inflammation
2. Stimulates release of macrophages
3. Macrophages release endogenous pyrogen
4. Prostaglandins released
5. Prostaglandins raises the hypothalamic set point
6. Results in initiation of "cold response"
7. Inc. heat production; dec. heat loss
8. Inc body temp to new set point = fever
150
What does aspirin do?
Suppresses the production of prostaglandins
151
During a fever, what does the body do to increase temp to "new normal"?
1. Vasoconstriction
2. Piloerection
3. Epinephrine secretion
4. Shivering
152
What does the body do after cessation of fever?
Hypothalamic set point reduced to normal level
- Vasodilation/sweating
153
What causes temperature to rise to 38-40°C?
Hard exercise
Febrile disease (fever)
- Temperature regulation efficient in febrile disease, health & work
154
What happens when temperature rises above 40°C?
Heatstroke = temp regulation shut down
Brain lesions
- Temperature regulation seriously impaired
155
What is hyperthermia?
Elevated body temp above normally accepted range
- Differs from fever bc set point remains unchanged (fever = set point changes)
156
Exercise hyperthermia
Core temp can reach 40°C w/o injury as long as heat loss mechanisms are present & effective
157
What happens during exercise hyperthermia?
- At the onset of exercise, the rate of heat production initially exceeds the rate of heat loss = core temp inc.
- When heat loss mechanisms are reflexly inc. sufficiently to equalize elevated heat production, core temp stabilizes slightly above resting point for duration of exercise
158
What happens during a heatstroke?
Thermoregulation overwhelmed & becomes seriously impaired
- Beyond 40.5°C
- Lack of compensatory heat loss measure = e.g. X sweating
- Damage to brain, liver, kidney, etc
159
What are the important physiological changes that occur during the acclimatisation process?
1. Inc. in rate of sweating (up to 2x) + sweat might start earlier
2. Inc. in plasma vol. (need more to sweat_
3. Dec. loss of salt in sweat & urine (due to inc. aldosterone)
if sweat effectively = lose a lot of salt = salt imbalance + retention of water in body affected
160
What is acclimatisation?
Inc. tolerance to heat with exposure to hot & humid conditions in 1-3 weeks
161
What is hypothermia?
Lowered core temp w/o reset of set point
- Temp regulation is impaired below 35°C
162
Artificial hypothermia
1. Therapeutic hypothermia = sometimes used to protect organs during surgery
- Hypothalamic activity depressed w drugs followed by cooling patient down
163
What happens if you sweat a lot w/o replenishing?
Dehydration = dec. bld vol. = feel faint = body temp inc. = heat exhaustion = heatstroke
164
What are the only means of heat loss when env. temp exceeds core temp?
Sweat
Evaporation
165
What happens to core temperature when you are not hydrated enough?
As long as you are not hydrated enough, body temp inc. vv fast
- doesn't matter if acclimated or unacclimated, hydration affects more!
