Exam #2 Flashcards

Question

(a) Light exercise that follows intense exercise could also be described as ...? i. How does this affect lactate removal post-exercise? And how does this occur? (b) What are the 3 ways that lactate shuttle occurs?

Answer 1

(a) "Active recovery" i. [Lactate] in light exercise < [Lactate] in no exercise ; via Lactate shuttle (b) Lactate shuttle: 1. 70% oxidized by Type I fibers in heart & within the same or nearby skeletal muscles 2. 20% → liver → glucose, via the process known as gluconeogenesis 3. 10 % → liver where it is synthesized into various amino acids (can also produce substrates from the kreb cycle)

Answer 2

Cori cycle: Converts lactate to glucose G6P @ Skeletal muscle (glycolysis) ↓ Pyruvic acid ↓ Lactic acid (end product due to high intensity or mito. is full) ↓ Enters bloodstream ↓ Liver pulls lactic acid out of blood ↓ At liver, lactic acid become pyruvic acid ↓ G6P → Glycogen @ liver as storage ↓ Leave phosphate and eneter as glucose in bloodstream ↓ Enters skeletal muscle (-1 ATP) at G6P to continue glycolysis

Answer 3

(a) ↑ blood glucose levels (b) ↑ release of insulin from pancreas (released when blood sugar is high & creating storage form of glycogen) (bi.) G6P becomes storage in the liver and muscle (glycogen)

Answer 4

(a) Respiratory exchange ratio (RER): A numeric value that represents: # CO2 produced/ # O2 consumed = VCO2/ VO2 (b) Primary substrate that is utilized during exercise (c) Valid druing rest → up to steady state (aerobic), sub max intensity exercise ; Assumes no protein is being used as fuel (d) Nutritional status, exercise intenisty & duration, aerobic fitness level of individual (e) 0.82 (0.71→ 0.91) (f) 0.70 (g) 1.00 (gi.) As it's aprecursor to oxaloacetate & malate, and needed to burn fuel (cannot burn fat w/o some carbs)

Answer 5

Crossover concept: (in the moment) - x-axis: % VO2max - y-axis: % substrate utilization SwiTchover concept: (big picture) - x-axis: Time (duration) - y-axis: % substrate utilization

Answer 6

(a) Fat → CHO (b) Gradual shift from type I to type II fibers. i. ↑ # of glycolytic enzymes ii. ↓ # of oxidative enzymes iii. Less mitochondrial density iv. Epinephrine is released (c) [Blood epi] i. ↑ rate of glycogenolysis, which leads to ii. ↑ glycogen phosphorylase activity, → iii. ↑ # glucose available → iv. ↑ rate of glycolysis (fast) → v. ↑ production of lactic acid, which is an vi. inhibitory modulator of HSL (d) Fats as primary source of ATP is around 30 -60ish % VO2 max; As exercise intenisty increase, using farts as fuel decrease & using CHO as fuel increase.

Answer 7

(a) Blood glucose, muscle glycogen, liver glycogen (b) At beginning of exercise or during high intensity exercise (given that its w/n the muscle cell and close to contractile proteins) (c) During lower intensity exercise (d) Majority of fat store subcutaneously or viscerally (e) (Due to presense of epinephrine) TG → glycerol (→ liver → glucose) + free fatty acids (→ can be oxidized in liver (→ketones), & muscle cell (→Acetyl CoA)

Answer 8

(a) < 1 hour: 2% ; 3-5+ hours: 5-15% (b) Alanine: Released as a by-product of skeletal muscle contractions (bi) i. (Muscle - contractions - alanine) → (Blood) → (Liver - alanine → glucose) → (Blood - blood glucose) → (Muscle - G6P = start of glycolysis) ii. Loses its amine group (NH2), forms double bond with oxygen → pyruvte (oxaloacetate & malate for Krebs to function. - Deamination (c) Valine, leucine, isoleucine (ci.) Longer duration, sub-max aerobic exercise

Answer 9

1. Low intensity (approx. 20% VO2 max) a. High% of energy expenditure is from fat ( approx. 66%) b. Total energy expenditure is low (approx. 3 kcals/min) c. Total fat oxidation is also low (approx. 2 kcals/min) 2. Higher intensity (approx. 60 % VO2 max) a. Lower % of energy expenditure is from fat (approx. 33 %) b. Total energy expenditure is higher (approx. 9 kcals/min) c. Total fat oxidation is also higher (approx. 3 kcals/min)

Answer 10

FATmax: a. The exercise intensity that represents the highest rate of Fat oxidation b. Generally, is an exercise intensity reached just before LT >

Answer 11

The higher the exercise intensity, the more HSL is inhibited.

Answer 12

(a) 37°C (or 98.6°F) (b) > 45°C: Can alter enzyme structure → ↓ ability to produce ATP, which can lead to cell death or death of organism (c) < 34°C: slows metabolism, can cause cardiac arrythmias (irregular heartbeat), which can lead to death

Answer 13

(a) Steady-state: Variable being maintained during exercise; EX: VO2 supply & demand (b) Homeostasis: Considers variable at rest (c) Various systems work together to maintain body temp. w/n a relatively narrow range (d) = (e) gain (f) loss

Answer 14

(a) To transport heat (b) To capture/transport heat (bi.) Blood flow to skin increases, which promotes loss of body heat to the environment; exposure to air will lose heat via blood plasma (c) Blood plasma

Answer 15

(a) Preoptic-Anterior Hypothalamus (POAH) (ai.) Maintain core temperature near 37°C (or 98.6°F) (b) Thermoreceptors in... 1. Skin (which are first to arrive), in addition to... 2. Spinal cord and POAH itself. These signals arrive second.

Answer 16

(a) Small! (b) Involuntary: 1. Shivering - Increases heat production 5x compared to resting values. 2. Non-shivering thermogenesis (hormones): - From thyroid gland: Thyroxin - From adrenal glands: Epi/NoE - All three hormones increase rates of cellular metabolism in all cells; (At rest, rate of ATP production increase → Energy!) (c) Voluntary: * 70 to 80% of energy (E) expenditure is lost as heat. * Heat produced during exercise that is not lost, is stored in body tissues → ↑ body temp

Answer 17

(a) Heat load → Receptors (skin & core) → POAH (integrator) → Effectors: Cutaneuos vasodilation & sweating (b) Thermal receptors in skin and core detect heat & send signals to POAH, which integrates the information (c) Effectors: 1. Cutaneuos vasodilation - Normla vasoconstrictor tone to skin is rmeoved, capillaries directly underneath skin dilate, which increase blood flow towards skin 2. Sweating - Sweat glands are stimulated, blood plasma moves to surface of skin (sweat). Sweat evaporates (heat is lost), which provides a cooling effect. (d) The stimuli for vasodilation of sweating are removed (vasodilation & sweat glands are removed)

Answer 18

1. Radiation: Heat transfer one surface to another, but no physical contact * Transfer of heat via: Infrared rays * Accounts for 60% heat loss during rest * Can be source of heat loss or gain! * Example: The sun heats the Earth's surface via infrared rays 2. Conduction * Heat loss due to physical contact between two surfaces * Example: After sitting on a cool metal chair for some period of time, when you stand, the surface of the chair is warm 3. Convection * Heat transferred from body to air or water molecules, which are warmed and move away from heat source, and are then replaced by cooler molecules. * Example: Sitting in front of a fan * If air and water are same temperature, water cools 25x better compared to air. (*If water and air are same temp.)

Answer 19

(a) Evaporation: when sweat gains sufficient heat, it is converted to gas (water vapor) (b) As sweat evaporates... i. Sweat doesn't cool skin but, the evaporation of sweat does ii. Evaporation accounts for 25% heat loss during rest, but, iii. Evaporation is a KEY MEANS of HEAT LOSS DURING EXERCISE (c) Evaporation rate depends on... i. Air temperature & relative humidity (RH) ii. Convective currents moving around the body iii. Amt. of skin surface exposed to the environment (d) Evaporation is more effective if atmospheric air is dry and not humid

Answer 20

(a) Relative humidity (RH): A measure of how much water vapor is in the air compared to the maximum amt. of water vapor that COULD be in the air at same temp. (b) Expressed as percentage (ci.) High - >60% (cii.) Moderate - 40-60% (ciii.) Low - <40%

Answer 21

(a) Core temp. is slightly warmer than other extremities due to body fat (b) ↑ due to ↑ works of ATP hydrolysis (c) ↑ due to ↑ works of ATP hydrolysis & also ↑ # of motor units recruited (Type I → Type II = ↑ body heat) (d) Core temp. increases (e) Hinders the ability to lose heat (ei.) Body will sweat more ( = loss of blood plasma vol.) & body heat will ↑ - Q = ↑ HR x SV (eii.) Decrease in venous return → blood becomes visous as well = ↑ HR & ↑ BP

Answer 22

(a) As exercise intensity increases... (↑# motor units recruited) i. Heat production ↑ ii. Body temperature increases linearly w/ increases in intensity iii. Core temperature increasesdue to # active muscle muscle mass iv. Increases reliance on evaporative heat loss (b) As ambient air temp. increases... i. N/C ii. ↓ due to decrease in temp. gradient iii. Temp. gradient ↓, ↓ in evaporative heat loss (RH) (c) Exercise in hot environment leads to decreased ability to lose body heat. i. ↑ in core temp. ii. ↑ HR → ↓SV (↓venous return due to sweating) iii. ↑ risk of hyperthermia & heat injury

Answer 23

1. CNS fatigue/dysfunciton - Decreaesed motivation/degraded cogntive function - Reduced voluntary activation of motor units (self-preservation) 2. Cardiovascular dysfunction - Reduced stroke volume: due to ↑ blood flow to skin → ↓ SV - Decreaesed cardiac output during high intensity exercise... - Decreased muscle blood flow... → ↓ # of O2 & nutrients to muscles →↓ # of CO2 & lactate clearance → ↓ # blood flow to liver → ↓ # glucose prod. via gluconeogenesis 3. Accelerated muscle fatigue - Increased radical production: Free radicals (released from muscle contraction) can bind to actin/myosin, causing damage → ↓ # of x-bridges formed →... fatigue - Decreased muscle pH: slow enzyme activity rates → slowing speed of contraction → fatigue - Muscle glycogen depletion: ~ Intenisty ↑ → ↑ glycogen phosphorylase activity → ↑ rates of G6P synthesis → ↑ rates of glycolysis → ↑# end product of fast glycolysis (lactic acid) → SLOWS ENZYME ACTIVITY

Answer 24

(a) Increase in core temp. (b) 7-14 days after initial exposure (c) 5 adaptations to heat exposure: 1. ↑ plasma volume, (10-12%); helps maintain central blood vol., stroke vol., & sweating capacity 2. ↑ sweat capacity by 3x vs. pre-acclimation. 3. Earlier onset of sweating. (able to control core temp.) 4. ↓ sweat loss of sodium & chloride due to ↑ secretion of aldosterone (prod. by adrenal cortex → ensures sodium & H2O reabsorption in kidneys) ; electrolyte at optimal level 5. ↑ rate of synthesis of heat shock proteins (protect cells from thermal damage)

Answer 25

(a) 3-7 days (b) 3-6 days (c) 5-9 days (d) 8-14 days

Answer 26

(a) 7 (b) 28; when you remove systemic & cellular stress, adaptations diminish, then dissapear

Answer 27

(a) Thermoreceptors: 1. skin, 2. core (ai) Thermoreceptors send nerve impulses to POAH, which initiates an appropriate response to cold stress, in an effort to maintain body’s set- point temperature (b) Cold → Receptors (skin & core) → POAH (integrator) → Effectors: Shivering, cutaneuos vasoconstriction (reduces # heat losts to environment), Non-shivering thermogeniss (Epi/NoE & thyroxin relesed - from thyroid gland & metabolic hormone)

Answer 28

(a) Cold stress: any environmental condition that challenges the body’s ability to maintain temperature homeostasis. (b) Hypothermia: A large decrease in core temperature (c) Not as lean, ↑ subcutaneous and visceral fat which insulates against heat loss (d) women

Answer 29

(a) Decreases due to periperal vasoconstriction (we lose less heat to the environment) (b) Gradient will be much larger in colder temp (40°F) vs. warmer temp (95°F0 (c) Given temp. gradient will be much larger in colder temp , there will be a faster, greater movement of molecules than warm temp.

Answer 30

1. Amt. of subcutaneous fat of a given individual; there is little difference in cold tolerance between men & women of similr body composition 2. Age a. Children have large surface to mass ratio vs. adults → proportionally greater heat loss & increased difficulty in maintaining temperature homeostasis. b. Elderly persons who have experienced sarcopenia have increased difficulty in maintaining temperature homeostasis due to loss of muscle mass. 3. Physical fitness level has a limited impact on cold tolerance when subjects have same % body fat. (no difference TR & UT)

Answer 31

1. Hands exposed to cold can become numb due to: a. Reduced blood flow due to subcutaneous vasoconstriction. b. Reduced rate of neural transmission (skin to CNS) c. Both ”a” and “b” (above) → loss of manual dexterity and affects motor skills such as throwing, catching, & possibly kicking. d. Cold-induced loss of manual dexterity is directly correlated with skin temperature, especially when skin temperature drops below 59°F. 2. Exercise in cold air rarely decreases muscular force production as temperature of exercising muscle rarely decreases. 3. Exercise in cold water could impact aerobic performance since water is 25x better heat conductor vs. air.

Answer 32

(a) lower (ai.) non-shivering thermogenesis (b) hand and feet temperature (c) improved ability; non-shivering thermogenesis (d) 7 continuos days

Answer 33

1. Prolonged cold-water immersion: a. Associated with cardiac arrhytmias and potentially cardiac arrest. b. Loss of judgement. c. Increased risk of death if core temp drops to 25°C or lower. 2. Cold air exposure. a. Can cause frostbite, which can lead to permanent tissue damage. (gangrene, for example) b. Can cause exercise induced asthma due to cooling and drying of airways → bronchoconstriction (narrowing of passageway)