Exercise I Flashcards
1
Q
define stressor:
A
- factors that threaten homeostasis
2
Q
exercise as a stressor:
A
- most potent
- nearly all body organs altered to copy w demands of exercising mm for nutrients, O2
- minimise increased generation of heat, increase lvls of acid, K+ and CO2 in plasma of veins
- ancestors relied on exercise for survival, we must have regular exercise to avoid chronic diseases assoc w current sedentary lifestyle
3
Q
regulation of body during exercise: dom by
A
- stress hormones
- esp Ad
- stimulation of sym NS
- inhibition of para nn
4
Q
ATP: function
A
- adenosine triphosphate
- mm need ATP for contraction, transport Ca back to SR (for mm relaxation- Ca pump) and Na/K pump
- high freq of AP during exercise causes increase K outflow and Na uptake in mm cells
5
Q
ATP: importance of Na/K pump
A
- preventing accumulation of K in plasma
- increases in plasma K conc. by only few mM can cause skeletal mm paralysis, cardiac arrhythmias
6
Q
ATP: features
A
- during strenuous exercise ATP production increases up to 100x vs. rest
- adenosine + 3 phosphate groups
- phosphate: weak acids
- negative charges, electrostatic repulsive forces btw phosphate groups
- bond broken, energy released
- energy will be transferred to linked reaction needing ext energy to proceed
7
Q
ATP: equation for ATP hydrolysis
A
ATP + H2O –> ADP + Pi + H+
8
Q
ATP: anaerobic type features
A
- absence of O2
- vital for rapid rate of ATP utilisation required at initiation of exercise
- short bursts of high-intensity activity
- produces quickly, min lag time (substrates used already within myocyte)
9
Q
ATP: aerobic type features
A
- limited by rate of delivery of O2 (depends of function of CV and respiratory sys
- 1-4 mins, sys regulated so O2 delivery matches increased demand by exercising mm
- not rapid enough for start or sudden acceleration
10
Q
anaerobic processes: ATP
A
- cells hav minimal amounts of ‘stored’ ATP
- used in first few sec of exercise
- mm ATP conc around 10mM, does not fall by more than 20% even in rapid high intensity exercise
11
Q
anaerobic processes: phosphocreatine features/ dev
A
- creatine mainly produced by liver
- plasma creatine enter cells via specific transport protein
- mm at rest: ATP derived from aerobic processes donated its 3rd phosphate group -> creatine = phosphocreatine
12
Q
anaerobic processes: phosphocreatine mechanism
A
- conversion catalysed by enzyme creatine (phospho) kinase
- at rest: conc of phosphocreatine ~30mM
- phosphorylation occurs in mitochondria (ATP provided by ox phos/ anaerobic glycolysis in cytoplasm
- ATP required: reaction reversed, ATP liberated from phosphocreatine to bind ATPases in cytoplasm
13
Q
anaerobic processes: phosphagen sys
A
- stored ATP and phosphocreatine together = phosphagen sys
- depletes 8-10s of intense whole body exercise
- in resting periods btw intense exercise phosphocreatine lvls returned to normal in a min
14
Q
anaerobic processes: anaerobic glycolysis features
A
- glycogen is biopolymer of glucose molecules built on glycogenin protein
- storage form of glucose in animal cells
- 1 glycogen = 120 000 glucose molecules
- glycogen made and stored primarily in liver, skeletal mm
- found in granules within cells at higher conc in liver
- most of body glycogen in skeletal mm
15
Q
anaerobic processes: anaerobic glycolysis- glycogen in liver
A
- source of glucose maintain normal conc of plasma glucose molecules
16
Q
anaerobic processes: anaerobic glycolysis- skeletal mm glycogen converts to
A
- glucose-6-phosphate molecules rather than glucose
17
Q
anaerobic processes: anaerobic glycolysis- can/can’t exit mm fibre
A
- can’t exit mm fibre coz charged phosphate group, mm glycogen can only utilised by the mm
18
Q
anaerobic processes: anaerobic glycolysis- pathway
A
- occurs in cytoplasm
- produces 2 ATP molecules when pathway starts w glucose-6-phosphate
- end product is pyruvate (if absent from O2 will be converted into lactate)
19
Q
anaerobic processes: anaerobic glycolysis- simplified equation for glycolysis
A
glucose + 2ADP + 2Pi + 2NAD+ –> 2 pyruvate + 2ATP + 2NADH + H20 + 2H+
20
Q
anaerobic processes: anaerobic glycolysis- in the presence of oxygen pyruvate
A
- ATP rapidly consumed to produce more ADP but reaction to continue the pyruvate, NADH and H+ must also be removed
- w O2, shift these 3 products into mitochondria feeding into Kreb’s cycle - electron transport chain reaction
21
Q
anaerobic processes: anaerobic glycolysis- in absence of oxygen pyruvate
A
- converted to lactate dehydrogenase
22
Q
anaerobic processes: anaerobic glycolysis- pyruvate/lactate equation
A
2pyruvate + 2NADH + H+ 2lactate + 2NAD+
23
Q
conversion of pyruvate to lactate: acidity?
A
- decreases acidity
- lactate + H+ exported to plasma by monocarboxylate transport proteins
24
Q
anaerobic processes: anaerobic glycolysis- lactate features
A
- plasma lactate is substrate for ox phos in most tissues (incl skeletal mm, heart mm, liver, kidney) that hav O2 available
- lactate also converted in liver to glucose (gluconeogenesis) exported into plasma
25
anaerobic processes: anaerobic glycolysis- acidification
- protons produced by glycolysis consumed in conversion of pyruvate to lactate to ATP hydrolysis likely source of acid
26
anaerobic processes: anaerobic glycolysis- mm contraction
- solely depends on anaerobic glycolysis for ATP production for 1.3-1.6min
- during that time increased acidity in myocytes, venous blood cont mm pain and fatigue
27
anaerobic processes: anaerobic glycolysis- acidity in mm cells effect
- inhibits enzymes involved in ATP production
- H+ ions compete w Ca ions for binding sites
- reduces ability of Ca to bind to tropomyosin C
28
anaerobic processes: anaerobic glycolysis- venous in exercising mm
- low pH, PO2 lvl
| - high PCO2
29
define metabolic acidosis
- excess acid in arterial blood
30
anaerobic processes: anaerobic glycolysis- does metabolic acidosis occur in excercise?
- no, H+ produced is buffered and excreted as CO2 in lungs
| - increased CO and ventilation rates means changes in PO2, PCO2, pH in arterial blood r minimal
31
aerobic ATP production: features
- mm activity continuing for any length of time requires immediate source O2, and remove CO2
- powered by glucose from glycogen and fatty acids (supports moderate exercise for many hrs)
- glucose -> fat as major fuel source
32
aerobic ATP production: high exercise intensity (>40% Vmax) what is dom substrate for ATP prod
- glycogen
- 4-5hrs dependant on intensity
- recover faster on carb diet vs mixed/fat diet
33
aerobic ATP production: O2 supplied into w pyruvate
- pyruvate from glycolysis, fatty acids, ketone bodies, certain aa
- fed in Kreb's cycle (citric) via acetyl-coA
- CAC produces reducing agents (NADH, FADH2, CO2) which provide H+ for ATP prod
- O2 takes last H+ = prod H2O
34
aerobic ATP production: mitochondria respiration aka
- CAC
35
aerobic ATP production: oxidative phosphorylation aka
- electron transport chain reaction
36
skeletal mm fibre: list types (3)
- slow twitch (type I)
| - fast twitch (type IIa, IIB)
37
skeletal mm fibre: type I fibre features
- many mitochondria
- high conc of myoglobin (trap and store O2)
- red colour
- ATP prod mitochondrial resp (aerobic)
- slow response time, slow fatigue
38
skeletal mm fibre: type I fibre location
- postural mm in spine, neck, legs
| - mm involved in low intensity repeated contractions (walking, non-competitive cycling)
39
skeletal mm fibre: type II fibres general features
- rapidly respond
- anaerobic prod
- lil myoglobin (white mm)
- bursts of intense activity (powerlifting, sprint 100m)
40
skeletal mm fibre: type IIa
- intermediate btw IIb and I slow twitch
- combo of anaerobic/aerobic
- mod lvl myoglobin, red mm
- dom: fast running (400m)
- weight training
41
aerobic capacity: VO2
- rate of O2 consumption
| - individual at rest, measure basal metabolic rate
42
aerobic capacity: VO2 equation
VO2 = (SV X HR) x (O2 aa - O2 veins)
43
aerobic capacity: use of exercise VO2 max
- measure of max aerobic capacity
44
aerobic capacity: how VO2 estimated
- increasing rate of exercise in step wise fashion while measuring O2 consumption/step
- intially O2 consumption directly proportional to work rate (straight line)
- eventually plateau (aerobic ATP can't suppport)
- VO2 max line is flat, fatigue ends exercise
45
aerobic capacity: VO2 body weight ~
3.5ml/min/kg
46
aerobic capacity: VO2 max range healthy
40-45 ml/min/kg
47
lactic threshold: why can't aerobic resp supply all ATP for exercise
- depletes well before VO2 max is reached
- rapid rise of plasma lactate conc around 60% of VO2 max
- pyruvate produced by glycolysis exceeds rate of pyruvate and NADH entry in CAC
48
lactic threshold: excess pyruvate converted
- converted into lactate by lactase dehydrogenase
| - oxidation of NADH -> NAD+
49
lactic threshold: lactate threshold is
- VO2 lvl where plasma lactate conc begins to rise at rapid rate
50
lactic threshold: exercise intensity below ~60% mm contraction by
- Type I (slow twitch)
| - using aerobic ATP prod
51
recovery: excess post exercise O2 consumption- (EPOC) features
- after exercise, VO2 takes ~10 mins to fall to 'at rest' lvls = SPOC (aka O2 debt)
52
recovery: excess post exercise O2 consumption- rapid component of EPOC
- O2 stored in myoglobin in mm replenished and ATP produced by ox phos (mitochondria)
- used to convert creatine back to phosphocreatine
53
recovery: excess post exercise O2 consumption- slow component EPOC
- removal of excess lactate from plasma
- achieved through conversion of lactate - pyruvate (back into Krebs)
- lactate converted to glucose in liver via gluconeogenesis
- both need O2
54
recovery: excess post exercise O2 consumption- pH of exercising mm
- during: 0.4-0.6 less than blood (pH= 7.4)
- mm known to fall to 6.2
- acid convert to HCO2- to CO2
- ventilation rates increase to excrete CO2 in breath (needs extra energy)
- HCO2 used to buffer acid, regenerated in kidney
55
recovery: excess post exercise O2 consumption- recovery after heavy exercise
- after v heavy exercise, recovery of normal pH, HCO3- and lactate
- several hrs
56
increased CO and increase O2 consumption by cardiac mm needed to
- cool body after exercise
