Week 8 Flashcards
define metabolism
the sum of all chemical reactions in the body - includes all anabolic, catabolic, endergonic and exergonic reactions. It is an endergonic process and requires a net input of energy
define metabolic rate (MR)
the energy cost per unit time
what are the 3 different pathways that we draw on to create ATP
- ATP-PCR
- provides immediate energy through the breakdown of stored high-energy phosphates - anaerobic glycolysis
- serves as a means of energy production in cells that cannot produce adequate energy through oxidative phosphorylation - aerobic glycolysis
- series of reactions wherein oxygen is required to reoxidize NADH to NAD+
we can think of the biological cost (ATP) in terms of…
- the amount of fuel we need to burn to get ATP
- the amount of O2 needed to burn the fuel
fuel substrate + O2 -> CO2 + H2O + ATP
what is the BEST way to measure biological cost
heat production is the best indicator of the energy transfer in the body
direct calorimetry
directly measuring how much heat the body is producing
uses a completely thermally isolated chamber - no heat exchanged.
gold standard method - provides direct measure of energy transfer in joules or kcal but very difficult
indirect calorimetry/respirometry
provides indirect measure of energy transfer/metabolic rate
can refine estimate by ALSO measuring CO2 production
respirometry involves the measurement of both:
- rate of O2 consumption
- rate of CO2 production
rate at which we use O2 =
= O2 consumption (VO2)
- little dot over V means rate - reported in L/min or mL/min
recap on oxygen consumption
- oxygen is required for whole process but isnt required until end
- goes to end of ETC and steals electrons from last complex which allows electrons to keep flowing
- etc releases a bit of energy which allows us to pump protons into the intermembrane space
- protons flow through atp synthase, spin turbines and make lots of ATP
get lots of ATP this way but pretty slow
how much of the atmosphere is O2, CO2, and nitrogen (%)
inspired O2 = 20.93%
nitrogen = 78%
inspired CO2 = 0.04%
steps to get O2 from air to mitochondria (oxygen cascade)
oxygen cascade:
air - airways - lungs - exchange across lungs through alveoli - into blood vessels - heart - arteries - capillaries - tiessues - cells - mitochondria
what does getting O2 into our bodies depend on?
- ventilation
- mechanically moving air into our bodies
- gas exchange
- from air to blood
- from blood to cell to mitochondria
- gas transport through circulation
- heart function
- blood vessel function
- metabolism
- mitochondrial function
how much O2 do we consume at rest?
around 250 mL/min
500 L O2 per day
highly variable depending on person and day
factors that affect rate of oxygen consumption
person:
- body mass - higher w/ size
- body comp - higher w/ lean mass
- sex - higher in males
- age - lower w/ age
- hormones
- genetics
the day:
- diet - what/how much you eat
- rest
- state of arousal - lower at true rest
- psych state - higher w/ anxiety/fear/agitation
- activity - what/how much you do
why is it important to understand VO2
allows for realistic estimates of functional capacity
allows calculation of energy (caloric) requirements to support
- weight management
- athlete (re)fueling
- determination of training load
VO2 rate influenced by
- type of activity
- intensity
- duration
how do we assess VO2 rate?
Assessing VO2 requires determining how much O2 enters the body and how much O2 leaves the body - the difference is what is consumed by the body
how do we measure VCO2?
we need to know how much CO2 leaves the body and how much CO2 enters. the difference is what is produced - more leaves than enters
under standard conditions, how many moles are in 1 L of O2?
22.4 L - 1 mol of ANY gas - avogadros law
describe boyles law (pressure)
volume varies inversely with pressure
as pressure increases, volume decreases
at higher pressure, 1 L of gas will contain more molecules
describe charles’ law (temp)
volume varies directly with pressure
as temp increases, vol increases
at a higher temp, 1 L of gas will contain fewer molecules
describe daltons law (pressure sum)
the total pressure of a mixture is the sum of the partial pressure of its components
total gas pressure = barometric (atmospheric) pressure
must account for water vapour pressure
what condition is Ve collected under
ATPS conditions
Ambient Temperature Pressure Saturated
what conditions do we need to adjust Ve to?
STPD conditions
Standard Temperature Pressure Dry
standard temp: 0 degrees or 273 K
standard pressure: 1 atm or 760 mmHg
dry: 0% humidity
describe absolute VO2
how much oxygen are you consuming over time (mL/min or L/min)
good for determining total energy cost of activities that are NOT weight bearing (rowing, cycling, etc..)
ok for comparing ppl of similar size
describe relative VO2
takes body mass into account
mL/kg/min
= VO2 (L/min) x 1000 mL/L / mass (kg)
more appropriate for determining energy cost of activities that require moving ones own body weight (running)
more appropriate for comparing ppl of different sizes
how does VO2 respond to exercise?
it always goes up
incremental exercise to max
exercise gets harder and harder until you get to your max capacity
examples include the VO2 max test
static resistance example
wall-sit, plank, etc…
isometric contraction - still hurts but not moving anything
10 mins or less
<100% MVC
anaerobic
dynamic resistance
muscle shortening/lengthening
ex: push-ups, biceps curls, leg extensions
sets / # reps
<100% 1RM
anaerobic
very short term high intensity example
sprint to catch bus
<3 min
~100 + % P max
anaerobic
short term light to moderate example
20 min walk with friend
~3-15 min
~30-<70% Pmax
aerobic
long term moderate to heavy example
uphill hike w/ backpack
~15 min - 1 hour
~70-90% Pmax
aerobic
describe VO2 response to short-term light to moderate PA
- time to reach steady state is directly proportional to intensity
- increased lag with increased activity
- increased lag in untrained and older individuals
what does EPOC stand for
Excess post-exercise O2 consumption
describe VO2 response to long term, moderate to heavy PA
- time to reach steady state is directly proportional to intensity
- O2 drift - increased VO2 over time at = intensity
mechanisms of O2 drift (what causes it)
increased fight or flight hormones
increased body temp
increased cost of ventilation
describe VO2 response to incremental exercise to max
- rectilinear increase until VO2 max
- plateau at the end indiciates the test is maximal because an increase in workload brought no further increase in VO2 max
- if not confident that it is truly the persons max, we call it the VO2 peak
