Lab 1 prep Flashcards
Dalton’s Law
- the pressure of a mixed gas is equal to the sum of the individual gas pressures
PP of indv gas = (% concentration) x (total gas pressure)
ex.
PPO2 = O2 fraction x total pressure
atmospheric or barometric pressure at sea level
~760mmHg
fraction of oxygen in air at sea level
20.93%
partial pressure of oxygen (PO2)
- dry
~160mmHg)
0.2093 x 760mmHg
partial pressure of oxygen (PO2)
- in the lungs
- why?
~150mmHg
(0. 2093 x (760mmHg - 47mmHg))
- PP of water vapour in lungs at 37’C = 47mmHg
** use this value for room air in the lungs for diffusion
partial pressure of CO2 in room air
0.2 mmHg
partial pressures and “CO2” exchange in pulmonary tissue
capillaries
- rest
in alveoli
PCO2 = 40mmHg
in tissues
PCO2 = 46mmHg
partial pressures and “CO2” exchange in pulmonary tissue
capillaries
- exercise
in alveoli
PCO2 = 40mmHg
in tissue
PCO2 = 85mmHg
partial pressures and “O2” exchange in pulmonary tissue
capillaries
- rest
alveoli
PO2 = 100-105mmHg
tissue
PO2 = 40mmHg
partial pressures and “O2” exchange in pulmonary tissue
capillaries
- exercise
alveoli
PO2 = 100-105mmHg
tissue
PO2 = 15mmHg
how PO2 can be decreased
1) reduced barometric pressure
2) decreased concentration in the air
affect of altitude
lower barometric pressure, same concentration in the air
ex. 3000m above sea level
- air remains at 21% oxygen
- barometric pressure = 517mmHg
avg tidal volume at rest
- what is it
Vt ~ 500mL
- amount of air breathed in and out with each breathe
avg inspiratory reserve volume
~3L
avg expiratory reserve volume
~1L
avg dead space volume
- what is it
- effect of increasing tidal volume
~150mL
- volume inspired air available for gas exchange
- doesn’t significantly change with tidal volume
- % dead space volume decreases
avg total lung capacity
~6L
avg vital capacity
- what is it
~5L
- maximum volume forcefully inhaled and exhaled
avg residual volume
~1.2L
- minimum air that always remains in the lungs
how to measure ventilation (air volume)
flow meter
- inspired air (Vi) “or” expired air (Ve)
- L/min
how to estimate VO2?
- 3 measurements
VO2 = Ve (FiO2 - FeO2)
gas analyzer - average FiO2 (fraction of inspired - average FeO2 (fraction of expired) flow meter - volume of air in 1 min
how to calibrate an O2 gas analyzer
use known oxygen concentration of room
- sea level 20.93%
estimate expired CO2 with O2 gas analyzer
% O2 change = % CO2 change
- inspired CO2 very low (~0.04% - insignificant)
VO2 at rest
0.393 L/min
VO2 = (0.2093 - 0.17) x 10 L/min
average Ve
10 L/min
average # of breathes per min
12-16
measuring HR
hand grip device
- senses pressure of pulse
heart rate monitor
- measures chest movements
ECG/EKG lead II set up
negative - right clavicle
positive - lower left side
ground - left clavicle
*heart depolarization negative to positive on an angle down from right to left
P wave
depolarization of atria
Q wave
depolarization of interventricular septum
R wave
depolarization of left ventricle
S wave
depolarization of basal regions of the heart
T wave
repolarization of ventricles
order of depol and repol
opposite direction
- ventricles last to depol, first to repol
- repol continues to atria
why is R-wave so big and sharp
- ventricles much larger, more cells
- all cell of ventricle depol in sync (same time)
why is T-wave positive (positive repol?)
repol wave in heart travels opposite direction
SA and AV nodes
SA - sets pace AV - slows conduction of current (depol) - coordinated contraction
unique feature of cardiac muscle cells
self depolarizing
- SA node fastest
- AV node slower
- purkinjie fibers slowest
Calculating mean arterial pressure
mean arteriole pressure = blood flow (Q) x total peripheral resistance (TPR)
average HR at rest
75bpm
length of systole and diastole
rest - 1/3 systole - 2/3 diastole exercise - 1/2 systole and diastole
when taking BP, name of the sound to listen for
Korotkoff sounds
two ways to take BP
indirect
- BP cuff and stethoscope
- listen for korotkoff sounds
direct
- insert a catheter
work (W) calculation
Work
= Force x Distance
= Mass x RPM
Work units
Joules (Newtons x meters)
power calculation and units
= work / time
- J/s
- Watts (W)
equipment used in first lab
- ventilation, frequency, volume, body temp
vernier equipment
changes with exercise
Increase
- co2
- temp
- BP (systole + mean arteriole pressure)
- increase HR
- increase Vt and f
*diastole minor increase or decrease