Mathematics AS Flashcards
What factors affect the anount of gaseous exchange?
Size
Level of activity
Peak flow meter
Measures rate at which air can be expelled from the lungs - often hsed for people with asthma to monitor lung function
Vitalographs
More sophisticated versions of peak flow meter - breathe out as fast as possible showing amount of air against how quickly it is expelled
What is forced expiratory volume?
Amount of air pushed out in 1 second
Spirometer
Used to measure different aspects of lung volume/investigate breathing patterns
What type of system is a spirometer?
Closed system with all of oxygen coming from within machine - so enough oxygen in chamber that person doesnt die
Why does patient have nosepiece on?
Unable to breathe through nose giving more accurate representation of lung function
Why does health matter with spirometer?
So that there are no diseases that impair lung function
What feature is on spirometer?
Counterweight to prevent any resistance - does not have to breathe in and foce up/down the whole weight of the spirometer lid for example
Why is there soda lime in spirometer?
All of CO2 produced (as a result of respirarion) is absorbed - which means that the trace eventually starts to decline as less gas breathed back into spirometer chamber than was breathed in - ONLY oxygen
Breathe in…
Lid moves down - line moves up
Breathe out
Lid moves up - line moves down
What is tidal volume?
Volume of air that moves into and out of the lungs with each resting breath - it is around 500cm^3 with adults which uses about 15% of the vital capacity of the lungs
What is vital capacity?
Volume of air that can be breathed in when strongest exhalation is followed by deepest possible intake
Inspiratiry reserve volume
Maximum volume of air you can breathe in over and above a normal inhalation
Expiratory reserve volume
Extra amount of air you can force out of your lungs over and above the normal tidal volume exhaled
Residual volume
Volume of air left in lungs after exhaling as hard as possible - cannot be measured directly
Total lung capacity
Total lung capscity = vital capacity + residual volume
Label all of those features on spirometer
Total lung capacity = whole graph
Residual volume = bottom section
Tidal volume = height of normal breaths
Inspiratory Reserve volume = peak of tidal to top of graph
Inspiratory capscity = trough of tidal to top of graph
Vital capscity = everything except residual volume
Breathing rate
Number of breaths per minute
Ventilation rate
Total volume of air inhaled in 1 minute
Ventilation rate = tidal volume * breathing rate
When body undergoes exercise?
Tidal volume increases from 15% to around 50% of vital capacity - breathing rate also increases thus increasing ventilation and so oxygen uptake during gaseous exchange can be increased to meet the demands of the tissues
What is used to calculate Diversity?
Simpson’s index of diversity
What does Simpsons include?
Species richness
Species evenness
Range that Simpsons lies in?
0 and 1
0 = no diversity
1 = infinite diversity
Formula of Simpsons
D = 1 - Σ(n/N)^2 n = number of individuals of each species N = all individuals of all species
Standard Deviation
Square root : (sum(x-average)^2)/n-1
Where x = data value
n = number of values
x(bar) = average
How to measure an outlier?
> or < mean +- (2*sd)
Chi-Squared test
x^2 = (sum of (observed frequency - expected frequency)^2) / expected frequency
Number of observations made?
The expected values depends on chance - ie if you toss a coin 10 times you get 5 heads and 5 tails but this is not always the case
If you increase the number of times the coin was thrown the difference between expected and observed decreases
What does chi-squared help you measure?
The size of the difference between the results you actually get and your expected - whether these differences are significant or not
Chi squared is used to find out whether the difference is due to chance alone - thus allowing us to accept/reject the H0
Degrees of freedom for chi squared
N-1 where n is the number of categories or possible outcomes present in the analysis
Yellow and green peas would be two categories and thus 1 degree of freedom
If chi squares is less than critical value
Then we do not have sufficiently strong evidence to reject our null hypothesis as there is more than a 5% likelihood that this difference is due to chance - we accept null hypothesis
If the calculated x^2 value is greater than critical value
We reject the null hypothesis as some other factor is likely to be causing a significant difference between expected and observed
T test
Is used to compare the means of two sets of data and determine whether they are statistical,y significant or not
Null hypothesis
No significant difference between two means and that any differences seen are due to chance
How to calculate t test?
Calculate mean for each data set
Calculate standard deviation for each set of data (s1 and s2)
Square the standard deviation and divide by n1 and n2 respectively
Add those two values and take the square root of it
Divide difference between the two means with the value calculated in the step before to get the t value
Degrees of freedom for a T-test
(n1 + n2) - 2 - unpaired ; different organisms/objects
n-1 for paired
If t value is greater than critical value?
Reject the null hypothesis because there is less than a 5% chance that the difference is down to chance
If t value is =/below critical value at 0.05
Then null hypothesis is accepted and there is no static tally significant difference
Types of correlation
No correlation - no relationship between data
Positive correlation - as one set increases in value, the other set of data also increases in value
Negative correlation - as one increases the other set of data decreases
What is the correlation test used to see?
If two different variables are correlated in a linear fashion in the context of a scatter graph
Formula of spearman’s rank
r = 1 - (6(sumof)d^2)/(n(n^2-1))
How to carry out a spearman’s rank
Data. For the two variables should be ordered from lowest to highest
If identical values exist then the average rank should be used - if two equal values appear
at rank 5 they are both assigned rank 5.5
Get rank difference d
Square it
Add them all up
Divide this by the number of pairs of data as n (shown in the equation)
Rs value of +1
-1
0
\+1 = perfect positive correlation -1 = perfect negative correlation 0 = no correlation
How to work out statistical strength of the correlation?
Value should be looked up in the correlation coefficient critical value tables - they will refer to the number of data pairs
For the data to be significantly significant, the spearman’s rank coefficient must be more than at 0.05% to give a certainty of more than 95%
