Human Phys Final

What percentage of the total body mass of a human is skeletal muscle?

40%

structural organization of a skeletal muscle

muscle, muscle fibers, myofibrils, sarcomeres composed of thick and thin filaments

tension

the force produced by a muscle fiber/whole muscle when it is stimulated.

twitch

a mechanical response (contraction) of a muscle fiber/whole muscle to a single stimulus (measured as tension).

Difference b/w whole muscle contraction and single sarcomere contraction

individual cells are all or none. They develop tension and shorten to the best of their ability considering the load they have to work on and their length. In the whole muscle, cells are indiscriminately stimulated, depending upon the current density passing through that region of the muscle during the application of the stimulus by a stimulator. Amplitude varies.

Latent period

time between application of the stimulus and development of tension. time it takes the muscle to start responding to the stimulus.

Recorded output of muscle

sum of the number of twitches simultaneously taking place during the recording.

Recruitment

When more fibers are stimulated. results from increasing the intensity of the stimulus and/or the duration.

length of a muscle

important. no stretch shows no response. too much stretch shows no response.

summation

when two twitches add together. occurs if frequency is high enough.

Why is summation possible?

Because the excitation process is of a much shorter duration than the contraction phase.

Tetanus

when twitches fuse into a steady tension development. Is a function of frequency. Can result in a very small amount of tension or a maximal development of tension.

contraction time (CT)

good indicator of the minimum frequency needed to induce a complete tetanus.

Fusion Frequency

(1 stimulus/CT in ms)(1000ms/sec) = stimuli/sec. Gives you the minimum frequency need to to induce tetanus.

Force of a twitch

(calibration factor in g/V) (Muscle twitch amplitude in V) = g

find Muscle twitch amplitude

put one cursor on the beginning of the twitch and the second cursor on the peak of the twitch. V2-V1 value in V is your answer.

find contraction time.

put one cursor on the beginning of the twitch and the second cursor on the peak of the twitch. T2-T1 value in ms is your answer.

find 1/2 relaxation time

put one cursor on the peak and put the other cursor where the V is 1/2 the muscle twitch amplitude. Then record T2-T1 value.

find latency

put one cursor at the beginning of the stimulus pulse (on the bottom graph) and place the other cursor at the beginning of the muscle twitch. T2-T1 value.

Twitch tension vs tetanus tension

the tension of a twitch is less than the tension produced by the muscle when it is in tetanus.

What causes the greater tension during tetanus?

not due to recruitment. The repeated stimuli allow the muscle to overcome the effect of elasticity in the muscle. The series of elastic components (membranes & connective tissue) can absorb some of the internal tension produced by the contractile filaments (active state). During tetanus, the muscle can overcome elasticity and exert more tension externally. The tension produced internally (active state) is the same for a twitch and tetanus.

Fatigue

failure to maintain maximal tension

Passive tension

due to the stretching of the elastic elements associated with the muscle as the muscle "resists" lengthening.

Equilibrium Length

the muscle isn't stretched and the muscle length is fairly short due to effect of parallel elastic elements. The thick filaments are touching the z lines and the ends of the thin filaments are overlapping.

Resting Length

optimal overlap of thick and thin filaments and optimal contraction and tension output by the muscle.

Maximal Length

Muscle stretched to point where it can't be stretched any more. filaments don't overlap ad no contraction or tension can occur when muscle is stimulated.

Fatigue index

(T2/T1)(100). T1 is maximum tension produced at the beginning of tetanus. T2 is the tension immediately before relaxation.

null hypothesis

assumes that the two samples have been drawn from the same pop and differ only b/c of random error. assumes no systematic or real difference.

standard deviation

A way of quantifying the variation in your data. measures the degree of dispersion. An interval bounded by one standard deviation on either side of the mean (-1.5 and +1.5) will include 68% of the area of the curve and therefore 68% of tall determinations. An area bounded by two standard deviations on either side of the mean (-2.5 and +2.5) will encompass 95% of the data.

what does mean +/- SEM tell you about the data?

It tells you that the actual mean falls within that range. If in this range, you are 68% confident the mean falls within that range. Mean +/- SEM x 2 means you are 95% confident.

SEM (Standard Error of the Mean)

A way of quantifying how precise your calculation of the mean is compared to the true population mean. Related to SD. 1 SEM is 68% confident. 2 SEM is 95% confident.

calculate % change from control

(Exp mean-control)/(control) x 100

if t value is < than table value

fail to reject the null at 5% or 1% significance level; not statistically significant.

if t value is > than table value

reject the null with 95% or 99% confidence; statistically significant

if P < 0.05

statistically significant, reject null

if the % change from control is negative...

there is a decrease relative to the control

What does mean +/- SD tell you about the data?

If it is one standard deviation on either side of the mean (-1.5 and +1.5), it is telling you that 68% of the data is encompassed by the range. If it is two standard deviation on either side of the mean (-2.5 and +2.5), it is telling you that 95% of the data is encompassed by the range.

t test

determines statistical significance of data. helps you reject or accept null hypothesis. Tells you whether your data was due to chance or due to the independent variable.

paired t test

when the data come from the same individuals.

unpaired t test

when the data come from different groups on individuals.

if the % change from control is positive...

there is an increase relative to the control

if p > 0.05

fail to reject null, not statistically significant

find Passive tension

overall baseline to baseline of specific twitch

find twitch tension

baseline of specific twitch to peak

find total tension

overall baseline to peak of specific twitch

mycardial cells

contract in a coordinated fashion to pump blood around the body

SA node

pacemaker of the human heart, located in the right atrium. contains weakly-contractile, modified muscle cells that are myogenic. AP travels via gap junctions to adjacent cells in the atria. Allows AP to move within the cells of both atria like a wave, causing the atria to contract at the same time. AP also spreads to AV node

myogenic cells

can produce their own action potentials without stimulation from the nervous system. Contain a class of ion channels that open and close spontaneously.

AV node

composed of weakly-contractil, myogenic muscle cells. AP moves slowly along electrical pathway and then travels rapidly along the Bundle of His and the Purkinje Fibers to the fibers of the ventricle. Slow transmission ensures the ventricles contract after the atria. Allows ventricles to fill with blood from the atria before ventricle contracts and ejects blood

frog heart

3 chambered; 2 atria, 1 ventricle

sinus venosus

frog equivalent to SA node

systole

heart undergoes isovolumetric ventricular contraction until pressure is sufficient to open the aortic and pulmonary valves and the ventricular ejection takes place

diastole

heart undergoes isovolumetric ventricular relaxation, during which the aortic and pulmonary valves close and no blood enters or leaves the heart. This is followed by the opening of the AV valves and ventricular filling, which occurs primarily via passive filling as well as blood flow pumped into the ventricle towards the end of diastole by atrial contraction.

Frank Starling Law of the Heart

cardiac muscle is not optimally stretched. if it were, an increase in EDV would lead to a decrease in SV. Instead, as EDV increases, stroke volume increases because the heart is producing stronger contractions.

Beat Period

cursors on the peaks of the waves. T2-T1 value.

calculate HR

(1 beat/beat period in s)(60s/min) = bpm

Duration of Systole

one cursor on start of contraction and second cursor on point of 1/4 relaxation.

Duration of Diastole

one cursor on 1/4 relaxation point, other cursor on start of next ventricular contraction

acetylcholine

injecting it decreases heart rate

What are the three waveforms in an EEG recording

the P wave, the QRS complex, and the T wave

P-Q interval

atrial depolarization/contraction, Delay at AV node, Atrial systole

Q-T Interval

ventricular systole

T-Q interval

ventricular diastole

P wave

atrial depolarization/contraction

QRS complex

ventricular depolarization/contraction and atrial repolarization/relaxation (masked)

T wave

ventricular repolarization/relaxation

What does an ECG measure

electrical activity in the myocardium

MAP (Mean Arterial Pressure)

measure of the perfusion pressure within the organs of the body.

calculate MAP

(2(Diastolic P) + Systolic P)/3) or Diastolic + 1/3 Pulse Pressure

Systolic pressure

peak blood pressure in the arteries during left ventricular systole

diastolic pressure

the lowest pressure seen in the arteries during left ventricular diastole

pulse pressure

the difference between systolic and diastolic pressure

how is blood pressure represented

systolic pressure/diastolic pressure in mmHg

calculate alveolar ventilation

f(Vt-Vds); (Respiratory Frequency)(Tidal Volume-Dead Space Volume) = L/min

calculate dead space volume

(1/3)(Tidal Volume) = L

calculate IRV

one cursor on pause between normal inhalation and maximal inhalation, other cursor at end of maximal inhalation. in L.

Calculate ERV

Vital capacity - IRV - mean Tidal Volume = L

Breath Period

one cursor on baseline before one breath, place other cursor at baseline before next one (or another one). in sec/beat. (e.g. |n |n)

Calculate Tidal volume

one cursor on baseline before one breath, place other cursor at baseline after the next one (or another one). (e.g. |n n|). in Liters.

calculate respiratory frequency

(60sec/min)/(mean breath period in sec/beat) = breaths/min

Calculate Inspiratory Capacity

Tidal Volume + IRV

Minute volume

(respiratory frequency)(Tidal Volume) = L/min

Units for BMR rate estimate

Cal/hr

How to calculate energy required to sleep for x hours

(BMR rate estimate in Cal/hr)(x hrs) = Cal

Units for energy required to excercise for 1 hour

Cal/hr

how to calculate energy required to exercise for x hours

(energy required to exercise for 1 hr in cal/hr)( x hr) = Cal

calculate how many days it would take to lose x pounds by changing food intake

Food calorie intake = daily energy expenditure

how much food intake are you taking away = calorie deficit

amount of cal required to lose x pounds / calorie deficit = days it would take

calculate how many days it would take to lose x pounds by changing exercise and sleep schedule

food calorie intake = daily energy expenditure

calculate new energy required to exercise, sit, and sleep. find difference between this value and original daily energy expenditure = calorie deficit.

amount of cal required to lose x pounds / calorie deficit = days it would take

calculate energy required to sit for x hours

(resting metabolism rate of subject per hour in cal/hr)(x hr) = Cal

Tidal Volume

the volume of gas inspired or expired in any respiratory cycle.

IRV

maximal amount of gas that can be inspired from the resting end inspiratory position.

ERV

maximal amount of gas that can be expired from the resting end expiratory position.

Residual Volume

amount of gas remaining in the lungs following a maximal expiration. about 1000 mL.

total lung capacity

the amount of gas contained in the lung at the end of a maximal inspiration.

vital capacity

maximal amount of gas that can be expelled in a forceful effort following a maximal inspiration.

inspiratory capacity

maximal amount of gas that can be inspired from the resting end expiratory position