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Physiology > Practical 3 > Flashcards

Practical 3 Flashcards

1
Q

does stimulus strength change the duration of the latent period in a muscle twitch?

A

no

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2
Q

what occurs during the latent period of a muscle twitch?

A

excitation contraction coupling.

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3
Q

what is motor unit recruitment?

A

the recruitment of more motor units when stronger contractions are required

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4
Q

what happens to the contraction of a skeletal muscle when stronger stimulus is applied and why?

A

a stronger contraction occurs because more muscle fibers are activated

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5
Q

what is maximal voltage?

A

when all muscle fibers in a skeletal muscle have been activated by a sufficiently strong stimulus and contraction strength can no longer increase. additional stimulus strength will not result in a stronger contraction at that point

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6
Q

what is treppe?

A

when subsequent muscle twitches increase in strength with each additional contraction.
muscle twitch will contract, relax, contract, relax but each contraction will be stronger than the last until a plateau has been achieved

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7
Q

what is wave summation?

A

when subsequent muscle twitches are summed together. a contraction occurs followed by a brief relaxation but before it can fully relax another contraction occurs. this results in a staircase like pattern

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8
Q

how is wave summation achieved?

A

a frequency of AP that is more frequent than treppe

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9
Q

what is skeletal muscle passive force?

A

passive force is generated by stretching the muscle and results from the elastic recoil of the tissue itself

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10
Q

what is passive force largely caused by?

A

the protein “titin” (molecular bungee cord)

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11
Q

what is skeletal muscle active force?

A

the force generated by a skeletal muscle contraction

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12
Q

what is total force?

A

the sum of passive and active forces

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13
Q

what determines the amount of active force that can be generated by a skeletal muscle?

A

cross bridge formation between actin and myosin

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14
Q

what is metabolism?

A

a broad range of biochemical reactions in the body that include anabolism and catabolism

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15
Q

what is goiter caused by?

A

the overstimulation of the thyroid gland. too much TSH overstimulates the thyroid. to much TRH will produce too much TSH thus also leading to goiter.

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16
Q

what does TRH stand for?

A

thyrotropin releasing hormone

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17
Q

what is propylthiouracil?

A

a drug that inhibits the production of thyroxine

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18
Q

METABOLIC RATE CALCULATIONS

how do you calculate oxygen consumption per hour?

A

mL O2 consumed/1 minute x 60 (minutes) = mL O2/hour

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19
Q

how do you calculate metabolic rate?

A

metabolic rate = (mL O2/hour)/(weight in kg) = (mL O2/kg/hr)

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20
Q

what is euthyroid?

A

“good” or normal thyroid levels

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21
Q

what is the BMR range for hypothyroidism, euthyroidism, nd hyperthyroidism?

A

hypothyroidism < 1600
euthyroidism 1650-1750
hyperthyroidism > 1800

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22
Q

which type of proprioceptor is involved with the patellar reflex?

A

skeletal muscle spindles

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23
Q

describe the knee-jerk reflex pathway

A

sensory neuron synapses directly with the motor neuron and stimulates contraction (monosynaptic reflex)

24
Q

describe the pathway for a crossed extensor reflex

A
  • muscle stretch causes muscle spindle to fire
  • splits off to different efferent neurons
  • the motor neuron responsible for contraction synapses directly with the sensory neurons axon terminal while the inhibiting neuron received information from sensory neuron via interneuron (reciprocal inhibition)
  • the result of this pathway is a muscle is contracted to cause movement while its antagonistic muscle is inhibited.
25
Q

what do muscle spindles consist of?

A

specialized thin muscle fibers called intrafusal fibers

26
Q

what are extrafusal fibers?

A

the muscle fibers that reflexively contract due to intrafusal fiber stretch

27
Q

what does the ankle jerk reflex test?

A

the medial popliteal nerve

28
Q

what is the end result of the ankle jerk reflex?

A

plantar flexion, that is the toes want to flex toward the floor

29
Q

what is the end result of the biceps jerk reflex?

A

slight flexion of the biceps

30
Q

what is the end result of the triceps jerk reflex?

A

slight flexion of the triceps

31
Q

where do you strike the arm for triceps jerk reflex?

A

about 2 inches above elbow

32
Q

does is heart automaticity?

A

the ability of the autorhythmic cells to stimulate the contractile cells in the absence of neural input

33
Q

what is heart rhythmicity?

A

intrinsic regulation of systole and diastole of the heart

34
Q

what is increased cardiac rate mostly due to in exercise?

A

increased cardiac rates are mostly due to decreased duration of ventricular diastole
(from the peak of the T wave to the beginning of the next QRS complex

a secondary cause is due to a shortening of ventricular systole, measured from QRS peak to the peak of the T wave

35
Q

what in the body conducts electrical activity of the heart and make it possible to get electrical readings from leads placed on different areas of the body?

A

a high concentration of electrolytes in the body

36
Q

what is the record of cardiac electrical activity taken by an electrocardiograph called?

A

electrocardiogram

37
Q

what is the standard chart speed of an ECG?

A

25mm per second

38
Q

how much time elapses between vertical lines in an ECG?

A

.04seconds

39
Q

what is the space between atrial depolarization and ventricular depolarization called in an electrocardiogram?

A

the PR interval

40
Q

what are the 3 ways to measure heart rate using electrocardiogram?

A

count the number of beats in a 3 second interval and multiply by 20

count the number of beats in a 6 second interval and multiply by 10

60 (seconds) / time between 2 R waves

41
Q

what is 1st, 2nd, and 3rd degree heart block?

A 
1st = PR interval > .20 seconds
2nd = 2 or more P waves before a QRS complex
3rd = P waves and QRS complexes are on their own inherent rate (20-45bmp)
42
Q

what is einthovens triangle?

A

a style of lead placement for an ecg where a lead (positive and negative electrode) is placed on both right and left forearms and one on the left calf

43
Q

what leads are used to determine mean electrical axis and where are they plotted?

A

leads 1 and 3 are used to determine mean electrical axis

lead 1 is plotted on the horizontal line and lead 3 is plotted on the offset graph

44
Q

what is normal mean electrical axis?

A

between 0 and 90 degrees

45
Q

how do you analyze each lead to find mean electrical axis?

A

measure distance (mm) from baseline to the peak of R wave (upward deflection)

then

measure the distance(mm) of downward deflection that projects below the baseline (use a negative number for this)

sum the two numbers and use the result in your mean electrical axis

46
Q

after the sum of deflections are plotted on a mean electrical axis, how do you determine the mean electrical axis?

A

draw a line from the center of the circle of the graph through the intersecting lines of lead 1 and lead 3

47
Q

describe how ventricular hypertrophy can result in left or right deviations

A

enlargement of one ventricle shifts the mean axis toward the hypertrophies ventricle because the larger ventricle takes longer to depolarize.

left axis deviation could mean the left ventricle is enlarged
right axis deviation could mean the right ventricle is enlarged

48
Q

describe how bundle-branch block can be seen on mean electrical axis

A

a conduction block in one of the av branches can cause a slower rate of depolarization

left deviation could mean the left branch is causing slower depolarization in the left ventricle
right deviation could mean the right branch is causing slower depolarization in the right ventricle

49
Q

describe how mean electrical axis can show evidence of myocardial infarction

A

deviations of electrical axis occur to varying degrees

50
Q

what is the tool that determines red cell count?

A

hemocytometer. it is a microscope slide used to determine the number of red cells in a cubic mm of blood

51
Q

what is the formula used with a hemocytometer to determine total red cells in a cubic mm of blood?

A

1) count the red cells in squares 1-5 (the squares on the 4 corners and the one in the center)
2) # of RBCs x 10000 = RBCs/cubic mm
3) RBCs/cubic mm / 1,000,000 = RBCs million/cubic mm

52
Q

what is hematocrit?

A

in a centrifuged blood sample it is the ratio of the volume of packed RBCs to the total blood volume

53
Q

how do you determine the hematocrit of a centrifuged blood sample?

A

1) measure the height of the total blood sample (mm)
2) measure the height of the packed RBCs (mm)
3) height of the packed RBCs (mm) / height of the entire blood sample (mm) x 100 = % of RBCs in entire blood sample (hematocrit)

54
Q

what is MCV and how do you calculate it?

A

MCV is mean corpuscular volume which is the size of your red blood cells

MCV (cubic micrometers) = hematocrit x 10 / RBC count (millions per cubic mm)

55
Q

describe the presence of antibodies and antigens in the different blood types

A

type A - type A antigens on RBCs/ type B antibodies in plasma
type B - type B antigens on RBCs / type A antibodies in plasma
type AB - type A and type B antigens on RBCs / no antibodies in plasma
Type O - no antigens on RBCs / type A and type B antibodies in plasma

negative - Rh factor not present on RBCs
positive - Rh factor present on RBCs

56
Q

what happens when you mix antigens and antibodies of the same type together

A

antibodies bind to antigens and agglutinate (clump together)

Physiology (5 decks)

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