BI206L Lab Exam #2 Study Guide

BI206L Lab Exam #2 Study Guide

Lab #5 Muscle, EMG, Skeletal Muscle Function (Online)

1. Describe the organization of a motor unit and explain how the action potential results in contraction of the associated muscle fibers.

• A motor unit consists of a single motor neuron and all muscle fibers it innervates
• An action potential travels along the nerve fiber which triggers the release of the neurotransmitter acetylcholine at the NMJ
• Acetylcholine binds to receptors and causes depolarization of the muscle fiber
• When the muscle fiber undergoes depolarization, calcium is released from the sarcoplasmic reticulum. Increased Ca2+ concentration in the cell results in the contraction of the muscle fibers through the activation of contractile machinery.

2. Describe what happens to the associated motor unit as a result of an electrical stimulation of a peripheral nerve.

• Exercise 3?
• The associated motor unit is activated when there is electrical stimulation of a peripheral nerve
  • By initiation of an action potential
• Causes brief contraction called a twitch

3. Describe what happens to the associated muscle as a result of increasing the magnitude of the electrical stimulation of a peripheral nerve, including what this phenomena represents.

• As the magnitude of electrical stimulation is increased, the amplitude of muscle response also increases
  • More motor axons fire in response to a greater stimulus
• This trend increases until a threshold is reached where all the muscle fibers are recruited
  • At this point, the response stops increasing even if the stimulus is increased more
• This phenomenon represents recruitment?

4. Explain what an electromyogram (EMG) depicts.

• An EMG is an electrical signal recorded from a contracting muscle
• It depicts the timing and pattern of muscle activity during complex movements

5. Define coactivation and explain its significance in joint movement.

• Coactivation is when the contraction of a muscle leads to minor activity in the antagonist muscle
  • Ex: when the biceps is activated forcefully there is minor increase in activity in the triceps
  • Helps to stabilize the joint

6. Explain nerve conduction velocity.

• Found by the distance between stimulation sites/ difference between latencies
• Measures how fast an electrical impulse moves through the nerves

7. Be able to calculate the length of time for an action potential to travel from lower motor neuron cell body to peripheral muscle.

• time= (distance traveled)/ (nerve conduction velocity)

8. Compare and contrast the two ways by which the nervous system can control the force generated by an entire muscle.

• Altering the # of motor units firing
  • Controls the number of twitching muscle fibers-> recruitment
• Changing frequency of action potentials
  • Causes summation bc muscle does not completely relax between twitches
  • Greater force of contraction
• Both summation and recruitment are similar in the fact that they increase force of contraction

Lab #6 Cardiovascular effects of exercise (Online)

1. Explain the relationship of heart rate (HR) and stroke volume (SV) in generating the cardiac output (CO).

• Cardiac output is the product of heart rate(bpm) and stroke volume(liters/beat)
• CO= the volume of blood that the heart ejects into circulation each minute
• Avg 5L/min in humans

2. Be able to use the formula: CO = HR x SV

• Got it

3. Explain the difference in cardiac output between a conditioned endurance athlete and a less fit individual.

• Fit athletes have a greater capacity to increase CO than less fit individuals
  • Conditioned endurance athletes have lower resting heart rates
    • So their SV at rest must be higher to equal the same CO as a person with/a higher HR
  • During exercise, when the athlete's HR is increased, they can increase their CO greatly because they will have a high SV and HR while the less fit individual will still have a lower SV when their HR is elevated from exercise

4. Explain how the sympathetic and parasympathetic innervation to the heart regulates heart rate based on physiological state.

• Vagal activity is predominate at rest, during exercise vagal activity diminishes and sympathetic activity increases
• Sympathetic stimulation increases HR
  • Fight or flight
  • Increased amount of blood pumped to the heart, brain, and muscles
• Parasympathetic stimulation decreases HR
  • Rest and digest
  • Slowing of blood flow to muscles

5. Describe the components and waveforms of an electrocardiogram (ECG), include what is occurring in the heart during each waveform or interval.

• P-R interval: conduction through the AV node and bundle
  • P wave -> atria depolarize
• QRS Duration: ventricles depolarize and atria repolarize
• ST interval: duration of ventricular contraction
  • T wave-> ventricles repolarize
• TP interval: segment where electrically quiet until the next interval

6. Be able to identify the waveforms and intervals on an ECG trace.

• P-R interval: flat to top of peak
• QRS Duration: duration of spike
• ST interval: bottom after peaking to next bump
• TP interval: segment where electrically quiet until the next interval, lil bump to other

7. Explain what the R-R interval represents.

• The R-R interval represents the contractile cycle length of the heart
• Measured from peak to peak

8. Calculate the heart rate from the R-R interval

• HR= 1/ R-R interval (cycle length) -> bps
• Multiply by 60s to get bpm

9. Explain what happens to the heart rate and mean pulse amplitude at rest, during exercise, and during recovery.

• Heart rate increases from its resting rate during exercise, during recovery it begins to decrease and gets closer to its resting value over time
• Mean pulse amplitude decreases during exercise because, during aerobic exercise, less volume of blood goes to the hand, and blood flow to skeletal muscle is increased. During recovery, the MPA began to increase again getting closer to its resting level over time.

10. Describe the role of peripheral arterioles in controlling the distribution of blood flow.

• Resistance of peripheral arterioles can be adjusted to divert blood to the tissues that need it
• Located before the capillary beds
  • Increase resistance to block blood flow
  • Decrease resistance to increase blood flow
  • During exercise blood gets diverted to active skeletal muscles and away from other tissues

11. Explain the difference in pulse pressure during aerobic systemic exercise versus localized hand exercise.

• During aerobic systemic exercise, pulse pressure decreases
  • The hand is not exercising which means less blood is diverted into it and is diverted into the skeletal muscle tissues that are exercising instead
• During hand exercise, pulse pressure increases
  • Since the hand is exercising extra blood is sent to that localized area

Updated Fall 2020

BI206L Lab Exam #2 Study Guide

Lab #7 Blood Pressure (Online)

1. Explain systolic and diastolic pressures, including what is occurring in the heart during each phase.

• Systolic pressure is pressure the highest pressure
  • Occur immediately after contraction of the ventricle
  • First sound
• Diastolic pressure is the lowest pressure
  • Relaxation phase
  • Measured immediately before the atria fill
  • When sound disappears

2. Explain the process of how a sphygmomanometer and stethoscope are used to measure blood pressure, be as specific as possible.

• A BP cuff is placed on the upper arm and inflated to stop arterial blood from to the brachial artery (cuff inflated to pressure higher than systolic BP)
• The pressure cuff is released slowly and the flow of blood in the artery is listened to through the stethoscope.
• When the cuff pressure falls below systolic BP, turbulent blood flow occurs which generates Korotkoff sounds heard through the stethoscope.
  • First flow=systolic pressure
• Cuff pressure is lowered more and when the sound is no longer heard blood flow is smooth
  • Indicates diastolic BP

3. Explain why blood pressures are variable depending upon the location of the blood pressure cuff in relation to the heart.

• Compared to measurements made at heart level…
  • Measurements made above the heart will be lower in pressure
  • Measurements made below the heart will be higher in pressure
• Due to hydrostatic pressure column

4. Explain the appearance and disappearance of the Korotkoff sounds and the associated anatomical and physiological characteristics at these points.

• Appearance
  • Due to turbulent blood flow
  • Blood squeezing through compressed artery during systolic phase
  • Measures systolic BP
• Disappearance
  • Return to smooth blood flow
  • Artery is normal diameter again
  • Measures diastolic bp

5. Explain the changes in the pulse pressure in relation to the systolic and diastolic pressures during gradual release of the air from the blood pressure cuff.

• When the blood pressure cuff is inflated, the pulse signal disappears
• When the diastolic pressure is recorded, the pulse pressure returns to normal
  • Return of normal blood flow through the arteries

Lab #8 Renal Function (Online)

1. Apply the formula Clearance of X = excretion rate of X (mg/min)

[X]_plasma (mg/ML plasma)

2. Explain why inulin or creatinine are often used to determine GFR.

• Inulin or creatine are often used to calculate GFR because they are not reabsorbed or secreted by the body

3. Determine Glomerular Filtration Rate (GFR) when given plasma inulin concentration and rate of inulin excretion.

• GFR (mL/min)= excretion rate (mg/min)/ concentration(mg/mL)

4. Apply the formula Excretion (E) = Filtration (F) – Reabsorption (R) + Secretion (S) to analyze the renal handling of a substance.

• ok

5. Analyze the renal handling of a substance and indicate if it is reabsorbed or secreted.

• Renal handling = the way in which the kidneys treat individual solutes
  • Includes filtration, reabsorption, secretion that results in excretion
• Excretion= filtration- reabsorption+ secretion
  • E= F-R+S

6. Describe how a urinalysis strip is used to test urine samples.

• Consists of a series of pads embedded in a reagent strip
  • Provides quick semi-quantitative assessment of various potential contents of urine
• The dipstick is either dipped directly into urine or soaked in it using a pipette
• Excess fluid is wiped off
• Wait a predetermined amount of time for results and then prepare against the standards that are provided

7. Analyze simulated urine sample results for color, pH, glucose, protein, and specific gravity when given a urinalysis test strip and urinalysis test key.

• Yes

8. Describe abnormal results that can be shown during urinalysis and provide an explanation of a situation or disease for each abnormal result.

• Specific gravity
  • Density of urine/density of water
  • Varies from 1.001 to 1.035
    • Normal is 1.010
  • Close to 1.001
    • Excessive hydration
    • Diabetes insipididis
  • Close to 1.035
    • Dehydration
    • Proteinuria
• pH
  • Range to 4.5 to 8.0
  • Low
    • Academia
    • Diabetes mellitus
  • HIGH
    • Alkalemia
    • UTI
• Glucose present (abnormal)
  • Hyperglycemia-> diabetes mellitus
  • Proximal tubule dysfunction
  • Diabetes mellitus
• Blood
  • UTI
  • Rhabdomyolysis
• Protein
  • UTI
  • Anemia
  • Renal damage

9. Determine potential causes of abnormal results obtained from urinalysis, focused specifically on characteristics of diabetes mellitus, renal failure, or urinary tract infection.

• Diabetes Mellitus
  • Low pH
  • High specific gravity
  • Glucose presence
• Renal Failure
  • Low specific gravity
  • Protein presence
    • Not filtered out of urine correctly by damages kidneys
• Urinary Tract Infection
  • High pH
  • Protein presence

Updated Fall 2020