Download On the basis of animal function

Recitations
and Labs # 01, # 02, #3
The goal of this recitations / labs is to review material for the
first test of this course. Info on osmosis, diffusion, metaboism,
transport across biological membranes, communication and
muscle, has been referred to in lectures and is presented in
labs as computer simulations related to homeostasis, signal
transduction, endocrine and neural communication, and
muscle function. Although no additional info is presented in
the lab section, its content allows for a better discussion of the
material presented in the lecture / recitation course.
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Question and answers related to the first seven lectures:
• 
Ranking of most important items for recitation / lab #1
–  An active learning technique to study physiology
• 
Ranking of most important items for recitation / lab #2
–  A recitation question with a structure and function of your choosing
• 
Ranking of most important items for recitation / lab #3
–  A recitation question involving neuroendocrine components
A Model of Active Learning
• 
Probably a single most important tip for the course is to prepare SENTENCES with what you
consider are the main “punch lines” for each lecture. You should RANK them in what you
consider is a list from most to less important ideas given in each lecture. You should EDIT
them, as for example, checking if more than one sentence might be combined into a better
sentence. Finally, make sure that your sentences cover the whole of the topic presented in
each lecture. Use this list to discuss material with fellow students and with your instructor."
• 
Please be aware that in order to write a single, concise and informative sentence you need to
UNDERSTAND, rather than memorize, a piece of information. To test yourself on how good
you are doing this, check if your sentence used your own words or if you are just borrowing
part of a sentence you read in your textbook. Consider that if you can not write an idea
into a single and simple sentence, you probably have not yet understood the material.!
• 
When you are editing your notes, either from lectures or from your textbook, it is important to
have a “PLAN” that tells you where are you going with your editing. A good suggestion for
this plan is to develop a set of QUESTIONS that you think each lecture was attempting to
answer. List all possible questions, then edit and rank the questions, and finally answer them
by merging your lecture notes and the notes you might have summarized from your textbook.!
• 
The PARAGRAPHS in the following slides are an example of notes you might have taken
from a lecture or from a textbook. Use these notes as an exercise by turning them into
sentences, then editing them, and finally by ranking them. Make sure you merge your notes
from lectures with your notes from your textbook and make sure your ranked sentences
cover the whole material presented in lectures. This is your recitation and Lab #01.!
1
Recitation question and Lab # 01
If you can not write an idea into a single sentence,!
you probably have not yet understood the material.
Recitation question and Lab # 01
Example of an answer based
on the pre-requisite material
Example of
questions
Example of
statements for
one of these
question
What is life ?
Energy is the capability to do work.
What is physiology ?
Energy originates from the sun, it is stored
in chemical bonds of macromolecules and
it is readily available from cellular ATP.
How is life mantained ?
What is structure - function ?
What is energy, where does
it comes from, how is it used
and how is it controlled ?
Use of physiological sources of potential
energy is regulated by enzymatic control of
intermediary metabolism (nt & hormones).
Specific cells, tissues, organs & organisms
have evolved biological structures in order
to optimized the use of energy for specific
functions (e.g. muscle vs mucosa cell).
A main source of potential energy is the
ionic difference across plasma membranes.
2
Recitation question and Lab # 01
Example of an answer based
on the pre-requisite material
Example of
questions
What is life ?
What is physiology ?
How is life mantained ?
What is structure - function ?
What is energy, where does
it comes from, how is it used
and how is it controlled ?
Example of a
statement for all
of these question
Life, whose only
purpose is to keep
being alive, is based
on enzyme - driven
chemical reactions, in
compartamentalized
environments.
Recitation question and Lab # 01
The main “punch-line” for this question is that
there is not a single best answer, but just the
one you understood the better.
Better answers will be correlated with a better
understanding of the background information
on which the topic material is based.
The next slide has a list of questions students
should ask themselves when attempting to
understand physiological issues (the circle), as
those required to answer the weekly questions.
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The “circle” as a way of thinking
• 
• 
• 
• 
• 
• 
• 
What is the goal for the system
or lecture topic you are now
studying ?!
Which are its main structures
and its main functions ?!
Which are its main structure function relationships, at the
different organizational levels ?!
Which are its main control
elements, at the different
organizational levels ?!
Which are its main inputs,
integrators, outputs, and
feedback elements ?!
Which are its main links or
relationship with other systems
or lecture related topics ?!
Which are its main homeostatic
failures or clinical pathologies ?!
Questions to be asked of
any homeostatic system"
Questions to be asked
of any homeostatic
system (“the circle”)"
4
Recitation questions # 02 & # 03
Sept 11"
If you can not write an idea into a single sentence,!
you probably have not yet understood the material.
Recitation questions # 02 & # 03
If you can not write an idea into a single sentence,!
you probably have not yet understood the material.
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Recitation questions # 02 & # 03
structure
a)
b)
Which, increase
or decrease?
function
How do
you know?
c)
Parts to total?
d)
Two feedbacks and
an absolute
requirement?
The “circle” as a way of thinking
An excellent way to pick-up “structure and functions” to answer
recitation questions is study classic experiments / approaches,
as those in the lab computer simulations course (1-credit). !
!
Lab simulations not only focus your thoughts on specific and
important aspects of material presented in lectures, but also
provide summaries, experiments, and tests that will help you
review the lecture / recitation and lab courses material. !
!
Finally, lab periods not only allow further discussion of each
recitation answers for the lecture / recitation course as well as
any lecture topic in doubt, but they also provide you with extra
time for answering all your tests, since they use two adjacent
periods on Wednesdays, when all tests are scheduled.!
If you can not write an idea into a single sentence,!
you probably have not yet understood the material.
6
Virtual Lab # 02
06
The goal of this virtual lab session is to
review pre-requisite material for the
integrative physiology course. This info
has been referred to in lectures and is
presented here in computer simulations
related to osmosis, diffusion, metabolism,
& transport across biological membranes.
Physiology Interactive Lab Simulation
(PhILS)
Students should review all simulated experimental labs
available in the software package used for this course.
Students should perform the different labs following the
instructions and time schedule defined for each lab.
Physiology Interactive Lab Simulations
(PhILS version 2.0 has fewer labs than PhILS version 3.0)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Frog heart function
18 thermal and chemical effects
19 refractory period of the heart
20 Starling’s law of the heart
21 heart block
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
ECG and heart function
22 ECG and exercise
23 the meaning of heart sounds
24 ECG and finger pulse
25 electrical axis of the heart
26 ECG and heart block
27 abnormal ECG
Resting potential
08 resting potential and external K
09 resting potential and external Na
Circulation
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Blood
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
28 cooling and peripheral blood flow
29 blood pressure and gravity
30 blood pressure and body position
31 pH and Hb - O2 binding
32 DPG and Hb - O2 binding
Respiration
33 altering body position
34 altering airway volume
35 exercise - induced changes
36 deep breathing and cardiac function
Digestion
37 Glucose transport
7
PhILS - Osmosis and Diffusion
(varying ECF concentration)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Use a virtual pipette to dispense a blood sample into a tube
2)  Use a virtual spectrophotometer to measure color of blood
3)  Show that RBCs take up water and burst in dilute NaCl solution
4)  Show that water leaves RBC and it shrives in high NaCl solution
5)  Relate concentration of incubating solution to RBC integrity
6)  Report the range of NaCl solutions isotonic to RBC
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Osmosis and Diffusion
(varying ECF concentration)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
Most cell membranes have very few open Na channels, so when they
are placed in solutions of NaCl, very few Na ions move across the
membrane. If the fluid inside the cell has a different concentration
from NaCl solution outside, water will move across the membrane.
If the NaCl solution is isotonic, there will be not net flux of water
across the membrane and cell integrity will be maintained.
Physiological saline is a 0.9% solution of NaCl or about 155 mM. This
lab shows that the integrity of sheep blood is maintained in this
solution.
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PhILS - Metabolism
(size and basal metabolic rate)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Perform least square linear regression and fit data to the formula
y=mx + b to calculate the rate of oxygen consumption
2)  Examine the effect of the weight on the metabolic rate of animals
of different sizes
3)  Demonstrate that the rate of O2 consumption is directly
proportional to the weight of the animal
4)  Demonstrate that the rate of O2 consumption by a cell is
indirectly proportional to the weight of an animal
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Metabolism
(size and basal metabolic rate)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
Smaller animals have fewer cells and consume less O2 than
larger animals. However, not all cells have the same metabolic
rate, and this lab shows that the cell from a smaller animal
consume more O2.
Rubner explained this observation in terms of surface area to
volume ratios and showed that one square inch of surface area
(skin) from a small animal is “served” by fewer cells. If cells
generate enough heat to maintain body temperature and
compensate for the heat lost across the skin, clearly the fewer
cells in smaller animals must work harder and consume more
O2 , than cells in larger animals.
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PhILS - Metabolism
(cyanide and electron transfer)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Use a virtual pipette to dispense a blood sample into a tube
2)  Use a virtual spectrophotometer to measure color of solutions
3)  Perform least square linear regression and fit data to the formula
y = mx + b to calculete the rate of color change
4)  Show that cyanide interferes with the electron transport sytem
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Metabolism
(cyanide and electron transfer)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
Cyanide poison the electron transport system and blocks ATP
production in the mitochondria. This concepts was demonstrated in
this experiment by using a dye that competed with the electron
transport system for electrons but was not poisoned by cyanide.
The rate of dye color changed increased in the presence of cyanide
because the breakdown of succinic acid made more electrons
available to the dye: no electrons went to the poisoned transport
system.
10
PhILS - Digestion
(glucose transport)
At the completion of this simulation you will be able to:
1)  Describe the steps involved in exposing and isolating a length of
small intestine from a small mammal
2)  Use a virtual pipette to dispense solutions into a tube
3)  Use a virtual spectrophotometer to measure a solution color
4)  Explain the role of the Na / K ATPase pump in the transport of
glucose across the wall of the small intestine.
Frog heart function
18 thermal and chemical effects
19 refractory period of the heart
20 Starling’s law of the heart
21 heart block
ECG and heart function
22 ECG and exercise
23 the meaning of heart sounds
24 ECG and finger pulse
25 electrical axis of the heart
26 ECG and heart block
27 abnormal ECG
Circulation
28 cooling and peripheral blood flow
29 blood pressure and gravity
30 blood pressure and body position
Blood
31 pH and Hb - O2 binding
32 DPG and Hb - O2 binding
Respiration
33 altering body position
34 altering airway volume
35 exercise - induced changes
36 deep breathing and cardiac function
Digestion
37 Glucose transport
PhILS - Digestion
(glucose transport)
Frog heart function
18 thermal and chemical effects
19 refractory period of the heart
20 Starling’s law of the heart
21 heart block
ECG and heart function
22 ECG and exercise
23 the meaning of heart sounds
24 ECG and finger pulse
25 electrical axis of the heart
26 ECG and heart block
27 abnormal ECG
Circulation
28 cooling and peripheral blood flow
29 blood pressure and gravity
30 blood pressure and body position
The Na / K ATPase pump and Na / glucose transporter molecules are
required for glucose transportation across the wall of the small
intestine. The pump is located in the baso-lateral membranes of the
absorptive cells and creates a creates a low concentration of Na
Blood
31 pH and Hb - O2 binding
inside the cell. A co-transporter molecule allows Na to enter down
32 DPG and Hb - O2 binding
this concentration gradient from the lumen of the gut. Glucose is
Respiration
transported into the cell with Na and then out of the cell by facilitated
33 altering body position
diffusion through the baso-lateral membrane, into the intertitial fluid.
34 altering airway volume
This exercise demonstrated the uptake of glucose across the gut
35 exercise - induced changes
36 deep breathing and cardiac functionwall and also showed that ouabain, a Na / KATPase pump poison,
halts glucose uptake.
Digestion
37 Glucose transport
11
Virtual Lab # 03
06
The goal of this virtual lab session is to
review material for the integrative
physiology course. This info has been
referred to in lectures and is presented
here in computer simulations related to
endocrine communication, neuronal
communication, and muscle function.
Physiology Interactive Lab Simulation
(PhILS)
Students should review all simulated experimental labs
available in the software package used for this course.
Students should perform the different labs following the
instructions and time schedule defined for each lab.
Physiology Interactive Lab Simulations
(PhILS version 2.0 has fewer labs than PhILS version 3.0)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Frog heart function
18 thermal and chemical effects
19 refractory period of the heart
20 Starling’s law of the heart
21 heart block
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
ECG and heart function
22 ECG and exercise
23 the meaning of heart sounds
24 ECG and finger pulse
25 electrical axis of the heart
26 ECG and heart block
27 abnormal ECG
Resting potential
08 resting potential and external K
09 resting potential and external Na
Circulation
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Blood
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
28 cooling and peripheral blood flow
29 blood pressure and gravity
30 blood pressure and body position
31 pH and Hb - O2 binding
32 DPG and Hb - O2 binding
Respiration
33 altering body position
34 altering airway volume
35 exercise - induced changes
36 deep breathing and cardiac function
Digestion
37 Glucose transport
12
PhILS - Skeletal Muscle
(resting potential and external K)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe the steps involved in dissecting tha fast extensor
muscle in the cryfish tail
2)  Use a virtual instruments to record and measure potentials from
muscle fibers
3)  Recognize that increasing the level of K in the Ringer solution
bathing the muscle depolarize the muscle
4)  Employ least square linear regression to illustrate the semi-log
relationship between ECF-K concentration and membrane
potential.
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(resting potential and external K)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
The level of K is much higher inside than outside the cell. The ECF-K
in cryfish Ringer is 5 Eq/L, and the membrane potential recorded in
this lab is around -65 mV. Increasing the concentration of K in the
Ringer solution depolarized the cell so that a concentration of 20
mEq/L gave membrane potential values or around -50 mV. If the
threshold for action potential production is 15 mV about resting
level, changing the ECF-K level from 5 to 20 mEq/L will depolarize
the membrane above threshold and will induce spontaneous muscle
contraction.
13
PhILS - Skeletal Muscle
(resting potential and external Na)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe the steps involved in dissecting tha fast extensor
muscle in the cryfish tail
2)  Use a virtual instruments to record and measure potentials from
muscle fibers
3)  Recognize that increasing the level of Na in the Ringer solution
bathing the muscle depolarize the muscle
4)  Employ least square linear regression to illustrate the semi-log
relationship between ECF-Na concentration and membrane
potential.
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(resting potential and external Na)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
The level of Na is much higher in the ECF than in the ICF. This means
that the membrane potential and the concentration gradient both
draw Na into the cell. This simulation shows that decreasing the
concentration gradient by decreasing Na outside the cell hyperpolarize the cell membrane. However, a 10-fold change in the Na
level produces a change in membrane potential by only 8 mV. This
small effect in membrane potential indicates that small fluctuations
in ECF-Na have a minimal effect on the membrane potential of the
cells in the body.
14
PhILS - Action Potentials
(the compound action potential)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting sciatic nerve from a frog
2)  Connect electrodes at different locations along the nerve
3)  Use a virtual Data Acquisition Unit to apply electrical shocks and
display evoked compound action potentials (CAPs) as a line
tracing on the screen
4)  Show threshold by rising the shock voltage and evoking a CAP
5)  Show recruitment by relating shock voltage to CAP amplitude
6)  Measure the CAP amplitude and illustrate data graphically and
by superimposing the tracing on the screen
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Action Potentials
(the compound action potential)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
In this lab a mild shock brought a few axons to threshold and elicited
a small CAP. Increasing shock voltage recruited more axons into the
response until all axons in the sciatic nerve were above threshold
and produced an action potential (AP). It is significant that the CAP
is produced by an AP in a population of axons with the same
conduction velocity. Imagine if these were motor axons supplying
fibers in the same muscle. AP produced simultaneously in several
motor neurons would travel down the axons at the same speed and
arrive at the neuromuscular junction at the same time. Clearly this
characteristic allows the CNS to control the timing of muscle fiber
activation and contraction.
15
PhILS - Action Potentials
(conduction velocity and temperature)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting sciatic nerve from a frog
2)  Connect electrodes at different locations along the nerve
3)  Use a virtual Data Acquisition Unit to apply electrical shocks and
display evoked compound action potentials (CAPs) as a line
tracing on the screen
4)  Measure the time difference between CAPs conducted along
different lengths of nerve and calculate the velocity of AP
conduction along axons in the sciatic nerve.
5)  Describe the effect of cooling on AP conduction velocity.
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Action Potentials
(conduction velocity and temperature)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
The sciatic nerve contains populations of axons that conduct AP at
similar conduction velocities. This lab studied a population of axons
that conduct AP at a velocity of around 30 m/s at room temperature.
Cooling the nerve to 10°C slowed the conduction velocity to about
20 m/sec. This observation is explained in terms of the effect of
cooling on the function of proteins, like enzymes and channels.
Decreasing the t°C slows the rate of channel opening and closing
thereby increasing the duration of the AP and slowing the speed of
the conduction along the axon.
16
PhILS - Action Potentials
(refractory period)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting sciatic nerve from a frog
2)  Connect electrodes at different locations along the nerve
3)  Use a virtual Data Acquisition Unit to apply pairs of electrical
shocks and display 2 CAPs) as a line tracing on the screen
4)  Measure the amplitude of the 2 CAPs and demonstrate how
amplitude of the second CAP changes with time. Use the data to
determine the relative refractory period.
5)  Explain the decline in the amplitude of the second CAP in terms
of smaller AP and sub-threshold stimulation of axons.
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Action Potentials
(refractory period)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
An AP is followed by a brief refractory period. During the absolute
refractory period the voltage-gated Na channels are inactivated, and
in the closed state membrane depolarization does not open these
channels so an AP can not be produced. During the relative
refractory period, many voltage-gated K channels are open. As a
result, the threshold for CAP production is increased and the
amplitude of any evoked CAP is reduced. In this lab, the second
CAP was smaller during the relative refractory period because some
axons were not firing (the shock was sub-threshold) and those that
fired produced a smaller CAP.
17
PhILS - Action Potentials
(measuring ion currents)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe the theory underlying the use of voltage clamp with a
squid giant axon
2)  Use a virtual DAT and voltage clamp to record ion currents when
the axon membrane is clamped to a given voltage
3)  Perfuse tetrodotoxin (TTX) onto the preparation to block
membrane voltage-gated Na channels and observe voltagegated K current.
4)  Perfuse tetraethylammonium (TEA) onto the preparation to block
membrane voltage-gated K channels and observe the voltagegated Na current.
TEA
TTX
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Action Potentials
(measuring ion currents)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
control
control
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
TEA
TTX
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
18
PhILS - Action Potentials
(measuring ion currents)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Depolarization of the axon membrane to a level above
threshold for action potential (AP) production opens
voltage-gated Na channels and voltage-gated K
channels.
TTX blocks voltage-gated Na channels and abolishes the
early inward current. TEA blocks voltage-gated K
channels and abolishes the late outward current.
These observations show that the action potential is
produced by a sequential opening and closing of Na and
K channels, and demonstrates that the two ions travel
across the membrane through their own channels.
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Synaptic Potential
(facilitation and depression)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting the extensor muscle
in the cryfish tail
2)  Use virtual instruments to record and measure potentials
from muscle fibers
3)  Apply pairs of shocks to a nerve to produce two APs in a
motor nerve and two EPSP in the muscle fiber
4)  Measure the amplitude of the two EPSPs
5)  Show relationship between the amplitudes of the two EPSPs
6)  Explain the data in terms of the release of synaptic vesicles
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
19
PhILS - Synaptic Potential
(facilitation and depression)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Synaptic Potential
(facilitation and depression)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
When pairs of EPSPs are produced in quick successions
there is an inverse relationship between the amplitudes
of the two responses.
During facilitation the second EPSP is larger than the
first and this can be explained by a slow removal of Ca
from the terminal. The second action potential enters the
terminal while Ca remains from the first, with the result
that the Ca concentration is higher, so more vesicles are
released and a a larger (second) EPSP is recorded.
During depression, the first action potential releases a
huge number of synaptic vesicles and creates a larger
EPSP. There are fewer vesicles available for release of
the second response so that the second EPSP is small.
Endocrine function
17 thyroid gland and metabolic rate
20
PhILS - Synaptic Potential
(temporal summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting the extensor muscle
in the cryfish tail
2)  Use virtual instruments to record and measure potentials
from muscle fibers
3)  Apply pairs of shocks to a motor axon to produce two
EPSPs in the muscle fiber
4)  Change time interval between the shocks and measure the
effect on the amount of muscle membrane depolarization
5)  Explain how decreasing the time interval increases temporal
summation and increases membrane depolarization
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Synaptic Potential
(temporal summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
21
PhILS - Synaptic Potential
(temporal summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
The time course of the action potential is usually shorter
than the EPSP it evokes in the postsynaptic cell. A high
frequency dicsharge of action potentials could produce
EPSPs such that the membrane potential would not
return to resting levels between responses. Thus EPSPs
could “piggy back” on one another, creating a phenomenon called temporal summation.
In this lab, temporal summation was recorded at a
response interval less than 140 ms and the total amount
of membrane depolarization created by the two EPSPs
was greater than that produced by a single response.
A pair of EPSP at an interval of 40 ms depolarized the
membrane above threshold for action potential
production.
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Synaptic Potential
(spatial summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in dissecting the extensor muscle
in the cryfish tail
2)  Use virtual instruments to record and measure potentials
from muscle fibers
3)  Apply pairs of shocks to a nerve to produce an AP in a
motor axon and an EPSPs in the muscle fiber
4)  Increase shock voltage to stimulate additional motor axons
and increase EPSP amplitude
5)  Measure the amplitude of EPSPs and demonstrate that
sufficient membrane depolarization will evoke an AP
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
22
PhILS - Synaptic Potential
(spatial summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Synaptic Potential
(spatial summation of EPSPs)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
In many chemical synapses, single EPSPs depolarize the
membrane to a level that is sub-threshold for an action
potential production. One strategy to produce spikes in
such a situation is a phenomenon called “spatial
summation”. EPSPs are created by several synaptic
neurons at the same time, so that the EPSPs add
together and bring the membrane potential above
threshold.
In this lab, brief electrical shocks were applied to a nerve
containing four motor axons. Activation of an axon to a
muscle fiber was seen when an EPSP either appeared or
increased in amplitude. Synchronous activity in several
motor axons was necessary to produce an action
potential in the muscle fibers.
Endocrine function
17 thyroid gland and metabolic rate
23
PhILS - Endocrine Function
(thyroid gland and metabolic rate)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Perform least square linear regression and fit data to the
formula y = mx + b to calculate the rate of O2 consumption
2)  Explain how cooling affects the rate of O2 consumption of
mice with a normal and with dysfunctional thyroid gland
3)  Explain why the rate of O2 consumption increases in the
cold
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Endocrine Function
(thyroid gland and metabolic rate)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
Stress increases the metabolic rate of most cells in the body by
increasing the level of thyroid hormones (T3-T4) in the blood. This
lab examines the effect of cooling on the rate of O2 consumption of
female white mice, on a normal diet and on a diet containing propylthiouracil (PTU), an additive that reversibly abolish thyroid function.
Cooling increases metabolic rate but at a certain temperature the
metabolic rate increases at a much faster rate as the animals begin
to shiver. Animals on the PTU diet shiver at a much warmer temperature presumably because diminished thyroid function is insufficient
to generate heat to maintain body temperature.
24
PhILS - Skeletal Muscle
(stimulus dependent force generation)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
At the completion of this simulation you will be able to:
1)  Describe steps involved in exposing a frog calf muscle
2)  Apply electrical shocks directly to exposed muscle and
correlate its contraction with a deflection of a line tracing
3)  Demonstrate threshold by increasing the shock voltage and
observing the appearance of a muscle contraction
4)  Illustrate recruitment by correlating shock voltage with
contraction amplitude
5)  Measure amplitude of each line tracing deflection and show
data graphically by overlying line tracing on the screen
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(stimulus dependent force generation)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
An action potential in a motor neuron produces an AP in and a
contraction of the muscle fibers it supplies. Motor neurons can be
activated by Aps in upper motor neurons whose axons run down
descending tracts in the spinal cord. Selective activation of motor
neurons allows the brain to control the number of active motor
neuron units, and thereby control the amount of muscle contraction.
25
PhILS - Skeletal Muscle
(length / tension curves)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
At the completion of this simulation you will be able to:
1)  Describe steps involved in exposing a frog calf muscle
2)  Use virtual instruments to apply electrical shocks directly to
the exposed muscle and display the amount of tension
produced by a contraction, as a line tracing on the screen
3)  Measure the amount of tension produced by a muscle held
at different lengths
4)  Demonstrate the relationship between resting length and the
amount of tension created by a single contraction
5)  Illustrate the relationship graphically and by superimposing
successive line tracings
6)  Explain the data in terms of cross-bridge number at different
sarcomers lengths
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(length / tension curves)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
The amount of tension produced by a contraction depends upon the
muscle length. If the muscle is too short, the thin filament overlap
one another and the thick filaments become compressed. At this
short length few cross-bridges can be made so little tension is
produced. At resting length there is optimum overlap between thick
and thin filaments so a maximum of cross-bridges can be formed
and a maximum of tension can be achieved. As the muscle is further
lengthened, the amount of overlap decreases and the number of
cross-bridges and tension declines.
26
PhILS - Skeletal Muscle
(summation / tetanus)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Describe steps involved in exposing a frog calf muscle
2)  Use virtual instruments to apply electrical shocks directly to
the exposed muscle and display evoked contraction, as a
deflection of a line tracing on the screen
3)  Measure the amount of tension produced by a muscle held
at different lengths
4)  Change the shock frequency and relate changes in the line
tracing to summation, incomplete and complete tetanus
5)  Determine the time taken for the sarcoplasmic reticulum to
take up calcium after a contraction
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(summation / tetanus)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
The frequency of muscle stimulation affects the evoked movement.
Low-frequency stimulation, produces single-twitches as seen when
your eyes twitch. Increasing stimulus frequency elicit summation
where the muscle fails to relax between contractions, and then
tetanus, where prolonged elevated Ca in cytoplasm increases
muscle tension. During normal limb movement, motor neurons
produce AP at a sufficiently high frequency to elicit complete
tetanus. This evokes a smooth contraction, not the shaking effect
elicited by incomplete tetanus. Under this conditions force produced
by muscle is controlled by changing number and type of contracting
muscle fibers.
27
PhILS - Skeletal Muscle
(EMG and twitch amplitude)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
At the completion of this simulation you will be able to:
1)  Demonstrate that patch electrodes placed on the skin can be
used to record electrical activity from contracting muscles
2)  Use virtual recording instruments to display the pressure
produced by a volunteer making a fist and the electrical
recording (EMG) produced by the contracting muscles
3)  Correlate the amount of tension produced by a single
muscle contraction of different intensities with the
amplitude of the EMG signalson the screen
4)  Relate the data to the recruitment of different number of
muscle fibers in the contraction response
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
PhILS - Skeletal Muscle
(EMG and twitch amplitude)
Osmosis and diffusion
01 varying ECF concentration
Metabolism
02 size and basal metabolic rate
03 cyanide and electron transfer
Skeletal muscle function
04 stimulus dependent force generation
05 the length - tension relationship
06 principles of summation and tetanus
07 EMG and twitch amplitude
Resting potential
08 resting potential and external K
09 resting potential and external Na
Action potentials
10 the compound action potential
11 conduction velocity and temperature
12 refractory period
13 measuring ion currents
Synaptic potential
14 facilitation and depression
15 temporal summation of EPSPs
16 spatial summation of EPSPs
Endocrine function
17 thyroid gland and metabolic rate
An AP in a motor neuron produces an AP in and a contraction in the
muscle fibers it supplies. Motor neurons can be activated by AP in
upper motor neurons, whose axons run down descending tracts in
the spinal cord. Selective activation of motor neurons allows the
brain to control the number of active motor units, and thereby
control the amout of muscle contraction. This concept was
illustrated in this lab as the amplitude of the electromyogram (EMG) ,
which indicates the number of muscle fibers contracting, was
correlated with amounts of tension produced by the muscle.
28