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Lecture 1

CAS BI 315 Lecture Notes - Lecture 1: Lipid Bilayer, Cardiac Muscle Cell, Electrical Polarity

Course Code
CAS BI 315
Elizabeth Co

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iWorx unit: four channel recording instrument that is used to record data to obtain pulse
rate (lab #1), action potentials of skeletal muscles (labs #4 & #5), waves of depolarization
and repolarization of cardiac muscle (lab #7) as well as the volume of respired air (lab
Labscribe 2 (LS2): software used to record data that permits electrical signals to be
displayed on the computer screen in a way that allows you to adjust and analyze the
image as needed.
Main window
oUp/Down zig zag icon
oLets you return to the main menu
oMagnifying glass icon
oBrings up new window where you can analyze data
oPencil icon
oBrings up marks dialogue box with a list of all the marks made; to find a mark
simply select it from the list
Mark Arrow
oShortcut to edit your marks or quickly scroll to your makes
Mark Box
oDelete mark, rename mark or jump to mark
Half Display
oSingle mountain icon
oDisplay time is halved thus time between divisions decreases
Double Display
oDouble mountain icon
oDisplay time is doubled thus time between divisions increases
Double Cursor
oTwo lines through grid
oTwo blue cursor will appear, drag these cursors to where you want the marks to
appear; left is dominant
Single Cursor
oOne line through grid
oOne blue cursor will appear, drag to a specific selection of data and type
oMeasures the time between events

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oWhen you’re ready to start recoding data; while recording changes to a “Stop”
oBest way to view data clearly; done during and after recording
Clean recordings: Data should look clear and waves should be separated
Noisy recordings: Waves should be closer together, all over the place and messy.
HR= (1 beat/period in sec) x 60 sec/min = _______ beats/min
Reflection Questions:
Reflection Question #1: For what reasons would you need to enter marks in LS2 during
or after data collection? (Page 7): B. To identify data collected from different individuals
Reflection Question #2 (Page 11): Fill in the blank: To “optimize the recording,” you
need to use the Zoom Between Cursors icon to highlight the region of data you will
analyze and the Analysis icon to fit the amplitude of the channel’s signal to the viewing
Post-Lab Questions:
Purpose Topic #1: The purpose of this lab was to become familiar with LabScribe2 and
to witness how electrical signals are displayed on the computer screen in order to make
changes and analyze data.
Several factors determine the rate of diffusion of a solute across a membrane
oSize, lipid solubility, mechanism of transport
Three mechanisms of transport
oSimple diffusion through lipid bilayer: small and large non-polar molecules down
their concentration gradients
O2, CO2
oSimple diffusion through protein channels: ions, H2O, and some polar molecules
down their concentration gradients
Na+, K+, Cl-
oMediated transport: ions and some large polar molecules down, OR against, their
concentration gradients
The greater the number of polar groups that form hydrogen bonds, greater hold the H2O
has on the solute, thus increasing its H2O solubility and decreasing the probability of its
entry into the lipid bilayer
Non-penetrating Solute: Don’t diffuse through cell membrane without an open channel or
mediated transport
Penetrating Solute: Solutes either readily diffuse through the membrane because of their
solubility in the lipid bilayer or cross the membrane by a mediated transport step that is
always active in the membrane.

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oUrea, H2O and glucose
Aquaporins: Water channel through the cells
Hyperosmotic: Greater concentration of solute in solution than within the cell
Osmolarity: A solution is the concentration of total solute particles, regardless if they are
penetrating or non-penetrating solutes
Tonicity: Measure of osmotic pressure caused by non-penetrating solutes
Hypertonic: Concentration of non-penetration solutes outside is less than the
concentration inside the cell
Isotonic: Concentration of non-penetration solutes outside is the same than the
concentration inside the cell
Hemolysis: When H2O moves into a cell, intracellular volume is increases, RBCs swell
enough and they will burst
oCell fragments will settle at the bottom of the test tube
oIntracellular and extracellular solutions will be transparent
oTransmission of light increases as the light is no longer absorbed
Crenate: When H2O moves out a cell, intracellular volume is decreases, RBCs shrink
% Transmission can be used to determine the tonicity of various solution
Rate of hemolysis will be used as an index of the rate of diffusion when RBCs are placed
in hyperosmotic solutions of penetrating solutes in the absence of non-penetrating solutes
To set transmittance: Set wavelength to 600 nm, set mode to transmittance, without a
tube in the machine turn left knob until it reads 0%. Insert test #1 and turn right knob
until it reads 100%. Repeat until stable
To measure transmittance: wipe tube with Kimwipe, insert tube into chamber, record
Reflection Questions:
Reflection Question #1: Why does urea need to use aquaporins to easily pass through the
cell membrane? (Page 18) D) it is relatively small and polar
Reflection Question #2: True OR False: In both hypo osmotic and hypotonic solutions,
hemolysis will occur. (Page 19) TRUE: In both hypo osmotic and hypotonic solutions,
hemolysis will occur.
Reflection Question #3: If a test tube has high turbidity, the fluid in the test tube is
(CLOUDY). If the test tube has low turbidity, we can infer that the cells have
(HEMOLYZED). (Page 19)
Reflection Question #4: Why is NaCl considered a non-penetrating solute in RBCs?
(Page 21) C) RBCs lack gated channels
Post-Lab Questions:
Purpose Topic #1- Effects of Non-Penetrating Solutes on H2O Movement: The purpose
of this topic was to prepare the solutions in the test tubes and observe the effects of non-
permeable solutes (NaCl) on the movement o H2O. This was observed by using a
spectrophotometer in order to record the amount of light transmitted through the
solution. Depending on our results, the conditions of the cells in each tube were labeled
as crenated, hemolyzed, or unchanged.
Purpose Topic #2- Relative Permeability of Different Solutes: The purpose of this topic
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