What are the 3 primary mechanisms of ion transport through a membrane?
Simple diffusion, facilitated diffusion, & active transport
What are the 2 primary forces that affect ion movement through a membrane?
concentration gradient,
potential difference
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What are the 3 primary mechanisms of ion transport through a membrane? -
ANSWER- Simple diffusion, facilitated diffusion, & active transport
What are the 2 primary forces that affect ion movement through a membrane? -
ANSWER- concentration gradient,
potential difference
If mutation in the sodium/potassium pump resulted in relatively less potassium
being moved across the nerve membrane, what would happen to the membrane
potential and excitability of the nerve? Explain. - ANSWER- The sodium-
potassium pump maintains the concentration balance, maintains negative voltage
inside the cell, and maintains the cell volume. In nerve cells, the sodium-
potassium pump creates gradients of both sodium and potassium ions. These
gradients are then used to transmit electrical signals that travel along nerves.
Without this process, your nerve cells wouldn't function. The sodium-potassium
pump sets the membrane potential of the neuron by keeping the concentrations
of Na+ and K+ at constant disequilibrium. If less potassium was being moved
across the nerve membrane, the concentration of potassium would be less on the
inside while the concentration of sodium would continue to increase on the
outside. There would be little potassium and sodium on the inside, but large
concentrations of both on the outside which would throw off the membrane
potential.
*Increase in hyperpolarizability= decrease in membrane potential = decrease in
exciteability
Draw the motor unit and label important components. Identify the range of
important dimensions. - ANSWER- (Drawn on notecard)
, The motor unit is composed of the neuron cell body located in the spinal cord,
the axon running from the spinal cord to the muscle, and all of the muscles fibers
innervated by that axon. It is the modular unit of control.
Plot a "standard" nerve action potential resulting from a depolarization. Label the
axes and show unit magnitudes for the axes. Describe what happens in a voltage
gated Na ion channel and how it relates to your figure. - ANSWER- (Drawn on
notecard)
In a voltage gated Na ion channel there are 2 gates that function independently.
One is an activation gate that opens on stimulation and lets sodium ions into the
cell. The other is an inactivation gate that closes to stop the entry of sodium ions.
At the resting potential, voltage-gated Na+ channels are closed. When the
membrane is depolarized, conformational changes open the voltage-gated
channel.
Type of transport: Facilitated transport
What else does this: K+ channels
What else drives this type of transport: Concentration gradient
If you are investigating a new reflex found in cheetahs during maximal running,
what size motor units would you expect to be involved? Why? - ANSWER- You
would expect to find fast motor units. Fast motor units are fast and fatigable.
They have anaerobic metabolism and are used for mid to high force, short
duration forces. You would expect them to be large. The larger units produce a lot
of force, they react quickly, but they are easily fatigued. When a lot of force or
speed is required, the larger and faster motor units will be used.
Draw a length-tension curve for your biceps muscle. Show 3 relevant spatial
relationships for actin/myosin fibers and identify the corresponding sections of
the curve. - ANSWER- (Drawn on notecard)
Assume the maximal excursion of a single sarcomere is 2.0 microns and the
force generated by a single sarcomere is 1 force unit (fun). What is the minimum
number of sarcomeres required to create a muscle that can both have an
excursion of 0.4 mm and generate 25 fun? Explain or show your work. - ANSWER-
(Drawn on notecard)
Draw a figure showing a muscle lifting a weight off the ground. Include important
information.
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