Lab Exam Flashcards
Diffusion is a _____ process dependent on a solute ______.
Diffusion is a passive process dependent on a solute concentration gradient.
Molecular weight is ______ to molecular size
Proportional becuase molecular weight is grams per mole and a mole is 6.626x10^23
How does solute concentration affect the rate of diffusion?
Higher concentration gradient the higher the rate
How does molecular weight affect the rate of diffusion?
Smaller molecules has a higher rate of diffusion because it has a higher rate of velocity.
KE=1/2mV^2
If KE is constant a lower mass will have a larger velocity.
What is the driving force behind diffusion?
Kinetic Energy of the colliding particles
What does MWCO stand for? what does a large MWCO mean?
Molecular Weight Cut Off. a large MWCO means that it is a large pore.
fastest to slowest diffusion of urea glucose albumin NaCL
NaCl> urea> glucose> NaCl
Why do some solutes require a carries protein to pass through the membrane?
They are too big or a lipid insoluble (hydrophilic / polar)
whats the difference in facilitated diffusion vs. smile diffusion?
Facilitated requires a carrier protein while simple diffusion is just diffusion through the membranes it self
How does the number of protein carriers affect the rate of diffusion?
The more protein carriers the faster rate of diffusion. # of transporters is the rate limiting factor!
Explain what happens when protein carriers are saturated?
When the protein carriers are saturated all of the channels are being used so this is the max rate of diffusion. A low number of protein carriers will take it longer to reach equilibrium.
What is osmosis?
Osmosis is the diffusion if H20
How does water diffuse in terms of concentration of water?
Water travels from a higher concentration of water to a lower concentration of water. In other words is travels from low solute to high solute concentration
What is and what creates osmotic pressures?
It is the pressure that opposes the flow of water. It is created by the non diffusing particle. The larger concentration of non diffusing particles the smaller the osmotic force because it wants water to flow towards the system
What determines what passes through during filtration?
the size of the molecules
What type of pressure highly effects filtration rate?
Hydrostatic pressure
What type of physiology changes will affect the hydrostatic pressure?
Increase in BP or afferent capillary vasodilation will increase the hydrostatic pressure = increase filtration rate
Why does filtration rate increase with an increase of hydrostatic pressure but the filtrate concentration doesn’t?
Both water and solute are traveling at a higher rate so the concentration would still be the same.
Why is the Na+/K+ ATPase an active transporter?
It is an active transport because it uses ATP to move Na+and K+ against the concentration gradient
What is the resting membrane potential and what affects it?
It the voltage difference between the inside and the outside of the cell. It is influenced by the permeability and the concentration difference between the inside and the outside
how does the cell body and axon differ in terms of resting membrane potential
it is the same
Why doesn’t Na+ change the resting membrane potential as much K+
K+ is more permeable to the membrane therefor changes the resting potential more.
What affects the conductance of K+ and Na+
Conductance is simply the movement of K+ and Na+ across the membrane. It is affected by the open channels for the ion and the concentration gradient.
Explain how the the conductance of Na+ and K+ changes throughout an AP
@ rest K+ is more permeable
when depolarization occurs Na+ channels open, increasing the conductance of Na+ ions
AP are initiated @
Axon hillock, trigger zone
TTX vs Lidocaine
TTX blocks irreversibly and lidocaine blocks Na+ reversibly over time.
Lidocaine can block the AP to nocireceptors = no pain
What is inactivation of Na+ channels
Inactivation occurs at the top of AP and will cause absolute refractory period where a new AP is unable to propagte
What is the difference between absolute refractory period and relative refractory period
Absolute refractory period is due to inactivated Na+ channels so no AP propagation. In relative refractory some of the Na+ channels already “closed” because of repolarization so another AP is possible with a greater stimuli
what happens to the threshold when the intervals between stimuli is decreased?
The threshold becomes higher bc it takes a higher stimuli to propagate an AP bc there is less Na+ channels able to open and a lot of K+channels are open to depolarize the cell
What affects the conduction velocity of a neuron?
The mylenation and axon diameter
conduction is measure in meters/second
Describe the difference between A, B, C fibers
A is the fastest conductor bc it is the largest in diameter and most mylenated
whats inside the neurotransmitter vesicle and how is it released?
Its release is dependent on an action potential large enough to open up the Ca2+ ion channels. The influx of Ca2+ ions will release the vesicle of ACH and ACH will bind to open Na+ channels
How does the neurotransmitter reach the ion channels it will bind to?
Diffusion
How does having a small amount of Ca2+ extracellularly / Mg2+ extracellularly / normal ECF Ca2+ differ?
Mg2+ blocks Ca2+ channels so there will be no ACH release
Low ca2+ going in will result in less vesicles of ACH released
Under normal ECF Ca2+, whats the difference between a small stimuli and large stimuli?
A large stimuli will cause more release of ACH (through more exocytosis of vesicles, the vesicles contain the same amount of ACH every time)
Describe why Mg2+ blocks the ca2+ channels
Mg2+ has the same charge as Ca2+ so it is attracted to the same channel but Mg2+ is larger than Ca2+ so it ends up clogging the channel
Explain how a synaptic potential can be “graded”
If there is a a larger number of presynaptic release of ACH vesicles then there is an AP larger in frequency being transmitted into the new axon
Interneurons respond to neurotransmitter stimuli with a
Graded potential
interneurons are receptors?
then the receptors will trigger another neuron and this neuron will propagate an AP?
Describe the activity between a sensory neuron to a receptor neuron and onto an efferent nueron
The sensory neuron will release Ach vesicles onto the receptor neuron which will propagate a graded AP. The higher the stimuli the more ACH releases by sensory the larger the graded potential which will send a higher frequency of AP onto the next neuron
How does volume and pressures change in respiration
Inspiration: diaphragm and external intercostals contract which causes volume to increase so pressure decreases
Expiration: diaphragm and external intercostals relax to decrease the volume so pressure increases