PHYS20008 membrane potential question

[MelonBar]

thanks, good point about the acetylcholine. for the first question, I'm thinking the vagus nerve has to do with gastric motility, so severing that would mean no motility in the lower GI tract.

the other options are, stop salivating at the sight of food (incorrect I believe, cranial nerve does this), increased production of gastric juices normally associated with eating would be delayed until food reached the stomach, the increase of chyme from the stomach into the small intestine would become impaired, and all smooth muscle sphincters would lock in the closed position - what do we think?

ehhh the ENS is still in tact, didn't consider that one

[LeviLamp]

Comparative Animal Physiology's theory component seems so much more straightforward than Human Phys, ahahahaha (though the four lab reports are a big pain). I actually think I'd appreciate it a lot more; we didn't cover any digestive physiology at all, other than a little bit of comparison between various animals and their digestion techniques also CHARLES

[hobbitle]

Obviously too late because the concept check has closed but might be worth a discussion anyway:

for the first question, I'm thinking the vagus nerve has to do with gastric motility, so severing that would mean no motility in the lower GI tract.

As you say below, the ENS is still in tact, so motility would continue presumably.

the other options are, stop salivating at the sight of food (incorrect I believe, cranial nerve does this),

Actually the "Vagus Nerve" slide says that the Vagus Nerve does trigger this kind of anticipatory response (long reflex).  what do you think?

increased production of gastric juices normally associated with eating would be delayed until food reached the stomach,

Yeah this would probably happen if vagus nerve was severed, as Vagus nerve stimulates acid secretion in anticipation of food entering stomach.

the increase of chyme from the stomach into the small intestine would become impaired,

Hmm sounds too far down the GI tract for the vague nerve to have effect, I think it works from the stomach and above?  Notes do say that the vagus nerve has an affect on the gastro-esophagael sphincter but the pyloric sphincter isn't mentioned.

and all smooth muscle sphincters would lock in the closed position - what do we think?

Nah don't think so............ as you say, ENS still in tact?

Hmm Digestive System is quite confusing!

[hobbitle]

Totes vasoconstricting the crap out of my sprained ankle with this ice pack.
But not too much you know because we don't want to disrupt the... physiology n stuff.

[hobbitle]

What happens if voltage gated Sodium channels can't open at all, is it possible to fire an AP at all, ever? Will APs be impossible?

[Shenz0r]

^I think it's impossible

[Starlight]

What happens if voltage gated Sodium channels can't open at all, is it possible to fire an AP at all, ever? Will APs be impossible?

^I think it's impossible

Agreed. The real stimulus for an AP is opening the VG sodium channels at threshold.

[hobbitle]

So I'm just turning this thread into a general PHYS20008 study thread.

I have a few questions where I'm not confident in my answers.  Can we discuss?

1) In which of the following scenarios would peripheral chemoreceptors most likely be dominant over central chemoreceptors in regulating ventilation?
A. When locked in a sealed environment
B. At high altitudes
C. During Exercise
D. At extremely low temperatures

2. How would removing inactivation gates from all Na+ Volatage Gated channels affect the MAXIMUM FREQUENCY at which a neurone can fire?
A. Increase frequency
B. Decrease frequency
C. No Change
D. Not enough information

3. How would blocking voltage-gated K+ channels affect the MAXIMUM FREQUENCY at which a neurone can fire?
A. Increase frequency
B. Decrease frequency
C. No Change
D. Not enough information

4.  What affect on the likelihood of the axon hillock reaching threshold potential would this have: Synchronising IPSPs arriving from different sources so they arrive at the same time.
A. More likely
B. Less likely
C. No difference
D. Not enough Information

5.  AP firing frequency is determined by an inward Na+/Ca2+ current called I Funny in which muscle cells? Cardiac auto rhythmic cells?

6.  EC coupling is dependant on Ca2+ binding to calmodulin in which muscle cells?  Smooth muscle?

7.  Which muscle cell type has no t-tubules? I have no idea - smooth muscle?

Do you all disagree or agree with my Bold answers?

My last question related to ventilation and I am having a TONNE of trouble getting my head around questions like the one I've attached. Does anyone have any ideas or good ways of visualising/conceptualising what happens? I seem to THINK I get it but then always seem to get the complete opposite answers.  Halp!

[Belgarion]

So I'm just turning this thread into a general PHYS20008 study thread.

I have a few questions where I'm not confident in my answers.  Can we discuss?

1) In which of the following scenarios would peripheral chemoreceptors most likely be dominant over central chemoreceptors in regulating ventilation?
A. When locked in a sealed environment
B. At high altitudes
C. During Exercise
D. At extremely low temperatures

2. How would removing inactivation gates from all Na+ Volatage Gated channels affect the MAXIMUM FREQUENCY at which a neurone can fire?
A. Increase frequency
B. Decrease frequency
C. No Change
D. Not enough information

3. How would blocking voltage-gated K+ channels affect the MAXIMUM FREQUENCY at which a neurone can fire?
A. Increase frequency
B. Decrease frequency
C. No Change
D. Not enough information

4.  What affect on the likelihood of the axon hillock reaching threshold potential would this have: Synchronising IPSPs arriving from different sources so they arrive at the same time.
A. More likely
B. Less likely
C. No difference
D. Not enough Information

5.  AP firing frequency is determined by an inward Na+/Ca2+ current called I Funny in which muscle cells? Cardiac auto rhythmic cells?

6.  EC coupling is dependant on Ca2+ binding to calmodulin in which muscle cells?  Smooth muscle?

7.  Which muscle cell type has no t-tubules? I have no idea - smooth muscle?

Do you all disagree or agree with my Bold answers?

My last question related to ventilation and I am having a TONNE of trouble getting my head around questions like the one I've attached. Does anyone have any ideas or good ways of visualising/conceptualising what happens? I seem to THINK I get it but then always seem to get the complete opposite answers.  Halp!

For the first one i would say at high altitudes b/c peripheral chemoreceptors respond more to O2 (central more to CO2) and at high altitudes there is a significant reduction in P(O2). During exercise, unless it is extreme exercise, O2 doesnt have much of an effect. All the other ones i agree with

[hobbitle]

Oh! Clever. Yes. Agree. Thankyou.