Chat Transcript Physiology: Excitable Tissue & Periphera

[Roxanita]

Physiology Chat: Sections II and III:
Excitable Tissue & Peripheral Circulation

20:07:41 [Roxanita] Hello group, what do we have tonight ?
20:08:24 [hutals] its supposed to be excitable tissues and peripheral circulation from physio
20:09:13 [Perudoc] hi kiran
20:09:49 [kiranadi] ok lets start now
20:10:54 [Roxanita] ok lets' start with EXCITABLE TISSUE.-
20:11:06 [Hmmmmmm] k
20:11:37 [Roxanita] What is CONDUCTANCE OF AN ION?
20:11:58 [Hmmmmmm] what is the function of voltage gated Na+ channels in neurons?
20:12:35 [hutals] conductance, number of channels that are open in membrane
20:12:39 [Hmmmmmm]conduction is directly proportional to no. of receptors
20:13:22 [Roxanita] the function of V-g, Na channels is vital for depolarization
20:14:17 [Roxanita] Types of K+ channels?
20:14:58 [kiranadi] k+ channels are both gated and ungated
20:15:17 [shamim] 2 types ungated and gated
20:15:21 [kiranadi] which are responsible for hyperpolarization
20:15:35 [Roxanita] ok, and what is Net Force of an ion?
20:15:43 [Hmmmmmm] Hyperpol: Cl - chloride and potassium K+
20:15:56 [kiranadi] thru ungated the repolarization is slow and thru gated it is fast
20:16:35 [shamim] NF, it is the sum of two forces
20:16:44 [Roxanita] what forces?
20:17:06 [hutals] concentration and electrical forces??
20:17:14 [shamim] concentration and electrical
20:17:22 [Hmmmmmm] agree
20:17:31 [kiranadi] concentration and electrical forces
20:17:50 [hutals] Is the potasium level [ ] higher inside or outside cell? what about sodium?
20:18:03 [kiranadi] Na higher outside the cell, K higher inside
20:20:19 [hutals] I remember it as "NOKIa" (like the name of my cell phone) for Na Outside and K Inside
20:19:44 [Roxanita] how do we determine if the ion is in equilibrium?
20:20:05 [Roxanita] what values should we look at?
20:20:10 [Hmmmmmm] Nerst equation
20:20:22 [shamim] when there is no net movement across memb
20:20:31 [kiranadi] charge and the concentration of the ions
20:21:03 [kiranadi] hi nina
20:21:15 [ninadnashua] hi
20:21:16 [Roxanita] that's a good one Hutals
20:21:34 [kiranadi] yup nice one
20:22:27 [hutals] didnt work too well with my old cell phone....motorola
20:22:35 kmonica26 enters this room
20:22:42 [kiranadi] hahahah
20:22:43 [hutals] hey mon
20:22:53 [kiranadi] hi monika
20:22:58 [kmonica26] hi all
20:23:04 [Roxanita] to determine if the ion is at equilibrium we lok at Em=membrane potential (IC) and Ex=equilibrium potential for the ion (EC)
20:23:12 [Hmmmmmm] lol hutals
20:23:25 [Roxanita] Hi monica, did you bring some questions on this chapters
20:23:50 [Roxanita] lol , hutals
20:23:55 [kmonica26] what are we discussing today?
20:24:17 [Roxanita] Why do we need to know Nernst equation?
20:24:18 [hutals] what are the normal equilibrium potentials for Cl, K, and Na?
20:24:48 [hutals] mon, today is excitable tissues and peripheral circulation
20:24:53 [Roxanita] can anybody explain the 10x concentration related to the equilibrium of the ion?
20:24:54 [shamim] cl=-90
20:25:01 [kiranadi] na-135-145Meq
20:25:14 [kiranadi] k+105Meq
20:25:31 [kiranadi] cl=-90
20:25:35 [Roxanita] Na and K important: Na+=+45mV and K+= -105mV
20:25:46 [Hmmmmmm] rox i didnt get ur q
20:25:48 [hutals] it comes out that a 10x increase concentration difference is the same as 60mV
20:26:00 sweta_med enters this room
20:26:18 [kiranadi] the net concentration force is 60Meq
20:26:32 [kiranadi] hi sweta
20:26:40 [hutals] yep, Cl=-90, K=-105 and Na=+45
20:26:47 [Roxanita] In the nernst equation......there is a relation : if there is a 10fold [ ] difference across the Mb, the CF has a magnitude of 60mV
20:27:08 [kiranadi] what is nernst equation?
20:28:01 [kiranadi] hey conc of Na+ is....is it 45 or 145
20:28:13 [kiranadi] i think it is 145!!!
20:28:29 [Roxanita] that is because the Nernst equation: Ex= -60mV/Z x Log[x]a/[y]b
20:29:45 [Roxanita] Na+ has a positive equilibrium potential value
20:30:01 [kiranadi] is it 45 or 145
20:30:08 [Roxanita] Log 10=1 right?
20:30:09 [shamim] +45
20:30:21 [hutals] 145 would probably be the serum conc of Na. The equilibrium potential of Na is +45mV. Two different things
20:30:41 [kiranadi] ok ok ok .....got confused!!!!
20:30:57 [Roxanita] it makes sense cause the equation will be canceled and we will only have Ex=60mV
20:31:11 [hutals] serum [Na] is normally 135-145 mEq/L
20:33:09 Lorena enters this room
20:33:25 [kiranadi] hi lorena
20:33:30 [Lorena] hi everybody
20:33:39 [shamim] hi
20:33:41 [hutals] hey lorena
20:33:46 [Roxanita] KIRAN: in the example the membrane potential is -90mV, if the Ex of Na is =+45; then the Na+ will have to leave to reach its equilibrium, am I right?
20:34:55 [Roxanita] we are talking about IONIC EQUILIBRIUM and MEMBRANE POTENTIAL
20:35:00 [hutals] the negative intracellular potential becomes more negative (eg. increased K efflux from a cell)....what is this an example of? Depol, hyperpol, transmembrane potential?
20:35:24 [Roxanita] hyperpol
20:35:41 [Lorena] hyperpolarization
20:35:54 [kiranadi] yeah i got it roxy
20:36:37 [Roxanita] what happen to an ion if its Ex (equilibrium potential)= Em (membrane potential)
20:36:48 [hutals] yep, its Hyperpolerization. Depol would be the negative intracellular potential moving toward zero (more positive) eg is Na influx
20:36:51 [Lorena] what is the other ion involved in hyperpolarization? specially in neurons?
20:37:01 [Roxanita] what happen if Ex=Em?
20:37:08 [shamim] no net movement
20:37:10 [kiranadi] Hyperpol: cl- i guess
20:37:23 [Lorena] yes kiran
20:39:52 [Roxanita] There is normally INFLUX of Na+
20:39:54 [hutals] are Na channels voltage gated or ungated?
20:40:02 [shamim] if memb pot and Eq poten are same then there will be no net movement of ion
20:40:12 [Lorena] it is Cl- for hyperpol , Ca++ is involved in depolarization
20:40:25 [Lorena] Na channels are V-gated
20:40:32 [kiranadi] voltage gated----Na+ channels
20:41:04 [hutals] yep, Na are voltage gated
20:41:16 [Roxanita] Na+ channels are Voltage gated only
20:41:30 sweta_med enters this room
20:41:35 [Lorena] if you prevent the opening of Na voltage gated channels in skeletal muscle what will happen?
20:42:09 [kiranadi] no depolarisation takes place
20:42:46 [hutals] i think that K can be both voltage gated and ungated, depending on conditions. but i think that Na is only voltage gated
20:43:02 [Lorena] yes kiran...and if you prevent the opening of Na voltage gated channels in cardiac muscle?
20:43:12 [hutals] hey sweta
20:43:21 [sweta_med] hi
20:43:24 [shamim] depolarization can take place due to Ca++ ion in cardiac muscle
20:43:44 [Lorena] K are gated and ungated ...the ungated ones are always open; Na+ are only voltage gated
20:44:45 [Hmmmmmm] Na+ channels are voltage gated...when there is increase of membrane potential (more +ve) then they open and depolarize the membrane.....K+ channels are both ungated (always open) and voltage-gated...
20:44:56 [Lorena] yes very good shamim .... due to slow ca channels in cardiac muscle, Depolarization still takes place but slower
20:44:59 [sweta_med] Cl is not involved in Depolarization
20:45:09 [Roxanita] Hi Sweta
20:45:21 [Lorena] CL along with K are involved in hyperpolarization , Cl specially in neurons.
20:45:24 [Hmmmmmm] CL is involed in hyperpolarization
20:45:27 [hutals] the importance is that you can have drugs that block opening of voltage-gated Na+ and will block depolarization, but drugs that block opening of V-gated K+ will not block repolarization because K+ also have Ungated slow channels.
20:45:33 [sweta_med] hi Roxanita
20:45:41 [Lorena] Ca+ and Na+ are involved in depolarization; Cl- and K+ in hyperpolarization.
20:45:53 [kiranadi] ok
20:46:30 [Roxanita] ok
20:46:39 [Lorena] yes, very good hutals
20:47:32 [Roxanita] hutals> right
20:48:59 [Roxanita] If the Em=-70, what is the Transmembrane Potential?
20:49:01 [Lorena] why is muscle so sensitive to extracellular K changes? and that doesnt happen with Na for example?
20:49:14 [hutals] we can take turns posting the transcript so everyone will know how eventually. we should also take turns posting about the chat on other sites so our group continues to get lots of participation
20:49:24 [Hmmmmmm] good idea hutals
20:50:02 [kiranadi] Transmembrane potential= 70mV (no sign)
20:50:24 [kiranadi] because k has both gated and ungated channels and Na+ doesnt
20:50:41 [sweta_med] b/c there r ungated as well as gated K+ channels but only V-gated Na+ channels
20:51:09 [Roxanita] in general changes in EC [K+] affect the Em
20:51:41 [Lorena] which means...
20:52:19 [Roxanita] we have Voltage gated and Ungated K channels-> sensitive
20:52:30 [hutals] because ungated which basically means its always open, so more sensitive to changes
20:53:15 [sweta_med] yes so even after the voltage gated channels are closed the K moves out through the ungated channels
20:53:18 [Lorena] the ungated channels re always open so there is always an efflux of K, if it increases in the ECF the efflux will stop and even an influx can take place = depolarization = arrythmias
20:53:51 [Lorena] yes, you guys are all right
20:53:51 [sweta_med] yes Lor
20:54:10 [hutals] what is the difference between absolute and relative refractory periods?
20:55:00 [sweta_med] absolute refractory period is that during which no stimulus can produce an action pot
20:55:28 [sweta_med] but ref period a stronger stimulus can
20:55:33 [Lorena] absoluite refractory period you can't have a action potential cauze the mechanical event is still taking place, but relative you would need a much than usual stronger stimulus
20:55:50 [Roxanita] the efflux of K will stop because increase EC[K], therefore it wont be a Net Force pulling it?
20:55:56 [kiranadi] absolute refractory periods dont respond for stimulus...but in relative r.p action potential summation of stimulus produces action pot
20:56:15 [sweta_med] absolute refractory period is due to the closure of the Na channels
20:56:19 [hutals] with absolute, there will not be a second action potential regardless of how strong the stimulus. with relative, you can have a second action potential, but it requires a larger stimulus than normal
20:56:27 [Roxanita] ABSOLUTE: can not produce
20:56:38 [hutals] everyone is right
20:58:12 [hutals] which types of fibers produce fast vs slow conduction? large vs small, unmyelinated vs myelinated?
20:58:26 [Lorena] becaue of the absolute refractory period cardiac muscle can't be tetanized
20:58:36 [kiranadi] myelinated-fast and unmyelinated-slow
20:58:49 [Lorena] myelinated ones are faster
20:58:50 [sweta_med] myelinated produce fast
20:59:03 [Roxanita] large and myelinated are faster, they got everything
20:59:06 [sweta_med] because od saltatory conduction
20:59:18 [Lorena] and bigger ones are faster
20:59:35 [Roxanita] I mean large diameter
21:00:02 [Lorena] agree with rox
21:00:09 [hutals] large myelinated=fast conduction, small unmyelinated=slow conduction. wonder what happens in large unmyelinated or small myelinated
21:00:31 [sweta_med] the drug that opens Na channels in a motoneuron also causes the the EM to reach E-Na
21:00:36 [Lorena] lol
21:00:59 [sweta_med] is Q10 on page 62 clear
21:01:07 [Roxanita] when in the neuron action pot, the Na has the greatest conductance and when the greatest Influx?
21:01:46 [sweta_med] during the depolarisation phase the Na conduction is thegreatest
21:01:53 [Lorena] in depolarization
21:02:38 [hutals] i agree
21:02:56 [Lorena] how is K conductance in the plateau phase of a cardiac cell?
21:03:32 [kiranadi] repolarisation
21:03:41 [sweta_med] K conductance is efflux
21:04:17 [hutals] k efflux via ungated K channels
21:04:22 [Roxanita] at the end of depolarization cause it's close to its Ex
21:04:41 [hutals] voltage gated K channels closed
21:04:55 [shamim] k conductance is only thru ungated channel during plateu phase
21:05:01 [Lorena] yes hutals
21:05:36 [Lorena] yes shamim therefore K conductance in the plateau phase is very low
21:05:50 [kiranadi] ok
21:06:01 [hutals] which phase of cardiac has the greatest Ca conductance?
21:06:33 [hutals] 0, 1, 2, or 3?
21:06:35 [shamim] plateu phase
21:06:39 [Roxanita] that's why K+ and Ca++ make the plateau (hyperpol vs depol)
21:06:50 [shamim] 2
21:06:57 [Lorena] phase 2
21:07:00 [Roxanita] 2
21:07:13 [sweta_med] 2
21:07:39 [hutals] very good, the slow Ca channels open and the voltage gated K closes.
21:07:49 [Roxanita] In resting conditions, what is the conductance of Na+?
21:07:52 [hutals] in phase 2 (plateu phase)
21:08:18 [sweta_med] the voltage gated channels are closed
21:08:37 [shamim] they r closed
21:08:49 [Roxanita] GOOD!
21:08:52 [kiranadi] closed
21:09:08 ninadnashua enters this room
21:10:07 [Lorena] therefore Na conductance is? decreased or zero?
21:10:23 [Roxanita] Difference between the Subtreshold Pot and the Axn Potential?
21:10:31 [Roxanita] ZERO
21:10:52 [sweta_med] the threshhold is the minimum memb pot to produce action potential
21:11:21 [kiranadi] below subthrehold the na+channels are closed...where as open in action potential....guess
21:11:24 [Roxanita] is once it reaches the Treshold when the channels of Na open to start depol
21:12:13 [Roxanita] I was confused on this, but there is a SUBTRESHOLD POTENTIAL and the ACTION POTENTIAL
21:12:22 [Hmmmmmm] agree with kiran
21:12:46 [Lorena] thats true for skeletal muscle , but for specilized cells there is always a leak on Na
21:13:10 [Roxanita] the subtreshold is all the hard work to get the treshold and start the axn potential
21:13:44 [sweta_med] subthreshold pot is summated to produce act pot
21:13:58 [Roxanita] ok let's talk about the Na leak into the cell
21:14:08 [Roxanita] sweta_med> good
21:14:23 [sweta_med] its in the cardiac cell
21:14:38 [Lorena] talking about threshold...what is the effect of sympathetic stimulation on it?
21:15:07 [kiranadi] threshold decreases
21:15:20 [hutals] since we have 2 topics today and 3 hrs max, we should probably wrap things up for excitable tissues and move onto peripheral circulation in about 15 mins or so....what do you think?
21:15:22 [sweta_med] yes it decrease
21:15:30 [Lorena] yes kiran
21:15:35 [sweta_med] thats right
21:15:45 [Lorena] aand sweta
21:15:52 [shamim] what is the role of Na /K ATPase pump in resting condition
21:16:00 [kiranadi] yes...lets move to peripheral circ. soon
21:16:32 [Roxanita] I mean another stimulus will get bigger initial depolarization, treshold is faster, decreases treshold
21:16:36 [kiranadi] or else we will not be able to cover it
21:16:46 [sweta_med] what is the organ with the highest resistance to blood flow?
21:17:02 [Lorena] Na/K ATPase turn the ions back where they belong
21:17:17 [Roxanita] Synaptic transmission?
21:18:03 [shamim] righ Lor
21:18:06 [Roxanita] Lorena> and because the great Net Force on Na, this one tends to leak? uhu
21:18:29 [Roxanita] we haven't done Synaptic transmission, HIGH YIELD
21:18:57 [hutals] I didnt mean to end the topic right away, just wanted to make everyone aware of the time so we can wrap things up around 9:30 and move onto next subject....sorry if it came out wrong
21:19:25 [Lorena] no problem hutals
21:19:28 [sweta_med] about the Na /k atpase
21:19:42 [sweta_med] it would decrease the k+ inside the cell
21:19:46 [kiranadi] i'm sorry too if i have hurt anyone
21:20:23 [hutals] what a great group
21:20:45 [Roxanita] hutals> no problem, we appreciate that you care about the timing chat
21:21:03 [Lorena] nobody gets hurt here for trying to do things more active hutals, great job
21:21:08 [kiranadi] swetha whats the answer to ur previous question...resistance to blood flow
21:21:33 docak enters this room
21:21:34 [sweta_med] its the Coronary circulation which has more resistant
21:21:47 [kiranadi] ok
21:21:56 [docak] hi guys
21:22:07 [kiranadi] hi docak
21:22:12 [sweta_med] 1) coronary > 2) cerebral > 3) renal > 4) pulmonary
21:22:32 [kiranadi] ok
21:22:42 [docak] hi hutals
21:22:52 [docak] howz it going guys?
21:23:09 [hutals] which is involved with hyperpol vs depol? EPSP or IPSP? which one is caused by sodium influx?
21:23:35 [kiranadi] epsp by sodium influx
21:23:40 [hutals] just wrapping up with excitable tissues docak.....hows your studying going?
21:24:03 [docak] not so good; i'm doing micro now, forgot physio
21:24:22 [Lorena] EPSP and IPSP? what do they stand for hutals?
21:24:33 [docak] sorry, if i am interupting
21:24:50 [Roxanita] Excitatory and Inhibitory
21:24:56 [hutals] thats too bad docak....but you will be ahead of us all when we do micro chat
21:25:02 [kiranadi] excitatory potential and inhibitory potential
21:25:09 [Lorena] ok thanks
21:25:12 [hutals] EPSP is depol by sodium influx,....excellent!
21:25:23 [docak] thanks hutals
21:25:55 [Lorena] Cl=inhibitory , Na is excitatory
21:26:17 [Roxanita] Synthesis if ACh? Where? rate limiting step?
21:26:40 [Lorena] presynaptic inhibition in a neuron, how does that happen?
21:26:48 [sweta_med] the tyrosine hydroxylase reaction
21:26:50 [docak] in cholinergic neurons
21:26:52 [Lorena] presynaptic nerve ending ....
21:27:09 [Roxanita] I have to go for a while, see you
21:27:09 [hutals] which are bidirectional vs unidirectional? electrical synapses vs chemical synapses?
21:27:10 [kiranadi] presynaptic membrame...synthesis and rate limiting step by choline esterase
21:27:50 [Lorena] i guess chemical are bidirectional, and electrical are unidirectional
21:27:57 [sweta_med] iam sorry the rate limiting step for epinephrine is tyrosine hydroxylase
21:28:49 [hutals] electrical are bidirectional and chemical are unidirectional
21:29:35 [Lorena] ok thanks hutals
21:31:12 [hutals] Ach is presynaptic nerve ending and rate limiting step not sure?
21:31:46 [docak] i think its choline acetyl transferase
21:31:49 [kiranadi] rate limiting step is choline esterase i think
21:31:58 [kiranadi] should refer once again
21:32:25 [docak] yeah
21:32:37 [hutals] transport of choline into the neuron terminal via a sodium dependent mechanism....i also think its choline acetyltransferase.
21:32:47 [Lorena] yes i think so
21:33:19 [Lorena] ok guys it was a pleasure as always, please post the transcript and see you tomorrow
21:33:29 [Lorena] gotta go
21:33:39 [docak] bye lorena
21:33:56 [kiranadi] bye lorena
21:33:58 [hutals] bye lorena. c ya tommorow
21:34:01 [sweta_med] bye lorena
21:34:15 [docak] r u guys chatting tomorow too?
21:34:55 shamim enters this room
21:35:22 [hutals] i think we are chatting everyday except sunday....is that right?
21:35:27 [hutals] hey shamim
21:35:51 [kiranadi] yeah now the chatting schedule is changed to everyday from mon to fri
21:35:54 [docak] i thought it was only tuesdays and fridays
21:36:05 [docak] ok
21:36:06 [kiranadi] 5 days a week, see announcements: changes in chat schedule
21:36:41 [kiranadi] just look at the chat schedule that has been posted ...for the exact schedule...i dont remember
21:36:58 [docak] thanks kiranadi
21:37:32 [hutals] so ready for peripheral circ?
21:37:44 [kiranadi] 
21:37:49 [kiranadi] yes
21:38:00 [sweta_med] yes
21:38:05 [hutals] my blood pressure is increasing just thinking about it....pun intended
21:39:16 [hutals] speaking of blood pressure, what is the formula for calculating mean arterial pressure (MAP)?
21:39:17 [kiranadi] should we remember all the pressure values in the blood vessels
21:39:22 [sweta_med] what are the two major reservoirs of blood
21:40:01 [sweta_med] MAP=COxTPR
21:40:02 [hutals] systemic veins and pulmonary system
21:40:04 [kiranadi] diastolic +1/3pulse pressure
21:40:49 [kiranadi] what are the factors affecting systolic and diastolic pressures?
21:41:14 [hutals] MAP= CO x TPR.....good
21:41:15 [sweta_med] preload and resistance
21:41:22 [kiranadi] do we need to byheart all the pressure values
21:41:58 [kiranadi] its stroke volume,heart rate,vessel compliance
21:42:14 [hutals] i think we need to know them....i don't know them yet, but i hope to before exam
21:42:19 [sweta_med] i think its not necessary to learn the values but a brief idea would be fine
21:42:45 [kiranadi] systolic---increase when there is an inc. in stroke vol,dec. in hr,decin vessel compl
21:43:29 [kiranadi] diastolic pr--decrease in when there is dec in hr,stroke volume,vessel compliance
21:43:41 [kiranadi] ok
21:44:45 [hutals] what is the most important factor for determining te resistance?
21:44:59 [kiranadi] compliance and stroke vol
21:45:05 [sweta_med] radius
21:45:41 [Roxanita] ok, still alive? sorry I had some dinner. Lorena?
21:45:47 [kiranadi] which is the most compliant artery in systemic circulation?
21:46:06 [hutals] there are a few factors affecting resistance, but the most important is the radius where a small change in radius will have a large change in resistance
21:46:19 [kiranadi] ok
21:46:22 [Roxanita] where are you guys now... let's see
21:46:26 [hutals] lorena had to go
21:46:41 [kiranadi] Resistance invers proportional to radius “ r ” to the power 4
21:46:43 [hutals] we're on peripheral circ
21:46:47 [kiranadi] now i remember!!!!
21:46:57 [sweta_med] aorta
21:47:49 [sweta_med] thats right
21:47:57 [hutals] if length of vessul is doubled, resistance doubles, but if the radius doubles, the resistance decreases to 1/16 the original
21:48:20 [kiranadi] ok
21:48:23 [sweta_med] the factors affecting the MAP
21:48:30 merjo13 enters this room
21:48:45 [hutals] cardiac output and TPR
21:48:49 [hutals] hey merjo
21:48:50 [kiranadi] CO
21:48:56 [kiranadi] TPR
21:48:59 [sweta_med] are stroke volume and tpr
21:49:01 [merjo13] Hey everybody
21:49:12 [sweta_med] thats right hutals
21:50:14 [hutals] which represents lowest resistance pathway? cerebral circ, coronary, or renal? (kap question)?
21:50:18 [kiranadi] below heart level and above heart level
21:50:31 [kiranadi] renal???
21:50:53 [sweta_med] what is the factor affects the pulse pressure
21:51:26 [hutals] Renal is the right answer. good kirandi
21:51:44 [hutals] compliance??
21:51:46 [kiranadi] thanks
21:51:54 [sweta_med] yes thats right
21:52:14 [kiranadi] compliance decreases
21:52:24 [sweta_med] more compliant arteries have low pp
21:52:39 [kiranadi] ooops!!!
21:53:02 [Roxanita] compliance in old people?
21:53:13 [merjo13] Decreases
21:53:17 [kiranadi] decreases
21:53:20 [sweta_med] is lesser
21:53:27 [hutals] decreases
21:53:37 [Roxanita] yes
21:55:38 [hutals] will dehydration increase or decrease capillary oncotic pressure?
21:57:36 [Roxanita] degydration will decrease ECV and therefore
21:57:54 [Roxanita] increase [solute] in EC
21:58:29 [sweta_med] increase the capillary oncotic pressure
21:58:39 [Roxanita] hutals> increases oncotic pressure
21:58:55 [hutals] yes, it would increase capillary oncotic pressure
21:59:07 [hutals] good both of you got it
21:59:11 [Roxanita] therefore this force will drive water from the IC to the EC
21:59:40 [Roxanita] the increase in [proteins] pull the water from the other compartment
21:59:47 [Roxanita] what about my question guys?
21:59:58 [Roxanita] During a marathon, a 28-year-old woman initially has pain and distress but suddenly feels exhilaration about halfway through the race. The best explanation is most likely to be increased release of: the options are: a)B Endorfin b) ACTH, c)epinephrin, d)glucagon, e)somatostatin
22:00:10 [kiranadi] ok guys i've to go now
22:00:47 [Roxanita] bye kiran 
22:00:57 [hutals] ok kirandi. c ya tommorow
22:01:11 [sweta_med] bye kiranadi
22:01:19 [merjo13] Bye
22:02:03 [sweta_med] epinephrine
22:02:09 [hutals] epi??
22:02:16 [Roxanita] I read this somewhere, I guess it was adrenaline ?
22:02:18 [merjo13] Epi?
22:02:32 [Roxanita] Can anybody explain it, it's an N* question
22:03:06 [sweta_med] there is vasodilation
22:03:37 [Roxanita] "feels exhilaration", what is that?
22:04:00 [Roxanita] yes with Adrenaline there is bronchodilation
22:04:15 [Roxanita] hutals> can you explain?
22:04:21 [hutals] epi speeds everything up and its a fight or flight situation. think of person on cocaine or caffeine....perks you up and gives you a "second wind"
22:05:21 [Roxanita] and the marathon in this case is the stress for the adrenal medula to release Epinephrin?
22:05:46 [hutals] exhilaration means like a feeling of excitement. so she went from exhaustion to excitement....what could cause this? probably something that stimulates sympathetic system
22:06:05 [Roxanita] ok, got it. Thanks hutals
22:06:45 [sweta_med] thanks hutal
22:07:04 [hutals] caffeine is the best example because we all use it. we're all exhausted in the morning (like running a marathon), and then we take caffeine and we feel "exhilarated"
22:07:35 [Roxanita] that's a good example hutals, thanks
22:07:59 [hutals] i could use some caffeine right about now
22:08:53 [hutals] most of the blood in Coronary Circulation occurs during systole or diastole?
22:09:38 [merjo13] Diastole
22:09:47 [Roxanita] Diastole?
22:09:49 [sweta_med] diastole
22:10:29 vladi enters this room
22:10:35 [hutals] diastole because it is literally getting mechanically compressed during systole so not much flow can occur
22:10:51 [hutals] everyone got it right
22:10:53 [sweta_med] what during inspiration, does happen to the circulation
22:10:56 [hutals] hey vladi
22:11:31 [sweta_med] hi vladi
22:12:09 [hutals] I think it decreases during inspiration for the same reason??
22:12:36 [sweta_med] yes
22:13:24 [hutals] wasn't sure about that one because i have a decrease of blood flow to my cerebral circulation right now
22:13:37 [Roxanita] it also decreases because most of blood goes to the lungs during inspiration
22:13:54 [hutals] speaking of which, what is the main factor regulating cerebral blood flow
22:13:55 [vladi] agree with diastole
22:13:58 [sweta_med] thats right as the left vent output decreases
22:14:16 [sweta_med] and the venous return to the right increase
22:14:28 [vladi] pCO2
22:14:32 [sweta_med] its autoregulating
22:14:42 [Roxanita] PCO2
22:15:26 [merjo13] pco2
22:16:13 [sweta_med] I will be back guys
22:16:24 [hutals] arterial PCO2 is the main factor. that is the reason why you cannot always give oxygen for treatment....you might turn of the blood flood to cerebral if you eliminate the regulating factor in some cases
22:16:32 [Roxanita] If a person switches from breathing room air to 100% O2, what happen with cerebral circulation?
22:17:54 [hutals] no change??
22:18:31 [Roxanita] and what happen with cerebral circulation when a large decrease in PO2 occurs?
22:18:39 [Roxanita] hutals> right
22:19:08 [hutals] increased cerebral blood flow in that case i think
22:19:24 [Roxanita] yes; here it's the low PaO2 what determines the Flow
22:20:01 [vladi] hut- you mean some cases e.g. emphysema when we giving O2 can get reverse effect, isn't it
22:20:56 [hutals] i was trying to remember the case (saw it on ER i think), and i think you're right. i think it was emphysema case
22:21:50 [vladi] yes- it's HYQ with emphysema
22:22:36 [hutals] so the emphysema pt has a large PCO2 because decreased compliance, but then you give oxygen and it balances out the PCO2 which takes away the pts resp drive....does that sound right?
22:24:00 [Roxanita] that's so right
22:24:10 [hutals] see, i did learn something from watching tv....despite what my mom always said
22:24:22 [Roxanita] Describe what happen when a person goes from supine to upright posture?
22:24:29 [vladi] exactly-hut
22:24:47 [Roxanita] when a person goes from supine to standing position: what happen first is: 1) the PRESSURE increases on dependent veins
22:26:02 [Roxanita] so the blood goes most to the lower limbs. 2) Blood Vol increases in dependent veins and 3) circulating blodd volume decreases (c.o.) 4) BP decreases and what reflex will occur here?
22:26:16 [hutals] carotid sinus reflex
22:27:21 [Roxanita] yes
22:27:33 [vladi] that's why in orthostatic people we can get dramatic decrease BP with collapse after fast standing up
22:27:45 [Roxanita] through carotid sinus reflex, TPR increases and HR increases
22:28:06 [Roxanita] so the BP returns to normal
22:24:29 [vladi] ok
22:28:43 [hutals] wow, these chats are really much more helpful when prepared....i was lost yesterday, but today learned alot
22:28:47 [Roxanita] does anybody knows?
22:28:32 [Roxanita] why do we call them Dependent veins?
22:30:33 [hutals] not sure rox?
22:30:52 [hutals] dependent on posture??
22:31:28 [Roxanita] they are called dependent because they depend on some factors, “help” to make the blood flow through them, like: 1)Muscular tissue around them "venous pump", 2) their VALVES 3) also breathing movements: inhale: moves blood up the veins, exhale: reverse but valves prevent backflow
22:31:31 [merjo13] something with gravity?
22:31:43 [vladi] what drug mc can cause orthostatic hypotension-HYQ
22:32:22 [hutals] beta blockers?
22:32:50 [hutals] t****done i think too
22:33:15 [Roxanita] before I didn't know why they are called Dependent, now it makes sense; I hope you are not bored with this 
22:34:11 [hutals] that was a very good explanation rox. thanks.
22:34:27 [hutals] now it makes sense to us too
22:34:49 [vladi] prazosin- as alpha-1 blocker
22:34:58 [hutals] hydralazine
22:35:31 [Roxanita] alpha 1 blockers, cause Orthostatic hypotension
22:35:34 [hutals] ah yes, prazosin
22:35:44 [vladi] prazosin - more severe because it's not too selective. i remember when we started to treat pats with BPH from prazosin we warned our patients about this reaction
22:36:43 [Roxanita] which vessel has the highest pressure?
22:36:51 [hutals] makes sense since alpha is a constrictor, so blocking it would cause dialation
22:37:22 [Roxanita]>[hutals] right
22:38:00 [hutals] is it the capilaries??
22:38:29 [vladi] aorta
22:38:51 [Roxanita] yes, remember, the pressure in the vessel will be higher as closer they are to left ventricle
22:41:19 [Roxanita] Let's talk what happen during exercise?
22:41:30 [Roxanita] what happen with CO?
22:41:41 [hutals] excercise produces and increase in the volume of work of the heart mainly due to an increase in what? heart rate or stroke volume?
22:41:57 [Roxanita] SV
22:42:02 [vladi] increase
22:42:32 [vladi] SV
22:42:48 [sweta_med] sv increases
22:42:59 [Roxanita] In the athlete what variations we could find?
22:43:07 [Roxanita] x.e. about his HR?
22:43:09 [hutals] in exercise, the heart rate increase is more significant
22:43:26 [vladi] HR increases
22:43:56 [Roxanita] at rest in an athlete, in your office what do you find?
22:44:15 [vladi] bradicardia
22:45:32 [hutals] think about exercising, the heart starts pumping fast, which leaves less time for filling. so the stroke volume is actually decreased. in athletes, they condition to increase their stroke volume which is why they can exercise without great effects on HR, but not in normal ppl.
22:45:34 [Roxanita] exercise will also redistribute blood to active muscles
22:46:44 [hutals] that was a tricky one, but a good learning point
22:47:33 [sweta_med] yes thanks hutal
22:48:38 [vladi] thanks hut- very valuable consideration
22:50:09 [Roxanita] Capillary exchange, remember mainly by SIMPLE DIFFUSION
22:50:29 [sweta_med] yeah
22:51:17 [Roxanita] what is the BULK FLOW?
22:51:45 [hutals] ok, thanks
22:52:06 [Roxanita] I saw it in a question: BULK FLOW
22:52:27 [sweta_med] bulk flow is across conc gradient
22:53:14 [Roxanita] BULK FLOW is the movement across plasma and interstitium by filtration or reabsorption
22:53:35 [Roxanita] at q--bank
22:53:53 [vladi] I haven’t heard about this either
22:54:20 [Roxanita] let's talk about what happen in Pulmonary edema?
22:54:40 [sweta_med] the capillary permeability increases
22:54:42 drsr enters this room
22:54:43 [Roxanita] why that condition happen?
22:55:13 [merjo13] Lt heart failure
22:55:29 [vladi] it's mostly hydrostatic origin of edema
22:55:34 [drsr] HELLO
22:55:39 [merjo13] so fluid backs up in the lungs
22:55:41 [hutals] resp distress Sd, Left heart failure
22:55:47 [Roxanita] Hi drsr
22:55:56 [drsr] HEY ROX
22:56:04 [sweta_med] increase in the filtration
22:56:16 [Roxanita] so, capillary hydrostatic pressure increases
22:56:46 [sweta_med] how is that relates with the intrathoracic pressure
22:57:36 [Roxanita] Intrathoracic P becomes more negative
22:58:10 [sweta_med] so that causes the blood vessels to constrict
22:58:49 [hutals] more negative intrathoracic press will increase filtration
22:59:52 [Roxanita] How do you calculate the blood flow through an organ?
23:01:34 [Roxanita] drsr we have 3 hours already
23:01:59 [drsr] WHAT TIME DO U FINISH?
23:02:00 [vladi] we are both in black today drsr
23:02:33 [hutals] edema is the excess fluid outflow into interstitium caused by incr capil pressure (heart failure), dec plasma prot ( nephrotic syndrome), inc cap permeability ( toxins, infections, burns), inc interstitial fluid colloid osmotic press (lymph blockage)
23:02:38 [drsr] good
23:02:55 [hutals] actually, we should be finishing up about now
23:03:14 [Roxanita] How do you calculate the blood flow through an organ?
Flow = Uptake /[O2]pv -[O2]pa. We are done for today!
23:03:19 [drsr] OK
23:03:34 [hutals] drsr, we start at 8 pm eastern and go for about 3 hrs max
23:03:47 [drsr] PEACE OUT
23:04:04 [hutals] nite merjo, see you tomorrow
23:04:29 [merjo13] Nite hutals and everybody
23:04:32 [hutals] i'm gonna go too. learned alot tonight. thanks rox and everyone
23:04:47 [Roxanita] sweta_med> next time push us with the time
23:05:20 [sweta_med] yeah
23:04:53 [vladi] actually for pacific side is not so good time and old schedule was perfect- right now i can't start from 5 bz i am working to 5.30 and then walk down to home
23:05:31 [hutals] what time can you join us?
23:05:44 [Roxanita] vladi> you mean, you would like to start at 9pm eastern time?
23:06:44 [vladi] as previously- from 9 ET e.g.
23:06:54 [hutals] we would need to change it when others are around because not many ppl are still here and they wouldn't know the time change
23:07:18 [Roxanita] maybe from Monday at 9pm as before?
23:07:27 [drsr] GREAT
23:07:36 [Roxanita] cause from next week we will have only weekdays monday through friday
23:07:42 [sweta_med] yes thats ok
23:08:09 [vladi] thanks- you are so kind- bz i miss you guys and get ready to take part everytime
23:08:30 [Roxanita] for tomorrow we have section IV and V
23:08:35 [hutals] its all the same to me, but others should probably have a say too and they already left for tonight. i'm sure they wouldn't mind, but it would be nice to include them
23:09:18 [Hmmmmmm] sorry hutals i kinda dozed off and then tried cook something burned
23:09:33 [Roxanita] lol
23:10:01 [Roxanita] tomorrow at 7pm eastern time
23:10:24 [Roxanita] but from next week only weekdays
23:10:37 [sweta_med] for tomorrow is section IV and V
23:10:38 [hutals] Skeletal Muscle & Cardiac Muscle
23:10:50 [Roxanita] sweta_med> please please culd you watch the time Good night.
23:11:20 [sweta_med] ok Good nite , see u tomorrow.