8-27 Cell Biology Flashcards
;what are the basics of an action potential
gatedd ion chanels
hat is one of the requirement of the AP?
that it reaches a threshold potentaial
what is an refractory period
the period that it taes for the sodiums channels o ractiad after they deacivated
what if there was no calcim channel in the heart muscles cells
the action potental would look like the nerve acton potential an itawould not have that long action potential duation
what is one of the n diereces for sletal nd caraca cells n ho the are ctited?
the heart cells are electrically conneced through gap junctions at thentercalated disk and seletal cells re not connectted
describe action potential propagaton
the cell s deplored o h threshold h allows the sodium channel open and depolarize and fre an AP, and then a local current flows and this will then depolarize the surrounding tissue or cell, then the AP propergates
how is AP dfferen from a wire conducing eleccity
the cell is no very conducve and t mut propigate he wave of poteal
what would be the reslt of a sodium channel blocker
local anesthetic
how is the spacial properggationn of AP different in skeletal and cardac cells
the cardiac cell propagates in three demensions and the nerve only propagaes down the axon of the nerve
what are some conditions that decresadw tha action potenal
inactivate sodium channels; application of local anesthetics like lidocaine that block the sodium channels; close the gap junctions. decreases cell diameter. this increases the resistance
what happens durring hypercholemia
this is the sodium high condition. this will depolarize the cell and inactivates the sodium channels and then you will get a week contraction or no contraction.
how do AP cause contraction:
in the skeletal: The AP will travel down the t-tubules and thei will cause the sarcoplasmic reticulum to release the calcum that will then cause the conltraction
what is the general cycle ofexcitation-contraction coupling
AP leads to calcum rise and this leads to force
describe calcium induded calcium rrelease
a little bit of callcim comesin the ca channel and hs activates RyR and opens the SR that will release ca and this will cause contraction. SERCA will aactely pump the ca back in. and na\ca atpase will pump ca out and ca pump also pump it out.
what would happen to the rate or relaxation if SERCA is blocked
slow the contraction relaxation rate down.
what if you releases more or less ca from the T-tubules:
you will get a stronger contraction
how do you get a stronger contraction in cardioac and skeletal
more ca release due to epinephrin and neuraepinephrin and in skeletal it is thourgh recruitment of more cell contraction fibers.
what hapens if you block the ca current in cardiac celss
then you awill shorteN THE AP and you will not hget a contractionl in the cell
how is the skeletal muscle contraction different
the channel from the tubule physically blocks the calcium channel from THE SR. and there are no ca pumps out of the cells
what if he neuron to a muscl is cut
no contraction! there is only one connction per mcle
what is achemical synapse and what is the cardiac comparison
the neurons individual onctacdt the muslce cells and pass acetylcholine to the mucle cell and tat binds to ligand gated channel that oppens and allows sodium to enter and depolarizes an then the sodium ion channels open nd properate the AP. in hear use gap junction
How to remmovet the atecholine from the synapse
acetylcholeneestterae eats the signal
what is an EPP in a skeletal muscle cell
this is the end plate potentail that will be caused by release of the acytelcholine in the cell
what will epinephrin and noreepinepherin do to the skeletal muscle cell contration
nothing
what if block ca input in a skeletal cell ie remove all extracellular ca
then nothing hapens
take extra cellular calcium away from cardiac muscle?
then the contraction stops!!
what is the muscle A band
the region of myson fiber in the muscle this includes the region of myson and actin overlap
what is the muslce H band
the region of just myson fibers
what is the muscle Z band
this is the actin fibers connections
what is the muscle I band
area of just actin fibers
Howdoes ath muscle fber contract
the myelin fiber cross bridges bind to the actin filaments and rachets and repeats
what is the function of tropomyosin
to cover the myson binding site of atin
what is troponin
the molecules that bind to ca and cause the tropomyosin to moveand allow actin to bind myosin
what is a isometric contraction
isometric means that there is constant length of the muscle while tension builds
what is a isotonic contraction
when the muscle moves when tension builds
what does a length tension curve tell us for isometric contraction
initially the tension will incraese as length until a certain point and then the passive tension builds and then the a isometric tension will decrease
why do we see a drop in tension as the muscle is stretched
the actin and myosin fibers would not overlap
why is the muscle stretched a lidttle by the tendons
to optmize the actin nad myosnn fiber overlap and increase tension
what happens to heart muslce tension as muslce length increases
the tension continues to increase! this is because the cardiac muscle operates on the ascending curve of the length and tension curve.
how does the amount of blood int hte heart afect the tension
the muscle will be stretched and the tension of the muscle will go up and a more vigorous contraction
how are velocity of contraction and ljoad related
higher load and slower velocity
describe the advantage of the skeletal muslc lever system
has to lift more load but through a much shorter distance
what is summation in skelletal cell?
the frequency of the AP leads to increased contraction tension
what is tetonic contraction
the AP are so close together that you get continuos tension
what are two ways to increase tension in skeletal muscle
summation and recruitment
how to increase tension in cardiac
epinepherin neuroepinephrn and stretching the muscles out with more blood in ventricle
where does all the exchange take place in the blood system
the cappillary
what causes the arterioles to contract
sypathetic nerve endings and norepinephrine
tranport accrossthe cappilary wlls
diffusion f water lipid solble substances like the oxygen and co2 and endocytosis for small vescles of water. then some space between cells for water etc.
how are the cappily dfferent int the brain
very tight, must have medted transport for glucse etc
how does the capilary bed relate to metabolic rate
directly related
why so many capillaries in the skn
temp control
what does the lymph system do
blind endedd tubes what cary interstitual fluid and leaked protiens and othter dranage bac ot the venous sde of the circuaton
where is all the blood in the body
in the venules ad veins
what moves water in and out of the capillary
starling pressure
what is starling pressure
the sum of the hydrostatic presure and the osmotic pressure
what drives water into the cappilaries
osmotic force
what drives the water out of the capilaries
the hydrostatic force
what filtration and ultrafiltradtion
filtration is water out of thecapillary
where does the filtration water go
to the lymphatic system or reabsorbed due to osmotic forces
how does the hydrostatic pressure change accross the capilaries
drops as we move to the venous system
why would water move back into the cappilaries as we approach the venoussystem
the hydrostatic curve drops andthe ossmotic pressure doesn;t so the water back in
what if theres a little blood loss
then the hydrostatic pressure down and then the osmotic pressure is the same and sends water back into capillary
what if blick th lymphatic system by parasites or worms
then the water not reabsorbed into the body and severe edema and elephantasis
what if severe prtein deficiency how is fluid balance
decrease the osmotic pressure and water will then stay in the interstitual tissue and not go back to the circulatory
what if severe burn wounds
increase the protein concentration in the intersttual fluid and then they hydrostatic force sends more fluid into the space and blisters and edema
what is edema
a build up of fluid in the interstitial space
what if elevate the venous blood pressure (back pressure) due heart failure or blood clots
venous pressure goes up and then overcome the osmotic pressure and edima occurs and can see pittin edema etc.
