BIOD43H3 Lecture Notes - Lecture 1: Swim Bladder, Maximum Force, Homeostasis
Questions to answer for tutorial (please check the tutorial folder for the questions
1) Lower pCa values correspond with higher calcium [ ], based on this swimbladder has higher
threshold to activate compared to the red muscle. Less calcium is required to start relaxation
for red and white muscle relative to swimbladder. Requires time for cell to pump calcium
ito SR → i this usle, ehais is preset hih allos it to otrat ad rela faster.
THus swimbladder relaxes faster with higher calcium concentration.
a) Swimbladder muscle starts relaxation with higher [ ] of calcium relative to the other
muscles.
2) Although PARV does not need to reach low threshold of calcium to start cycle, cannot be all
the calcium there as contraction continues must remove calcium from TNC for contraction
to start.
a) During period of PARV easily saturated is releasig Mg → More sites for Ca to id
b) Some Ca is released during relaxation, maintaining a threshold for relaxation cycling.
i) PARV has soe harateristi of oleules → a’t e fast, ut just the
necessary speed to take some calcium to reach threshold.
ii) There is a period (end) an interval b/n calls and during interval PARV
releases Ca2+ in SR then starts the phase 1 again.
c) First PARV plas a ke role, ithout PARV it’s ot the ai plaer that oes
aliu ito SR. It’s just the eessar speed to aitai threshold to start cycle
again.
i) PARV aot hold for the etire all period to aitai hoeostasis → the
threshold. Thus the period or interval where nothing is happening is when
PARV finish moving Ca.
3) Figure 6. During the start of relaxation, the calcium has not reached the threshold. But you
can see that the threshold has not been reached and that the cross-bridge attachment or
detachment is not the limiting factor as you can see the calcium [ ] is decreasing and is lower
than that of the relaxation thus calcium is limiting.
4) A) What else is taking room in locomotor fibers
a) Mitochondria and SR
5) 4B) amount of mitochondria found in them, thus limited in red muscle cycles type 1.
a) depending on muscle composition ratio, then cross section area could be affected by
that
i) Size of fiers ad also aout of itohodria → Thus liits the size ad
cannot be bigger
ii) also affects the # of bridges that can be formed.
iii) Red muscle has high mitochondrial content, white has low mitochondria
content.
Tutorial Lecture 1
Why are animals able to limit items significantly higher than their own weight
→ Cross setioal area is iportat as hages are er sall relatie to size of the aial →
determines the # of bridges that can be generated and the force that can be generated.
Scaling of muscle forces
1. Maximum isometric force generally scales with the # of cross-bridges working in parallel
a. Muscle cross-sectional area
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
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