Calcium Handling in Skeletal Muscle Flashcards
____ % of total body calcium is in bone
99
_____ % of total body calcium is non-bound called ionized or free dialysable
.5
_____% of total body calcium is bound to anions
.1
____% of total body calcium is in blood/protein bound (albumin)
.4
explain the negative feedback loop if there is excess Ca+
-thyroid releases calcitonin
- osteoblasts build up bone
- kidney secretes extra
- Ca+ level in blood decreases and thyroid stops releasing calcitonin
explain the negative feedback loop if there’s not enough Ca+
- parathyroid releases PTH
- ostoclasts break down bone
- kidneys reabsorb more Ca+
- small intestines increase ca+ absorption
- Ca+ levels in blood increase and parathyroid stops releasing PTH
what are some general Ca+ benefits
- bone health
- muscle function (heart!)
- blood clotting
- teeth health
- nerve functioning
- protects against colon cancer
- transports other minerals throughout body
Ca+ is a ________- molecule
SIGNALING
what are 2 processes that are possible because of Ca+ as a signaling molecule
- (mitochondria) Ca+ induced activation of respiration and mitochondrial adaptation
- (nucleus) change in myofiber type specific gene expression “myofiber shifting”
_______ initiates muscle contraction
calcium
_________ - Ca+ rises to near saturating levels, but since contraction is slow, force does not reach maximal
single stimulus
_______ - Ca+ stays high long enough for force to reach maximal
multiple stimuli
What are the 4 calcium removal systems
- SERCA
- PMCA
- NCX
- MCU
SERCA
- 2 Ca+ into SR for each ATP
- uses 20% of ATP in muscles
PMCA
- 1 Ca+ out of cell per ATP
(bigger role in cardiac muscle)
NCX
- I ca+ out per every 3 Na in cell
- driven by Na potential
MCU
- facilitated diffusion of Ca into matrix of mitochondria
- driven by electronegative potential
What are the 3 control mechanisms of SERCA
- sarcolipin
- phospholamban
- myoregulin
sarcolipin is in type ______ muscle and turns on or off
1
phospholamban is in what type of muscle
smooth and cardiac
- slows or regulates Ca+
myoregulin is in type ______ muscle
2a, 2x
T or F: sarcolipin, phospholamban, and myoregulin control how fast ATP is hydrolyzed and speed of Ca+ sequestrin
F: just speed of Ca+ sequestrin not how fast ATP is hydrolyzed
