Card Set Information
physio exam 3
c. Sarcoplasmic Reticulum
How does myosin go from "sprung" to "cocked?"
This part of the muscle is the structural and functional unit of skeletal muscle
What keeps myosin from binding with actin?
What does troponin do in the muscle?
Binds Calcium Ion to tropomyosin which moves it out of the way so myosin can attach to actin
Once Myosin is attached to actin, how does it detach?
ATP recocks myosin and allows it to detach from actin
What is Excitation Contraction? How does it function?
It is how a muscle cell is excited through a motor neuron:
1. The motor neuron releases ACh, received by nicotinic cholinergic receptors
2. This depolarizes the muscle cell, leading to an AP across entire sarcolemma.
3. The response from the motor neuron on the muscle cell is called a "Twitch"
What is tetanus? What is its limitation?
It is the maximal sustained contraction
- This maximum contraction cannot be sustained for too long, and fatigue will occur.
What defines a motor unit?
A somatic motor neuron and its associatted skeletal muscle fibers
What is asynchonous recruitment?
To sustain a prolonged action, one grou of motor units will be activated while another group will be resting to take over when the first group fatigues.
What is isometric contraction?
Gets shorter (bicep curling a dumbell)
What is eccentric contraction?
Gets longer (lowering dumbell after curling it)
What are the 3 ways muscles get ATP?
1. Cellular respiration
3. Phosphagen system
Which muscle fiber uses cellular respiration for ATP?
Which muscle fiber uses glycolysis for ATP?
T or F: White muscle fiber has creatine phosphate and glycogen granules
T or F: White muscle fiber has mitchondria and lots of blood vessels for oxygen and cellular respiration
This type of muscle contracts 30x slower than skeletal, but can sustain constraction with very little ATP needed.
How are smooth muscles stimulated? (4 ways)
1. Autonomic motor neurons
2. Stretching of muscle
4. Environmental stimuli (chemicals)
What 2 parts of the smooth muscle can, A) make the tube smaller, and B) squeezing it to help push things along the tube
a) circular layer
b) longitudinal layer
How are cardiac muscles connected together?
Gap junctions and desmosomes
What is the Frank-Starling Law of the heart?
Within reason, the heart will pump out all the blood returned to it.