Muscle Physiology Basics
Starting from the outer region moving inward, this is the hierarchy of a muscle.
Muscle, bundle of fibers, muscle fiber(cell), myofibrils, myofilaments
The process which thin filaments slide over thick filaments, causing the shortening of the sarcomere is known as this.
Sliding Filament Theory
The RyR channel is located in this membrane.
Sarcoplasmic reticulum
Ca+ is stored within this organelle
Sarcoplasmic reticulum
The proteins responsible for pumping Ca+ back into the Sarcoplasmic reticulum are named this
SERCA pumps
These are the two types of muscle in the body.
Striated & unstriated
The H zone is comprised of this myofilament.
Myosin head groups
In order for contraction to end, SERCA pumps must reuptake Ca+ into the sarcoplasmic reticulum. For this to occur however, there must be sufficient amounts of this molecule.
ATP
The neurotransmitter released from a neuron for muscle contractions is this.
Acetylcholine
Cardiac and skeletal muscle belong to this type of muscle group.
Striated.
These are the two main myofilaments aiding with muscle contraction
thin myofilament (actin chain) & thick myofilament (myosin head)
During muscle contraction, these 2 regions of the sarcomere shorten.
I band & H zone
List or draw the steps of the sliding filament theory.
1. Rigor(locked in 45 angle)
2. ATP attaches to the ATP binding site of the myosin head group, myosin releases from actin.
3. ATP is hydrolized to ADP, energy harnessed for myosin head group to swing back toward z-disc and weak cross bridge formation. (P still there)(90 angle)
4. Ca+ released, binds to troponin, moving tropomyosin off actin binding site for strong cross bridge formation to occur.
5. POWER STROKE: the release of P gives enough energy for myosin to pull actin (shorten) toward M-line. Only ~10nm.
6. ADP released, back to rigor.
The binding of acetylcholine to ligand gated channels allows for Na+ in and K+ out of the cell. If enough Na+ enters the cell, this type of event is said to occur.
Depolarizing
Each muscle cell receives input from this many neuron(s).
1!!!
The myosin head group is comprised of these two regions.
ATP binding site & actin binding site
In order for muscle contraction to occur, this protein must be shifted off of the actin binding site.
Tropomyosin
Draw graph(from PowerPoint)/ talk through hypothetical effects of ATP and Ca+ on tension in the muscle.
ATP added and Ca+ present= can be hydrolized and cross bridge formation can occur with power stroke- TENSION
ATP removed from system=cross bridge formation cannot break- STILL TENSION
ATP re-added to system= can break cross bridge- NO TENSION
Add Ca+ back to system and process can happen again-TENSION
DHPR is located within this membrane.
Sarcolema
During rigor, the myosin head group is locked at this angle with the actin filament.
45 degree
The region of a myofibril spanning from 1 Z-disc to another is termed this.
Sarcomere
During contraction, actin filaments are pulled toward this region of the sarcomere.
M line
Explain the process of excitation-contraction coupling
AP travels down T-tubule to get deeper into the sarcolema and reach sarcoplasmic reticulum.
Voltage change down tubule, leading to conformational change of DPHR, unplugging RyR in sarcoplasmic reticulum and releasing Ca+ for contraction.
The voltage change from an AP causes a conformational change of the DHPR, causing it to unplug this channel, resulting in the release of Ca+
RyR
No question.
You’re doing great! :)