Test 3 Flashcards
What is visceral muscle
also called smooth muscle
- found in the walls of hollow organs and is involuntary
- pushes fluids around by contracting
Ex; stomach, airways, blood vessels
what is skeletal muscle
long, multi-nucleated parallel cells
- most voluntarily
- creates movement by pulling bones
ex: deltoid, Biceps brachii
What is cardiac muscle
One nucleus per cell, striated with intercalated discs
- involuntary keeps the blood pumping
- only found in the heart
Ex: heart
describe the microscopic anatomy of skeletal muscle
Sarcomere - Contractile unit of muscle fibers
- thick and thin filament
describe the events that happen in the neuromuscular junction
The synaptic connection between the terminal end of a motor nerve and the muscle
- tells the muscle to contract
what is resting potential
The in-balance of electrical change that happens between the nerve cells and their surrounds
what is depolarization
NA ions go in which causes a rise
what is action potential
The high point of the contraction
what is repolarization
K ions go out which slowly brings down the reaction
What are the three connective tissue sheaths
Epimysium, perimysium and endomysium
what is the epimysium
dense irregular connective tissue that surrounds the entire muscle
what is the perimysium
fibrous connective tissue that surrounds fascicles
what is the endomysium
fine areolar connective tissue that surrounds each muscle fiber
what is the sarcolemma
the muscle fiber plasma membrane
what is the sarcoplasm
muscle fiber cytoplasm
what is a myofibril
a densely packed rodlike element found in the muscle
smallest section in muscle fibers
what is the a band
dark region found in myofibrils
what is the H zone
a lighter region in the middle of the A band
what is the M line
line of proteins that bisects the H zone vertically
what is the I band
the lighter regions
what is the Z disc (line)
sheet of proteins on midline of light I band
actin is
thin filaments
myosin is
thick filaments
what is the muscle twitch
the contraction and relaxation of the muscle
List the 4 steps for muscle contraction
Neuromuscular junction
muscle fiber exitation
excitation- contraction coupling
cross bridge cycle
list the 4 main parts of the neuromuscular junction
- motor neuron fires an AP down the axon
- motor neuron releases ACh into synaptic cleft
- ACh binds receptors to sarcolemma \
- ACh binding causes end plate potential (EPP)
what happens during muscle fiber excitation
Local depolarization (EPP) triggers an AP in adjacent sarcolemma
what are the three steps in Excitation-contraction coupling
- AP in sarcolemma travels down the T-tube
- Sarcoplasmic reticulum releases CA2
- Ca2 binds troponin which shifts tropomyosin to show myosin-binding sites on actin
what happens in the cross bridge cycle
contraction occurs via cross bridge cycle
What are the 4 steps of the cross bridge cycle
- Myosin and actin attach
- myosin pulls actin towards M-line
- Cross bridge detachment : ATP attaches to myosin which causes detachment
- ATP cocks myosin into high energy state
