Muscle Physiology

Tendon

Cordlike CT. Connects muscles to bone

Aponeurosis

Thin, Flat sheet of CT, Connects muscles to bone

Deep Fascia

Separates different muscles while 

binding them together 

Superficial Fascia

Areolar and adipose tissue, Separates muscles from skin.  

Unipenate Muscle

Bipenate Muscle

Multipenate : branched tendon

Agonist

Prime mover muscle, Creates main movement

Antagonist

Opposes / Brings skeleton back to its original shape after movement from agonist

Synergist

a muscle that helps an agonist perform its movement. helps stabilize the skeleton.

The origin is the _____ point of attachment

fixed

The insertion is the _____ point of attachment

moving

During Myoblasts, muscle cells fuse to become

long muscle fibers

Some myoblasts become _________ , which support and repair muscle fibers

satelite cells

myoblasts

muscle making cells

Each muscle cell is a singular cell with ______

multiple nuclei

The entire muscle is wrapped in a layer of dense CT ______

epimysium

fascicles are surrounded by

perimysium

the ____ surrounds and reinforces every muscle fiber 

endomysium

muscle fibers are also called

muscle cells

sarcomere

the contracting unit of the muscle

Sarcoplasm

the ‘cytoplasm’ (fluid) of the sarcomere. contains organelles and myofibrils

Myofibrils

‘thick’ and ‘thin’ filaments

Sarcolema

the membrane of a muscle cell

invaginations in the sarcolema create ____

T-Tubules

Transverse Tubules (T-Tubules)

Run perpendicular to the myofibrils in a muscle cell. Runs deep and helps transmit electrical signals that move muscles using ion gated channels.

Actin

“thin filaments” have active sites where myosin bind onto

Myosin

“thick filaments” have heads that bind to active sites on actin

Z line

Where a sarcomere ends, and where a new one begins.

Thin filaments attach onto ______

Z-lines

Thick filaments attach onto ___

M-lines

M-line

the center attachment point for myosin in a muscle. anchors myosin and keeps the structural integrity of a muscle as it contracts.

Muscle fibers have abundant _____ for the large amount of energy they need to work

mitochondria

Myoglobin

a protein in the muscle cell that stores and transports oxygen (saves oxygen for aerobic atp production)

Lots of myoglobin in an animals meat can give it a _______ color

dark red

Sarcoplasmic Reticulum

Surrounds each myofibril. When a nerve impulse travels down the T-Tubules is triggered to release calcium into the sarcoplasm resulting in contraction

Terminal Cisternae

Sacs of SR found next to the T-tubules that serve as calcium reservoirs.

Calcium Pumps

Uses Active Transport (Transport against the gradient) using ATP to move calcium from the sarcoplasm back into the SR when the muscle is relaxed.

Calcium Channels

Voltage sensitive channels that respond to electrical signals from the T-Tubules. When they open calcium floods into the sarcoplasm. results in a contraction

G-Actin

individual actin proteins.

F-Actin

Formed when G-Actin strands come together. Like beads on a string. Made of 2 thin strands intertwined.

Tropomyosin

Protein that blocks receptor heads on the actin when the muscle is relaxed

Troponin

Protein bound to tropomyosin. When calcium binds to it, causes tropomyosin to move off of the active sites, so myosin heads can attach and cause contraction.

A band

The whole length of the thick filament.

H zone

the part of the thick filament with no thin filaments that overlap. shortens with muscle contraction

I band

thin filaments and Titin (elastic filament that anchors thin filaments). shortens with muscle contraction

during contraction myosin pulls on actin, creating an

overlap of the filaments, resulting in contraction.

Synapse

where a motor neuron meets a muscle cell

Synaptic cleft

the gap between the neuron and the muscle. where neurotransmitters travel

The motor neuron of a muscle is usually found at its __

center / mid region

Synaptic Knob / Vesicles 

Filled with ACh, calcium pumps, and channels in the membrane

1. When an AP (action potential) travels down a motor neuron ___

Ion channels on the neuron open, letting calcium in.

2. When calcium enters the neuron ___

Synaptic vesicles fuse with the synaptic membrane and releases ACh into the synaptic cleft (exocytosis)

3. When the ACh releases down the synaptic cleft ____

Binds to ACh receptors on ion gated channels on the muscle cell

4. When the ion gated channels on the muscle cell open

Sodium travels into the muscle fiber, and potassium exits the muscle fiber. The membrane becomes less negative

Acetylcholineesterase

breaks down ACh after neurotransmission ceases.

End plate potential (EPP)

Occurs when enough sodium has traveled into the muscle fiber and changes the charge of the motor end plate to be less negative

When the EPP has reached its threshold ____

an action potential is triggered down the sarcolemma, t-tubules and the SR

When an AP is triggered down the sarcolema ___

It travels down the T-tubules which open its calcium channels that flood into the muscle fiber, causing the filaments to slide past each other and contract.

Calcium binds to ______ which makes tropomyosin move out of the way so that the myosin heads can attach onto the actin

troponin

When ATP is on a myosin head ___

it hydrolyzes, and becomes ADP and inorganic phosphate

When ADP and Phosphate are on the Myosin head ___

It can bind to an actin receptor, creating a cross bridge.

The Powerstroke occurs when ____

The ATP and P from the myosin head release, and the head pulls to shorten the sarcomere (pulls actin inward)

The myosin detaches from the actin active site when ____ attaches to the myosin head

ATP. Head recocks and process can continue again. Tropomyosin also recovers the actin active site.

When muscle contraction stops, calcium is brought back into the SR using ____

active transport