BIOL 319 Laboratory 7: PowerLab Study on Muscle Structure, Function, and Electromyography

transducer

converts the signal of interest (BP, body temp) into an analog voltage

signal conditioning

process of modifying an amplification and filtering it; removing unwanted voltages

PowerLab unit

recording instrument that measures electrical signals through the inputs on its front panel

frequency

the number of occurrences of a repeating event per unit time

amplitude

height of the wave from baseline to crest

waveform

shape and form of a signal

wavelength

length from the crest of one peak to the crest of the next peak

What are the three types of muscle tissue?

skeletal, cardiac, smooth

skeletal muscles cells make up about what % of all cell mass?

40%

in an animal skeleton, the skeletal muscles do the majority of work in which two ways?

locomotion and support

each muscle is made up of __ organized in fascicles

muscle fibers (muscle cells)

upper motor neuron lesions

strokes damaging neurons in the brain

excitibility

electric charge differential that produces a an intracellular muscle response

contractibility

muscle cells contract when stimulated

extensibility

muscle cells can be stretched more than their resting length

elasticity

muscle cells, after being stretched, can recoil to their resting length

tendons

connective tissue that attaches bone to muscle

insertion

the bone or structure that is moving

origin

the bone or structure that mostly does not move

direct attachment

periosteum or perichondrium is fused with the muscle's epimysium

indirect attachments are ___

durable, smaller, and more common

example of an indirect attachment

aponeurosis or tendon

tendons

mostly collagen rope-like extensions of a muscle's connective tissue

aponeurosis

sheet-like extensions of a muscle's connective tissue

2+ muscles usually work in this manner

antagonistically

antagonist muscles explanation

as one muscle shortens and contracts, the antagonist muscle relaxes and elongates

sarcolemma

plasma membrane of a muscle fiber

sarcoplasm

cytoplasm of a muscle fiber

myoglobin

stores oxygen in muscle cells

glycosomes

granules of glycogen that can be broken down to supply ATP from glucose for energy

myofibrils

repeating units of sarcomeres; organelles that take up most of the intracellular volume of skeletal muscle cells

sarcomeres

smallest "Atomic" contractile units of skeletal muscle fibers

skeletal muscle is striated because of the ___ and ___

dark A bands and light I bands

H zone/band

middle region of the A band that is slightly lighter

Z line

I Band's dark midline region

Sarcomere runs from where to where?

Z line to Z line; each half I band to half I band with an A band in the middle

thick filaments contain the protein __ and run the length of the A band

myosin

when a muscle contracts, the globular myosin heads link the thick and thin filaments together making __ and swivel as motors to create force that shortens the sarcomere?

cross bridges

thin filament consists of a helix of two actin subunit strands plus the proteins __ and __

tropomyosin and troponin

elastic filaments, made of the protein __, run from Z Line to the thick filaments to hold them in place and provide flexible recoil to the sarcomere as it contracts, relaxes, and stretches

titin

Cross Bridge cycle

repeated sequential interactions between myosin and actin filaments at cross-bridges that cause a muscle fiber to contract

4 steps of the repeating cross bridge cycle

1. Binding- myosin head binds to an exposed myosin-binding site on actin

2. Power Stroke- ADP and inorganic phosphate are released from the myosin head, returning to its low-energy state

3. Detaching- ATP binds to myosin head, causing detachment

4. Cocking- Hydrolysis of ATP into ADP and inorganic phosphate repositions the myosin head in its high-energy configuration

sarcoplasmic reticulum

the very elaborate smooth ER in muscle

terminal cistern

large perpendicular cross channels formed by the sarcoplasmic reticulum

T tubules

elongated tubular extensions of the sarcolemma that dive deeply into the cell (allow electrical signal to be carried deep in the muscle to every sarcomere)

triad is made of what two things?

T tubules and terminal cisterns

polarization

a resting charge where the inside of the cell is more negative than outside

depolarization

events that make the inner surface of the sarcolemma less negative

when at resting potential (polarized), the outside of the sarcolemma/cell is positive OR negative due to a higher concentration of __ ions

positive; Sodium (Na+)

when at resting potential (polarized), the inside of the sarcolemma/cell is positive OR negative due to a higher concentration of __ ions and _

negative; Potassium (K+) and negatively charged proteins

sodium __, potassium __

out; in

depolarization begins at the end plate and is thus termed the ___

end plate potential

muscle action potential

sodium channels open and spread the signal in the form of a depolarization wave along the sarcolemma

repolarization

when the potassium channels opens, and the membrane becomes more negative as the positive K exits down the concertation gradient

steps of action potential

resting state, depolarization, repolarization, hyperpolarization

resting state

no ions move thru voltage-gated channels

depolarization

Na+ flowing into the cell

repolarization

K+ flows out of the cell

Hyperpolarization

K+ continuing to leave the cell

refractory period

while polarizing, the cell cannot be stimulated again until the membrane is sufficiently negative

excitation-contraction coupling

the events to the contraction of the muscle

cross bridge cycling

the movement of the myosin head to the active sites then releasing back to its original position and then attaching again

what occurs multiple times during a single muscle contraction?

cross bridge cycling

muscle tension

the force exerted by a contracting muscle on an objec t

load

opposing force applied on the muscle by mass of the object being moved

motor unit

the motor neuron and all of the individual muscle fibers that it innervates