Lab 6 Quiz

Recruited muscle cells

the central nervous system (CNS) is responsible for coordinating these muscle cells for a given movement

Somatic motor neurons

deliver messages by releasing the neurotransmitter acetylcholine to the muscle cells that need to be activated

Effectors

What step are the skeletal muscle cells in a negative feedback loop? Hint: They are structures that can act to adjust the system

Actin and Myosin

the location in muscle cells where force is actually produced is the bond between proteins

Sarcomeres

These contractile proteins (actin and myosin) are arranged within repeating patterns called

Myofibrils

Sarcomeres are arranged end to end along the length of the cell within structures called

Sarcoplasmic reticulum

myofibrils are surrounded by this structure

Calcium ions

like the endoplasmic reticulum in some cells, the sarcoplasmic reticulum is a membranous organelle that contains large quantities of

Sarcolemma

The membrane of the muscle cell is called the

Transverse tubules

Extensions that run deep into the cell, and allow an action potential to spread rapidly through the muscle cell

Muscular force or tension

Is generated by the interaction of the contractile proteins, actin and myosin Hint: The more actin-myosin bonds formed at any given point in time, the more

number of contractile proteins within that cell

The only way to increase the potential for generating force by a single muscle cell is to increase the

resistance or weight training

Protein synthesis is stimulated in skeletal muscle cells through

transcription factors

Steroid hormones serve as _____ to initiate the steps involved in protein synthesis

Upregulation

In muscle, when the rate of protein synthesis increases (________) more contractile proteins are produced and added to the myofibrils

size and number

Myofibrils will enlarge and split, leading to the increases in both _______ of these bundles of filaments (thick and thin) within the cell

hypertrophy

The enlargement of a whole muscle cell is called

atrophy

The loss of cell size, as seen when someone stops training, is in a cast, or spends time in outer space

somatic motor neurons

Muscle cells are innervated by

Fine motor skills

In muscles that are involved in ________ (tiny, well controlled movements) there is a low ratio of muscle cells to somatic motor neurons

gross motor skills

During ______ the large, powerful muscles (quadriceps muscles, gastrocnemius, biceps brachii) have a ratio that is much larger (one motor neuron may innervate 100 muscle cells)

motor unit

A single motor neuron and all of the muscle fibers it innervates is called a

motor unit summation

Increasing force by recruiting more and more motor units is referred to as hint: this is the primary way that you are able to adjust the amount of force your muscles produce to lift a weight

sarcomere

As the length of a cell changes, so does the length of the

Thin

The actin protein is found on the (thin/thick) filament.

thick

The myosin protein is found on the (thin/thick) filament

pre-stretch

When the muscle is active, lengthening or stretching the muscle just prior to shortening it will increase the force and power (force x velocity) of a contraction

Elastic component of muscle

The downward movement of the squat applies a stretch (pre-stretch) to the muscle that is going to propel you upwards. This pre-stretch takes advantage of the

Elastic energy (potential energy)

When myosin is attached to actin, the stretch pulls the head back, temporarily storing

Power stroke

Upon release of the stretch, the myosin head springs back, applying force that is added to the normal contraction process

series elastic energy

Support proteins within the cell, and connective tissue surrounding the cell also have elastic properties that can contribute to the _____ enhancement of contraction force

Contract

This word means to shorten and reduce in size

Isometric contraction

When there is no change in the length of an activated muscle it is referred to as an

Eccentric contraction or action

The lengthening muscle action is called an

eccentric

This word means away from the norm or center, not falling within the range of what is “normal”

Muscular fatigue

The inability to perform muscular work at a given level is

depletion of creatine phosphate (ATP-CP system)

When a weight lifer lifts a heavy weight or a runner sprints a 50- to 100-meter sprint for up to 10-15 seconds, but cannot continue at the same pace beyond that, the cause of fatigue is a

Accumulation of lactic acid

For activities such as a 400-meter sprint or other activities that can be sustained for up to 60-90 seconds at high to maximum work output, the cause of fatigue is an

CP depletion and lactate accumulation

The onset of fatigue between 20 and 60 seconds is usually a combination of

depleted

At some point in time (hours into the workout,) muscle glycogen stores are going to be

Gluconeogenesis

When this happens, the cells will break down protein to make glucose through

Liver

Where does gluconeogenesis occur?

Central fatigue

When proteins are contributing more and more to the energy demands of an activity, the person will experience

depleting glycogen stores (stored glycogen)

Some amino acids from protein degradation can cross the blood-brain barrier and cause the person to feel exhausted- that is central (as in CNS) fatigue, which is

strength

The ability to generate force

hand dynamometer

What we use to test our grip strength by squeezing this

force transducer

A dynamometer is a special ______ that detects that application of force and converts it to an electrical signal that the computer can process

kilograms (kg)

Force is measured through these units

Motor control

The sub-maximal test is actually a test of

Electromyography

The measurement of electrical activity of skeletal muscle is called

millivolts (mV)

The units for measurement of electrical activity

ions into and out of the cell

Electrical activity in cells is due to the movement of

Surface electrodes

This change in membrane potential charge will be monitored with hint: you place them on your skin

needle electrodes

Surface electrodes are less intimidating than

baseline

In figure 6.1, the middle line represents the

Troughs

The points labeled B1 and B2 are the lowest points below the baseline, which are called

minimum value

When interpreting a wave, the lowest point of the trough would contain the ______ of the entire wave

peaks

The points labeled A1-A3 are called the highest points above the baseline called

maximum value

The peak contains the ______ of the entire wave

Duration

You can measure how long a wave lasts (______) by measuring the distance from one point to another along the X-axis

Wave

You can measure the duration of one full ____ cycle by measuring the amount of time between one peak and the next, or between one trough and the next

frequency

Biopac can calculate the wave _____ which is the number of wave cycles that take place in a certain amount of time

cycles per second or Hertz

Frequency is usually reported in the units _______ or ____ (1 cycle/sec = 1 Hz)