Upgrade to remove ads
physiology lecture 10 questions/vocab
Terms in this set (65)
the wasting away of a body organ or tissue; any progressive decline or failure; to waste away
increase in muscle size/cell size
the enlargement of an organ or tissue because of an abnormal increase in the number of cells in the tissues
increase in number of cells
series elastic component
-tendons and connective tissue are elastic and absorb tension as the muscle contracts
-they recoil as muscle relaxes and spring back to resting length
refers to the activation of additional motor units to accomplish an increase in contractile strength in a muscle. A motor unit consists of one motor neuron and all of the muscle fibers it stimulates
increased force of contraction by a skeletal muscle fiber when a twitch occurs before the previous twitch relaxes
a quick cycle of contraction and relaxation when stimulus is at threshold or higher
A single quick, jerky muscular contraction from a single nerve impulse followed by relaxation.
a sustained muscular contraction resulting from a rapid series of nerve impulses
Muscle contracts but there is no movement, muscle stays the same length
muscle tenses but doesnt shorten
A muscle contraction that pulls on the bones and produces movement of body parts.
muscle contracts and shortens
A motor neuron and all of the muscle fibers it innervates
a motor neuron and all the muscle cells it stimulates
The resting length of a muscle and the tension the muscle can produce at this resting length.
Maximum oxygen uptake; most oxygen used when working the hardest you can
The point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production.
a cumulative deficit of oxygen resulting from intense exercise
the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose
stored in skeletal muscle and is used during anaerobic activity to prouce ATP with the assistance of the enzyme creatine kinase
found in muscle tissue; provides a rapid source of high-energy ATP for muscle contraction
Slow Twitch (Type I)
fibers such as those in the long muscles of the back, are often called red fibers because they contain the red, oxygen-storing pigment myoglobin. They contain many mitochondria, which is an adaption for the aerobic reactions of cellular respiration. These fibers have a high respiratory capacity and can generate ATP fast enough to keep up with the ATP breakdown that occurs when they contact. They can contract for long periods without fatiguing
Fast Twitch (Type II)
• Used for short bursts of strength or speed
fibers are also called white fibers because they have less myoglobin and have a poorer blood supply than red fibers. These fibers have fewer mitochondria and have a reduced respiratory capacity. However, they have more extensive sarcoplasmic reticulum to store and reabsorb calcium ions, and their ATPase is faster than that of red fibers. They contract rapidly, although they fatigue, lactic acid accumulates and as the ATP and the biochemicals to regenerate ATP are depleted
Fast-twitch glycolytic fibers (Type IIb)
white fibers / found in hands and eyes
- less myoglobin
- poorer blood supply
- fewer mitochondria = reduced respiratory capacity
- more SR
- susceptible to fatigue
An oxygen-storing, pigmented protein in muscle cells.
Extreme tiredness, exhaustion
physical and/or mental weariness resulting from exertion, that is, an inability to continue exercise at the same intensity with a resultant deterioration in performance
CPK (creatine phosphokinase)
cardiac or liver function
a drug that blocks nicotinic acetylcholine receptors
a neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle
a drug which keeps muscles from contracting and wrinkling the skin
neurotoxin injected into muscles of the face to prevent the muscles from contracting and causing wrinkles
What is atrophy?
Loss of muscle mass
How is the muscle structure changed in atrophy
There is a breakdown of actin and myosin
What causes atrophy
Atrophy results when the muscle fibers
do not receive neuronal stimulation.
What is hypertrophy
Increase in muscle mass
How is the muscle structure changed in hypertrophy?
More actin and myosin filaments are created within the muscle fiber
What causes hypertrophy
Excessive neuronal stimulation, as occurs with extensive muscular activity
What effect does aging have on muscle mass past middle age
Past middle age - mass slowly decreases, this is due to a gradual loss of neurons -> gradual loss of activation by ACh. And muscle loss is replaced by fibrous tissue and adipose tissue.
What is the effect of Botulinum toxin (Botox) on the NMJ
It prevents the exocytosis (release) of ACh
What does Black Widow venom do
Causes an explosive release of ACh
How does Curare (IntocostrinTm) work?
It is an antagonist and binds to ACh receptors, so blocks the activity of ACh.
What is a motor unit?
Any somatic motor neuron and all of the muscle fibers innervated by it
If a motor neuron reaches threshold do all of the fibers it innervates form action potentials
Do all the fibers in a motor unit fire in unison
Does a muscle have > 1 motor unit
Are all the motor units in a muscle the same size
Do all the motor units in a muscle have the same threshold
Is there a relationship between motor unit size and threshold
Yes, small motor units have lower
thresholds than larger motor units
Is there a relationship between motor unit size and function
Yes, small motor units give you a fine
degree of control i.e. your hands have many small motor units to control the fine moments of the
Does activating different #s of motor units give different levels of contraction strength
Yes, this is referred to as recruitment (just like with neurons)
How is it determined by you how many motor units should be activated
The brain estimates how many motor units you will need... more and more are activated until you get the desired effect
What part of your brain do you use to activate motor units
Motor cortex - the precentral
Can different fibers within a single motor unit be activated independently (asynchronously)
Can different motor units within a single muscle be activated independently
What is the difference between isotonic and isometric contractions
In isotonic contraction, the force/tension remains the same as the muscle shortens in length. In isometric contraction, there is no shortening, but more and more force/tension is generated.
Why is the lag time between stimulus and actual muscle shortening greater when lifting a rock than when lifting a feather
In both, there is an equal lag time in which the series elastic components need to be "tightened", however, when lifting the rock, more force/tension (isometric contraction) needs to be produced to be able to lift the rock before the isotonic contractions (shortening) will occur.
Can muscle cells generate ATP via aerobic and/or anaerobic metabolism?
Which is a more efficient use of fuel- ATP via aerobic or anaerobic metabolism?
Aerobic, uses oxidative phosphorylation pathway and can generate ~36-38 ATP molecules/ glucose
does atp via aerobic or anaerobic metabolism generate ATP faster
Anaerobic, which is the process
of glycolysis, will quickly generate 2 net ATP without O2.)
Under what circumstances does a
muscle use anaerobic metabolism and can it continue after its glycogen stores are used up
Anaerobic metabolism actually includes two different processes; glycolysis and fermentation.
Anaerobic metabolism is used in the first 45 to 90 seconds of moderate to heavy exercise, because
with these levels of exercise even the amount of oxygen stored in myoglobin is not enough to
convert all the pyruvate to ATP (so you are producing ATP from glycolysis and converting
pyruvate (pyruvic acid) to lactate (lactic acid) which is sent back to the liver via the
bloodstream). Anaerobic metabolism also occurs when you are at about 60% of the total
maximum oxygen uptake, in other words when a person reaches their "lactate threshold" (our
definition of heavy exercise). Anaerobic metabolism can continue after glycogen is used up
because the lactic acid (lactate) being sent back to the liver will be converted to glucose and sent
back to the tissues to be used in glycolysis.
Furthermore, most muscles are made up of a combination of fast glycolytic, fast oxidative and
slow oxidative fiber types (note that in a motor unit, all the muscle fibers will only be one type).
It is not unusual for the fast glycolytic fibers to be activated/recruited first in light exercise (recall
that these use primarily glycolysis and fatigue quickly) then as exercise proceeds in duration and
intensity, you will activate the fast oxidative and finally the slow oxidative fibers. As these later
fiber types use up their glycogen stores, lactate will be produced by them and fermentation will
What is the role of creatine-P in muscle metabolism
It is a fast way to create new ATP
molecules from ADP, in which the phosphate group from creatine-P is transferred directely to
the ADP molecule.
What are some of the suspected causes of muscle fatigue?
1. An increase in extracellular
potassium. 2. A change in the membrane potential which decreases the amount of Ca++ released
from the SR. 3. Depletion of ACh at the neuromuscular junction. 4. CNS control - the brain
decides that it is time to quit using the muscles, before all ATP is consumed
Are all the fibers within a muscle alike
What are the three types of muscle fibers
Slow twitch (Type I) AKA Slow oxidative, and fast-twitch (Type IIA) AKA fast oxidative and (Type IIX) AKA fast glycolytic
What is the main difference between fast and slow fibers
Resistance to fatigue and method of ATP production
What are the differences between the two types of fast fibers
Type IIA (fast oxidative) uses oxidative phosphorylation pathway and appear very white to pinkish in color. Type IIX (fast glycolytic) uses glycolysis and appears VERY white in color.
Why does one fast fiber appear red and the other white
The red (or pinkish) color is due the myoglobin in
the fibers, that is a pigment, like hemoglobin, and stores oxygen for fibers to use in the oxidative
phosphorylation pathway. The Type IIX rarely uses the oxidative phosphorylation pathway, and
therefore contains virtually no myoglobin, thus giving it the white appearance
Which fiber type fatigues the fastest
The fast-twitch, with Type IIX fatiguing the fastest
Which fiber type can generate ATP the fastest
The Type IIX fibers
What is the relationship between predominant fiber type in a muscle and its function
Slow twitch is for endurance, fast twitch is
for a lot of force quickly
Can a single motor unit have > 1 fiber type
No - all the fibers of a particular motor unit are believed to be composed of the same fiber type.
What 9 variables can you think of that can affect skeletal muscle contraction
1. # of motor units
2. Frequency of stimulation
3. Length of muscle at beginning of contraction
4. Use of muscle - state of atropy
6. Weight of load
7. Size of muscle
8. State of fatigue
9. Motor neuron damage
Recommended textbook explanations
Clinical Reasoning Cases in Nursing
Julie S Snyder, Mariann M Harding
Winningham's Critical Thinking Cases in Nursing
Barbara A Preusser, Julie S Snyder, Mariann M Harding
Winningham's Critical Thinking Cases in Nursing
Barbara A Preusser, Julie S Snyder, Mariann M Harding
Sets with similar terms
Physio Exam 2 Lecture 3
Chapter 11c: The Behavior of Whole Skeletal Muscles
Ch. 10 Muscles (part 2)
Other sets by this creator
physio lecture 25 questions and answers
physiology lecture 24 questions and vocab
physiology lecture 22 vocab and questions
physiology lecture 21 questions and vocab
Other Quizlet sets
Econ 100C test 1 practice
Math 001 Vocabulary and Questions
Pharmacology Final Prep