muscles Flashcards
What happens to a muscle when it is used? (4)
gets larger, stronger, more resistant to fatigue and more efficient
What happens to a muscle when it is not used? (2)
muscle weakness and atrophy (wasting)
Give 4 common examples of aerobic or endurance exercises.
walking, jogging, biking and swimming
Give 3 changes that happen to a muscle when a person does aerobic or endurance exercises.
more capillaries, more mitochondria, and more myoglobin
What type of exercise results in muscle hypertrophy?
high intensity, resistance exercise
Give 2 common examples of resistance exercise.
weight lifting - low rep and heavy or isometric exercises
What happens within a muscle to make muscles hypertrophy?
increased size of individual fibers - more myofibrils, more mitochondria, more glycogenalso increased CT between fibers (possibly some splitting or tearing and regrowth using satellite cells - controversial)
What is a common term for someone who doesen’t work antagonistic muscle pairs evenly and they become awkward and inflexible?
muscle-bound
Why should a hard workout be followed by a day of rest?
to prevent overuse injuries
a degeneration and loss of mass in muscles from inactivity
disuse atrophy
How much muscle strength can be lost each day with disuse atrophy?
5% per day
What is lost or damaged muscle tissue replaced with?
fibrous CT - scar tissue
What are the 4 factors that determine the force of a muscle contraction?
- number of fibers
- size of the fibers
- frequency of stimulation
- degree of muscle stretch
What is the term for an enlargement of a muscle?
hypertrophy
What is the term for the force generated by the cross bridges in a muscle?
internal tension
What is the term for the force generated on the load or resistance by the entire muscle at the insertion?
external tension
What is the term for an increase in the force of contraction due to an increased frequency of stimulation?
summation of twitches or wave summation
the degree of overlap between thick and thin myofilaments can permit more or less sliding and therefore more or less force
length-tension relationship
What are two ways muscle fibers are classified?
- speed of contraction
2. how they make ATP
What are the two main types of fibers based upon speed of contraction, and what makes them different speeds?
fast twitch - ATPase works fast and Ca2+ is pumped quickly
slow twitch - ATPase works more slowly and Ca2+ isn’t pumped as quickly
What do we call the fibers that rely more on oxygen and aerobic respiration?
oxidative fibers
What do we call the fibers that rely more on anaerobic respiration?
glycolytic fibers
What are the three types of fibers based upon both speed and ATP generation?
slow oxidative
fast oxidative
fast glycolytic
Which muscle fiber is resistant to fatigue and has a high endurance but not a lot of power?
slow oxidative
Which muscle fiber tires quickly but has power?
fast glycolytic
Which muscle fiber is the most rare and has some traits of the other two?
fast oxidative (intermediate)
What determines which fibers predominate in a muscle?
Most muscles are mixtures that are genetically determined but can be altered by conditioning.
Who needs more fast glycolytic fibers, a marathon runner or sprinter?
sprinter
Who needs more slow oxidative fibers, a marathon runner or a sprinter?
marathoner
What is another name for the resistance to contraction?
load
How does load affect contraction speed?
more load makes contraction slower.
the inability to contract even when the muscle receives stimuli
fatigue
states of continuous contractions because the crossbridges don’t detatch when there is no ATO
contractures
What is a common example of a contracture that most people have experienced?
writer’s cramp
How long can a typical muscle work on its ATP reserves?
4-6 seconds
What is ATP?
adenosine triphosphate, usable energy in a cell made by respiration, the only energy used directly for cell activities
After the stored ATP is used, what are three ways it can be regenerated?
- creatine phosphate rephosphorylating ADP
- glygolysis (anaerobic respiration)
- aerobic respiration
a high energy molecule that stores phosphate to quickly phosphorylate ADP to ATP
CP - creatine phosphate
How much CP can be stored in a muscle? How long will the CP stored in a muscle last?
Muscle cells can store 2-3 times as much CP as ATP. It will last an additional 10 seconds for a total of 14-16 seconds with the ATP stored.
what is the term for the initial breakdown of glucose? What is glucose broken into? How much energy is produced?
glycolysis - 2 pyruvic acids makes 2 ATP
What is the difference between aerobic and anaerobic respiration?
aerobic uses oxygen and is more efficient (makes more energy or ATP) Aerobic is slower than anaerobic
What about muscle activity slows oxygen delivery?
Bulging muscles compress blood vessels.
What is the byproduct of anaerobic respiration, and what does it do to muscles?
lactic acid makes muscles tired and sore - some muscles are more tolerant of lactic acid buildup
What is the advantage of anaerobic respiration?
It is faster so when large amounts of energy are needed in a short time, it works best.
Where in the muscle does anaerobic respiration occur?
cytoplasm
Where in the muscle does aerobic respiration occur?
mitochondrion
What are the chemical products of aerobic respiration? How much energy is made?
carbon dioxide and water and 32 ATP per glucose
When exercise demands exceed the ability of muscle a muscle to do reactions to keep it supplied with energy and the muscle converts to anaerobic glycolysis, what has been reached?
anaerobic threshold
What three things must occur for a muscle to recover?
- breathe hard to recycle lactic acid and pay back the oxygen debt
- sweat to release excess heat
- pump ions like sodium, potassium, and calcium back to their resting locations
How is the CT component of smooth muscle different from that of skeletal muscle?
Smooth has much less CT, just a little endomysium
What are the two layers of smooth muscle? What does each do?
longitudinal - shortens and dilates the organand circular lengthens and constricts the organ
Together they mix and push materials through the lumen.
What is the name for the propulsive movement of smooth muscle?
peristalsis
What is the result of unwanted smooth muscle contraction in the stomach? the airways?
cramping - asthma
What portion of the nervous system innervates smooth muscle?
autonomic
How are the connections between autonomic fibers and smooth muscle different from the neuromuscular junctions of motor neurons and skeletal muscles? Give 5 differences.
called diffuse junctions
- numerous varicosities -large bulbous swellings
- wide cleft
- less developed SR
- no t-tubules - caveolae instead
- calcium comes from caveolae not SR
Give 6 ways smooth muscle is different from skeletal muscle.
- no striations
- no sarcomeres
- fewer thick myofilaments but they have myosin heads along their entire length so it can still be as powerful
- no troponin complex - calmodulin instead
- thick and thin myofilaments are arranged diagonally - spiral
- have non-contractile intermediate filaments with dense bodies attached to sarcolemma
How is the contraction of smooth muscle different from that of skeletal muscle? Give 7 ways
- slower - 30 times longer
- synchronized by gap junctions
- some cells act as pacemakers and set the rythm
- self-excitatory but can be modified by nerves and hormones
- can last much longer with much less energy used
- uses different neurotransmitters with different outcomes
- can contract without neural stimulation at all
How is the contraction of smooth muscle similar to the contraction of skeletal muscle? Give 3 ways.
- sliding filaments of actin and myosin
- calcium is the trigger
- ATP provides the energy
Sarcoplasmic Reticulum
The ER of a muscle cell or fiber
Skeletal muscle
Cylindrical, multinucleate, striated, voluntary muscle found attached to bones
Sliding filament theory
The explanation of how muscle contracts, think myofilaments pull and slide along thin myofilaments
Smooth muscle
Fusiform (tapered at both ends), uninucleate, non-striated, involuntary muscle found in hollow internal structures that move other than the heart
Striated
Banded or striped in appearance due to alteration of thick and thin filaments
the study of muscles
myology
the four characteristics of muscle
contractility, excitability, elasticity, extensibility
the ability of a muscle to shorten
contractility
the ability of a muscle to respond to a nerve
excitability
the ability of a muscle to stretch
extensibility
the recoil ability of muscle to snap back to its original position
elasticity
the muscles that work in opposition to one another - give examples
antagonists - biceps and triceps and quadriceps and hamstrings
the striped or banded appearance of some muscle tissue
striations
What causes muscle to appear striated
alternating thick and thin myofilaments
the protein that builds thick myofilaments
myosin
What is the shape of a myosin molecule
golf club
the protein that builds the majority of the thin myofilaments
actin
What is the shape of the actin molecule?
G actin - globular (spherical)
F actin - filaments (threads) of G actin
What are the two regulatory proteins on the thin myofilaments?
troponin and tropomyosin
Which regulatory protein is the site of calcium binding?
troponin
What happens when calcium lands on the troponin?
The troponin bends and moves the tropomyosin
the contractile unit of skeletal muscle, goes from z-line to z-line
sarcomere
the line of protein fibers that holds thick myofilaments together
M-line
the protein filaments that hold the thin myofilaments together
Z-line
the length of the thick myofilaments, darker
A band
the region between the thick myofilaments
I band