Muscular system Flashcards
What’s another name for muscle cells?
Muscle fibers
What are the three roots that refer to muscles?
Myo,mys, and sarco
What are the 4 characteristics of muscle fibers?
Excitability, contractility, extensibility, and elasticity
What are the functions of the muscular system?
To produce movement, maintain posture and position, stabilize joints, generate heat, protect viscera, form valves, dilate pupils, and form the arrector pili
What are the three types of muscle?
Skeletal, cardial, smooth
What are the characteristics of skeletal muscle?
It’s multi-nucleated, striated, and voluntary
What are the characteristics of cardial muscle?
It’s uni-nucleated, striated, and involuntary
What are the characteristics of smooth muscle?
It’s uni-nucleated, involuntary, visceral, and not striated
What type of muscle is multi nucleated, striated, and voluntary?
Skeletal
What type of muscle is uni-nucleated, striated, and involuntary
Cardial
What type of muscle is uni-nucleated, involuntary, visceral, and not striated?
Smooth
Is each skeletal muscle an organ? Why?
Yes, each skeletal muscle is an organ because it contains things like contractile tissue, nerves, vessels, and connective tissue.
What does skeletal muscle contain?
Contractile tissue, nerves, vessels, and connective tissue.
What is each skeletal muscle served by?
One nerve, an artery, and one or more veins.
Where is the entrance and the exit of a skeletal muscle located?
Near the center and the branch
What type of muscle contains contractile tissue, nerves, vessels, and connective tissue?
Skeletal muscle
What type of muscle is serviced by one nerve, an artery, and one or more veins?
Skeletal muscle
What type of muscle has a rich blood supply? Why?
The skeletal muscle, because it needs lots of nutrients
What is another name for cell membrane?
Sarcolema
What is another name for sarcolema?
Cell membrane
What is another name for cytoplasm?
Sarcoplasm
What is another name for sarcoplasm?
Cytoplasm
What is another name for one contractile unit?
A sarcomere
What is another name for a sarcomere?
One contractile unit
What are the three types of tissue of the skeletal muscles?
The epimysium, perimysium, and endomysium
What connective tissue of the skeletal muscle is a dense irregular tissue and is considered the “overcoat”?
The epimysium
What connective tissue of the skeletal muscle surrounds the fascicles?
The perimysium
What are fasicles?
Fiber bundles
What are the fiber bundles of the skeletal muscle called?
Fasicles
What connective tissue of the skeletal muscle surrounds each muscle fiber?
The endomysium
What is the epimysium?
It’s a dense irregular tissue and is considered the “overcoat” of the skeletal muscle
What does the perimysium do?
It surrounds the fascicles of the skeletal muscle
What is the endomysium?
It’s a connective tissue that surrounds each muscle fiber of the skeletal muscle
How do muscles contract?
A fiber contracts, which makes the fibers shorten. Shortening occurs a little bit in each sarcomere, and fibrils pull on connective tissue which then moves other structures
What is the primary protein of the thin filaments?
Actin
What is actin?
The primary protein of the thin filaments
What covers up the binding sites when relaxed?
Tropomyosin
What does troponin bind to?
Tropomyosin, actin, and calcium
What is the sliding filament theory?
As actin is exposed, myosin binds
What is the function of the sarcoplasmic reticulum?
To store calcium ions
What stores calcium ions?
The sarcoplasmic reticulum
What surrounds each myofibril?
The sarcoplasmic reticulum
What is the sarcoplasmic reticulum?
The elaborate smooth ER of a muscle cell
Describe the sarcoplasmic reticulum
It’s the elaborate smooth ER of a muscle cell, it surrounds each myofibril, it’s associated with large numbers of mitochondria, and its major job is to regulate intracellular levels of calcium
What is the major job of the sarcoplasmic reticulum?
To regulate intracellular levels of calcium
What are the t-tubules?
It’s the tube of the sarcolemma that extends perpendicular to the muscle fibers
What is the tube of the sarcolemma that extends perpendicular to the muscle fibers?
The t-tubules
What forms a triad?
The sarcoplasmic reticulum and the t-tubules
What conducts nerve impulses into the deepest part of muscle?
The t-tubules
What do the t-tubules do?
They conduct impulses to the deepest part of the muscle and to each sarcomere
What are action potentials?
Nervous stimulations
What is a characteristic of nervous stimulations?
They’re all or none
What do action potentials do?
They send impulses along the sarcolema
What is the neuromuscular junction?
The place where the neuron and the muscle meet
What are the two parts of the neuromuscular junction?
The synaptic cleft and the neurotransmitter
What is the synaptic cleft?
The space between the axon and the sarcolemma
What is the space between the axon and the sarcolemma?
The synaptic cleft
What is a neurotransmitter?
The substance that carries the action potential across the synaptic cleft
What is the name of the muscle neurotransmitter?
Acetylcholine
What is acetylcholine?
The muscle neurotransmitter
What is the generation of potential on the sarcolemma?
Nervous stimulation
What happens during the generation of potential on the sarcolemma?
Acetylcholine is binded to the receptors
What is the sarcolemma’s original state?
Polarized
What happens during relaxation [of muscles]?
The sarcoplasmic reticulum reclaims calcium ions from the cytosol, the calcium releases from troponin, troponin changes shape and returns the tropomyosin, and the myosin releases from actin
What reclaims the calcium ions from the cytosol (pump)?
The sarcoplasmic reticulum
What changes shape during relaxation?
Troponin
What releases from the actin during relaxation?
Myosin
What is muscle tension?
The force exerted by contracting muscle
What is the force exerted by contracting muscle called?
Muscle tension
What is load?
The force opposing muscle contraction
What is the force opposing muscle contraction?
The load
What is isometric?
When the load is greater than the tension
What is it called when the load is greater than the tension?
Isometric
What is isotonic?
When the tension is greater than the load
What is it called when the tension is greater than the load?
Isotonic
How many nerves serve each muscle?
One nerve serves each muscle
What are nerves made up of?
Hundreds of neuronal axons
What do hundreds of neuronal axons make up?
A nerve
What are some characteristics of a neuronal axon?
Each neuronal axon branches many times
What does each branch of an axon form?
a neuromuscular junction (NMJ) with a single fiber
What is a motor unit?
A motor neuron and all the fibers it supplies
What is a motor neuron?
Part of a motor unit
How many fibers make up a motor unit?
Anywhere between four and hundreds
What is a muscle twitch?
The response of a motor unit to a single action potential
What is the response of a motor unit to a single action potential called?
A muscle twitch
What are the three phases of a muscle twitch?
The latent period, the period of contraction, and the period of relaxation
What happens during the latent period of a muscle twitch?
E-C coupling. It’s stimulated but no response yet
What happens during the period of contraction of a muscle twitch?
The cross bridges are active
What happens during the period of relaxation of a muscle twitch?
The SR reclaims
What do the mitochondria do in the muscles?
They turn glucose into ATP, but need oxygen to do so
What are the three metabolic processes of general muscle metabolism?
Creatine phosphate, glycolysis, and aerobic respiration
What does creatine phosphate give?
Creatine phosphate can give its phosphate to ATP
What do muscles store a lot of?
Creatine phosphate
How long can the use of creatine phosphate last?
14-16 seconds
What does creatine phosphate allow for?
It allows for a metabolic shift
What is the purpose of glycolysis? What is one unintended product.
To generate at least a little ATP, but it also creates lactic acid and oxygen debt
About how many ATP does glycolysis generate?
Around 2 ATP per glucose
What process generates lactic acid?
Glycolysis
What us the only drawback of aerobic respiration?
It requires more time, nutrients, and oxygen
What is the term for when the body switches over from aerobic respiration to anaerobic?
Aerobic endurance / anaerobic threshold
What is aerobic endurance/ anaerobic threshold?
When the body switches over from aerobic respiration to anaerobic
What is muscle fatigue most likely a result of?
The buildup of potassium in the t-tubules, which halts calcium release
Generally, what’s the pattern when it comes to how long it takes to recover from muscle fatigue?
The shorter duration of muscle fatigue equals a quick recovery and vice versa
What is oxygen used for when it’s restored after an oxygen deficit?
To restore muscle chemistry, replace muscle glycogen, and replenish creatine phosphate
What percentage of muscle activity is lost as heat?
60%
What percentage of muscle activity is actually used as work?
40%
What is muscle response graded by?
The frequency or strength
What is the force of contraction controlled by?
The number of fibers stimulated, the size of the stimulated fibers, and the frequency of stimulation
What happens during recruitment?
Multiple motor unit summation
Which fibers are recruited first?
Smaller muscle fibers are recruited first, biggest ones last
Why are fibers recruited from smallest to largest?
To allow for smooth and gradual muscular contractions
What does endurance exercise do to the body?
It increases the capillaries, mitochondria, and myoglobin
What does muscular hypotrophy/ resistance training do to the body?
It increases the muscle fiber size, and creates more mitochondria, myofilaments/fibrils, and causes the body to store more glycogen
What’s another name for muscular hypotrophy?
Resistance training
Where is smooth muscle found?
It lines hollow organs
How is smooth muscle organized?
In sheets
What are the two types of smooth muscle?*
Longitudinal and circular
What does smooth muscle allow for?*
Peristalsis
What are varicosities?
The swellings of nerves
What are the swellings of nerves called?
Varicosities
Compare the junctions of smooth muscle with that of skeletal muscle
Smooth muscle has diffuse junctions, and skeletal muscle has much more efficient junctions
What does smooth muscle lack that skeletal muscle has?
Smooth muscle lacks tissue sheaths, its sarcoplasmic reticulum isn’t as organized, and it doesn’t have t-tubules or striations
What are pacemaker cells?
They set the beat to which the whole muscle/ group of cells moves
How long does it take smooth muscle to contract and relax compared to skeletal muscle?
It takes 30 times as long as it takes the skeletal muscle to contract and relax
