Skeletal Muscle tissue Flashcards
What are 4 functions of skeletal muscle
- Voluntary movement 2. Sphincters regulate release of urine and feces 3. Body temperature regulation 4. Protection
What are 5 characteristics of muscle tissue
- Excitability 2. Conductivity 3. Contractility 4. Extensibility 5. Elasticity
Excitability
exhibits a resting state from which it can be excited
Conductivity
able to receive/carry impulses
Contractility
able to forcibly shorten from resting length
Extensibility
Able to extend beyond resting length
Elasticity
returns to resting length following shortening/lengthening
What are the levels of organization of a muscle
- Muscle 2. Fascicle 3. Muscle fiber 4. Myofibrils 5. Myofilaments
Muscles contain
Fascicles
Fascicles contain
Muscle fibers
Muscle fibers contain
Myofibrils
Myofibrils contain
Myofilaments
Muscles are surrounded by
Epimysium
Fascicles are surrounded by
Perimysium
Muscle fibers are surrounded by
Endomysium
What are the 2 types of muscle tissue attachments
- Tendons 2. Aponeurosis
Tendon
Cord of dense regular CT
Tendons attach
muscles to bone
Aponeurosis
Thin sheet of CT
Aponeurosis attach
muscles to bone and sometimes other muscles
Point of origin
Less moveable site of attachment for a muscle
Point of insertion
More moveable site of attachment
What is the plasma membrane of a muscle cell
sarcolemma
What carries electrical impulse in a muscle cell
t-tubules
Where are t-tubules found
attached to the sarcolemma
What is the cytoplasm of a muscle cell
sarcoplasm
What are the thick bundles of proteins capable of contracting muscle cells
myofibrils
What are the 2 types of myofibrils
- Thick filaments 2. Thin filaments
Thick filaments
composed of myosin
Thin filaments
composed of actin, troponin, and tropomyosin
What stores and releases calcium in muscle cells
Sarcoplasmic reticulum
Because muscle cells have high energy demand they have lots of what 4 things
- Mitochondria 2. Myoglobin 3. Glycosomes 5. Creatinine phosphate
Myoglobin
binds oxygen
Glycosomes
stores glucose
Creatinine phosphate
used for immediate energy
Each thick myofilament has two ____ and two _____ wrapped around each other
heads and tails
Thick myofilaments have binding sites for ____ and ____
actin and ATP
The binding site for myosin on thin myofilaments is located on
actin
What protein in thin myofilaments is used to prevent binding when at rest
tropomyosin
What protein in thin myofilaments is used to expose binding sites on actin to allows binding
Troponin
When myosin binds to actin what happens
muscle contraction
What is the basic contractile units of muscle
Sarcomere
What gives muscles its striated appearance
sarcomere
What is the ends of the sarcomere
Z disc
Muscle fibers exhibit
Resting membrane potential
Resting Membrane Potential
resting state exhibited by excitable cells
RMP of a muscle cell at rest
-90 mV
A muscle membrane is considered _____ at rest
polarized
Skeletal muscles fibers at rest have a high concentration of ____ and ______
extracellular sodium and intracellular potassium
The inside of a skeletal muscle fiber at rest is
negatively charged
Where is intracellular calcium stored
sarcoplasmic reticulum
Sarcomeres are in a ______ state when the muscle fiber is at rest
relaxed
Skeletal muscle is innervated by
somatic motor neurons
Motor unit
single somatic motor neuron and all muscle fibers it servers
Smaller motor units =
more control
Larger motor units =
less control
The specific location where a motor neuron innervates a muscle cell
Neuromuscular junction
What are the 3 components of a NMJ
- Synaptic knob 2. Synaptic cleft 3. Motor end plate
Synaptic knob
end of somatic motor neuron
Synaptic cleft
space between neuron and muscle cell
Where are neurotransmitters released
Synaptic cleft
Motor end plate
region of sarcolemma that contains neurotransmitter receptors
In the termination of muscle contraction what enzyme is release to breakdown ACh in the synaptic cleft
Acetylcholinesterase
In the termination of muscle contraction calcium returns where
Sarcoplasmic reticulum
In the termination of muscle contraction ______ returns to relaxed state
sarcomeres
Muscle cells can only store enough ATP for how much activity
5 seconds
What are the 3 ways to generate ATP in skeletal muscle
- Immediate supply via phosphate transfer 2. Short-term supply via glycolysis 3. Long-term supply via aerobic cellular respiration
Immediate supply via phosphate transfer provides how much energy
10 seconds
What two sources can provide a phosphate for Immediate supply
- Creatinine phosphate 2. ADP
Does Immediate supply require oxygen
No
How many ATP are produced from immediate supply
1
How much energy does short-term supply provide
60 seconds
Short-term supply is also known as
glycolysis
Short-term supply converts glucose to
pyruvate
Does glycolysis require oxygen
No
How many ATP does short-term supply provide
2
How much energy does long-term supply provide
from the 50-60 second mark until contraction ends
Where does long-term supply occur
mitochondria of cells
What is long-term supply also known as
cellular respiration
What does long-term supply break down
pyruvate
Does long-term supply require oxygen
yes
How many ATP does long-term supply yield
30
Oxygen debt
amount of oxygen needed to restore muscle to resting conditions
Why does oxygen debt occur
the body’s demand for oxygen exceeds the body’s ability to deliver it to the cells
Muscle fibers are classified by what 2 criteria
- Type of contraction generated 2. Means of supplying ATP
What are the 2 types of classifications under type of muscle contraction generated
- Slow-twitch fibers 2. Fast-twitch fibers
What are the 2 types of classifications under means of supplying ATP to muscle
- Oxidative fibers 2. Glycolytic fibers
What are the 3 types of muscle fibers
- slow oxidative fibers (red) 2. Fast glycolytic fibers (white) 3. Fast oxidative fibers (pink)
Slow oxidative fibers or “marathon” fibers use mostly _______ means of ATP production
aerobic
Slow oxidative fibers are _______ to fatigue
slow
Fast glycolytic fibers use mostly ______ means of ATP production
anaerobic
Fast glycolytic fibers are ______ to fatigue
quick
What type of exercise results in increased muscle vascularization, increased # of mitochondria, and stimulates myoglobin synthesis
Cardiovascular exercise
what type of exercise results in muscle hypertrophy, increased strength, increased endurance, and increased bone density
Resistance exercise
Little/no exercise leads to muscle ______
atrophy
The overload principle
forcing a muscle to work hard promotes increased muscle strength and endurance
What are the 2 types of muscle contraction
- Isometric contraction 2. Isotonic contraction
Isometric contraction
muscle contracts but produces no movement
Isotonic contraction
muscle contracts and produces movement
What are the 2 types of Isotonic contraction
- Concentric 2. Eccentric
Concentric
Shortens
Eccentric
lengthens
Calcium binds to ______ to displace tropomyosin and expose binding sites on actin
troponin
