PHYS 206 Exam 2 Questions With Answers
A+ Graded
Cardiac muscle - ANSWER striated and involuntary
Skeletal Muscle - ANSWER striated and voluntary
Smooth muscle - ANSWER not striated and involuntary
What are the properties of muscle - ANSWER contractility, excitability, extensibility,
elasticity
Contractility - ANSWER ability to generate force via contraction (shortening)
Excitability - ANSWER ability to respond to a stimulus
extensibility - ANSWER ability to stretch beyond resting length without being damaged
Elasticity - ANSWER ability to return to resting length after being stretched
What is the primary function of muscles - ANSWER to generate force (produce
movement)
What kind of movement does skeletal muscle deal with - ANSWER locomotion
What kind of movement does cardiac muscle deal with - ANSWER blood flow
What kind of movement does smooth muscle deal with - ANSWER move substances
within or out of the body
ex: blood, urine, and food
What is the secondary function of skeletal muscle - ANSWER - maintain posture
- stabilize joints
- generate (shivering is muscles contracting trying to generate heat)
How is skeletal muscle attached to bone and how does this causes joint movement -
ANSWER tendons
- contraction generates force on tendon which allows joint movement
Origin - ANSWER - point of muscle attachment that remains stationary
- closer to midline of the body
insertion - ANSWER - the place on the bone that moves during the action of the muscle
,- distal/further from the midline of the body
agonist - ANSWER prime mover of the action
antagonist muscle - ANSWER act on the same joint to produce opposite actions
can muscles push and pull - ANSWER NOOOOOO they can ONLY pull
what are muscle fibers bundled into - ANSWER fascicles
What covers the fascicles - ANSWER perimysium
What covers the muscle fibers - ANSWER endomysium
What is the epimysium? - ANSWER surrounds entire muscle connects to tendon allowing
contraction
What are the different types of parallel muscles and their location - ANSWER parallel =
abdominal muscles
fusiform = biceps brachii
parallel muscles - ANSWER - range of motion
- fascicles that are arranged in the same direction as the long axis of the muscle
Different types of pennate muscles and their location - ANSWER unipennate = digital
extensor
bipennate = rectus femoris
multipennate = deltoideus
Pennate muscles - ANSWER - able to generate more force because of their design
- orientated at an angle (like feathers)
Where are convergent muscles located - ANSWER pectoralis
Where are circular muscles located - ANSWER orbicularis oculi
myofiber - ANSWER - muscle cell
- striated
- multi-nucleated (nuclei are pushed to the edge)
Structure of a myofiber - ANSWER - myofibrils are bundled together and are covered in
the sarcoplasmic reticulum
- cell membrane is the sarcolemma (transverse tubules act as channels essentially)
- sarcoplasm (like cytoplasm)
,Sarcomere - ANSWER - functional unit of muscle contraction
- goes from z disc to z disc
- cause striations in skeletal and cardiac muscle
- point of attachment for thin filament
What is the largest protein - ANSWER - titin
- gives passive tension to the muscle
What happens during a muscle contraction - ANSWER - thin filament slides between
thick filament
- distance between z-discs shortens
- I bands (actin only) shorten
- H band (myosin only) shortens
- A band (actin/myosin overlap) does NOT shorten
What causes the sarcomere to shorten - ANSWER - Thick and thin myofilaments sliding
past one another, sliding filament mechanism
- cross-bridge is formed and a power stroke happens pulling thin myofilament to overlap
thick which shortens the sarcomere and generates force
Steps of the cross-bridge cycle - ANSWER 1. ATP binds to myosin head in low energy
configuration
2. ATP splits into ADP and Pi (ATP hydrolysis) energizing the mysoin head causing it to
move into high energy configuration
3. The myosin head attaches to the actin (thin filament) forming a cross-bridge
4. Pi is released which initiates a powerstroke pulling the actin myofilament towards the
m-line
5. New ATP molecule displaces the ADP causing myosin head to detach and go into low
energy configuration and get ready to repeat the cycle
How is cross-bridge formation regulated - ANSWER - tropomyosin lies in a groove along
the thin filament and blocks the active binding site during relaxation (low calcium
concentration)
- troponin is attached to tropomyosin
- when calcium is released from the sarcoplasmic reticulum it binds to troponin altering
the configuration and displacing tropomyosin
, - this exposes the active site allowing for cross-bridge to be formed
motor unit - ANSWER - A motor neuron and all of the muscle fibers it innervates
- each axon branches to innervate multiple fibers
- each muscle fiber receives a single axon terminal from its motor neuron
- motor neuron will only innervate one type of muscle fiber
Characteristics of motor units - ANSWER -All or none: when a motor neuron is activated,
all the muscle fibers it innervates are depolarized
-innervation ratio: ratio of motor neuron: muscle fibers (if the muscle is bigger there will
be more muscle fibers to generate more force)
-muscle fibers within a motor unit are spread throughout the muscle because they don't
all activate at the same time
-fibers of a motor unit are all the same fiber-type
What are the steps of excitation-contraction coupling - ANSWER 1. Somatic motor
neuron releases ACh
2. Binds to nicontinic receptors on the sarcolemma and open voltage-gated Na channels
3. Na diffuses in and depolarizes triggering an action potential
4. action potential travels down the transverse tubules and triggers the opening of
voltage-gated Ca channels to open
5. Ca is released from the sarcoplasmic reticulum
6. Ca binds to troponin which moves tropomyosin out of the way so a cross-bridge can
be formed stimulating contraction
How do muscles relax - ANSWER - action potential must cease
- ACh-esterase degrades ACh
-Ca release channels close
- Ca is pumpted against concentration gradient back into SR (has to use ATP for this)
HAVE TO GET RID OF CALCIUM
Myasthenia Gravis epidemiology - ANSWER - women 20-30 yrs. old
- men 50-60 yrs. old
- less than 200,000 patients in US
A+ Graded
Cardiac muscle - ANSWER striated and involuntary
Skeletal Muscle - ANSWER striated and voluntary
Smooth muscle - ANSWER not striated and involuntary
What are the properties of muscle - ANSWER contractility, excitability, extensibility,
elasticity
Contractility - ANSWER ability to generate force via contraction (shortening)
Excitability - ANSWER ability to respond to a stimulus
extensibility - ANSWER ability to stretch beyond resting length without being damaged
Elasticity - ANSWER ability to return to resting length after being stretched
What is the primary function of muscles - ANSWER to generate force (produce
movement)
What kind of movement does skeletal muscle deal with - ANSWER locomotion
What kind of movement does cardiac muscle deal with - ANSWER blood flow
What kind of movement does smooth muscle deal with - ANSWER move substances
within or out of the body
ex: blood, urine, and food
What is the secondary function of skeletal muscle - ANSWER - maintain posture
- stabilize joints
- generate (shivering is muscles contracting trying to generate heat)
How is skeletal muscle attached to bone and how does this causes joint movement -
ANSWER tendons
- contraction generates force on tendon which allows joint movement
Origin - ANSWER - point of muscle attachment that remains stationary
- closer to midline of the body
insertion - ANSWER - the place on the bone that moves during the action of the muscle
,- distal/further from the midline of the body
agonist - ANSWER prime mover of the action
antagonist muscle - ANSWER act on the same joint to produce opposite actions
can muscles push and pull - ANSWER NOOOOOO they can ONLY pull
what are muscle fibers bundled into - ANSWER fascicles
What covers the fascicles - ANSWER perimysium
What covers the muscle fibers - ANSWER endomysium
What is the epimysium? - ANSWER surrounds entire muscle connects to tendon allowing
contraction
What are the different types of parallel muscles and their location - ANSWER parallel =
abdominal muscles
fusiform = biceps brachii
parallel muscles - ANSWER - range of motion
- fascicles that are arranged in the same direction as the long axis of the muscle
Different types of pennate muscles and their location - ANSWER unipennate = digital
extensor
bipennate = rectus femoris
multipennate = deltoideus
Pennate muscles - ANSWER - able to generate more force because of their design
- orientated at an angle (like feathers)
Where are convergent muscles located - ANSWER pectoralis
Where are circular muscles located - ANSWER orbicularis oculi
myofiber - ANSWER - muscle cell
- striated
- multi-nucleated (nuclei are pushed to the edge)
Structure of a myofiber - ANSWER - myofibrils are bundled together and are covered in
the sarcoplasmic reticulum
- cell membrane is the sarcolemma (transverse tubules act as channels essentially)
- sarcoplasm (like cytoplasm)
,Sarcomere - ANSWER - functional unit of muscle contraction
- goes from z disc to z disc
- cause striations in skeletal and cardiac muscle
- point of attachment for thin filament
What is the largest protein - ANSWER - titin
- gives passive tension to the muscle
What happens during a muscle contraction - ANSWER - thin filament slides between
thick filament
- distance between z-discs shortens
- I bands (actin only) shorten
- H band (myosin only) shortens
- A band (actin/myosin overlap) does NOT shorten
What causes the sarcomere to shorten - ANSWER - Thick and thin myofilaments sliding
past one another, sliding filament mechanism
- cross-bridge is formed and a power stroke happens pulling thin myofilament to overlap
thick which shortens the sarcomere and generates force
Steps of the cross-bridge cycle - ANSWER 1. ATP binds to myosin head in low energy
configuration
2. ATP splits into ADP and Pi (ATP hydrolysis) energizing the mysoin head causing it to
move into high energy configuration
3. The myosin head attaches to the actin (thin filament) forming a cross-bridge
4. Pi is released which initiates a powerstroke pulling the actin myofilament towards the
m-line
5. New ATP molecule displaces the ADP causing myosin head to detach and go into low
energy configuration and get ready to repeat the cycle
How is cross-bridge formation regulated - ANSWER - tropomyosin lies in a groove along
the thin filament and blocks the active binding site during relaxation (low calcium
concentration)
- troponin is attached to tropomyosin
- when calcium is released from the sarcoplasmic reticulum it binds to troponin altering
the configuration and displacing tropomyosin
, - this exposes the active site allowing for cross-bridge to be formed
motor unit - ANSWER - A motor neuron and all of the muscle fibers it innervates
- each axon branches to innervate multiple fibers
- each muscle fiber receives a single axon terminal from its motor neuron
- motor neuron will only innervate one type of muscle fiber
Characteristics of motor units - ANSWER -All or none: when a motor neuron is activated,
all the muscle fibers it innervates are depolarized
-innervation ratio: ratio of motor neuron: muscle fibers (if the muscle is bigger there will
be more muscle fibers to generate more force)
-muscle fibers within a motor unit are spread throughout the muscle because they don't
all activate at the same time
-fibers of a motor unit are all the same fiber-type
What are the steps of excitation-contraction coupling - ANSWER 1. Somatic motor
neuron releases ACh
2. Binds to nicontinic receptors on the sarcolemma and open voltage-gated Na channels
3. Na diffuses in and depolarizes triggering an action potential
4. action potential travels down the transverse tubules and triggers the opening of
voltage-gated Ca channels to open
5. Ca is released from the sarcoplasmic reticulum
6. Ca binds to troponin which moves tropomyosin out of the way so a cross-bridge can
be formed stimulating contraction
How do muscles relax - ANSWER - action potential must cease
- ACh-esterase degrades ACh
-Ca release channels close
- Ca is pumpted against concentration gradient back into SR (has to use ATP for this)
HAVE TO GET RID OF CALCIUM
Myasthenia Gravis epidemiology - ANSWER - women 20-30 yrs. old
- men 50-60 yrs. old
- less than 200,000 patients in US
