Week 3 Flashcards
What is the origin
The fixed point of attachment
Whats the insertion
Moveable point of attachment,usually distal to the origin
Whats a flexor
Muscles whose lines of action cross the anterior side of a joint
Eg.biceps brachili, triceps brachili
Whats an extensor
Muscles who’s lines of action cross the posterior side of a joint
What is a lever
A lever is a rigid structure of the moves on a fixed point called a fulcrum
What does an applied force result in
It results in an exerted force
What do lever systems change
The direction of an applied force
The distance and speed of movement produced bu the applied force
The magnitude of the exerted force relative to the applied force
Parallel muscles
The muscle fibre bundles are parallel to the long axis of the muscle
-attach to skeleton with little or no tendon
Eg sartorius muscle
Pennate muscles
The muscle fibre bundles are shorter than the muscle and run at an angle to the principal axis of the muscle
-attach to skeleton via and external tendon
Eg rectus femoris muscle (bipennate)
Function consequences of gross muscle architecture
Pennate muscles have a cross sectional area that is higher than thay of the parallel fibred muscle so has more force
Paralled fibred muscles can undergo longer length chanhes and can shorten more quickly
Whats fascicles
The muscles fibre bundles
Circular muscles
The muscle fibre bundles are concentrically arranged around an opening
They control the diameter od body openings or hollow organs
Moment equation
Moment=force x distance
Work equation
Work=force x distance
Power equation
Work/time
Muscle actively shorten=_________
Concentric contraction
Muscles as motors generate_____
Positive work and positive power
Muscles as brakes absorb_______
Absorb energy and generate negative power
Muscle actively lengthens=
Eccentric contraction
When muscles are brakes
Muscles as struts generate______
Force wirhout shortening (isometric contraction)
What is the heirarchal organisation in skeletal muscles
Whole muscle (connective tissue)
Muscle fibres
Myofibrils
Sarcomeres
Describe muscle fibres
10-100um
Often run full length
Bundles (fascicles)
Describe myofibrils
1-3um arranged in groups
Made up of sarcomeres
Describe sarcomeres
Muscle proteins (myosin and actin) assemble in to thick and thin filaments
Seperated by z disks
2:1 ratio of thick and thin filaments
What are the 3 layers of connective tissue:
Epimysium-covers the outside muscle
Perimysium-covers the fascocles
Endomysium-surrounds individual fibres
Thick filaments
Held in position by titin
Made up of myosin but different cross bridge cycling rates
Myosin
Has two heads (motor) (16nm) And a tail (155nm)
Thin filaments
- Made up of actin
- G actin is a globular protein;polymerises in to double stranded helix filamentous, F actin
- z disk contains alpha acitinin which anchors the tjin filaments
- nebulin holds the thin filament together
- thin filaments also contain the proteins tropomyosin and tropomin
Tropomyosin
Lies in the grooves of F actin
Sarcoplasmic reticulum
Forms a network of vesicular elements that surround the myofibrils
Calcium ions to calsequestrin in the terminal cisternae in relaxed muscle
When free calcium ions diffuses to the myofibrils and binds with Tn-C
Tm-C undergoes conformational change allowing cross bridges to form
What does activation mean?
Increase in calcium ions
Binding of Calcium ioma to troponin
Binding of cross bridges to actin and development of force
What does deactivation mean?
Decrease in calcium ions
Release of calcium ions from troponin
Release of crossbridges actin and decrease in force (relaxation)
Sliding filament hypothesis
Filaments
Dont change length
During contraction a band stays the same but z lines moce closer and i band fet smaller
Sarcomeres shorten ans myofibrils pulled toward its centre
Isometric twitches
Produced in repsonse to a single stimulus
Delay between stimulus and rise in force=
Latency period
The infraspinatus has its insertion on the:
- greater tubercle of the humerus.
- tuberosity of the radius.
- lesser tubercle and intertubercular groove of the humerus.
- clavicle and scapula.
- vertebral border near the spine.
-greater tubercle of the humerus.
Which of the following does not originate on the humerus?
- anconeus
- brachialis
- brachioradialis
- biceps brachii
- anconeus and brachioradialis
biceps brachii
Individuals who are engaged in repetitive hand movements such as typing or playing the piano may suffer wrist pain, especially during palmar flexion. All of the following are true concerning this condition except that it:
- is called carpal tunnel syndrome.
- results from inflammation of the synovial tendon sheaths.
- never causes muscle weakness.
- results from inflammation of the carpal retinacula.
- irritates the median nerve.
-never causes muscle weakness.
Which of the following controls adduction at the shoulder?
- supraspinatus
- subscapularis
- teres major
- infraspinatus
- teres minor
-teres major
In a ________ muscle, the fascicles are concentrically arranged around an opening.
- convergent
- parallel
- straight
- pennate
- circular
-circular
A muscle that assists another by preventing movement at another joint is called a(n)
- synergist.
- fixator.
- agonist.
- prime mover.
- antagonist.
-fixator
Nerves and blood vessels that service a muscle fiber are located in the connective tissues of its
- endomysium.
- perimysium.
- sarcolemma.
- sarcomere.
- myofibrils
-endomysium.
Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?
- epinephrine
- thyroid hormone
- testosterone
- parathyroid hormone
- calcitonin
-testosterone
The region of the sarcomere containing the thick filaments is the Z line. M line. H band. A band. I band.
A band
When acetylcholine binds to receptors at the motor end plate, the sarcolemma becomes
- more permeable to sodium ions.
- less permeable to sodium ions.
- more permeable to calcium ions.
- less permeable to potassium ions.
- less permeable to potassium and sodium ions
-more permeable to sodium ions.
The sequence of processes that links the action potential to contraction is called
- neuromuscular junction.
- action potential propagation.
- excitation-contraction coupling.
- cross bridge formation.
- sliding filament theory.
-excitation-contraction coupling.
he action potential is conducted into a skeletal muscle fiber by:
- motor end plates.
- neuromuscular junctions.
- transverse tubules.
- triads.
- sarcoplasmic reticulum.
-transverse tubules.
Which skeletal muscle fiber type?slow or fast?contains more mitochondria?
- slow
- fast
slow
The type of contraction where the tension exceeds the load is called:
- isometric contraction.
- isotonic eccentric contraction.
- isotonic concentric contraction.
- isometric concentric contraction.
- isometric eccentric contraction.
-isotonic concentric contraction.
A muscle that dorsiflexes the foot is the:
- tibialis anterior.
- tibialis posterior.
- peroneus brevis.
- soleus.
- gastrocnemius.
-tibialis anterior.
Muscles of the rotator cuff include all of the following except the
- supraspinatus.
- infraspinatus.
- subscapularis.
- teres minor.
- rhomboid.
-rhomboid.
The only knee flexor that originates superior to the acetabulum is the
- biceps femoris.
- gracilis.
- sartorius.
- iliopsoas.
- semimembranosus.
-sartorius.
Which quadriceps femoris muscle is not visible from the superficial anterior thigh? (Figure
- vastus lateralis
- vastus medialis
- vastus intermedius
- rectus femoris
- biceps femoris
-vastus intermedius
The ability of smooth muscle to function over a wide range of lengths is called
- elasticity.
- contractility.
- extensibility.
- plasticity.
- variability.
-plasticity
Which of the following is not characteristic of smooth muscle?
- The striations are due to the orderly arrangement of actin and myosin.
- Neurons that innervate smooth muscles are under involuntary control.
- Smooth muscle cells are uninucleate.
- Smooth muscles do not contain sarcomeres.
- The thin filaments of smooth muscle fibers are attached to dense bodies.
-The striations are due to the orderly arrangement of actin and myosin.
