AP LECTURE Exam 4

Origin

The attachment of a muscle’s tendon to the STAIONARY bone (usually PROXIMAL)

Insertion

The attachment of the muscle’s other tendon to the MOVABLE bone (usually DISTAL)

How do muscles produce movement?

• Most skeletal muscles produce movement by exerting a force on tendons, which then pull bones or other structures

• Most muscles cross one joint (sometimes 2; 2 joint muscles) and they can create movement at joints they cross

Agonist (Prime mover)

Contracts to cause an action

Antagonist

Stretches and yields to the effects of the agonist

What is an example of Agonist & Antagonist?

When flexing the elbow, the biceps is the agonist and the triceps is the antagonist.

Name the muscles of the RESPIRATION/BREATHING group

Diaphragm, internal & external intercostals

Name the muscles of the ABDOMINAL group

Rectus abdominis, Transverse abdominis, external obliques, and internal obliques

Name the muscles of the ROTATOR CUFF group

Supraspinatus, infraspinatus, teres minor, and Suprascapularis

Name the muscles of the HIP ADDUCTORS group

Gracilis, adductors longus, adductor magnus, and pectineus

Name the muscles of the GLUTEAL group

Gluteaus maximus, gluteus medius, and gluteus minimus

Name the muscles of the QUADRICEPS

Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius

Name the muscles of the HAMSTRINGS

Bicep femoris, semitendinosus, and semimembranous

Masseter

• One of the strongest muscles in the body

Describe the ACTION of the MASSETER

Elevates and protracts the mandible; closes the mouth

What is the ORIGIN of the STERNOCLEIMASTOID?

Manubrium and sternal end of clavicle

What is the INSERTION of the STERNOCLEIMASTOID?

mastoid process (temporal bone)

Describe the ACTION of the STERNOCLEIMASTOID

• Bilateral contraction - Flexes the neck

• Unilateral contraction - Lateral flexion to its own side and rotation of the opposite side

What does the diaphragm separate?

Thoracic and abdominal cavities

Describe the ACTION of the DIAPHRAGM

Contracts during inspiration and relaxes during expiration

What is the ACTION of the RECTUS ABDOMINIS?

Trunk flexion and compression of abdomen

What is the deepest abdominal muscle?

Transverse abdominis

What is the ACTION of the EXTERNAL OBLIQUES?

Bilateral trunk flexion and unilateral lateral flexion and rotation of the trunk (to opposite side)

What is the ACTION of the INTERNAL OBLIQUES?

Bilateral trunk flexion and unilateral lateral flexion and rotation of trunk to same side

What is the ACTION of the TRAPEZIUS?

Elevation and depression of scapula; rotation & retraction of head

What is the ACTION of the LATISSIMUS DORSI?

Extension, adduction, and medial rotation of shoulder

What is the ORIGIN of the PECTORALIS MAJOR?

Medial clavicle, sternum, and ribs

What is the INSERTION of the PECTORALIS MAJOR?

Intertubercle groove of humerus

What is the ACTION of the PECTRAOLIS MAJOR?

Adduction, flexion, and medial rotation of shoulder

What is the ACTION of the DELTOID?

Adduction, flexion, and rotation of the shoulder

What is the ACTION of the SUPRASPINATUS?

Abduction of the shoulder

What is the ACTION of the INFRASPINATUS?

Lateral rotation of the shoulder

What is the ACTION of the TERES MINOR?

Adducts and laterally rotates shoulder

What is the ACTION of the SUBSCAPULARIS?

Medial rotation of the shoulder

What is the ACTION of the BICEPS BRACHII?

Flexion and supination of elbow/forearm

What is the ACTION of the TRICEPS BRACHII?

Extension of elbow/forearm; extension and adduction of the shoulder

What is the ACTION of the SARTORIUS?

Flexes hip and knee; laterally rotates hip

What is the ACTION of the INNER THIGH MUSCLES?

Adduction of thigh

What is the ACTION of the GLUTEAL MUSCLES?

Responsible for hip extension

What is the ACTION of the RECTUS FEMORIS?

Flexion of hip and extension of knee

What is the ACTION of the VASTUS LATERALIS, MEDIALIS, and INTERMEDIUS?

Extension of knee

What is the ACTION of the HAMSTRINGS?

Flexion of knee and extension of hip

What is the ACTION of the GASTROCNEMIUS?

Plantarflexion of ankle (and flexion of knee)

What is the ACTION of the TIBIALIS ANTERIOR?

Dorsiflexion of foot

What muscles are 2 jointed?

Biceps brachii, triceps brachii, sartorius, rectus femoris, biceps femoris, and gastrocnemius

What are the functions of the muscular system?

• Producing body movement

• Stabilizing body positions

• Protection & support

• Storing/moving substances within the body

• Generate heat

What are the properties of muscular tissue?

• Electrical excitability & conductivity

• Contractility

• Extensibility

• Elasticity

Why is elasticity so important of muscular tissue?

It helps the muscle to return to original length and shape after contraction or extension

What are the different types of muscle tissue?

Skeletal, cardiac, and smooth

What are the characteristics of the skeletal muscle?

• Striated

  • Light and dark protein bands

• Multinucleated

• Voluntary

What are the characteristics of the cardiac muscle?

• Striated

  • Light and dark protein bands

• Single nucleus

• Involuntary

What are the characteristics of the smooth muscle?

• Found in the walls of internal hollow structures such as blood vessels

• Non-striated

• Single nucleus

• Involuntary

What 3 connective tissue layers are present in muscle tissue?

Epimysium, perimysium, and endomysium

Epimysium

Outermost layer of dense irregular CT that encircles entire muscle

Perimysium

Surrounds groups of muscle fibers/bundles called fascicles (dense irregular CT)

Endomysium

Separates and surrounds individual muscle fibers (thin sheath of areolar CT)

Somatic motor neurons

Neurons that penetrate a skeletal muscle

What characteristics are unique to SKELETAL MUSCLES?

• Multinucleated

• Cannot undergo cell division

Multinucleated

Each mature skeletal muscle fiber has a hundred or more nuclei (groups of embryonic myoblasts fuse to form single skeletal muscle fibers)

What are the components of the Skeletal muscle fiber?

• Sarcolemma (transverse tubules)

• Sarcoplasm

• Myofibrils (sarcoplasmic reticulum)

• Myofilaments (actin & myosin)

• Sarcomere

Sarcolemma

Plasma membrane of a muscle cell

Transverse tubules

Ensures that action potentials excite all parts of muscle fiber at the same instant

Sarcoplasm

Contains myoglobin (protein found only in muscle that releases oxygen needed by the mitochondria for ATP production)

Myofibrils

• Contractile organelles of skeletal muscle

• 80% of the contents of each muscle fiber

Sarcoplasmic reticulum

Store calcium ions that when released, trigger a muscle contraction

Myofilaments

Smaller muscle protein structures within myofibrils

Thick filaments

Formed from bundles of hundreds of myosin protein molecules

Thin filaments

Composed of 2 strands of the actin protein

Sarcomere

Myofilaments within the myofibril are arranged in repeating units/compartments called sarcomeres (basic functional units of the myofibril)

What are the components of the sarcomere

• Z-discs

• A-band

• I-band

• H-zone

• M-line

Z-discs

Narrow regions of dense material that separate one sarcomere from the next

A-band

Dark, middle part of sarcomere that extends the length of the thick filaments and parts of thin filaments that overlap with thick filaments

I-band

Lighter area of sarcomere that contains rest of the thin filaments, but no thick filaments

H-zone

Narrow region in center of each A band that contains thick, but no thin filaments

M-line

Region in center of H zone that contains proteins at center of the sarcomere

Tropomyosin

When skeletal muscle is relaxed, it prevents myosin from binding to actin (covers the myosin binding sites on the actin)

Troponin

Allows myosin to bind to actin, enabling a muscle contraction

What’s the difference between tropomyosin & troponin?

tropomyosin relaxes muscle, troponin contracts muscle

What is the muscle hierachy?

Myosin & actin protein molecules > myofilaments > sarcomere > myofibrils > muscle fiber > fascicle > muscle

What are the components of the neuromuscular junction?

• Synaptic knob

• Motor plate

• Synaptic cleft

Synaptic knob

End of motor neuron and contains synaptic vesicles filled with acetylcholine (neurotransmitter)

Motor end plate

Region of the sarcolemma of a muscle fiber that contains acetylcholine receptors

Motor unit

Consists of a somatic motor neuron plus all of the skeletal muscle fibers that stimulates/control

Resting membrane potential

The relative difference in charge across the plasma membrane of a cell

What is the steps for excitation of skeletal muscle fiber?

• Propagation of nerve signal

• Release of acetylcholine

• Binding of acetylcholine

Propagation of nerve signal

Triggers calcium to move down its concentration gradient into the synaptic knob and bind to the synaptic vesicles

Release of acetylcholine

When calcium binds to synaptic vesicles, this triggers the release of acetylcholine into the synaptic cleft

Binding of acetylcholine

Acetylcholine diffuses across the synaptic cleft and binds to the receptors in the motor end plate > causes excitation of a muscle fiber

How is the end plate developed at the motor end plate?

Acetylcholine (Ach) binds to the Ach receptors in the motor end plate of a skeletal muscle fibers > sodium diffuses into the skeletal muscle fiber & potassium diffuses out

How does depolarization happen in muscle tissue?

1. Sodium channels open in the sarcolemma

2. Sodium moves into the muscle fiber

3. The side of the muscle fiber becomes positive

How does repolarization happen in muscle tissue?

1. In response to the opening of the sodium channels, potassium channels open

2. Potassium moves out of the muscle fiber

3. The negative resting membrane potential is restored

What does the sarcoplasmic reticulum release?

Calcium into the sarcoplasm

What are the steps to calcium binding?

1. Calcium that is released from the sarcoplasmic reticulum binds to troponin

2. Changes shape

3. Tropomyosin is moved and the myosin binding sites of the actin are exposed

What are the steps of crossbridge cycling?

1. Crossbridge formation

2. Power stroke

3. Release of the myosin head

4. Reset of the myosin head

Crossbridge formation

1. Myosin head attaches to actin

2. Crossbridge forms between the thick and thin filaments

Power stroke

Thin filaments pull past the thick filaments toward the center of the sarcomere

Sliding filament theory

• When the thick and thin filaments slide past one another (no not shorten)

What are the steps of the sliding filament theory?

1. H zone disappears

2. I band narrows and may disappear

3. Z discs move closer together

4. The sarcomere shortens

What are the steps of muscular contraction?

1. Action potential travels down motor neuron

2. Calcium binds to synaptic vesicles (in neuron)

3. Triggers release of acetylcholine

4. Acetylcholine binds to motor end plate (of muscle fiber)

5. Sodium moves in and potassium moves out of muscle fiber

6. Action potential travels along sarcolemma (T-tubules)

7. Ca released from sarcoplasmic reticulum into sarcoplasm

8. Ca binds to troponin

9. Myosin attaches to actin

10. Thin filaments slides past thick filament

11. Sarcomere shortens (contraction)

What are 3 ways muscle fibers can produce ATP

• Phosphagen system

• Anaerobic cellular respiration

• Aerobic cellular respiration