chapter 8 and 9

Example of lever action

--Bending and straightening of upper limb at elbow •During bending, forearm bones act as rigid bar •Elbow joint acts as fulcrum •Hand moves against resistance provided by weight/load •*** Third-class lever; arranged in resistance-force-fulcrum sequence

Excitation-Contraction Coupling

-Connection between muscle fiber stimulation and muscle contraction •During muscle relaxation: oCa2+ ions are stored in SR oTroponin-tropomyosin complexes cover binding sites on actin filaments •Upon muscle stimulation: oMuscle impulses cause S R to release Ca2+ ions into the cystol oCa2+ ion binds to troponin to change its shape oEach tropomyosin is held in place by a troponin molecule; change in shape of troponin alters the position of tropomyosin oBinding sites on actin are now exposed oMyosin heads bind to actin, forming cross-bridges

•Distinguish between fast and slow twitch muscle fibers- Fast

-Fast-twitch fatigue-resistant fibers (Type IIa): •Intermediate twitch fibers •Intermediate oxidative capacity •Intermediate amount of myoglobin •White fibers •Resistant to fatigue •Rapid ATPase activity -Fast-twitch glycolytic fibers (Type IIb): •Anaerobic respiration (glycolysis) •White fibers (less myoglobin) •Poorer blood supply than slow-twitch fibers •Fewer mitochondria than slow-twitch •More SR than slow-twitch- amount of calcium to unraviel and allow for more contractions to occur. •Susceptible to fatigue •Fast ATPase activity; contract rapidly

Interaction of Skeletal Muscles

-Most skeletal muscles function in groups, and we see different roles taken: i.Agonist: Muscle that causes an action ii.Prime mover: Agonist primarily responsible for movement (In some cases, the terms "agonist" and "prime mover" are used interchangeably) iii.Synergists: Muscles that assist agonist/prime mover iv.Antagonist: Muscles whose contraction causes movement in the opposite direction of the prime mover Fixator = muscle that holds the scapular firmly in place

body movement

-When bones or body parts move, bones and muscles act as levers -4 basic components of levers: 1.Rigid bar or rod (bones) 2.Fulcrum or pivot on which bar moves (joint) 3.Object moved against resistance (weight/load) Force that supplies

• Compare the contraction mechanisms of skeletal and cardiac muscle cells

-striations (smooth lacks striations) -actin and myosin - mononucleated

•Be able to identify each type of joint movement by description or if given a type of joint movement, be able to show and describe the associated movement

1 Flexion 2 Extension 3 Hyperextension 4 Lateral flexion 5 Abduction 6 Adduction 7 Dorsiflexion 8 Plantar flexion 9 Circumduction 10 Rotation 11 Medial rotation 12 Lateral rotation 13 Supination 14 Pronation 15 Inversion 16 Eversion 17 Protraction 18 Retraction 19 Elevation 20 Depression

muscle contraction

1. The impulse arrives at the synapse and travels through the T. tubules. 2. The muscle impulse reaches the SR and Ca2+ is released. 3. Ca2+ floods the sarcoplasm and binds to troponin molecules leaving active sites. 4. Myosin heads bind to exposed active sites on actin, forming cross-bridges. 5. Thin filaments are pulled over the thick filaments. 6. The muscle fiber shortens and contracts.

• Distinguish between the structures and functions of multiunit smooth muscle and visceral smooth muscle

1.Multi-unit Smooth Muscle: •Cells are less organized •Function as separate units •Fibers function independently -Examples: Iris of eye, walls of blood vessels •Stimulated by neurons, hormones 2. Visceral Smooth Muscle: •Single-unit smooth muscle; cells respond as a unit •Sheets of spindle-shaped muscle fibers •Fibers held together by gap junctions •Exhibit rhythmicity •Conduct peristalsis ( eating and digestion) •Walls of most hollow organs •More common type of smooth muscle

Cross-Bridge Cycling

1.Myosin head attaches to actin binding site, forming cross-bridge 2.Myosin cross-bridge pulls thin filament toward center of sarcomere 3.ADP and phosphate are released from myosin 4.New ATP binds to myosin 5.Linkage between actin and myosin cross-bridge break 6.ATP splits 7.Myosin cross-bridge goes back to original position, ready to bind to another binding site on actin

•List the energy sources necessary for skeletal muscle fiber contraction

1st Choice: ATP Reserves •"Go To" for energy for muscle contraction •Limited: cells store a small amount (2 seconds) 2nd Choice: Creatine Phosphate •Initial source of energy to regenerate ATP from ADP and P •Energy = phosphate bond (like ATP) •ATP + creatine phosphate can only fuel ~10 seconds of intense muscle contraction 3rd Choice: Cellular Respiration •Must be used to fuel longer periods of muscle contraction •Breaks down glucose to produce ATP •Glucose stored as glycogen in muscle cells

Slightly movable

Amphiarthrotic

Oxygen supply and cellular respiration

Anaerobic (Lactic Acid) Threshold: oShift in metabolism from aerobic to anaerobic, during strenuous muscle activity, when the above systems cannot supply the necessary O2 oLactic acid is produced a. Anaerobic reactions of cellular respiration yield few ATP molecules, whereas aerobic reactions of cellular respiration provide many ATP molecules. b. Hemoglobin in red blood cells carries oxygen from the lungs to body cells. c. Myoglobin in muscle cells temporarily stores some oxygen

Plantar flexion

Ankle movement which points toes downward

Dorsiflexion

Ankle movement which points toes upward

Lateral flexion

Bending to the side

H zone

Center of A band; composed of thick myosin filaments

M line

Center of sarcomere and A band; anchors thick filaments

•Distinguish among the six types of synovial joints and provide an example of each type

Classified by shape and movements they allow They are all Diarthrotic ( freely moveable) 1) Ball-and-Socket Joint 2) Condylar Joint 3) Plane Joint 4) Hinge Joint 5) Pivot Joint 6) Saddle Joint

A band

Dark band; thick myosin filaments with portions overlapped with thin actin filaments

Atrophy

Decrease in size and strength if unused

Freely movable (hip, elbow and shoulder)

Diarthrotic

•Describe oxygen debt

During rest or moderate exercise, respiratory and CV systems supply enough O2 Oxygen Debt: oMost of O2 in strenuous exercise is used to produce ATP for muscle contraction, not for converting lactic acid to glucose oAt end of strenuous exercise, muscles may be left with O2 debt oThis is amount of oxygen needed by liver cells to convert the accumulated lactic acid to glucose, and to restore muscle ATP and creatine phosphate concentrations

Hypertrophy

Enlargement resulting from exercise

Hyperextension

Extension beyond normal anatomical position

Pronation

Forearm rotation so palm faces downward or backward, or lying down face down (prone)

describe how a muscle may become fatigued

Inability to contract muscle •Common causes of muscle fatigue: oDecreased blood flow oIon imbalances across the sarcolemma oAccumulation of lactic acid (controversial) a. Athletes usually have an increased ability to supply oxygen and nutrients to muscles.

•Explain how various types of muscular contractions produce body movements & help maintain posture

Isometric isotonic

I band

Light band; thin actin filaments

Depression

Lowering a body part

Protraction

Movement of a body part forward

Circumduction

Movement of a part of body in circular path

Lateral rotation:

Movement of limb so anterior surface moves away from midline

Medial rotation

Movement of limb so anterior surface moves toward midline

•Rotation:

Moving a part of body around an axis

Abduction

Moving a part of body away from midline (with the fingers and toes the middle phalanx is the midline)

Adduction

Moving a part of body toward midline

Interaction of Skeletal Muscles in a bicep curl

Prime Mover: (agonist) = biceps brachii Synergist = brachialis Antagonist = triceps brachii Fixator = muscle that holds the scapular firmly in place such as the rhomboideus

Elevation

Raising a body part

Z line (Z disc)

Sarcomere boundary; in center of I band anchors filaments in place

•Distinguish between fast and slow twitch muscle fibers- slow

Slow-twitch fibers (Type I): •Always oxidative •Resistant to fatigue •Red fibers •Abundant myoglobin •Good blood supply •Many mitochondria •Slow ATPase activity •Slow to contract

Extension

Straightening of parts at a joint

Immovable

Synarthrotic

Eversion

Turning of foot so plantar surface faces away from midline

Inversion

Turning of foot so plantar surface faces midline

•Distinguish the differences between a twitch and a sustained contraction- twitch

Twitch: •Contractile response of a single muscle fiber to a single impulse •Twitch Time Periods: a.Latent period: Delay between stimulation and start of contraction b.Period of contraction: Fiber pulls at attachments c.Period of relaxation: Pulling force decreases

. Recording of a muscle contraction

a. A twitch is a single, short contraction of a muscle fiber. b. A myogram is a recording of the contraction of an electrically stimulated isolated muscle or muscle fiber. c. The latent period is the time between stimulus and responding contraction. d. The length to which a muscle is stretched before stimulation affects the force it will develop. 1. Normal activities occur at optimal length. 2. Too long or too short decreases force. e. Sustained contractions are more important than twitch contractions in everyday activities.

heat production

a. Muscular contraction generates body heat (shivering in cold or due to fever/change in set point). b. Most of the energy released by cellular respiration is lost as heat.

Recruitment of motor units

a. One motor neuron and the muscle fibers associated with it constitute a motor unit. b. Muscles whose motor units have few muscle fibers produce finer movements. c. Motor units respond in an all-or-none manner. d. At low intensity of stimulation, relatively few motor units contract. e. At increasing intensities of stimulation, other motor units are recruited until the muscle contracts with maximal tension. •A motor neuron plus all of the muscle fibers it controls •A whole muscle consists of many motor units •Coarse movements are produced with large #'s of fibers in a motor unit •Precise movements are produced with < muscle fibers in a motor unit

relaxation

a.Acetylcholinesterase rapidly decomposes acetylcholine remaining in the synaptic cleft, preventing continuous stimulation of a muscle fiber. b. The muscle fiber relaxes when calcium ions are transported back into the sarcoplasmic reticulum. c. Cross-bridge linkages break and do not re-form, then the muscle fiber relaxes. -When neural stimulation of muscle fiber stops •Acetylcholinesterase (enzyme) rapidly decomposes ACh remaining in the synapse. •Muscle impulse stops when ACh is decomposed. •Stimulus to sarcolemma and muscle fiber membrane ceases. •Calcium pump moves Ca2+ back into sarcoplasmic reticulum (SR). •Troponin-tropomyosin complex again covers binding sites on actin. •Myosin and actin binding are now prevented. •Muscle fiber relaxes until ..........

sarcomere shorten and lengthen..

but microfilaments will not change in size but may move

•Describe how joints are classified by tissue type and degree of movement possible at a joint

categorized by structure and function Joint (Articulation): •Functional connections between bones •Join the parts of the skeletal system together -Purpose: •Enable the body to respond to skeletal muscle contractions without breaking •Make bone growth possible Ease the stress of childbirth Structural Classifications: •Fibrous: Held together by dense connective tissue •Cartilaginous: Held together by cartilage (hyaline and fibrocartilage) •Synovial: Have a complex structure Functional Classifications: •Synarthrotic: Immovable •Amphiarthrotic: Slightly movable •Diarthrotic: Freely movable (hip, elbow and shoulder)

Hyperflexion

chin goes down to chest

Anaerobic Phase

does not use oxygen •Glycolysis •Occurs in cytoplasm •Produces little ATP

Origin end and exmaple

less movable end a. Coracoid process b. Supraglenoid tubercle

Forceful exercise stimulates

mainly fast-twitch fibers; in response, fibers produce new actin and myosin filaments, and the muscle enlarges

Insertion end and example

more movable end a: Radial tuberosity

Retraction

movement of a body part backward

•Describe the neural control of skeletal muscle contraction (NMJ)

myoneural junction •A type of synapse •Site where an axon of motor neuron and skeletal muscle fiber interact •The stimulation by a motor neuron is the only way to initiate sk. muscle contraction

Aerobic exercise stimulates

slow-twitch fibers; in response, fibers increase their capillaries and mitochondria

threshold stimulus

the minimal stimulus needed to elicit a muscular contraction.

Aerobic Phase:

uses oxygen •CAC and ETC •Occurs in the mitochondria •Produces the most ATP Myoglobin stores extra oxygen in muscles

Stimilus

•Acetylcholine (ACh) is the neurotransmitter •Mechanism: 1.Nerve impulse causes release of ACh from synaptic vesicles 2.ACh binds to ACh receptors on motor end plate 3.ACh causes changes in membrane permeability to Na+ and K+ ions, which generates a muscle impulse (action potential) 4.Impulse causes release of Ca2+ ions from SR, which leads to contraction

Condylar Joint

•Also called ellipsoidal joint •Oval condyle fits into elliptical cavity •Back-and-forth, side-to-side movement •Biaxial movement, no rotation example: Joints between metacarpals and (proximal) phalanges

Plane Joint

•Also called gliding joint •Almost flat, or slightly curved •Back-and-forth and twisting •Nonaxial movement example: Wrist and ankle joints

Saddle Joint

•Also called sellar joint •Both bones have concave and convex surfaces •Biaxial movement (in 2 planes) example:Carpal and metacarpal of thumb

Ball-and-Socket Joint

•Also called spheroidal joint •Round head in cup-shaped cavity •Widest range of motion •Multiaxial, plus rotation example: Hip, shoulder

Pivot Joint

•Also called trochoid joint •Cylindrical surface rotates within ring of other bone •Uniaxial movement •Rotation only example: Atlas (C1) and dens of axis (C2)

•Describe the shoulder joint and explain how its articulating parts are joined together

•Ball-and-socket •Head of humerus and glenoid cavity of scapula •Loose joint capsule •Ligaments prevent displacement •Glenoid labrum •Several bursae •Very wide range of movement, including rotation, circumduction •Major ligaments of the shoulder joint: 1.Coracohumeral ligament 2.Glenohumeral ligaments 3.Transverse humeral ligament

•Describe the hip joints and how their respective articulating parts are joined together

•Ball-and-socket joint •Head of femur and acetabulum of hip bone •Acetabular labrum •Heavy joint capsule •Many reinforcing ligaments •Variety of movements, yet less than at shoulder joint •Major ligaments of the hip joint: 1.Iliofemoral ligament (strongest ligament) 2.Pubofemoral ligament Ischiofemoral ligament

Synchondrosis

•Bands of hyaline cartilage unite bones •Synarthrotic •Some are temporary, such as epiphyseal plate (ossification converts this to a synostosis) •Some are permanent, such as between manubrium and the first rib (costal cartilages)

Flexion

•Bending of parts at a joint

Syndesmosis

•Bones bound by a sheet of dense connective tissue (interosseous membrane) or a bundle of dense connective tissue (interosseous ligament) •Amphiarthrotic (flexible, may twist) example: between tibia and fibula

Gomphosis

•Cone-shaped bony process in a socket •Synarthrotic (immovable) •Root of a tooth in maxilla or mandible held in place by periodontal ligament

•Explain how cartilaginous joints hold bones together and name an example of each type of cartilaginous joint

•Connected by hyaline cartilage or fibrocartilage •There are 2 types of cartilaginous joints •Synchondrosis •Symphysis

Hinge Joint

•Convex surface fits into concave surface of other bone •Uniaxial movement (in 1 plane) example: Elbow, joints between phalanges

Supination

•Forearm rotation so palm faces upward or forward, or lying down face up (supine)

•Explain how fibrous joints hold bones together and provide an example of each type of fibrous joint

•Held together with dense connective tissue containing many collagen fibers •Found in bones with close contact Suture and Gomphosis are synarthritic Syndesmosis is amphriarthrotic 3 types of fibrous joints: 1.Syndesmosis 2.Suture 3.Gomphosis

•Describe the elbow joints and how their respective articulating parts are joined together

•Hinge Joint: Between trochlea of humerus and trochlear notch of ulna -Flexion/extension only •Plane (gliding) joint: -Between capitulum of humerus and fovea on head of radius -Pronation/supination -Several reinforcing ligaments •Major ligaments of elbow joint: 1.Radial collateral ligament 2.Ulnar collateral ligament Anular ligament

A sarcomere consists of these 5 structures:

•I band •A band •H zone •Z line (Z disc) •M line

Compare the contraction mechanisms of skeletal and smooth muscle cells

•Interaction between actin and myosin •Both use calcium and ATP •Both are triggered by membrane impulses

Describe the knee joints and how their respective articulating parts are joined together

•Largest and most complex synovial joint *Consists of 3 bones: 1. Femur: Medial and lateral condyles of distal end 2. Tibia: Medial and lateral condyles of proximal end 3. Patella: Articulates with anterior surface of femur •Strengthened by many ligaments and tendons •Cushioned by bursae, fat pads •Menisci separate femur and tibia •Modified hinge joint between condyles of femur and tibia •Plane joint between femur and patella •Movements: Flexion/extension, and some rotation when knee is flexed *Major Ligaments: 1. Patellar ligament 2.Oblique popliteal ligament 3.Arcuate popliteal ligament 4.Tibial (medial) collateral ligament 5.Fibular (lateral) collateral ligament 6.Anterior cruciate ligament (ACL) 7.Posterior cruciate ligament

Isotonic:

•Means "equal force" •Muscle contracts and changes length - body weight workouts : squat or pushup •2 Types: oConcentric: shortening contraction; occurs when lifting an object oEccentric: lengthening contraction; occurs when force not sufficient to lift object

•Describe or sketch the general structure of a synovial joint

•Most joints are synovial •All are diarthrotic joints •More complex than fibrous or cartilaginous •Articular cartilage covers articular ends of bones •Joint capsule consists of 2 layers: -Outer fibrous layer, composed of ligaments -Inner layer, synovial membrane, which secretes synovial fluid •Articular cartilage •Joint capsule •Ligaments •Synovial membrane •Synovial cavity •Synovial fluid •Meniscus (-i) in some joints •Bursa (-ae) in some joints knee is an example

Parts of the Neuromuscular Junction

•Motor neuron: controls sk. muscle fibers •Motor end plate: Specialized folded portion of sk. muscle fiber that binds to a neurotransmitter •Synaptic cleft: Space between neuron and muscle fiber where the neurotransmitter travels •Synaptic vesicles: Membrane-bound sacs of neurotransmitters •Neurotransmitters: Chemicals released by motor neuron to signal the muscle fiber

•Explain how skeletal muscles produce movements at joints

•Movement at a synovial joint occurs when a muscle contracts, and its fibers pull the insertion toward the origin -Origin: Relatively fixed end of a skeletal muscle -Insertion: More movable end of a skeletal muscle

•Name the major parts of a skeletal muscle fiber and describe the functions of each part

•Multinucleated •Sarcolemma: Cell membrane of muscle fiber •Sarcoplasm: Cytoplasm of muscle fiber •Sarcoplasmic reticulum (SR): The ER of muscle; stores calcium •Many myofibrils: oLong, parallel structures that run down fiber oConsist of thin actin filaments and thick myosin filaments oSarcomeres: Units that connect end-to-end, to make up myofibrils •Transverse ("T") tubule: Relays electrical impulses to the SR •Triad: Unit consisting of 1 T tubule and 2 SR cisternae striations are made from thin and thick filaments -Thin filaments: •Composed of actin protein •Associated with troponin and tropomyosin, which prevent cross-bridge formation when muscle is not contracting -Thick filaments: •Composed of myosin protein •Heads form cross-bridges with thin filaments -Contraction •Requires interaction from several chemical / cellular components •Results from a movement within the myofibrils, in which the actin and myosin filaments slide past each other, "shortening" the sarcomeres •Muscle fiber shortens and pulls on attachment points

Isometric

•Muscle contracts but does not change length •Means "equal length" •Tension develops, but parts attached to muscle do not move example: wall sit

importance of origin and insertion

•One end of a skeletal muscle is more fixed (origin) and the other end is more movable (Insertion) : •When a muscle contracts, insertion is pulled toward origin

•Describe the structure of a skeletal muscle, the tissues associated with it, and striations seen

•Over 600 skeletal muscles in the body •Are organs of the muscular system •Attached to bones, and skin of face •Under conscious control (voluntary) -Skeletal muscles are composed of: •Skeletal muscle tissue •Nervous tissue •Blood - Connective tissue -Connective Tissue coverings over skeletal muscles: •Fascia: Thin covering around a muscle (more to come) •Tendon: Thick, cord-like mass that connects muscle to bone •Aponeurosis: Thin layers creating a sheet-like mass that connects a muscle to bone, skin, or another muscle Connective tissue in and closely surrounding a muscle: •Epimysium: surrounds whole muscle; lies beneath fascia •Perimysium: surrounds fascicles within a muscle. •Endomysium: surrounds muscle fibers (cells) within a fascicle

Symphysis

•Pad of fibrocartilage between bones •Articular surfaces covered by hyaline cartilage •Amphiarthrotic (limited movement) •Pubic symphysis •Joint between bodies of adjacent vertebrae (intervertebral discs)

The Sliding Filament Model

•Sarcomeres shorten as thick and thin filaments slide across each other but do NOT change length •Overlap between filaments increase -H zones and I bands narrow -Z lines move closer together

•Name and describe the three types of muscle

•Skeletal muscle: -Attached to bones of skeleton and skin -Voluntary •Cardiac muscle: -Makes up most of the wall of the heart -Involuntary -Responsible for pumping action of the heart •Smooth muscle: -Found in walls of internal organs, such as those of digestive tract -Involuntary •Body Movement •Maintaining Posture •Joint Stability •Heat Production •Blood Circulation

•Distinguish the differences between a twitch and a sustained contraction- Sustained Contractions

•Smaller motor units (smaller diameter axons) - recruited 1st •Larger motor units (larger diameter axons) - recruited later •Summation and recruitment can produce sustained contractions of increasing strength •Whole muscle contractions are smooth movements oMuscle tone (tonus): Continuous state of partial contraction in resting muscles

Differentiate the contraction mechanisms of skeletal and smooth muscle cells

•Smooth muscle lacks troponin; uses calmodulin instead •Two neurotransmitters affect smooth muscle: Acetylcholine (Ach) and Norepinephrine (NE) •Hormones can stimulate or inhibit smooth muscle •Stretching can trigger smooth muscle contraction (Food and water consumption) •Smooth is slower to contract and relax •Smooth is more resistant to fatigue -Smooth can change length without changing tautness

suture

•Thin layer of connective tissue (sutural ligament) connects bones •Synarthrotic (immovable) between flat bones of skull