1. MOVEMENT/LOCOMOTION OF BODY
2. STABILIZE BODY POSITION/POSTURE
3. STORAGE & MOVEMENT OF SUBSTANCES WITHIN BODY: URINE, LYMPH, BLOOD
4. PRODUCE HEAT (THERMOGENESIS) THAT HELPS TO REGULATE BODY TEMPERATURE

TRUE OR FALSE:

ENTIRE MUSCLES LIKE THE BICEPS BRACHII ARE ORGANS WITH BLOOD VESSELS, NERVES & LYMPHATICS

TRUE OR FALSE:

SKELETAL MUSCLE TISSUE IS CALLED SKELETAL BECAUSE IT MOVES MOST OF THE BONES OF THE SKELETON

TRUE OR FALSE:

SKELETAL MUSCLE HAS LONG CYLINDRICAL FIBERS WITH A PARALLEL ARRANGEMENT AND MANY ADAPTATIONS FOR CONTRACTIONS

TRUE OR FALSE:

THE EPIMYSIUM, PERIMYSIUM, AND ENDOMYSIUM CTs ARE ALL CONTINUOUS WITH EACH OTHER; THE COLLAGEN IN THESE LAYERS ATTACHES TO PERIOSTEUM OF BONE AND TO OTHER CT ASSOCIATED WITH MUSCLE

MESODERM → MYOBLASTS → SKELETAL MUSCLE FIBERS

MYOBLASTS FUSE; SKELETAL MUSCLE IS A MULTINUCLEATED SYNCYTIUM

TRUE OR FALSE:

AFTER FUSION NO MITOSIS OCCURS IN SKELETAL MUSCLE; THE NUMBER OF MUSCLE FIBERS IN AN INDIVIDUAL IS ESSENTIALLY SET BEFORE BIRTH

TRUE OR FALSE:

DURING EMBRYONIC DEVELOPMENT, MANY MYOBLASTS FUSE TO FORM ONE SKELETAL MUSCLE FIBER

• INVAGINATIONS OF SARCOLEMMA FROM SURFACE TO CENTER OF FIBER
• OPEN TO OUTSIDE OF FIBER AND FILLED WITH INTERSTITIAL FLUID
• THEY CARRY THE MUSCLE ACTION POTENTIAL (AP) TO ALL PARTS OF THE FIBER
• REACH EACH MYOFIBRIL

• LOCATED WITHIN THE SARCOLEMMA
• THE CYTOPLASM OF A MUSCLE FIBER
• CONTAINS A SUBSTANTIAL AMOUNT OF GLYCOGEN
• ALSO CONTAINS A RED COLORED PROTEIN-MYOGLOBIN WHICH BINDS O₂ 
• MITOCHONDRIA LIE IN ROWS THROUGHOUT

• CONTRACTILE ORAGANELLES OF SKELETAL MUSCLE
• THREAD-LIKE APPEARANCE
• RUNS THE ENTIRE LENGTH OF THE MUSCLE
• EACH HAS THICK & THIN PROTEIN FILAMENTS
• APPEAR STRIPED/STRIATED DUE TO THE SPECIFIC ARRANGEMENT OF THE PROTEIN FILAMENTS (ka MYOFILAMENTS)

• SER OF MUSCLE
• STORES Ca⁺² IN MUSCLES RELAXED STATE AND RELEASES IT FROM TERMINAL CISTERNS TO TRIGGER MUSCLE CONTRACTION
• HAS ACTIVE TRANSPORT PUMPS AND RELEASE CHANNELS FOR Ca⁺² 
• HANGS LIKE A LOOSE SLEEVE AROUND EACH MYOFIBRIL
• SWOLLEN ENDS ARE CALLED TERMINAL CISTERNS

TRUE OR FALSE:

ALTHOUGH EACH MYOFIBRIL RUNS THE ENTIRE LENGTH OF THE MUSCLE, THICK & THIN FILAMENTS DO NOT. FILAMENTS ARE ARRANGED IN COMPARTMENTS CALLED SARCOMERES

TRUE OR FALSE:

BOTH THICK AND THIN FILAMENTS ARE DIRECTLY INVOLVED IN THE CONTRACTILE PROCESS

TRUE OR FALSE:

MYOSIN IS A MOTOR PROTEIN THAT CONVERTS ATP'S CHEMICAL ENERGY TO MECHANICAL ENERGY TO PRODUCE FORCE 

TRUE OR FALSE:

MYOSIN HEADS ALSO HAVE ATP BINDING POCKETS AND ATPase

TRUE OR FALSE:

MYOSIN HEADS HAVE AN ENERGIZED AND UNENERGIZED POSITION; ENERGY IS FROM ATP

TRUE OR FALSE:

ACTIN IS ASSOCIATED WITH THE 2 REGULATORY PROTEINS TROPONIN & TROPOMYOSIN

TRUE OR FALSE:

INDIVIDUAL ACTIN MOLECULES JOIN TO FORM A TWISTED HELIX

TRUE OR FALSE:

EACH CROSS-BRIDGE ROTATES TOWARD THE M LINE AND GENERATES FORCE THAT PULLS THE THIN FILAMENT PAST THE THICK FILAMENT; MYOSIN HEADS BIND SUCCESSIVE BINDING SITES ON ACTIN, PULLING ACTIN CLOSER & CLOSER TO THE M LINE AT THE CENTER OF THE SARCOMERE 

TRUE OR FALSE:

THOUSANDS OF INDIVIDUAL SARCOMERES ARE ARRANGED END TO END & RUN THE LENGTH OF THE MUSCLE; AS ALL THE SARCOMERES SHORTEN, THE ENTIRE MUSCLE SHORTEN/CONTRACTS; I BAND LOOKS SMALLER IN FULLY CONTRACTED MUSCLE

1. ATP HYDROLYSIS
2. ATTACHMENT OF MYOSIN TO ACTIN TO FORM CROSSBRIDGES
3. POWER STROKE
4. DETACHMENT OF MYOSIN FROM ACTIN

• ATP BINDS MYOSIN HEAD AT ATP BINDING SITE; ATPase IS PRESENT:ATP→ADP+PHOSPHATE+ENERGY
• THIS ENERGIZES & REORIENTS THE MYOSIN HEAD
• ADP & PHOSPHATE REMAIN ATTACHED TO MYOSIN

• ENERGIZED MYOSIN HEAD ATTACHES TO ACTIN (BOUND HEADS ARE REFERRED TO AS CROSSBRIDGES)
• PHOSPHATE IS RELEASED

• MYOSIN HEAD ROTATES/SWIVELS INWARD TOWARD THE CENTER OF THE SARCOMERE
• THIS GENERATES FORCE THAT PULLS ON THE ACTIN SO IT SLIDES INWARD PAST THE MYOSIN

• MYOSIN IS STILL ATTACHED TO ACTIN
• MYOSIN BINDS ANOTHER ATP
• ONLY AFTER A NEW ATP BINDS WILL THE MYOSIN DETACH FROM ACTIN

TRUE OR FALSE:

THE CONTRACTION CYCLE REPEATS FOR AS LONG AS THERE IS Ca⁺² & ATP AVAILABLE; EACH MYOSIN HAS 300 MOLECULES W/2 HEADS EACH; THESE 600 HEADS CAN ATTACH/DETACH 5 TIMES PER SECOND; THEY DO NOT ALL BIND AT ONCE - THEY BIND SEQUENTIALLY SO SOME ARE READY TO BIND WHEN OTHERS ARE LETTING GO OF ACTIN

TRUE OR FALSE:

• THE MUSCLE AP TRAVELS VIA T-TUBULES TO SARCOPLASMIC RETICULUM (SR)
• Ca⁺² IS RELESED FROM Ca⁺² RELEASE CHANNELS ON SR
• Ca⁺² BINDS TROPONIN; TROPONIN CHANGES SHAPE
• AS TROPONIN CHANGES SHAPE, IT PULLS TROPOMYOSIN (TO WHICH IT IS ATTACHED) AWAY FROM THE BINDING SITES ON ACTIN
• THIS EXPOSES THE MYOSIN BINDING SITES ON ACTIN
• ACTIN & MYOSIN BIND FORMING CROSS-BRIDGES

TRUE OR FALSE:

• THE SR RELEASES Ca⁺² FROM RELEASE CHANNELS ONLY WHEN THERE'S A MUSCLE AP
• SR ALSO HAS Ca⁺² ACTIVE TRANSPORT PUMPS
• THESE PUMP Ca⁺² BACK INTO SR
• INSIDE THE SR, Ca⁺² BINDS TO THE PROTEIN CALSEQUESTRIN
• WHEN NO MUSCLE AP EXISTS Ca⁺² IS SEQUESTERED W/IN THE SR

TRUE OR FALSE:

SOMATIC MOTOR NEURONS STIMULATE SKELETAL MUSCLE FIBERS TO CONTRACT

TRUE OR FALSE:

THE MUSCLE AP ARISES IN RESPONSE TO AN AP FROM A SOMATIC MOTOR NERVE; THE MUSCLE AP ARISES AT THE NMJ

TRUE OR FALSE:

THERE ARE ELECTRICAL (GAP JUNCTIONS) AND CHEMICAL SYNAPSES

TRUE OR FALSE:

THE ACh RECEPTORS ARE ALSO LIGAND GATED ION CHANNELS MAINLY SPECIFIC FOR Na⁺¹

TRUE OR FALSE:
PRELIMINARY STEP IN CONTRACTION & RELAXATION OF A SKELETAL MUSCLE FIBER

• AP FROM SOMATIC MOTOR NEURON ARRIVES AT SYNAPTIC END BULB
• THIS NERVE AP CAUSES A CHANGE IN VOLTAGE ACROSS THE NEURON'S MEMBRANE
• THIS VOLTAGE CHANGE OPENS Ca ⁺² VOLTAGE GATES SO Ca ⁺²   ENTERS END BULB (NEURON TERMINAL)
• WITHOUTH THIS Ca⁺²  RELEASE OF THE ACh COULD NOT OCCUR

PRODUCTION OF MUSCLE AP

(RECALL THAT THE MUSCLE AP CAUSES SR TO RELEASE Ca⁺² , Ca⁺² BINDS TROPONIN)

ACETYLCHOLINESTERASE (AChE) ON COLLAGEN IN THE EXTRACELLULAR MATRIX OF THE SYNAPTIC CLEFT DEGRADES ACh:

                          AChE 

ACh ————> ACETYL + CHOLINE

TRUE OR FALSE:

EACH FIBER HAS A NMJ WHICH IS TYPICALLY LOCATED AT MIDPOINT OF MUSCLE FIBER; A MUSCLE AP ARISES AT NMJ & TRAVELS ALONG T-TUBULE TO BOTH ENDS OF FIBER AND TO EACH MYOFIBRIL

TRUE OR FALSE:

WORKING MUSCLES USE INCREASED ATP TO RELAX (ATP MUST BIND MYOSIN BEFORE ACTIN IS RELEASED), TO CARRY ON NORMAL METABOLIC FUNCTIONS & TO ACTIVELY TRANSPORT Ca⁺² . NORMAL ATP STORES LAST ONLY A FEW SECONDS DURING ACTIVE MUSCLE CONTRACTION.

1. CREATINE PHOSPHATE
2. ANAEROBIC RESPIRATION
3. AEROBIC RESPIRATION

FATIGUE DOES *** SEEM TO BE RELATED TO ATP DEPLETION. POSSIBLE FACTORS INCLUDE:

DEPLETION OF Ca⁺² FROM SR

INSUFFICIENT OXYGEN

INSUFFICIENT ACh RELEASE

DEPLETION OF CP

DEPLETION OF GLYCOGEN, NUTRIENTS

BUILDUP OF LACTIC ACID

TRUE OR FALSE:

PROLONGED MUSCLE CONTRACTION INCREASES RESPIRATION RATE; INCREASED RESPIRATION RATE CONTINUES AFTER EXCERCISE STOPS

• CONVERT LACTIC ACID TO PYRUVIC ACID; SOME LA IS CONVERTED TO GLYCOGEN IN THE LIVER
• RESYNTHESIZE CP AND ATP IN MUSCLE
• REPLACE OXYGEN REMOVED FROM MYOGLOBIN (MYOGLOBIN STORES OXYGEN)

TRUE OR FALSE:

INCREASES IN BODY TEMP, METABOLIC RATE, WORK OF SKELETAL & CARDIAC MUSCLE, ATP CONSUMPTION, & RATE OF TISSUE REPAIR INCREASES THE USE OF OXYGEN AFTER EXCERCISE WHICH IS WHY THE TERM RECOVERY OXYGEN UPTAKE IS A MORE ACCURATE DESCRIPTION.

TRUE OR FALSE:

• A SINGLE NERVE AP CAUSES A SINGLE MUSCLE AP IN ALL THE MUSCLE FIBERS IT SUPPLIES
• ALL NERVE APs ARE THE SAME SIZE; ALL MUSCLE APs ARE THE SAME SIZE
• A FIBER GENERATES MORE FORCE/TENSION IF THE RATE AT WHICH APs ARRIVE AT THE NMJ INCREASES
• THE RATE OF AP ARRIVAL IS THE FREQUENCY OF STIMULATION

VOCAL CORDS: 2-3 MUSCLE FIBERS/MOTOR UNIT (SMALLEST IN BODY)

EXTRAOCULAR MUSCLES: 10-20 MUSCLE FIBERS/MOTOR UNIT

• LATENT PERIOD: 2 MSEC, MUSCLE AP MOVES ALONG SARCOLEMMA & Ca⁺² RELEASED FROM SR
• CONTRACTION PERIOD: 10-100 MSEC, Ca⁺² BINDS TROPONIN, CROSSBRIDGES FORM, PEAK TENSION BECAUSE MUSCLE IS CONTRACTING (POWER STROKE)
• RELAXATION PERIOD: 10-100 MSEC, MANY VARIATIONS IN DURATION, DURING THIS PHASE Ca⁺² IS ACTIVELY TRANSPORTED BACK INTO SR, MYOSIN HEADS DETACH FROM ACTIN, TENSION DECREASES

• WAVE SUMMATION: 2ND STIMULUS OCCURS AFTER REFRACTION BUT BEFORE RELAXATION IS COMPLETE; CONTRACTION IS STRONGER AND LONGER
• UNFUSED TETANUS: INCREASED STIMULUS RATE(20-30/SEC); ONLY PARTIAL RELAXATION OCCURS; SUSTAINED WAVERING CONTRACTION
• FUSED TETANUS: GREATLY INCREASED STIMULUS RATE(80-100/SECOND); NO RELAXATION AT ALL; CAN NO LONGER DISTINGUISH INDIVIDUAL TWITCHES

TRUE OR FALSE:

A MUSCLE CONTAINS 100s-1000s OF MOTOR UNITS; THEY GENERALLY ARE NOT ALL STIMULATED AT ONCE; MOTOR UNITS FIRE ASNYCHONOUSLY PRODUCING SMOOTH, SUSTAINED CONTRACTIONS & DELAYING FATIGUE; WEAKEST MOTOR UNITS ARE THE 1ST TO BE RECRUITED; IF MORE FORCE IS NEEDED STRONGER MOTOR UNITS ARE RECRUITED

TRUE OR FALSE:

NEURONS IN THE BRAIN & SPINAL CORD CAUSE INVOLUNTARY CONTRACTIONS. THERE IS NOT ENOUGH FORCE TO GENERATE MOVEMENT. EX: POSTURAL MUSCLES KEEP HEAD UPRIGHT, SMOOTH MUSCLE OF VISCERA: DIGESTIVE ORGANS, BLOOD VESSELS

SLOW OXIDATIVE

FAST OXIDATIVE - GLYCOLYTIC

FAST GLYCOLYTIC

TRUE OR FALSE:

RED MUSCLE FIBERS HAVE INCREASED MYOGLOBIN CONTENT / WHITE MUSCLE FIBERS HAVE LOW CONTENT OF MYOGLOBIN & INCREASED GLYCOGEN

INCREASED MYOGLOBIN IN RED MUSCLE FIBERS

ATPase ACTS SLOWLY; INCREASED PRODUCTION OF ATP

AEROBIC RESPIRATION: MANY BV & MITOCHONDRIA

RESIST FATIGUE, CAPABLE OF PROLONGED HOURS, SUSTAINED CONTRACTIONS, POSTURE, ENDURANCE, AEROBIC EXERCISE

WHITE MUSCLE FIBERS: INCREASED GLYCOGEN

ATPase ACTS FAST: DECREASES PRODUCTION OF ATP

ANAEROBIC RESPIRATION: DECREASE IN BLOOD VESSELS & MITOCHONDRIA

FATIGUES EASILY, GENERATES THE MOST POWERFUL CONTRACTIONS, INTENSE ACTION OF SHORT DURATION; WEIGHT LIFTING

TRUE OR FALSE:

CARDIAC MUSCLE LIKE SKELETAL MUSCLE HAS MYOSIN, ACTIN, TROPONIN, TROPOMYOSIN

Z DISCS, I & A BANDS

T-TUBULES 

TRUE OR FALSE:

UNLIKE SKELETAL MUSCLE, CARDIAC MUSCLE HAS:

 INTERCALATED DISCS W/ DESMOSOMES & GAP JUNCTIONS (ELECTRICAL SYNAPSES)

PROLONGED Ca⁺² DELIVERY FROM SR & INTERSTITIAL FLUID

MUCH LONGER CONTRACTION & RELAXATION

AUTORHYTHMIC BUT UNDER (AUTONOMIC NERVOUS CONTROL)

TRUE OR FALSE:

VISCERAL/SINGLE UNIT SMOOTH MUSCLE HAS MANY GAP JUNCTIONS/ELECTRICAL SYNAPSES

1 STIMULUS → MANY FIBERS CONTRACT AS ONE OR AS A SINGLE UNIT

AUTORHYTHMIC W/ ANS INPUT FOR HOMEOSTASIS

VERY COMMON IN SMALL ARTERIES, VEINS, HOLLOW VISCERA: GUT, UTERUS, BLADDER

TRUE OR FALSE:

MULTIUNIT SMOOTH MUSCLE HAS FEW, IF ANY GAP JUNCTIONS

EAHC CELL CONTRACTS INDEPENDENTLY (HAS ITS OWN NMJ)

INDIVIDUAL FIBERS SUPPLIED BY INDIVIDUAL COLLATERALS CONTRACT INDIVIDUALLY

CONTROLLED BY AUTONOMIC NERVOUS SYSTEM (ANS)

FOUND IN LARGE ARTERIES, BRONCHIOLES, ARRECTOR PILI, MUSCLES OF CILIARY BODY (FOCUS), IRIS/PUPIL (PUPIL DIAMETER)

TRUE OR FALSE:

THICK, THIN, & INTERMEDIATE FILAMENTS ARE PRESENT IN SMOOTH MUSCLE

NO A, I BANDS, NO SARCOMERES, NO T-TUBULES; ONLY SCANTY SR

SMOOTH MUSCLE HAS SMALL INVAGINATIONS CALLED CAVEOLAE THAT CONTAIN EXTRACELLULAR Ca ⁺²

NO Z DISCS BUT DENSE BODIES TO WHICH INTERMEDIATE FILAMENTS & ACTIN ATTACH

TRUE OR FALSE:

BECAUSE THERE ARE NO T-TUBULES IT TAKES Ca ⁺² LONGER TO REACH FILAMENTS IN THE CENTER OF THE FIBER AND IT ITTAKES LONGER TO GET RID OF Ca ⁺²

TRUE OR FALSE:

NEITHER TROPONIN NOR TROPOMYOSIN IS FOUND IN SMOOTH MUSCLE

TRUE OR FALSE:

CALMODULIN - Ca ⁺² ACTIVATES ANOTHER ENZYME (A KINASE) THAT PHOSPHORYLATES AND ACTIVATES THE MYOSIN HEAD

1. MYOTOME: FORMS SKELETAL MUSCLE OF HEAD, NECK, LIMBS
2. DERMATOME: FORMS CT INCLUDING DERMIS OF SKIN
3. SCLEROTOME: FORMS THE VERTEBRAE