THE MUSCULAR SYSTEM

FUNCTIONS OF MUSCLE PRODUCING MOVEMENT – BOTH INTERNAL AND WHOLE – BODY MAINTAINING POSTURE STABILIZING JOINTS GENERATING HEAT

3 TYPES OF MUSCLE TISSUE 1.SKELETAL MUSCLE – USED TO MOVE BONES 2.SMOOTH MUSCLE – MOVES DIGESTIVE TRACT, URINARY SYSTEM, REPRODUCTIVE ORGANS, AND DIAPHRAGM 3.CARDIAC MUSCLE – PUMPS HEART

SKELETAL MUSCLE ANATOMY MUSCLES CELLS ARE LONG FIBERS COVERED BY THE SARCOLEMMA (PLASMA MEMBRANE) EACH MUSCLE CELL HAS MANY NUCLEI PUSHED ASIDE BY LONG ORGANELLES CALLED MYOFIBRILS MYOFIBRILS HAVE LIGHT AND DARK BAND, THAT GIVE MUSCLE A STRIPED (STRIATED) APPEARANCE MYOFIBRILS ARE MADE OF CHAINS OF TINY CONTRACTING UNITS CALLED SARCOMERES.

A SARCOMERE IS MADE OF THREADLIKE PROTEINS CALLED MYOFILAMENTS THERE ARE TWO TYPES OF MYOFILAMENTS THIN (ACTIN) FILAMENTS THICK (MYOSIN) FILAMENTS

AREAS OF THICK MYOSIN (AND ACTIN) FILAMENTS MAKE UP THE DARK “A” BANDS AREAS BETWEEN THESE THICK FILAMENTS ARE LIGHT “I” BANDS

MUSCLE CONTRACTIONS MYOSIN FILAMENTS HAVE PROJECTIONS CALLED “HEADS” THESE MYOSIN HEADS GRAB HOLD OF THE ACTIN FILAMENTS AND PULL THEM TOGETHER THIS CAUSES MUSCLES TO CONTRACT HOWEVER, THIS DOESN’T HAPPEN ON ITS OWN

REVIEW OF ATP IN ORDER TO CONTRACT MUSCLES, NEED ATP ATP IS A MOLECULE FOUND IN THE BODY THAT SUPPLIES ENERGY IT IS ALSO CALLED ADENOSINE TRIPHOSPHATE ENERGY IS RELEASED FROM ATP WHEN THE LAST PHOSPHATE IS REMOVED FROM IT.

MUSCLES CAN GET ATP FROM 3 PROCESS USING CREATINE PHOSPHATE (CP) CREATINE PHOSPHATE IS A HIGH – ENERGY MOLECULE FOUND IN MUSCLE FIBERS BUT NOT OTHER CELLS IT MAKES ATP BY ADDING ON A PHOSPHATE GROUP TO ADP

BENEFITS AND DOWNFALLS OF USING CREATING PHOSPHATE THIS WORKS GREAT TO CREATE ATP QUICKLY, BUT CP SUPPLIES MAY BE USED UP IN ABOUT 15 SECONDS

USING AEROBIC RESPIRATION ABOUT 95% OF MUSCLE ENERGY (ATP) IS MADE USING AEROBIC RESPIRATION AEROBIC RESPIRATION BREAKS GLUCOSE INTO CARBON DIOXIDE AND WATER USING OXYGEN IN THE MITOCHONDRIA OF CELLS.

BENEFITS AND DOWNFALLS OF USING AEROBIC RESPIRATION AEROBIC RESPIRATION IS VERY GOOD AT MAKING A LOT OF ATP BUT CAN BE SLOW AND REQUIRES A CONSTANT SUPPLY OF OXYGEN IN THE FIRST STEPS OF AEROBIC RESPIRATION, GLUCOSE IS SPLIT INTO TWO MOLECULES OF PYRUVIC ACID AND 2 ATP ARE RELEASED. AFTER THIS, IN THE PRESENCE OF OXYGEN, THE PYRUVIC ACID WILL GO ON TO CREATE MORE ATP.

USING ANAEROBIC RESPIRATION ANAEROBIC RESPIRATION, TOO, CONTAINS THE FIRST STEPS TO CREATE PYRUVIC ACID IN ANAEROBIC RESPIRATION, HOWEVER, THERE IS NOT ENOUGH OXYGEN FOR PYRUVIC ACID TO COMPLETE THE STEPS TO CREATE MORE ATP. THIS CAN HAPPEN BECAUSE THE SUPPLY OF OXYGEN OR GLUCOSE IS TOO LOW THE MUSCLE ACTIVITY IS TOO INTENSE IN THIS CASE, THE PYRUVIC ACID IS TURNED INTO LACTIC ACID AND NO MORE ATP IS PRODUCED.

BENEFITS AND DOWNFALLS OF USING ANAEROBIC RESPIRATION ANAEROBIC RESPIRATION ONLY MAKES ABOUT 3% AS MUCH ATP AS AEROBIC RESPIRATION THE BUILDUP OF LACTIC ACID DURING PROLONGED PERIODS OF ANAEROBIC RESPIRATION MAY CAUSE A BURNING SENSATION THAT EXISTS DURING EXERCISE. HOWEVER, ANAEROBIC RESPIRATION IS OVER 2X FASTER THAN AEROBIC AND CAN PRODUCE MUCH OF THE ATP NEEDED FOR UP TO A MINUTE OF STRENUOUS ACTIVITY

MUSCLE CONTRACTION IN ORDER FOR MUSCLES TO WORK, THEY HAVE TWO SPECIAL FUNCTIONS… IRRITABILITY (THE ABILITY TO RECEIVE AND RESPOND TO STIMULUS) CONTRACTIBILITY (THE ABILITY TO SHORTEN WHEN ADEQUATE STIMULUS IS RECEIVED) MUSCLES ALSO NEED NERVES IN ORDER TO BE STIMULATED TO WORK (CONTRACT) ONE NERVE CELL MAY STIMULATE A FEW MUSCLE CELLS OR HUNDREDS OF THEM, DEPENDING ON THE MUSCLE AND THE WORK IT DOES SKELETAL MUSCLES MOVE BY THE LAW OF “ALL-OR-NONE” CONTRACTION IN A MUSCLE CELL. THAT IS, IT WILL ONLY FULLY CONTRACT OR NOT CONTRACT AT ALL. HOWEVER, MUSCLE ORGANS (CONSISTING OF 100S OF MUSCLE CELLS) WILL REACT TO STIMULI WITH GRADED RESPONSES.

THEY MAY CHANGE THE FREQUENCY OF CONTRACTION IN CELLS, OR CHANGE THE NUMBER OF CELLS BEING CONTRACTED. MUSCLES CAN VARY IN THE AMOUNT OF ENERGY PUT INTO THE CONTRACTIONS THEY DO. TWITCHES ARE SHORT JERKY MOVEMENTS OF MUSCLES CAUSED BY BREAKS BETWEEN CONTRACTIONS OF MUSCLE CELLS. UNFUSED TETANUS IS WHEN MUSCLES ARE STIMULATED MORE RAPIDLY, SO THAT THERE IS ALMOST NO RELAXATION BETWEEN CONTRACTIONS. FUSED TETANUS IS WHEN MUSCLE IS STIMULATED SO RAPIDLY THAT IT DOES NOT RELAX BETWEEN CONTRACTIONS. (CREATES A SMOOTH CONTRACTION)

2 TYPES OF MUSCLE CONTRACTIONS THERE ARE TWO TYPES OF MUSCLE CONTRACTIONS…. ISOTONIC (SOME TONE/TENSION) – NORMAL CONTRACTIONS; MYOFILAMENTS SLIDE TOWARD ONE-ANOTHER, MUSCLE SHORTENS, MOVEMENT OCCURS ISOMETRIC (SOME LENGTH) – UNSUCCESSFUL CONTRACTIONS; TENSION INCREASES BUT MYOFILAMENTS DO NOT SLIDE, MUSCLE STAYS SAME LENGTH, NO MOVEMENT OCCURS. HAPPENS WHEN WE ARE STRUGGLING TO MOVE SOMETHING WE CANNOT (EX: 2- TON TRUCK)

MUSCLE TONE MUSCLE TONE IS THE STATE OF CONTINUOUS PARTIAL CONTRACTION IN THE MUSCLE IT IS TYPICALLY UNNOTICEABLE IT OCCURS WHEN A MUSCLE IS FIT AND HEALTHY

MUSCLE FATIGUE MUSCLE FATIGUE MAY OCCUR WHEN WE EXERCISE OUR MUSCLES STRENUOUSLY FOR A LONG PERIOD OF TIME A MUSCLE BECOMES FATIGUED WHEN IT WILL NOT CONTRACT EVEN THOUGH IT IS STIMULATED TO DO SO. MUSCLE FATIGUE IS BELIEVED TO BE CAUSED BY OXYGEN DEBT. OXYGEN DEBT IS THE STATE OF LACKING THE NECESSARY AMOUNT OF OXYGEN TO SUSTAIN RIGOROUS MUSCLE ACTIVITY (WITHOUT OXYGEN, MUSCLES CANNOT PRODUCE ENOUGH ATP TO KEEP FUNCTIONING)

POSITIVE EFFECTS OF AEROBIC EXERCISE AEROBIC EXERCISE IS ANY SUSTAINED ACTIVITY THAT INCREASES THE NEED FOR OXYGEN. IT IS BENEFICIAL IN THAT IT….. 1.CREATES STRONGER, MORE FLEXIBLE MUSCLES 2.MAKES OVERALL BODY METABOLISM MORE EFFICIENT 3.IMPROVES DIGESTION 4.ENHANCES COORDINATION 5.MAKE SKELETON STRONGER 6.ENLARGES HEART TO PUMP MORE BLOOD 7.MAKES LUNGS MORE EFFICIENT AT GAS EXCHANGE

POSITIVE EFFECTS OF RESISTANCE EXERCISE RESISTANCE EXERCISES RESULT WHEN MUSCLES ARE WORKING AGAINST AN ALMOST IMMOVABLE OBJECT. THESE EXERCISES HAVE SOME BENEFITS, LIKE…… 1.INCREASE IN MUSCLE SIZE AND STRENGTH 2.INCREASE IN CONNECTIVE TISSUE HOLDING MUSCLE