DO NOW

• WHAT HAPPENS WHEN YOU WORK OUT WITHIN YOUR MUSCLES? (THINK BACK TO BIO AND THE TOPIC OF CELLULAR RESPIRATION!)

MUSCULAR RESPONSES

OBJECTIVES

• TO EXPLAIN WHAT HAPPENS DURING MUSCULAR FATIGUE

• TO IDENTIFY DIFFERENT MUSCULAR RESPONSES

• TO LABEL AND EXPLAIN THE DIFFERENT STAGES OF CONTRACTION

MUSCLE FATIGUE• CELLS UNDERGO BOTH AEROBIC AND ANAEROBIC RESPIRATION TOO SUPPLY

AMPLE ATP (LACTIC ACID FERMENTATION)

• LACTIC ACID CREATES AN OXYGEN DEBT BECAUSE THE LIVER CELLS MUST NOW USE OXYGEN TO BREAK DOWN THE LACTIC ACID (CAN TAKE SEVERAL HOURS)

• LACTIC ACID LOWERS THE PH, WHICH DIMINISHES THE MUSCLE FIBERS RESPONSE TO STIMULATION

• MORE EXERCISE = MORE GLYCOLYTIC ENZYMES = INCREASED CAPACITY FOR GLYCOLYSIS= INCREASED CAPACITY FOR AEROBIC RESPIRATION!! … START WORKING OUT

MUSCLE CONTRACTION• A MUSCLE FIBER WILL CONTRACT

AFTER THRESHOLD STIMULUS HAS BEEN REACHED.

• ONCE STIMULATED, THE ENTIRE FIBER COMPLETELY CONTRACTS WHICH IS CALLED THE ALL-OR-NONE RESPONSE.

• *THE EXTENT OF SHORTENING DEPENDS ON RESISTANCE.

MYOGRAM• TWITCH= SINGLE MUSCLE

CONTRACTION

• LATENT PERIOD: TIME BETWEEN STIMULATION AND RESPONSE

• PERIOD OF CONTRACTION: MUSCLE IS CONTRACTED

• RELAXATION: FIBER RETURNS TO FORMER LENGTH

HYPERTROPHY VS. ATROPHY• HYPERTROPHY- MUSCLES RESPOND TO

EXERCISE AND ENLARGE

• SLOW TWITCH FIBERS ACTIVATED BY LOW INTENSITY EXERCISE SUCH AS SWIMMING OR RUNNING, DEVELOP MORE MITOCHONDRIA AND CAPILLARIES, PROLONGING FATIGUE

• FAST TWITCH FIBERS ACTIVATED BY WEIGHT LIFTING CAN PRODUCE NEW MYOFILAMENTS & ENLARGE THE MUSCLE (THEY ARE STILL FATIGABLE)

• ATROPHY- WHEN REGULAR EXERCISE STOPS, CAPILLARY NETWORKS SHRINK, MITOCHONDRIA DECREASE, ACTIN & MYOSIN DECREASE, AND MUSCLE SHRINKS.

TYPES OF GRAPHS• TWITCH- FULL CONTRACTION

• SUMMATION- FORCE OF EACH TWITCH COMBINES INCOMPLETE TETANUS- MINIMAL AMT. OF RELAXATION AFTER EACH STIMULUS

• COMPLETE TETANUS- NO RELAXATION, CONTINUOUS CALCIUM ION DEPOSIT

TETANUS• CAUSED BY CLOSTRIDIUM BACTERIA

PRESENT IN SOIL

• BACTERIA PRODUCES A NEUROTOXIN WHICH BLOCKS THE RELEASE OF INHIBITORY NEUROTRANSMITTERS.

ISOMETRIC VS. ISOTONIC• ISOMETRIC- NO CHANGE IN MUSCLE

LENGTH

• ISOTONIC- MUSCLE LENGTH CHANGES