2.  SKELETAL – attached to bone/voluntary  CARDIAC – heart/ involuntary  SMOOTH – other organs/involuntary

3. 1. Producing body movements 2. Stabilizing body positions 3. Generating heat

4.  Organs  Wrapped in connective tissue ◦ Extends to form tendons – attaches muscle to bone

5.  Fascicles: bundles of muscle fibers (cells). Connective tissue around each fascicle.

6.  Long, skinny cylinders – a cell  Cytoplasm = glycogen  Contains myofibrils ◦ Thin (actin) and thick (myosin) filaments inside

7.  Muscle surrounded by connective tissue.  Inside are many bundles (surrounded by connective tissue).  Many muscle fibers inside bundle (fascicles)

8.  Inside muscle fiber are myofibrils  Filaments inside myofibrils

9.  What triggers it?

10.  A neuron connects to a muscle fiber [called the neuromuscular junction (NMJ)]  Arrival of nerve impulse causes release of acetylcholine (ACh: a neurotransmitter – a chemical).  ACh diffuses to receptors on muscular membrane, opening a Na + ion channel, causing Na + to enter the muscle fiber.  Changes electrical conditions and produces an action potential (electrical current)

12.  Action potential triggers : ◦ Unblocks actin (thin) so myosin (thick) heads can bind to them ◦ Filaments slide past one another, shortening the muscle (Sliding filament mechanism)

15.  What triggers a muscle contraction?  What is the location called where a neuron connects with a muscle?  Does a muscle contraction mean it gets longer or shorter?  Do muscle fibers fold or slide to get shorter?

16.  Botulinum toxin from bacterium Clostridium botulinum blocks exocytosis of ACh ◦ BOTOX

17.  Muscle fibers: all-or-none  Strength of muscle contraction: depends on # of contracting fibers  Affects energy usage ◦ Energy = capacity to do work ◦ Types: chemical, mechanical, heat, electrical

18.  ATP broken down during contraction  Store little ATP, must produce it  3 ways: ◦ Aerobic respiration: slow, requires O2, lots ATP made ◦ Anaerobic glycolysis and lactic acid formation: faster, no O2 needed, less ATP made ◦ Creatine phosphate and ADP: CP not found in other cells, very fast, doesn’t last

19.  No contraction even with stimulation - occurs from oxygen debt (lactic acid builds up and ATP runs low)

20.  The more oxygen your body can take in and use determines your endurance

21.  The reaction of creatine phosphate and ADP generates ATP quickly or slowly?  The ability of your body to use oxygen to produce ATP is _____ respiration.  True or False: The strength of a muscle contraction is determined by the amount of muscle fibers that are contracting.

22.  Why are some people better at endurance activities?  Why are some people FAST?  Is it genetic? Is it training?

23.  1. Slow oxidative fibers ◦ Little power (small in diameter); fatigue resistant; many mitochondria. Adapted for maintaining posture & endurance activities  2. Fast oxidative-glycolytic fibers ◦ Intermediate in diameter, faster than #1 but briefer in duration. Adapted for: walking/sprinting  3. Fast glycolytic fibers ◦ Large diameter (contract strongly/quickly); tire quickly; large amount lactic acid build up ◦ Short, rapid, intense movement ◦ Adapted for intense anaerobic movements of short duration: weight lifting/throwing a ball

24.  Muscles are a combo of different fibers  Proportion of fibers is individual

25.  Muscles tug on tendons which pull on bones  One bone is pulled towards another  Insertion towards origin  Origin stays still  Most cross a joint

26.  Flexion – decreases angle of joint  Extension – increases joint angle. Past 180 is hyperextension

27.  Rotation – around the longitudinal axis  Abduction – moving limb away from body midline  Adduction – moving limb towards midline  Circumduction – whole limb outlines a cone (circular)