The Muscular System

Do Now: Happy New Year!! Get your Clicker Name as many muscles as you can (anterior & posterior)

Facial Muscles

Shoulder

Abdominal Muscles

Back Muscles

Leg Muscles

Id the Masseter 1 2 3 4 5 6 7

Id the orbicularis oculi 1 2 3 4 5 6 7

Id the deltoid 1 2 3 4 5 6 7

Id the rectus abdominis 1 2 3 4 5 6 7 8 9

Id the sternocleidomastoid 1 2 3 4 5 6 7 8 9

Id the gastrocnemius 1 2 3 4 5 6 7

Id the biceps femoris 1 2 3 4 5 6 7

Id the sartorius muscle 1 2 3 4 5 6 7

Homework: Find and print a picture of your favorite athlete (bathing suit preferred to see as many muscles as possible) Hand label the visible muscles on their body using the muscles we discussed in class

Do Now: Grab your Clicker Take out your HW – athlete pic w/labeled muscles Review names of muscles from hotlist & diagram

Id the orbicularis oris 1 2 3 4 5 6 7

Id the temporalis muscle 1 2 3 4 5 6 7

Id the serratus anterior 1 2 3 4 5 6 7 8 9

Id the trapezius 1 2 3 4 5 6 7 8 9

Id the exterior obliques 1 2 3 4 5 6 7 8 9

Id the soleus 1 2 3 4 5 6 7

Id the semimembranosis 1 2 3 4 5 6 7

Id the semitendonosis 1 2 3 4 5 6 7

Id the vastus medialis muscle 1 2 3 4 5 6 7

Id the rectus femoris muscle 1 2 3 4 5 6 7

Do Now: Why do you think that muscle- enhancing supplements (steroids, creatine, andro) are so popular at all levels of fitness and athletics (high school, college, pro, etc.) and do you see any problems with this?

Muscle Tissues Cardiac Smooth Skeletal Involuntary striated muscle Dinucleated Communicate via intercalated disks Natural contraction cycle determined by pacemaker cells Smooth Lines blood vessels, digestive organs, urinary system, and parts of respiratory system Involuntary nonstriated muscle Ca+ triggers contractions differently (lacks sarcomeres) Skeletal Voluntary striated muscle Multinucleated cells called muscle fibers Controlled by motor nerve cells

Functions of Skeletal Muscle Produce Movement Contractions pull on tendons and move bones Maintain posture and body position Continuous contractions maintain posture Support/protect soft tissues Abdominal wall Floor of pelvic cavity Guard entrances and exits Voluntary control of swallowing, defecation, and urination Maintain body temp Some energy from contractions lost as heat

Gross Anatomy of Skeletal Muscle Each cell is called a “muscle fiber” Contains several tissues: Connective Blood vessels Nerves – control contractions Skeletal muscle

Microanatomy of Skeletal Muscle Sarcolemma – cell membrane Sarcoplasm – cytoplasm Myofibrils – bundles of myofilaments Thin filaments – actin proteins Thick filaments – myosin proteins Sarcoplasmic reticulum – smooth ER (stores Ca+) Sarcomeres – repeating units of myofilaments

Muscle Fiber Contraction http://www.youtube.com/watch?v=CepeYFvqmk4

Classwork: Draw a flowchart or diagram showing how muscle contraction and relaxation occurs at a cellular level

Muscle Mechanics Muscle cells pull on collagen fibers producing tension (can only contract!) Amount of tension dependent upon Frequency of neural stimulation Latent period (2msec) – action pot. & release of Ca+ Contraction phase (15msec) – cross bridges form Relaxation phase (25msec) – tension, cross bridges and Ca+ decrease # of muscle fibrils activated Motor unit - # muscle fibrils controlled by singe motor neuron Fine control of movement determined by size of motor unit Ex. Eye vs. Leg muscles During sustained contraction – motor units activated on a rotating basis (some rest/some contract)

Muscle Tone Tone – resting tension Stabilizes the position of your joints Any skeletal muscle not stimulated on a regular basis will atrophy – fibers become smaller and weaker Initially atrophy is reversible Extreme atrophy is permanent

Energetics of Muscle Activity Active Skeletal Muscle fibril requires 600 trillion ATP/sec! Sources of ATP Stored (ADP + Creatine-P  ATP) Lasts 15 sec Aerobic Metabolism (Krebs  Oxidative Phosphorylation) Provides 30% of ATP needed during peak exertion Anaerobic Metabolism (glycolysis) Main E source Lactic acid builds up Ineffective Muscle Fatigue – no contraction despite stimulation Lack of ATP or lactic acid build up Recovery Period – returns to pre-exertion levels

Muscle Performance Force and endurance depends on: Types of muscle fibers Fast Twitch (white) Powerful contractions Fatigue rapidly (few mitochondria) Slow Twitch (red) Extended contraction (many mitochondria) Extensive capillary network Myoglobin binds O2 Physical conditioning ( increase power and endurance) Anaerobic Frequent, brief intense workouts (hypertrophy of muscle fibrils) Aerobic Sustained low levels of activity Carb-load the day before; drink glucose rich sports drinks

Muscle Review What muscle do you use to shrug your shoulders? What muscle would be well developed in a trumpet player? What is the most likely cause of a muscle cramp? What muscle do you use to stand on your tippy-toes? What muscle do you use to close your eye-lids What muscle do you use when using a “butterfly” machine? Compare “white” muscles to “red” muscles A friend wants to bulk up his arms. What would you suggest to him? What are the 3 sources of energy for muscles? What limits each?