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Muscular System
Read Ch 6
Assignment: pp 198 M/C #3 – 8, S/A #2, 10, 15 Clinic #2, 6
Types of Muscles Skeletal—
voluntary—connects to bones
■Smooth; involuntary, found in hollow organs
■Cardiac—involuntary—found in heart only~!
Functions of the Muscular System
Movement of body parts—by pulling on bones. Bones act as levers, joints as the fulcrum.
Guard entrances and exits
Posture Stabilizing joints Create heat
Muscle Attachment Fibers Tendons—connect
muscle to bone (cordlike) Origin—fixed end
(proximal end of bone) Insertion—moveable
end (distal end of bone)
Aponeuroses—connect muscles to muscles (sheetlike)
Microscopic Muscle Anatomy
Plasma membrane = sarcolemma
Cytoplasm = sarcoplasm ER = sarcoplasmic
reticulum Functions are similar as
in other body cells, but the name is different
•Lots of mitochondria and several nuclei in each cell•Myofibril—fibers extending lengthwise in muscle cell, made up of myosin and actin
Microscopic Anatomy con’t:
Myosin—thick filaments Actin—thin filaments Sarcomere—segment between 2 Z-lines
functioning as a contractile unit A bands appear dark and thick I bands are narrower and lighter
Video of sarcomere shortening
Muscle Physiology…Reason for Motion
Brain
MuscleCell
If enough Ach, contraction occurs
Acetylholine (Ach) is the
NeurotransmitterStimulating Muscle Cells
Motor Nerves
Energy necessary for all this to happen comes from the generation of ATP
Muscle Physiology con’t: Nerve impulse arrives at muscle cell Ca+2 released from SR into sarcoplasm Ca+2 combines with troponin molecules in the
thick filaments of myofibrils (Myosin) Troponin without Ca+2 doesn’t interact like this
Myosin interacts with Actin and pulls toward center
Contraction of muscle Video of contraction occuring… Animation of entire process…
Muscle Physiology “All or none” law
—a muscle cell contracts all the way or not at all.
It’s the number of stimulated muscle cells that decides how much the entire muscle will contract…
You can sort of contract your bicep or you can really contract your bicep…
Muscle Fatigue Definition: A muscle’s inability to contract
despite being stimulated Results from being unable to get enough
oxygen to muscle cells during exercise Blood isn’t reaching muscle cells fast enough
Lactic acid (a waste product of anaerobic respiration) builds up causing poor muscle contraction
Once you get enough O2 and ATP back into body, lactic acid is removed.
Types of ContractionsTwitch—quick jerky response to
a stimulusTetanic—more sustained and
steady than a twitch. A series of stimuli—contractions melt together to produce a sustained contraction.
Types of Contractions con’t: Isotonic—usually produces movement at a
joint. Muscle shortens and insertion end moves toward the origin. Eg., walking, breathing, lifting and twisting
Isometric—increase tension of muscle by NOT shortening it. No movement, so the muscle remains the same length. Repeated isometric exercise will result in larger and stronger muscles. eg., pushing against a wall.
Muscles and Exercise--Benefits
Endurance exercise—Aerobic activity Stronger, more flexible muscles, but no
increase in size of muscles. More blood is circulated to muscles so
muscles increase number of mitochondria…making them more efficient. More efficiency = less lactic acid produced
Other benefits: better digestion, better elimination, bigger heart and better gas exchange
Muscles and Exercise--Benefits
Resistance exercise—strength training Bigger, stronger muscles, less flexibility
though and no improvement in endurance
If you want ideas of types of strength training available…talk to your coaches or see me after class.
Recovery of musclesBody needs to replenish ATP and
CP and get rid of LA—cool down exercises will speed this along.
LA removal with exercise—1/2 to 1 1/3 hour
LA removal without exercise—1 – 3 hours
Recovery of muscles con’t: Recovery of ATP— ~70% within 30
seconds, 100% within 3 – 5 minutes of activity
Recovery of glycogen depends on the type of exercise and the amount of carbs used during recovery—could take 2 – 8 days! Within first 10 hours, 60% glycogen is
recovered…make sure to take in carbs during first 48 hours of recovery!
Recovery of musclesDuring hours 1 – 10, eat simple
and complex sugars…after 10 hours, complex carbs only!
If you only have 30 minutes between events, only consume simple sugars…no complex carbs!
Body Movements Flexion—
decreasing the angle of the joint by bringing the bones closer together
Extension—extends a joint by increasing the angle between the bones
Body Movements Rotation—movement
around an axis (partway around)
Circumduction—a combination of flexion, extension, rotation and abduction. Eg., throwing a ball
Body MovementsAbduction—
moving away from the midline
Adduction—moving toward the midline
Special Movements Pronation—motion
of palm from anterior position to posterior position
Supination—palm moves from posterior position to anterior position
Special MovementsInversion—turning
the sole of your foot medially
Eversion—turning the sole of your foot laterally
Special MovementsDorsiflexion—
pointing your toes up toward your shin
Plantar Flexion—pointing your toes downward
Factors used in naming muscles
Direction of muscle fibersRectus = straight, oblique =
slantedMuscle size
Maximus, minimus, longusLocation of muscle
Temporalis, frontalis, zygomaticus
Factors used in naming muscles
Number of originsBiceps (2), triceps (3), quadriceps (4)
Location of origin and insertionSternocleidomastoid
Shape of muscleTrapezius = trapezoid shaped
Action of muscleFlexor, extensor, adductor
Steroids—read page 180 and handout
Drug What does it do? Risks
Human Growth hormone (hGH)
Erythropoietin (EPO)
Testosterone
Steroids/
androstenedione
Stimulants
Break down fat for energy use
Disfigure bones and muscles, jutting of forehead, heart issues and metabolism
Increase RBC # Thickens blood and causes clots
Build muscle, quicker recovery, aggressive
Heart disease, liver cancer, impotence
Artificial testosterone (see above)
See above
Delays muscle fatigue
Overrides the “stop” message
…this is dangerous
Overall impressions of steroids/drugs
Positives Negatives
■Increases muscle mass■More Oxygen carried■More aggressive
■Distortion of breast tissue■Bloated facial features■Small repro organs (testes and ovaries)■Infertility■Liver damage■Retain more cholesterol■Mental disorders
Muscle Show and Tell
Head Muscles
www.slackbooks.com
Frontalis
www.grendahl.com
Orbicularis Oculi
daphne.palomar.edu
Orbicularis Oris
Head Musclesen.wikipedia.org
Buccinator
www.ivy-rose.co.uk
Zygomaticus
www.deltadental.com
Masseter
Head/Neck Muscles
en.wikipedia.org
Temporalis
www.answers.com
sternocleidomastoid
Abdomen/Chest Muscles
fr.wikipedia.org
Pectoralis Major
Abdomen/Chest Muscles
www.courses.vcu.edu
Intercostals
summit.stanford.edu
Rectus Abdominus
Abdomen/Chest Muscles
www.easyvigour.net.nz
Transverse Abdominus
www.swamij.com
Diaphragm
www.getbodysmart.com
Obliques
Back Muscles
Trapezius
www.fotosearch.com
Latissimus Dorsi
www.answers.com
Deltoid
Arm Muscleswww.fitnessnet.nl
Biceps Brachii
www.waynesburg.edu
Brachioradialis
www.iemily.com
Triceps brachii
www.rad.washington.edu
Arm Muscles
www.dubinchiro.com
Arm Muscles
Extensor Digitorum
www.rad.washington.edu
Arm Muscles
Flexor Digitorum Superficialis
www.waynesburg.edu
Arm Muscles
www.answers.com
Leg Muscles
courses.washington.edu
Leg Muscles
www.vancouveryoga.com
Leg Muscles
Adductor Group
www.waynesburg.edu
Leg Muscles
www.octc.kctcs.edu
Leg Muscles
www.octc.kctcs.edu
Leg Muscles
Leg Muscles—Hamstrings
www.memorial.ecasd.k12.wi.us
Leg Muscles
www.answers.com
en.wikipedia.org
Leg Muscles
www.octc.kctcs.edu
Extensor Hallucis Longus
www.courses.vcu.edu
education.yahoo.com
Leg Muscles
Leg Muscles
www.memorial.ecasd.k12.wi.us
www.arthroscopy.com
