MUSCLES Ch Topics *Important: See objectives for our focus!

Anatomy-  You must be able to identify and label the general body musculature on p. 279 and p This is important as it shows major muscles in the human body. Expect to see this diagram on your test!  You must be able to label the sarcomere in box 11-1 on p This is important when learning about the contractile unit of the muscle cell.  You must be able to label the structure of the thin and thick myofilament in figure 11-4 on p. 315 as this is imperative to understanding the physiology of muscle contraction.

Muscle Types

Attachment of Muscles The origin is fixed. Insertion can move. Muscles work as antagonists and act by contracting the insertion to the origin. Muscle contraction is very important for this unit. We will spend several slides learning this sequence.

Naming Muscles  Location (ex: gluteus muscle)  Function (ex: adductor—will adduct leg to midline of body)  Shape (ex: deltoid- triangle shape)  Direction of Fibers (ex: rectus---means straight)  Number of heads/divisions (ex: sternocleidomastoid has sternum and clavicle as origin and mastoid as insert  Size (ex: gluteus maximus vs. gluteus minimus)

Muscle Arrangement  Muscle fibers are arranged differently in different muscles depending on function. Spincter (circular)- open in center. Convergent- Converge at insertion. Parallel- run parallel and can contract a great distance. Pennate- many fibers in condensed area. Can be unipennate, bipennate, or multipennate.

General Function of Muscles  MOVEMENT  HEAT PRODUCTION  POSTURE

Muscle Contraction Animation  hill.com/sites/ /student_view0/chapter1 0/animation__action_potentials_and_muscle_contracti on.html hill.com/sites/ /student_view0/chapter1 0/animation__action_potentials_and_muscle_contracti on.html  hill.com/sites/ /student_view0/chapter1 0/animation__breakdown_of_atp_and_cross- bridge_movement_during_muscle_contraction.html hill.com/sites/ /student_view0/chapter1 0/animation__breakdown_of_atp_and_cross- bridge_movement_during_muscle_contraction.html  hill.com/sites/ /student_view0/chapter1 0/animation__myofilament_contraction.html hill.com/sites/ /student_view0/chapter1 0/animation__myofilament_contraction.html

Sarcomere Contraction Animation  hill.com/sites/ /student_view0/chapte r10/animation__sarcomere_contraction.html hill.com/sites/ /student_view0/chapte r10/animation__sarcomere_contraction.html

Important to Understand  SR= sarcoplasmic reticulum- This holds and releases calcium for muscle contraction.  THIN myofilament is ACTIN. Actin binds to…  THICK myofilament which is MYOSIN.  TROPOMYOSIN and TROPONIN block the binding sites on the actin so myosin can’t bind. They will shift in response to calcium release.

ATP makes it all possible

Let’s Put the Following in Order PS- These are out of order!!! A) Energized myosin crosses bridges of the thick myofilaments bind to actin and use their energy to pull thin myofilaments toward the center of each sarcomere. Repeats as long as ATP is available. B) Ca+ is released from the SR into the sarcoplasm where it binds to troponin in thin myofilaments. C) Nerve impulse reaches end of motor neuron, releasing acetylcholine. D) As the thin filaments slide past thick myofilaments, the entire muscle fiber shortens. E) Troponin and tropomyosin shift, exposing actin binding sites. F) Acetylcholine diffuses and binds to acetycholine receptors in muscle fibers.

Aerobic vs. Anaerobic Respiration  Which one requires oxygen?  Which one is short term?  Which one causes a byproduct of lactic acid?  Where do each take place?  Which one makes the most ATP?

Slow vs. Fast vs. Intermediate Fibers  Slow fibers are also called RED fibers because they contain a high concentration of myoglobin (reddish pigment that stores oxygen). Their myosin acts at a SLOW rate yet can avoid fatigue. What kind of muscles may this be useful for?  Fast fibers are also called WHITE fibers as there is a low concentration of myoglobin. Their myosin works faster because Ca+ is delivered faster by their SR. But ATP is depleted fast and so this is a short duration. What kind of muscles in your body would be suited for this?  Intermediate fibers fall in between.

How do these differ in athletes?  Your book has some great graphs showing differences in concentrations of muscle types. (p. 320)  PubMed, the U.S. National Library of Medicine, reports studies done observing athletes and fiber differences.  Example: ool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Results Panel.Pubmed_RVDocSum&ordinalpos=12 ool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Results Panel.Pubmed_RVDocSum&ordinalpos=12

Muscle Fatigue  Physiologically, this would be caused by a lack of what energy molecule?  If you lack this energy molecule, think about what would not be able to result?  Lacking this energy molecule would mean that a depletion of oxygen and/or glucose in muscle fibers may be present. What byproduct can occur if oxygen is lacking?  Psychological fatigue will produce the feeling that usually stops us from continuing muscular activity but physiological fatigue would prevent an actual contraction.

Effects of Exercise on Skeletal Muscle  Prolonged inactivity causes disuse atrophy  Muscle hypertrophy is enhanced by strength training since muscles are given heavy resistance training. This can increase the number of myofilaments in each muscle fiber. This can increase the mass of the muscle.  Endurance training (aka aerobic training) does NOT result in hypertrophy but it increases the number of blood vessels in the muscle without increasing its size. More blood vessels can allow better delivery of oxygen and glucose. Also aerobic training can cause an increase in the number of mitochondria which would produce more of what energy molecule?

Abnormal Muscle Contractions  Cramps- involuntary muscle spasms. Often a muscle is inflamed but it can also be a symptom of irritation or ion/water imbalance.  Convulsions- Abnormal, uncoordinated tetanic contractions. Disturbances in the brain can cause output along motor nerves to be irregular and disorganized.  Fibrillation- abnormal contraction where individual fibers do not contract at the same time. Produces flutter but no movement. Can occur in cardiac muscle.

Diagram of Actin and Myosin  Take a look at p It has pictures of actin and myosin. I want you to diagram the myosin head and its ability to bind to actin.  You need to be able to explain the order of contraction, as I will ask EACH person in the group a part of the sequence. You are not done until your entire group answers it correctly.  Not shown in picture, but I want you to include is calcium (what does it do?) and ATP.

Trapezius Superior extensor retinaculum Soleus Gastrocnemius Pectoralis major Peroneus longus Sternocleiodomastoid Peroneus brevis Patellar Tendon

Peroneus longus Soleus Calcaneal tendon Peroneus brevis Gastrocnemius Sternocleidomastoid Splenius capitis