Muscle Study Questions

Mader Chapter 71-5 on page 133

1. Name & describe the 3 types of muscles, & give a general location for each type (p. 111)

1. Skeletal – voluntary (attached to skeleton)

2. Cardiac – involuntary (heart)3. Smooth – involuntary (walls of

hollow internal organs)

2. List & discuss 4 functions of muscles. (p 111)

1. Produce movement – picking up an object2. Resist movement – posture, blood pressure

(Newton’s 3rd Law: muscles generate a force (static tension) that exactly opposes and equal but opposite force being applied to a body part

3. Generate heat – contraction of our muscles accounts for > 75% of all heat generated by the body – shivering thermogenesis

4. Stabilizing joints – stabilize & strengthen

3. Describe the anatomy of a muscle, from the whole muscle to the myofilaments w/in a sarcomere. Name the layers of fascia that cover a skeletal muscle & divide the muscle interior. (p 113) A group of many individual cells, all w/same

origin and insertion and all with the same function (p. 115)

Arranged in bundles called fascicles Each bundle is enclosed in a sheath of fibrous

connective tissue called fascia Each fascicle contains 12 to 1000s of individual

muscle cells – called muscle fibers The outer surface of the whole muscle is

covered with several more layers of fascia – at the ends all come together forming tendons

Muscle Cells to sarcomere Tube shaped 3 cm – 30 cm (thigh) Can contain more than one nucleus just

under the cell membrane (skeletal) Nearly entire cell is packed with long

cylindrical structures in parallel called myofibrils

Myofibrils are packed with contractile proteins called actin and myosin

When myofibrils contract the muscle cell also contracts

Myofibrils = muscle fibers Each skeletal muscle fiber is a long,

cylindrical cell w/multiple oval nuclei just beneath the sarcolemma (plasma membrane) surface

Fibers are large, 10 to 100 m in diameter, and up to hundreds of centimeters long

Sarcoplasm, similar to cytoplasm of other cells, but has numerous glycosomes (=organelle full of glycogen) and a unique oxygen-binding protein called myoglobin, similar to hemoglobin

Sarcomere = contractile unit (6)sarco – Gk for “flesh”

Sarcomere / contractile unit (6) A single myofibril within one muscle

cell (in your biceps) can contain > 100,000 sarcomeres arranged end to end.

100,000 sarcomeres all shortening at once produces a muscle contraction

Understanding muscle shortening is simply understanding how a single sarcomere works

Sarcomere = contractile unit

From Z to shining Z

Sarcomere structure

2 kinds of proteins

1) Myosin – thick filaments interspersed @ regular intervals with a different protein

2) Actin – thin filaments that are structurally linked to the Z-line

Myosin filaments are completely contained within the sarcomere

Muscle contractions depend on the interaction of these 2 filaments

4. List the sequential events that occur when a nerve impulse reaches a muscle.1. Nerves activate skeletal muscles2. Activation releases calcium3. Calcium starts the sliding filament

mechanism4. Contraction ends when nerve

activation ends

Sliding filament model of contraction

http://video.google.com/videosearch?ndsp=18&um=1&hl=en&q=sliding%20filament%20of%20contraction&ie=UTF-8&sa=N&tab=iv#

grants.hhp.coe.uh.edu/clayne/6397/Unit3.htm

5. How is ATP supplied to muscles? What is oxygen debt? (p. 114)

1. Lots of mitochondria form ATP by aerobic cellular respiration

2. Muscles contain creatine phosphate (high E storage supply) used to regenerate ATP indirectly

3. ATP produced anaerobically when oxygen supply is limited

Oxygen Debt

Continued intake of oxygen (panting) to complete the metabolism of lactic acid (built up anaerobically)

Lactic acid is transported to the liver and broken down into carbon dioxide and water