1. By Brennan, Jacob, and Colby
Muscular System
By Brennan, Jacob, and Colby

2. 3 Types of Muscle Skeletal Cardiac Smooth Latin Prefixes:
Myo- means muscle
Sarco- means flesh

3. Smooth Muscles Not Striated Not strong, can go for a long time
Requires Ca++ to contract
Contracts toward center
Has one nucleus per muscle fiber
Footballish shaped
Has Actin(thin) and Myosin(thick) filaments, thin filaments are anchored by dense bodies
Dense bodies are the same as Z-discs and is fastened to the sarcolemma

4. Smooth Muscle
Makes its own connective tissue which is called Endomysium that connects the muscle fibers to each other and the whole muscle is wrapped with connective tissue called Epimysium
Involuntary Muscle

5. Cardiac muscle Striated Muscle Myocardium Energizer Bunny
Goes on forever (Really, think about it, does your heart just stop)
Quickly Spreads electrochemical signals so that all the cells can contract together

6. Cardiac Muscle Muscle Fibers contain a single nucleus + striated area
Light bands are thin filaments made of actin that allow light to pass through
Myosin pulls the actin filaments together like an accordion
All heart cells are connected
Contractions are set to its own rhythm due to pacemaker cells

7. Skeletal Muscle Striated muscle There are 640 skeletal muscles
Gluteus Maximus is the largest
The smallest is the stapedius located in the inner ear
Requires conscious thought to move
Each has its own nerve to allow movement and its own vein/artery to keep it oxygenated

8. Skeletal Muscles- Structure
Tendon- attaches muscle to bone.
Epimysium- protective tissue around the muscle.
Fascicle- a bundle of muscle fibers.
Muscle Fibers- a single muscle cell.

9. Skeletal Muscle- Muscle fibers/cells
Sarcolemma- A thin, tubular sheath that envelops the fibers of muscle cells. Transverse tubules (t-tubules) are extensions of the sarcolemma that penetrate down to the sarcomeres.
Sarcoplasm- The cytoplasm of striated muscle cells.
Sarcoplasmic Reticulum- specialized smooth ER that regulates the calcium concentration in the cytoplasm of skeletal cells. Interact with the calcium channels on the muscle cell that receives action potentials.
Multinucleated-skeletal muscles become multinucleated due to the fusion of muscle cells.

10. Skeletal Muscle- Myofibrils
Myofibril: The basic unit of a skeletal muscle cell.
Sarcomere: The section of a myofibril located between two Z-lines. Made up of two filaments:
Myosin aka the thick filament.
Actin aka the thin filament. Protected by the proteins troponin and tropomyosin.

11. Neuromuscular junctions
Action potential releases acetylcholine
Action potential generated on sarcolemma and T-tubules which opens up the calcium channels in the cell.
Sarcoplasmic reticulum releases Ca2+
Myosin cross bridges form

12. Sliding filament model of muscle contraction
ATP binds to myosin head → ADP + Pi
Ca2+ (brought in through the T-tubules) exposes binding sites on actin filaments by pulling away the tropomyosin and troponin proteins.
cross bridges form as the myosin head binds to actin.
ADP + Pi are released and sliding of actin occurs with the myosin head pulling the actin filament. This (many times) causes the Z-lines on either side to get closer, shrinking the sarcomere.
ATP causes unbinding (rigor mortis) as it binds to the myosin head.
bootyhole

13. Cool links for cool cats
Interactive models:
Sliding filament model crash course vid:
Cool links for cool cats