1. MUSCLES!!

3. 3 Types of Muscles
Smooth
Cardiac
Skeletal

4. Smooth Muscle No striations Single nucleus
No/underdeveloped transverse tubules
Involuntary
Contracts in waves called peristalsis

5. Peristalsis
Educational:

6. Cardiac Muscle Like skeletal muscle but found only in the heart
Mononucleated
Involuntary
Well developed transverse tubule system
Contracts as a unit

7. Skeletal Muscles Move bones at joints Voluntary Striated
Multiple nuclei
Transverse tubules systems– WELL DEVELOPED

8. Structure of a muscle
Know this!

9. Myofilaments Within each myofibril are myofilament. Filaments:
Actin: Thin
Myosin: Thick
When a muscle contracts, actin slides past the myosin, shortening the sarcomere.

10. Tropomyosin-troponin complex
Calcium is like a key.
Tropomyosin is like a chain around your bike tires
Troponin is the lock attached to the chain.
The tires are the crossbridge of actin and myosin
The pedals are like ATP

11. The Sarcomere: The functional unit of the muscle

12. Sliding Filament Theory

13. Neuromuscular Junction
Where the terminal button of the motor neuron meets the motor endplate of the muscle. Includes the synaptic cleft.
Acetylcholine (ACh)is the neurotransmitter for muscles.
The synaptic vesicles release ACh into the synapse where it stimulates ACh receptors on the muscle fiber to begin contraction.

14. Sarcoplasmic reticulum releases calcium ions
Calcium binds to the actin filaments sites, opening them.
Myosin heads form cross bridges with actin at the binding site.
Cocked position -> Power stroke
ATP binds to cross bridge, releasing myosin from the actin
ATP breakdown provides energy to “cock” unattached myosin cross bridge.
Process repeats as long as there is ATP and calcium available.

15. Energy Supply
Myofibrils need oxygen for cellular respiration, which creates a lot of ATP.
Muscles can also use creatine phosphate to make ATP.
Glycolysis does not need oxygen but only makes a small amount of ATP. A by-product of this reaction is lactic acid.

16. Muscle Conditions Muscle fatigue: Lactic acid build up
Muscle cramps: A lack of ATP.
Soreness : Rips in the muscle.

17. Slow oxidative twitch
Slow-oxidative twitch muscles have a protein called myoglobin which temporarily holds oxygen. This makes the muscle look dark or red.
That way, slow-oxidative twitch is used for aerobic long distance exercise.

18. Fast Twitch Glycolytic
Uses glycolysis.
White meat because few myoglobin proteins
Short distance, anaerobic
Less mitochondria

19. Fast twitch oxidative
In the middle of slow twitch oxidative and fast twitch glycolytic
Well vascularized
Pink meat

20. Types of Contractions Isotonic: Change in length
Concentric: Shortening of the distance (flexing)
Excentric: Elongating muscle (extending)
Isometric: Change in force
Tetanus
Fused: Smooth contraction
Unfused: Shaky contraction

21. Disease
Myasthenia Gravis (MG): Autoimmune disorder that attacks receptors for ACh at neuromuscular junctions.
Symptoms: Abnormal muscle weakness (esp. facial muscles), chronic fatigue, trouble breathing

22. Things to ponder
Do all muscles have fascia?
Discuss with class