1. Muscle Structure and Function
Biology 2121
Chapters 9-10

2. Introduction 1. Functions 2. Naming (321)
Movement, Posture; Heat and Joints
2. Naming (321)
Location; Shape (temporalis; deltoid)
Size (gluteus maximus)
Fiber Direction (abdominus rectus)
Origins (bicep)
Location of Attachment (sternocleidomastoid)

3. Major Muscle Groups Chest and Shoulder Group Abdominals
Quadriceps and Hamstring Group

4. Histology of Muscle Tissue- Skeletal Muscle
Voluntary
Found in major muscle groups
Striated
Multinucleated
Peripheral

5. Smooth Muscle Involuntary
Found in digestive system organs, bladder, etc.
Non-Striated
Uninucleated
Spindle-Shaped nuclei

6. Cardiac Muscle
Involuntary
Heart only
Branching Fibers
Uni-Nucleated

7. Gross Anatomy 1. Whole muscle 2. Fascicles 3. Muscle Fiber Cells
Epimysium
2. Fascicles
Perimysium
3. Muscle Fiber Cells
Long and multi-nucleated
Sarcolemma and sarcoplasma
Endomysium

8. Attachments
Tendons
Aponeurosis
Direct or Indirect Attachments

9. Microscopic Anatomy – Myofibrils
1. Contractile proteins
2. Sarcomeres
Actin and myosin
3. Myofilaments
Actin (thin)
Myosin (thick)

10. Sarcomere 1. A ‘sarcomere’ 2. Structural Proteins
Z to Z
I-Band (light zone)
A-Band (dark zone)
2. Structural Proteins
Elastic filaments – Titan
3. Sliding Filament Model of Contraction
Link

11. Sarcomere Contraction

12. Chemical Stimulation and Muscle Contractions
1. Stimulation and Neurotransmitters
Acetylcholine
2. Neuromuscular Junction
Junction – muscle/nerve interface
Separation – “synapse”

13. Neuromuscular Junction

14. Events at the Neuromuscular Junction
1. Nerve Impulse
2. Calcium ions – Axon Terminal of Nerve
3. Vesicle and release of ACh
4. ACh receptors and Acetylcholinesterase
5. Sodium-Potassium exchange
6. Action Potential formed

15. Neuromuscular Junction

16. Action Potential 1. Resting Membrane 2. Reversal of Charges
-70 mV
Na+ and K+
2. Reversal of Charges
Depolarization
3. Moves in one Direction

17. What Happens after the Action Potential is Formed?

18. Excitation and Contraction
1. Action Potential moves along the sarcolemma
2. Down the T-Tubule
3. Sarcoplasmic Reticulum and Release of Ca++
4. Ca++ moves to the sarcomere

19. Formation of a Cross-Bridge
1. Ca++ interacts with troponin
2. Removes tropomyosin
3. Allows for Myosin Head Attachment
4. Formation of a cross- bridge

20. Cross-Bridge Cycling 1. Myosin heads attach forming cross- bridge
2. Working Stroke
3. ATP breaks cross- bridge
4. ATP hydrolysis
5. High-energy configuration – New Cross-bridge

21. ATP and Muscle Metabolism
ATP Functions – Driving Cellular Work

22. ATP Production 1. Creatine Phosphate – Quick and Fast!!!
2. Anaerobic Respiration
“Lactic Acid Fermentation”
1 glucose molecule = 2 ATP Net
3. Aerobic Respiration
1 glucose molecule = 36 ATP Net
Mitochondria of the Cell

23. Aerobic Respiration

24. Fermentation Glycolysis (2) Pyruvic acid molecules (3-C)
Blood flow restricted during vigorous exercise (low oxygen)
Lactic acid formed
Anaerobic glycolysis