1. Muscular System Functions
Body movement
Maintenance of posture
Production of body heat
Communication
Constriction of organs and vessels
Heart beat

2. Muscle Tissue Types Skeletal Smooth Cardiac Attached to bones
Striated, Voluntary and involuntary (reflexes)‏
Smooth
Walls of hollow organs, blood vessels, eye, glands, skin
Not striated, involuntary
Cardiac
Heart
Striations, involuntary, intercalated disks

3. Smooth Muscle
Smooth muscle is found in the walls of blood vessels, tubular organs such as the stomach and uterus. It has the ability to stretch and maintain tension for long periods of time. It is not under voluntary control and each cell exists as a discreet independent unit that is innervated by a single nerve ending. The myofilaments are loosely organized and attached to dense bodies.

4. Cardiac Muscle

6. Skeletal Muscles Biceps Triceps
Biceps-Triceps Muscles Represent an Antagonistic Pair.
One contracts while it’s antagonist relaxes.

8. Organization III:

9. Structure of Skeletal Muscle: Connective Tissue Covering
Epimysium (upon, outside)‏
Surrounds entire muscle
Perimysium (around)‏
Surrounds bundles of muscle fibers
Fascicles (bundle)‏
Endomysium (within)‏
Surrounds individual muscle fibers

10. Connective Tissue, Nerve, Blood Vessels

11. Muscle cell (myofiber) Structure
Sarcolemma
Muscle cell membrane
Myofibrils
‏contractile protein strands
Striations due to presence of sarcomeres

12. Contraction

13. Sarcomere – the functional unit of myofibrils

14. Sarcoplasmic reticulum – storage for calcium ions that are used for muscle contractions

15. CONTRACTILE PROTEINS THIN FILAMENT Has 3 parts; i) ACTIN PROTEIN
(i.e. the main molecule of this filament).
FUNCTION: Binds to myosin head of thick filament.
ii) TROPONIN
FUNCTION: Regulatory function by binding to Ca 2+
iii) TROPOMYOSIN
FUNCTION: Has a regulatory function by blocking/unblocking
the binding site of actin to the myosin head

16. CONTRACTILE PROTEINS THICK FILAMENT – made of myosin protein
- has 2 main parts
i) MYOSIN HEAD - forms cross-bridge with actin.
ii) MYOSIN TAIL – forms the shaft of thick bands.

17. Calcium ?
Click for video

18. Sliding Filament Model I:
Actin myofilaments sliding over myosin to shorten sarcomeres
Actin and myosin do not change length
Shortening sarcomeres responsible for skeletal muscle contraction
During relaxation, sarcomeres lengthen

19. Mechanism of muscle contraction

20. SLIDING FILAMENT THEORY

21. MOTOR UNIT

22. Motor Unit Single motor neuron & muscle fibers it innervates
Eye muscles – 1:1 muscle/nerve ratio
Hamstrings – 300:1 muscle/nerve ratio

23. The Neuromuscular Junction
Site where motor neuron meets the muscle fibre
Separated by gap called the neuromuscular cleft
Motor end plate
Pocket formed around motor neuron by sarcolemma
Acetylcholine is released from the motor neuron
Causes an end-plate potential (EPP)‏
Depolarisation of muscle fibre

24. Neuromuscular Junction
Click for a Video

26. Rigor Mortis
Rigor mortis is one of the recognizable signs of death (Latin mors, mortis) that is caused by a chemical change in the muscles after death, causing the limbs of the corpse to become stiff (Latin rigor) and difficult to move or manipulate.[1]
After death, respiration in organisms ceases to occur, depleting the corpse of oxygen used in the making of ATP. ATP is no longer provided to operate the SERCA pumps in the membrane of the sarcoplasmic reticulum, which pump calcium ions into the terminal cisternae.[1] This causes calcium ions to diffuse from the area of higher concentration (in the terminal cisternae and extracellular fluid) to an area of lower concentration (in the sarcomere), binding with troponin and allowing for crossbridging to occur between myosin and actin proteins. [2]
Unlike normal muscle contractions, the body is unable to complete the cycle and release the coupling between the myosin and actin, creating a perpetual state of muscular contraction, until the breakdown of muscle tissue by digestive enzymes during decomposition.

27. Rigor Mortis
Respiration ceases and Oxygen used in making ATP is depleted.
ATP is no longer provided to operate the pumps in the membrane of the sarcoplasmic reticulum, which pump calcium ions.
Unlike normal muscle contractions, the body is unable to complete the cycle and release the crossbridges between the myosin and actin, creating a perpetual state of contraction until the breakdown of muscle during decomposition.

28. Muscle Function
All or none law – fibre contracts completely or not at all
Muscle strength gradation
Multiple motor unit summation – more motor units per unit of time
Wave summation – vary frequency of contraction of individual motor units

29. Animation Links!!
hill.com/sites/ /student_view0/chapter10/animation__action_potentials_and_muscle_c ontraction.html
hill.com/sites/ /student_view0/chapter10/animation__sarcomere_contraction.html
hill.com/sites/ /student_view0/chapter10/animation__breakdown_of_atp_and_cross- bridge_movement_during_muscle_contraction.html
hill.com/sites/ /student_view0/chapter10/animation__function_of_the_neuromuscular_j unction__quiz_1_.html