3. MUSCLE ENERGETICS

4. TETANUS and TETANY Tetanus
Neurological disorder that results from a decrease inhibitory input to alpha motor neurons

5. Mechanism of Action ---Tetanus
Cause—Bacteria Clostridium tetani Toxin ---- Tetanospasmin Mechanism of action—Retrograde intraneuronal transport. (Retroaxonally)

6. Symptoms- -Locked jaw -Opisthotonus -Breathing problems.
-Sudden powerful and painful contraction of muscles
-Irritability, muscle cramps.
-Weakness
-Difficulty in swallowing
-Sardonic smile

7. OPISTHOTONUS

8. TETANUS Antibiotic to kill the bacteria.
Injecting antibiotics that bind the toxin.
Muscle relaxants.
Mechanically ventilating the lungs
Prophylaxsis— Immunization

9. TETANY Low serum calcium levels (8.5-10.5 mg/dl)
CAUSES– 1-Lack of calcium
2-Excess of phosphate
3-Underfunctioning of thyroid
gland.

10. Mechanism of Action --Tetany
Decrease Calcium ion concentration Sodium channels become activated by very little increase in membrane potential.

11. TETANY
SYMPTOMS— 1- Hyperflexia 2- Carpopedal spasm 3-Cramps 4-Laryngospasm Treatment I/V calcium 2-Oral calcium +Vitamin D 3-Surgical removal of parathyroid glands

12. TYPES OF SKELETAL MUSCLE FIBERS
SLOW-TYPE FAST- TYPE II
OXIDATIVE GLYCOLYTIC
RED WHITE

13. TYPES OF SKELETAL MUSCLE FIBER
SLOW-TYPE I OXIDATIVE RED
FAST-TYPE II GLYCOLYTIC WHITE
Myosine with low ATPase activity
Myosine with high ATPase activity
Cross bridge cycling is slow
Cross bridge cycling is fast
Maximal shortening velocity is low
Maximal shortening velocity is high
Glycogen content is low
High
Enzymes for anaerobic glycolysis are low
Mitochondria--- High
Capillary density---- High
Myoglobin content---- High
Oxidative metabolism capacity is high
Low

14. TYPES OF SKELETAL MUSCLE FIBER
SLOW TYPE-I OXIDATIVE RED
FAST TYPE II GLYCOLYTIC WHITE
Diameter moderate
Diameter large
Calcium pumping capacity of SR is moderate
Calcium pumping capacity of SR is high
Speed of contraction slow
Speed of contraction fast
Latent period long
Latent period short
Fatigue resistance
Fatigable

15. Some Diseases related to Muscles
Tetanus
Tetany
Rigor Mortis
Myasthenia Gravis
Dystrophy (Duchenne’s Muscular Dystrophy)

16. RIGOR MORTIS
Several hours after death all the muscles of the body go into a state of contracture .
Loss of all ATP
Muscle protein deteriorates to 25 hours later. (Autolysis).
All these events occur more rapidly at higher temperatures.

17. Function of Skeletal Muscles
Movement
Posture (both agonist & antagonist function together, Co- activation)
Heat Production
Interaction with the Environment (Expression)
Exert Rapidly adaptable force
Voluntary control

18. Some terms Related to Muscles
Disuse Atrophy
Atrophy {
Denervation Atrophy
Hypertrophy
Fibrillation
Fasciculation

19. Atrophy Denervation atropy:1. Neurons are destroyed
Decrease in the diameter of nerve fiber
Decrease in the amount of contractile proteins.
Disuse atrophy : Muscle is not used for a prolong period of time.
Denervation atropy:1. Neurons are destroyed
2. Neuromuscular junction
becomes non functional.
(ATP dependent ubiquitin – proteasome pathway)

20. Hypertrophy
Increase in the diameter of nerve fiber.
Increase in the amount of contractile proteins
Muscle is loaded during the contractile process

21. Rapid ,irregular and unsynchronized Fasciculation
Fibrillation
Rapid ,irregular and unsynchronized
contraction of muscle fiber.
Fasciculation
Small local, involuntary muscle contraction and relaxation which may be visible under the skin

22. Smooth Muscles

23. Objectives
At the end of this lecture you should be able to know types of smooth muscles and their anatomical location.
Arrangement of myofilaments and sarcoplasmic reticulum
Steps involved in Contraction
Functional differences

24. SMOOTH MUSCLE
Diameter – 1-5 micrometers
Length micrometers

25. Smooth Muscles Generally Divided into Two Types 1. Multi-unit.
Composed of :
discrete, Independent fibers innervated by separate single nerve ending
e.g. iris and
piloerector muscles
Multi unit
Smooth M Fiber

26. Unitary Smooth Muscle 2. Unitary:
fibers but contract as a unit.
due to presence of gap junctions
e.g. in most of the viscera

27. Input Influencing Smooth muscle Contractile activity
Spontaneous electrical activity in the plasma membrane of the muscle cell.
Neurotransmitters released by autonomic neurons.
Hormones
Locally induced changes in the chemical composition of ECF surrounding the cell
(acidity, oxygen,osmolarity, ion concentration)
Stretch.

28. Arrangement of Actin & Myosin
Smooth M Fiber

29. Neuromuscular Junction of Smooth Muscle

30. Non striated
Dense bodies--- Z-lines
Protein Calmodulin--- Troponin complex.
No Typical branching end feet as in Sk. Muscles
Multiple Varicosities. No Schwann cells at Varicosities. Diffuse junctions.
Contact junctions
Neurotransmitter is released at Varicosities –may be
Ach or Noradrenalin.

31. Sarcoplasmic Reticulum Smooth Muscle
S.R

32. Action Potential in smooth Muscle
RMP… mv
Action Potential in Unitary Smooth Ms e.g. Viscera
Two forms:
1. Slow waves
2.Spike Potential m.sec duration
3. Action potential with plateau.
4. Junctional potential

33. Calcium channels Far greater voltage gated calcium channels
Few voltage gated sodium channels

35. Steps involved in the Contraction of Smooth Muscle
Ca++ binds with Calmodulin
Calmodulin-Ca++ combinedly activates Myosin Kinase (phosphorylating Enzyme)
One of the Light chain of Myosin Head (Regulatory chain) is Phosphorylated in response to this myosin kinase.
The head of Myosin gets capability to repetitively attach & detach with active sites of Actin filaments. - Slow cycling of Cross Bridges than skeletal muscles.
Dephosphrylation–Myosin phosphtase in sarcoplasm

36. Latch Phenomenon
The energy required to maintain full force of contraction , (once developed full contraction initially) in smooth muscles is very negligible (1/300 that of Sk. Muscle)
This phenomenon allows long term maintenance of tone in many smooth muscles without much expenditure of energy.

37. Comparison of Smooth and Skeletal muscle contraction
Slow cycling of the myosin cross bridges.
Low energy requirement to sustain smooth muscle contraction.
Slowness of onset of contraction and relaxation of the total smooth muscle tissue.
Maximum force of contraction (4-6Kg /cm.sq)
Latch mechanism
Stress relaxation of smooth muscle