ppt

1. Muscles physiology

2. Muscles function
Contract!
Generate motion
Generate force
Generate heat
Support

3. Muscular Functions
 Body movement (Locomotion)
 Maintenance of posture
 Respiration
 Diaphragm and intercostal contractions
 Communication (Verbal and Facial)
 Constriction of organs and vessels
 Peristalsis of intestinal tract
 Vasoconstriction of b.v. and other structures (pupils)
 Heart beat
 Production of body heat (Thermogenesis)

4. Properties of Muscle
 Excitability: capacity of muscle to respond to a
stimulus
 Contractility: ability of a muscle to shorten and
generate pulling force
 Extensibility: muscle can be stretched back to its
original length
 Elasticity: ability of muscle to recoil to original
resting length after stretched

5. Muscle Types
 Cardiac – heart
 Smooth – internal organs
 Skeletal – "voluntary"
Attach to bone
Move appendages
Support body
Antagonistic pairs
Flexors
Extensors

6. Categories of skeletal muscle actions
 Categories Actions
 Extensor - Increases the angle at a joint
 Flexor- Decreases the angle at a joint
 Abductor - Moves limb away from midline of body
 Adductor - Moves limb toward midline of body
 Levator - Moves insertion upward
 Depressor Moves insertion downward
 Rotator - Rotates a bone along its axis
 Sphincter -Constricts an opening

7. Types of Muscle
 Skeletal
 Attached to bones
 Makes up 40% of body weight
 Responsible for locomotion, facial expressions, posture, respiratory
movements, other types of body movement
 Voluntary in action; controlled by somatic motor neurons
 Smooth
 In the walls of hollow organs, blood vessels, eye, glands, uterus, skin
 Some functions: propel urine, mix food in digestive tract,
dilating/constricting pupils, regulating blood flow,
 In some locations, auto rhythmic
 Controlled involuntarily by endocrine and autonomic nervous systems
 Cardiac
 Heart: major source of movement of blood
 Auto rhythmic
 Controlled involuntarily by endocrine and autonomic nervous systems

8. Connective Tissue Sheaths
 Connective Tissue of a Muscle
Epimysium. Dense regular c.t. surrounding entire muscle
Separates muscle from surrounding tissues and organs
Connected to the deep fascia
Perimysium. Collagen and elastic fibers surrounding a
group of muscle fibers called a fascicle
Contains b.v and nerves
Endomysium. Loose connective tissue that surrounds
individual muscle fibers
Also contains b.v., nerves, and satellite cells (embryonic
stem cells function in repair of muscle tissue
 Collagen fibers of all 3 layers come together at each end of
muscle to form a tendon or Aponeurosis.

9. Muscle Types
Figure 12-1: Three types of muscles

10.  About 40% body mass
 Muscle fibers – cells
 Fascicle – bundle
 Motor unit
 Muscle
 sheath
 Attach to tendons (which attach to bone)
Skeletal Muscle Anatomy

11. Nerve and Blood Vessel Supply
 Motor neurons
stimulate muscle fibers to contract
Neuron axons branch so that each muscle fiber (muscle
cell) is innervated
Form a neuromuscular junction (= my neural junction)
 Capillary beds surround muscle fibers
Muscles require large amounts of energy
Extensive vascular network delivers necessary oxygen
and nutrients and carries away metabolic waste produced
by muscle fibers

12. Skeletal Muscle Anatomy

13. Skeletal Muscle Anatomy

14.  Multiple nuclei
 Sarcolemma
 T-tubules
 Sarcoplasmic reticulum
 Sarcoplasm
Mitochondria
Glycogen & ions
Myofibrils
Muscle Fiber Structure

15. Muscle Fiber Structure
Figure 12-3b: ANATOMY SUMMARY: Skeletal Muscle

16.  Actin –"thin fibers"
 Tropomysin
 Troponin
 Myosin – "thick fibers"
 Titin – elastic anchor
 Nebulin – non-elastic
Myofibrils: Site of Contraction

17. Myofibrils: Site of Contraction

18. Sarcomere: Organization of Fibers
Figure 12-6: Titin and nebulin

19. Skeletal Muscle Contraction: Mechanism
Figure 12-11a: Excitation-contraction coupling

20. Skeletal Muscle Contraction: Mechanism

21. Energy for Contraction: ATP & Phosphocreatine
• Aerobic Respiration
• Oxygen
• Glucose
• Fatty acids
• 30-32 ATPs
• Anaerobic Respiration
• Fast but
• 2 ATP/glucose
• Phosphocreatine ATPs

22. Energy for Contraction: ATP & Phosphocreatine
Figure 12-13: Phosphocreatine

23. Smooth Muscle
 Fusiform cells
 One nucleus per cell
 Nonstriated
 Involuntary
 Slow, wave-like
contractions

24. Smooth Muscle
• Cells are not striated
• Fibers smaller than those in skeletal
muscle
• Spindle-shaped; single, central
nucleus
• More actin than myosin
• No sarcomeres
• Not arranged as symmetrically as
in skeletal muscle, thus NO
striations.
• Caveolae: indentations in
sarcolemma;
• May act like T tubules
• Dense bodies instead of Z disks
• Have noncontractile intermediate
filaments

25. Smooth Muscle
• Grouped into sheets in walls of hollow organs
• Longitudinal layer – muscle fibers run parallel to organ’s long axis
• Circular layer – muscle fibers run around circumference of the organ
• Both layers participate in peristalsis

26. Smooth Muscle
• Is innervated by autonomic nervous system (ANS)
• Visceral or unitary (single unit) smooth muscle
• Only a few muscle fibers innervated in each group
• Impulse spreads through gap junctions
• Whole sheet contracts as a unit
• Often autorhythmic
• Multiunit:
• Cells or groups of cells act as independent units
• Arrector pili of skin and iris of eye

27. Smooth Muscle Cell

28. Myosin of Smooth Muscle
• Different isoform than that found in skeletal
muscle
• Smooth muscle myosin ATPase activity is
much slower, contraction is longer
• Myosin light chain in the myosin head
regulates contraction and relaxation

29. Smooth Muscle
• Relatively little sarcoplasmic reticulum
• Lacks T-tubules
• Chemically linked to the cell membrane,
rather than mechanically linked
• Ca +2 storage is supplemented by caveolae ,
small vesicles that cluster close to the cell
membrane. Voltage/ligand gated Ca +2
channels

30. Single-Unit Muscle

31. Properties of Single-Unit Smooth Muscle
• Gap junctions
• Pacemaker cells
with spontaneous
depolarizations
• Innervation to few
cells
• Tone = level of
contraction without
stimulation
• Increases/decreases
in tension
• Graded Contractions
• No recruitment
• Vary intracellular
calcium
• Stretch Reflex
• Relaxation in
response to sudden
or prolonged stretch

32. Multi-Unit Muscle

33. Comparisons Among Skeletal, Smooth, and Cardiac Muscle

34. Thank you