The Musculoskeletal System Support, Protection, Movement and Locomotion

1
The Musculoskeletal SystemSupport, Protection,
Movement and Locomotion
2
Functions

1. Motion
2. Maintenance of posture
3. Heat production
4. Protection of internal organs

3
Origin of muscle tissue

• Forms from the mesoderm germ layer
• Triploblasts? simplest flatworms
• Segmentation ? annelids, arthropods, vertebrates

4
Types of muscle tissue

• Skeletal
• Attached to bones
• Striated and voluntary
• Cardiac
• Heart wall
• Highly branched
• Striated and involuntary
• Smooth
• Walls of hollow internal structures
• Nonstriated and involuntary

• Striated
• Voluntary movements
• Longitudinal or circular in shape
• Smooth
• Involuntary movements

• Vertebrate muscles

• Invertebrate muscles

5
Muscle action

• Motion produced by action of muscles on bones ?
  levers
• Tendons ? attach muscles to bones (e.g. Achilles
  tendon)
• 1 fixed point of attachment (origin) and 1 moving
  point of attachment (insertion)
• Fascia ? sheets that cover muscles
• Muscles work in antagonistic or opposing pairs

6
Organization of skeletal muscles
7
Overview of the Sliding Filament Theory
The muscle fiber is stimulated.
Ca2 ions are released.
Thin filaments move to middle of sarcomere.
Muscle fiber contracts.
Muscle tension increases.
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
Muscle twitch

• Cycle of contraction and relaxation generated
  from one stimulus
• All or none response of muscle fibers
• Force Summation
• Increasing and size of fibers contracting
• Increasing frequency at which action potentials
  are sent to muscle fibers

12
Slow and Fast Twitch Fibers

• Slow Twitch
• More ATP from aerobic respiration
• Continuous extended contractions over time
• More myoglobin
• Fast Twitch
• Anaerobic metabolism (creatine phosphate and
  lactic acid fermentation)
• Short bursts of speed
• Fatigue quickly

13
Muscle and exercise
14
(No Transcript)
15
Cramps

• Painful sensations caused by contraction/
• overshortening of muscles
• Causes
• Hyperflexion
• Inadequate oxygenation
• Changes in temperature
• Dehydration
• Low amount of electrolytes in blood
• Treatment
• Correct breathing
• Increasing intake of water and electrolytes