Transcript Muscles - Needham.K12.ma.us

Muscles
And their close connection to the
nervous, skeletal, and
respiratory/cardiac systems
Skeletons
• Hydrostatic Skeletons: Fluid is held
underpressure and muscles control
movement. Ex. Circular and longitudinal
muscles in worms.
• Hard Skeletons: Hard supporting elements
such as bones, plates that are moved by
muscles.
– Ex. Endoskeletons & Exoskeletons
Exoskeletons vs. Endoskeletons
• Compare and contrast
– Material
– Position
– Mechanism for
movement
3 Roles for the Human Skeletal
System
• Protection
• Movement
• Blood cell formation
• Can you think of a
bone that is an
example of each?
Skeletal and Musclar Systems
Interact
Be able to distinguish
• Muscles
• Bones
• Tendons
• Ligaments
• Joints
• Cartilage
Muscles contract for movement
• Antagonistic pairs.
– One contracts (Flexor)
– One relaxes (Extensor)
Skeletal Muscle at the
microscopic level
• Note that each muscle
cell contains actin and
myosin arranged in a
specific manner.
Describe a Muscle Contraction
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Sarcomere:
A band:
Z lines:
H band:
I band:
M line:
Sliding Filament Theory
Structure Meets Function: How
do the heads bind?
• Role of Ca2+
• Role of Tropomyosin
• Role of Troponin
Control: How nerves control
muscles
Similar to threshold
• Tetanus
– Action potentials
combine together and a
series at high
frequency leads to a
contraction.
Which would have more
mitochondria?
• Fast fibers
– Quick rapid
contractions
– Need lots of calcium
storage
– “White Meat”
• Slow Fibers
– Long sustained
contractions require
steady energy.
– Less smooth ER
(sarcoplasmic
reticulum)
– “Dark meat” rich
blood supply
Goals
• Review muscles with Campbell’s activities
49C and 49D
• Observe a frog’s muscles.
• Use the web and microscopes to observe the
structural differences and determine the
functions of skeletal, cardiac, and smooth
muscle.
Comparison
of Muscle
Tissue