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

• 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