The Muscular System

3 kinds of muscle• All have cells specialized to contract for movement

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Skeletal muscle•moves bones•Long, thin cells called fibers

•More than one nucleus per cell

•Striated•voluntary QuickTime™ and a

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Smooth muscle

• Found in walls of hollow organs & blood vessels

• Smaller cells, not striated• One nucleus• involuntary

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Cardiac muscle• Found in the heart• Contracts without signals from nervous system

• Involuntary• Striated• multinucleated

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The Muscular System

(skeletal muscle)• Structure of a muscle: a bundle of muscle fibers

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Functions of muscles

• Over 600 muscles produce the varied movements of the body

• Origin: side of muscle that attaches to the non-moving bone

• Insertion: attaches to the moving bone

• Joints are like levers and muscles provide force whereas the mass of the bone is the resistance

Functions of muscles

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Muscles work together

• Antagonistic pairs• One contracts while the other relaxes (reciprocal innervation prevents nervous signals to the relaxing muscle so that both cannot contract at the same time)

• Each responsible for an opposing movement

• Example: biceps/triceps. Can you think of any others?

Muscles work together

• Synergistic groups: contraction of one adds force or stabilizes the movement of the others

2 functional types of skeletal muscle

fibers• “slow” or “red” fibers

• Myoglobin pigment binds oxygen• More blood vessels deliver more oxygen• More mitochondria- lots of ATP, sustain slow contractions over long periods of time

• “fast” or “white” fibers• Less myoglobin, blood vessels, mitochondria

• Use lactic acid fermentation to make smaller amts. of ATP

• Faster, more powerful contractions can’t be sustained over long periods of time

Fast & slow fibers

• Muscles have a combination of both, depending on their job and location, they may have more of one or the other

• Find a slow fiber and a fast fiber…

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Athletes• Percentage of fast and slow fibers is genetically determined

• Athletes can train to increase the size and power of fast fibers or the endurance and stamina of slow fibers (especially In the legs)

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Discuss…• In turkey, the dark meat is muscle with lots of slow fibers, light meat is muscle with lots of fast fibers.

• Which parts of the turkey are light & dark? Think about a turkey’s life style. See if this makes sense.

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Physiology: T 11.8.11

• Word of the Day: striation (skeletal and cardiac muscle fibers have striations)

• TCB• Study guide online and some paper copies

• GOALS/AGENDA• Complete muscle basics (5 min)• Lab- musclemania

Physiology: T 10.12

• Lab: musclemania!• Follow instructions and fill in questions on lab sheet

• Clean up- return slides to case and microscopes to cart

Musclemania

•View prepared slides of muscle tissue and draw what you see

•Create a wet mount of skeletal muscle tissue and view under the microscope

•Complete musclemania lab sheet

Musclemania part 2

• Safety concerns: biostain, raw meat, sharp tools

• Cleanup: rinse all materials and return to side bench

• Procedure: watch demo, keep methylene blue and water containers on side bench

Physiology: W 11.9

• Word of the Day: sarcomere (the contractile unit of a muscle is a sarcomere)

• TCB• Quiz corrections today

• GOALS/AGENDA• Complete musclemania (20 min)

• Introduction to how muscles contract

How Muscles Contract• A muscle contracts when

individual cells within it shorten

• Basic unit of contraction= sarcomere

• Contractile proteins- actin (thin filaments) & myosin (thick filaments)QuickTime™ and a

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How muscles contract

• When the sarcomere contracts it gets shorter but the filaments do not change in length. How is that possible?

Contracting filament

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Physiology: Th 11.10• Word of the day: power stroke (a

muscle contraction involves a series of power strokes by the myosin heads)

• TCB• Don’t forget to email me! • Continued review opportunities• Next week

• GOALS/AGENDA• Quick look at study guide• Period 1 complete muscle contraction notes

• Muscle contraction skits (teams. For a grade)

Muscle Contraction Skits• Create a skit showing the actions of

sarcomeres during a muscle contraction• 60 seconds (no more)• No speaking allowed (sound effects ok)• Props OK, check w/ me before using something

from the classroom• No written words, symbols/drawings OK• Include actin, myosin, cross-bridges, Calcium,

ATP• Everyone must be in it

Watching the skits

• Critique!– Did it help you understand sarcomere

contraction? (yes, no, sort of)– Was it creative? (yes, no, sort of)– Did you know what/who the actin, myosin,

calcium and ATP were? (yes, no, sort of)