Download Muscles

Muscles
Muscle Tissue
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Contains many mitochondria to power
contractions
Muscles are longer than they are wide
Muscles are divided into fibers
Muscle fibers contract (or shorten) when
stimulated by the nervous system
Muscle fibers do not elongate
Skeletal Muscle
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Helps you move your body
Under voluntary (conscious) control
Tendon – band of connective tissue that
attaches muscle to bones
The Achilles tendon attaches
the calf muscle
(Gastrocnemius) to the heel /
ankle bone
Skeletal Muscle Functions
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Moves bones at joints
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Pushes substances such as blood, food
and fluids throughout the body
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Helps regulate body temperature,
providing heat through contractions and
causing you to shiver when you are cold
Features of Skeletal Muscle
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Cell is rectangular and has multiple nuclei
Striations = alternating light and dark
bands/stripes created by the arrangement
of the two types of proteins that make up
the muscle fiber
Structure of Skeletal
Muscle
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Muscle fiber is made
up of long strands of
protein called myofibrils
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Myofibril is divided into
multiple sarcomeres
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Sarcomere is the
“functional unit” of the
muscle
The Sarcomere
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The sarcomere contains two types of
filaments, both made up of protein.
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Actin = thin filament
Myosin = thick filament
Skeletal Muscle Contraction
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These protein
filaments - actin
and myosin cause muscle
contraction
The thick myosin
filaments anchor
the thin actin
filaments as they
“slide” or contract
Animation – skip to section
6: Muscle Contraction
The Role of the Nervous System
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Muscle contraction is controlled by the
nervous system.
The nervous system causes calcium ions to
be released, which stimulates the protein
filaments to pull.
Muscle contraction is all or nothing. It
requires the shortening of millions of
sarcomeres.
Smooth Muscle
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Not striped
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Cells only
have one
nucleus
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Completely
involuntary
Smooth Muscle Function
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Moves food
through
digestive system
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Empties the
bladder
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Controls blood
flow
Cardiac Muscle
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Found only in heart
Looks like a combination of skeletal and smooth
muscle types
Adjacent cells are separated by intercalated disks
- Striated
- Oval-shaped
- Many nuclei
Cardiac Muscle Function
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Have more mitochondria and ATP energy
than other muscle cells (even skeletal)
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Involuntary
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Impulse from the pacemaker causes cardiac
muscle contraction
Brainstem can modify rate of contractions
Make sure you can label these parts of
skeletal muscle
Practice labeling these parts of a sarcomere
Make sure you can tell the three
types of muscle apart
____________
muscle
.____________
muscle
.____________
muscle
This sarcomere
is:
______________
This sarcomere
is:
______________
Which diagram shows a sarcomere (functional unit of muscle) that is contracted?
Which diagram shows a sacromere that is relaxed? Label above.