Study Guide Ch 9.docx - Bio 120- Anatomy & Physiology I...

Bio 120- Anatomy & Physiology I
Chapter 9
Muscles
Functions:
1. Produce movement: responsible for all locomotion and manipulation
2. Maintain posture and body position
3. Stabilize joints
4. Generate heat as they contract
Types of Muscles:
1. Skeletal
a. Skeletal muscle tissue is packaged into skeletal muscles:
attached to bones and skin
b. Skeletal muscle fibers are longest of all muscle and have
striations (stripes)
c. Also called voluntary muscle: consciously controlled
d. Contract rapidly; tire easily; powerful
2. Cardiac
a. Cardiac muscle tissue found in heart
i. Makes up bulk of heart walls
b. Striated
c. Involuntary: not controlled consciously
i. Contracts at steady rate due to heart’s own pacemaker,
but nervous system can increase rate
3. Smooth
a. Smooth muscle tissue: found in walls of hollow organs
i. Examples: stomach, urinary bladder, and airways
b. Not striated
c. Involuntary: not controlled consciously
Characteristics of Muscle Tissue
 Excitability: ability to receive and respond to stimuli
 Contractility: ability to shorten forcibly when stimulated
 Extensibility: ability to be stretched
 Elasticity: ability to recoil to resting length
SKELETAL MUSCLE ANATOMY :
Nerve and Blood Supply
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Bio 120- Anatomy & Physiology I
 Skeletal muscle organ features: nerve and blood supply, connective
tissue sheaths, and attachments
 Each muscle receives a nerve, artery, and veins
 Contracting muscle fibers require huge amounts of oxygen, nutrients
and waste removal
Connective Tissue Sheaths
 From external to internal:
o Epimysium: dense irregular connective tissue surrounding
entire muscle; may blend with fascia
o Perimysium: fibrous connective tissue surrounding
fascicles (groups of muscle fibers)
o Endomysium: fine areolar connective tissue surrounding
each muscle fiber
Attachments
 Muscles span joints and attach to bones
 Muscles attach to bone in at least two places
o Insertion: attachment to movable bone
o Origin: attachment to immovable or less movable bone
 Attachments can be direct or indirect
o Direct (fleshy): epimysium fused to periosteum of bone or
perichondrium of cartilage
o Indirect: connective tissue wrappings extend beyond
muscle as ropelike tendon or sheetlike aponeurosis
MUSCLE FIBER MICROANATOMY & SLIDING FILAMENT MODEL
 Sarcolemma- muscle fiber plasma membrane
 Sarcoplasm- muscle fiber cytoplasm
 Myofibrils
o densely packed, rodlike elements
o Single muscle fiber can contain 1000s
o Accounts for ~80% of muscle cell volume
 Striations
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