Chapter 9 Part 1 (Lecture) Flashcards
Epimysium
- Surrounds entire skeletal muscle
- Collagen fibers
- Separates muscles from tissues/organs
- Connected to deep fascia
Organization of muscle structures (Largest to smallest)
- Muscle
- Muscle Fiber
- Myofibrils
- Myofilaments
- Thick (Myosin; Club-Head) and Thin (Actin; Troponin; Tropomyosin) Filaments
Perimysium
- Surrounds fascicles (bundles of muscle fibers)
- Collagen and elastic fibers
- Contains blood vessels and nerves to fascicles
Endomysium
- Delicate, elastic connective tissue
- Surrounds individual skeletal muscle cells (Fibers)
- Contains:
- Capillary networks
- Satellite cells
- Nerve fibers
Skeletal Muscle Characteristics
- Long, thin, multinucleate fibers
- Striations (sarcomeres)
- Voluntary control
- Arranged into packages called muscles; attach to and cover bony skeleton
- Contracts rapidly & vigorously, but tires easily
- May exert great force
Cardiac Muscle Characteristics
- 1-2 nuclei
- Network of fibers; intercalated disks
- Only in heart
- Striations (sarcomeres)
- Involuntary control
- Contracts at rhythmic, steady rate (auto-rhythmic)
Smooth Muscle Characteristics
- Spindle-shaped, one centrally-located nucleus (uninucleate)
- Lacks striations (no sarcomeres)
- Involuntary control
- Walls of hollow organs & blood vessels
- Slow & sustained contractions
Sarcoplasmic Reticulum (SR)
- Network of membranous channels that surround each myofibril and run parallel to it
- Same as endoplasmic reticulum in other cells
- Has a HIGH CONCENTRATION OF CALCIUM IONS compared to sarcoplasm
- Membrane becomes more permeable to calcium ions when stimulated
T (Transverse) Tubules
- Set of membranous channels that extend into sarcoplasm as invaginations continuous with sarcolemma
- Filled with extracellular fluid and extend deep into the cell
- Carries action potential to SR
Terminal Cisternae
Dilated ends of sarcoplasmic reticulum
Triads
Terminal Cisternae butt against T Tubule on both sides of T Tubule Triad= TC-T-TC
Sarcomeres
- Length of myofibril divided into sarcomeres
- Sarcomere- functional unit of myofibril
- Z disc- separate one Sarcomere from the next sarcomere
Sarcomere Structures
- Z Line
- A Band
- I Band
- H Zone
- M Line
Functions of the Skeletal Muscles
- Produce Skeletal Movement
- Maintain Body Posture and Body Position
- Support Soft Tissues
- Guard Entrances and Exits
- Maintain Body Temperature
- Store Nutrient Reserves
Sarcolemma
Cell Membrane
Sarcoplasm
Cytoplasm
Excitability
The ability to receive and respond to stimuli.
Contractility
The ability to shorten forcibly when stimulated.
Elasticity
The ability to return to the original length after being stretched or shortened
Extensibility
The ability to be stretched or extended
Z Line
Dense material between sarcomeres
A Band
Dark band (Length of thick)/ thick & thin filaments
I Band
Thin, but no thick
H Zone
Center of A Band (Heavy)
M Line
Middle line of sarcomere; supporting proteins that hold thick filaments together; center of H Zone
