Lab 7: General Muscular System Flashcards
Muscle Organization
Muscle Organ (Epimysium)
Muscle Fasicle (Perimysium)
Muscle FIber (Endomysium)
Myofibrils
Myofilaments (Actin & Myosin)
Muscel Fiber Model
- Endomysium
- outermost layer
- Sarcolemma
- tan layer
- T-tubles
- holes/orange horizontal lines
- Sarcoplasmic Reticulum
- white webbing
- Terminal Cisternae
- surround t-tubule; white lines
- Myofibril
- includes myofilaments
- Myosin
- thick red lines in myofibril
- Actin
- thin red line in myofibril
- Z-line
- pink horizontal line
- Sarcomere
- z-line → z-line
- Cell Nucleus
- blue structure
- Satellite Cell
- tan structure
- Neuromuscular Junction
- Acetylcoline (yellow circles)
- Mitochondria (blue structures)
A flattened, tendinous sheet derived from interwoven fibers of the endomysium, perimysium, and epimysium of skeletal muscle
Aponeuroses
plasma membrane of a skeletal muscle cell (fiber)
Sarcolemma
actin (contractile protein)
Thin myofilament
theory on the mechanism for muscle contraction
Sliding filament theory
connective tissue (deep fascia) encircling many skeletal muscle fascicles
Epimysium
a bundle of many skeletal muscle cells (fibers)
Fascicle
connective tissue encircling a single skeletal muscle fascicle
Perimysium
skeletal muscle cell endoplasmic reticulum
Sarcoplasmic reticulum
Junction of a motor neuron and a skeletal muscle fiber
Neuromuscular junction
Myosin (contractile protein)
Thick myofilament
Connective tissue covering surrounding a skeletal muscle cell (fiber)
Endomysium
Contractile protein filaments consisting of mainly actin and myosin
Myofilaments
Bundles of myofilaments found in a single muscle cell
Myofibril

- Tendon
- Epimysium
- Endomysium
- Bone
- Perimysium
- Fasicle
- Blood vessel
- Muscle fiber

Identify, describe, and provide an example

- Parallel/ Longitudinal - fascicles parallel to long axis of muscle; Sartorius
- Parallel muscle with tendinous bands - Rectus abdominus
- Convergent - fascicles spread over a large area converge to a single tendon; Pectoralis major
- Unipennate - all fascicles converge to one side of a tendon; Semimembranosis
- Bipennate - fascicles converge to both sides of a tendon; Rectus femoris
- Multipennate - tendon branches converge to a single tendon; Deltoid
- Circular - concentrically arranged fibers surrounding an opening; Orbicularis oris

Muscle Fiber
All muscle fibers are only innervated by a single neuron
However, a single neuron can innervate many muscle fibers
A muscle fiber consists of many sarcomeres arranged side by side
Describe the difference between the origin of a muscle and the insertion of a muscle.

- Myofibril
- Myofilaments
- Thin Filament (actin)
- Thick Filament (myosin)
- Mitochondria
- Sarcolemma
- Triad
- Sarcoplasmic Reticulum
- Terminal Cisterna
- T-tubules


- Sarcomere
- H zone
- Actin
- M-line
- Myosin
- Z-line
- A-band
- I-band

Microscope Components of Skeletal Muscle
- Individual muscle fibers
- Sarcolemma
- Nuclei
- A-band (Dark bands)
- I-band (Light bands)
- Endomysium

Skeletal Muscle

Sliding Filmaent Theory
- ATP binds to myosin cross-bridge headm which split ATP into ADP and Pi and energy. Energy is used to swivel the cross-bridges to a “ready” (90º) position
- Motor neuron at neuromuscular junction releases acetylcholine, which binds to receptors on sarcolemma, causing an action potential
- Action potential spreads throughout sarcolemma and down he t-tubules
- This causes the sarcoplasmic reticulum (SR) channels to open and release calcium ions (Ca2+)
- Ca2+ bind to troponin-tropomyosin complex on actin, exposing binding sites for myosin
- Myosin cross-bridges attach to actin (and release Pi) causing myosin to swivel to 45º, pulling actin and their z-lines towards cell center, shortening sarcomere
What is the difference between tendons and ligaments?
What layers of the connective tissue sheath(s) form a tendon?
Why are skeletal muscle cells called fibers?
What are the terminal cisternae and what are their functions?
The dark band in the muscle vell striations are composed of…
The light band in the muscle cell striations are composed of…