ANAT 100 Lecture Notes - Lecture 3: Endoplasmic Reticulum, Myocyte, Skeletal Muscle

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Week 3: Muscular System
Chapter 4: 109-111, Chapter 10: 288-299, 302-303, 308-310, 314-315
Chapter 11: 322-329, 331-332, 336-340, 341-346
Chapter 4: 109-111
Classification of Muscles Tissue (Types): Pg. 312, Table 10.8. Composed of muscle fibers
1) Skeletal Muscle Tissue: Cylindrical muscle cells, muscle fibers
a. Striated and voluntary (only voluntary muscle), contraction require stimulation
b. Responsible in movement in daily life, most attachment to bones at each end of
tendons
2) Cardiac Muscle Tissue: Located in thick mid-layer of heart wall, myocardium
a. Shorter than skeletal muscle fibers, have 1 or 2 centrally located nuclei, and is
bifurcated (branched)
b. Responsible for rhythmic heart contraction that pump blood through blood
vessels
c. Striated and involuntary, because nervous system not required in contraction
d. Neural activity and hormone module these muscles
3) Smooth Muscle Tissue: Lack striations (Light/ Dark bands for thick/think filaments)
a. Visceral tissue”, because they are found in viscera (Stomach, urinary bladder,
and more)
b. Controlled by autonomic nervous system
c. This muscle tissue help control and proper material in these visceral organs
Function:
1) Excitability: Responsiveness of muscles
a. Response via stimuli
b. Muscle cells stimulated by nervous system and stretch
c. Response by electrical changes that go across plasma membrane
d. Signal eventually leads to muscle contraction
2) Contractile: Cells shorten when stimulated (contraction)
a. Results in pulling bones or movement of body part
3) Elasticity: Ability to reform to original position when tension is released
4) Extensibility: Extensiveness to contraction of opposing muscle cells
Chapter 10: 288-299, 302-303, 308-310, 314-315
Skeletal Muscles: Many functions that include the following;
1) Body movement
2) Maintenance of posture and stabilizing joints
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3) Temperature regulation- thermoregulation and homeostasis for example
4) Storage and movement of material- Digestion for example
5) Support
Gross Anatomy of Skeletal Muscles: Composed of muscle tissues (muscle fibers, blood
vessels and nerves) and connection tissue
Connective tissues surround muscle cells and attach the ends of each muscle to bones
Connective Tissue Components (3):
Microscopic Anatomy of Skeletal Muscle (**Pg. 292, Table 10.2c **):
1) Muscles cells (Myofiber): They are multinucleated
a. Sarcolemma: Plasma membrane of muscle fiber, surround
a.i. muscle fiber and regulates material into and out of it
b. Sarcoplasm: Cytoplasm of muscle fiber
b.i. Area for metabolic processes for normal muscle fiber activity
c. Multinucleated: Having more than 1 nucleus per cell
d. Myofibrils: Organized bundles of myofilaments
d.i. Cylindrical myofilaments involved in muscle contraction
2) Myofibrils:
a. Sarcoplasmic reticulum: Smooth endoplasmic reticulum in muscle fiber
a.i. Stores calcium ions used in muscle contraction
b. Transverse tubule: “T-tubule”
b.i. Narrow, tubular extension of sarcolemma into the sarcoplasm
b.ii. Transports muscle impulse from sarcolemma throughout entire muscle
fiber
c. Myofilaments: Involved in muscle contraction
3) Myofilaments: Bundled in form
Bundle Classification:
a) Thick filaments: Diameter ~ 11 nanometers
a. Bundles formed from the protein myosin-Free globular head that move
to the edges and attached to elongated tails at that move to the center
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