Anatomy
The Muscular System
Notes Outline
I. Introduction
 The human body has over 400 skeletal muscles, which accounts for ~ ____% of the body weight!
 Muscles are generally named for their ___________, __________, _____________ of fibers, or
______________ of attachments.
 The gluteus maximus is the ________________ muscle in the body.
 The strongest muscle in the body is the ___________________.
II. Key Terms
 ________________: muscle attachment on immovable bone; usually proximal
 ________________: muscle attachment on movable bone; usually distal
 ________________: major contractile muscle producing movement
 ________________: muscle assisting PM
 ________________: muscle stretched when PM contracts
III. Functions – Characteristics
A. ___________________: ability to shorten**
B. ___________________: (responsiveness or irritability) ability to receive and respond to stimuli
C. ___________________: ability to be stretched or extended
D. ___________________: ability to recoil after stretch
Functions – General
A. PROVIDES FOR _____________________ via contraction of fibers
B. Maintaining _____________
C. Stabilizing _______________
D. Generating __________
E. Protect _____________ organs
IV. Types
A. _______________ (skeletal)
1. Attached to bone
2. Controlled by the _______________
3. Responsible for body movements
4. Wrapped in connective tissue
called _______________
5. Fascia merges to form a __________
B. ________________ (involuntary)
1. Found in _____ of digestive and urinary
2. Found in blood _________ and bronchi
C. ________________ (Involuntary)
1. Found only in the ___________
2. Can go without blood for only a short time
V. Structure
A. _______________: “overcoat” of dense irregular connective tissue surrounding entire muscle
B. _______________: fibrous connective tissue surrounding each fascicle
C. _______________: reticular connective tissue surrounding each individual muscle fiber
D. _______________: organ
E. _______________: bundle of muscle cells
F. _______________: striated cell; covered by sarcolemma (membrane)
G. _______________: rod-like contractile unit of muscle fiber
H. _______________: contractile unit of a myofibril
I. Tendon (rounded)/________________(flattened): connective tissue wrapping extending from muscle
SLIDING FILAMENT THEORY
I.
Neuromuscular Junction
A.
connection between the _______________ and ________________ fiber
B.
In response to a motor nerve __________________, the end of a motor nerve secretes a
neurotransmitter, ________________________, which stimulates the mm. fiber.
1.
One motor neuron and the muscle fibers associated with it is a ____________ ______.
C.
The __________________ __________________ is the minimal stimulus needed to cause a
muscular contraction.
1.
All the fibers of a motor unit contract together. This is an _______________________
response.
II.
Skeletal Muscle Contraction (Figure 9.10 p. 292)
A.
Muscle fiber contraction results from ____________ sliding over ________________.
1.
The ________________ is the structural and functional unit of the myofibril and contains the
protein filaments.
B.
Contraction stimulus
1.
Skeletal muscle fiber is stimulated by ______________________, released from the
distal end of a motor neuron.
2.
ACh causes the mm. fiber to conduct an impulse over the surface of the mm. fiber and
by ____________ tubules (myofibril membrane channels) into the fiber.
3.
The impulse stimulates the sarcoplasmic reticulum (the ER of mm. cells) to release ________.
4.
A ________________ forms between actin and myosin, and ___________ filaments
move inward causing the muscle to shorten.
5.
The muscle fiber relaxes when the calcium ions move back into the SR.
6.
____________________, an enzyme in the neuromuscular junction, decomposes ACh.
7.
Actin-myosin cross-bridge ____________.
8.
Muscle fiber ______________.
C.
__________ supplies the energy for mm. fiber contraction, and ____________ ___________,
stores energy that can be used to synthesize ATP.
D.
Other responses
1.
A ___________ contraction is a single contraction that lasts only a fraction of a sec.
2.
A rapid series of stimuli may produce a combining of twitches and a ______________
contraction.
3.
A _____________ contraction is forceful and sustained.
4.
___________ ___________ is the minimal sustained muscle contraction even when it
appears to be at rest. This is important for maintaining posture.
5.
A _________________ may show these responses as it is a recording of muscle
contraction.
III.
Muscular Response to Exercise
A.
__________________ is the protein in muscle cells that stores _____________ temporarily.
B.
During rest or moderate exercise, oxygen supply is ________________ to support aerobic
respiration.
1.
Energy released from respiration is lost as __________. Thus, muscle use represents
an important source of body heat.
C.
During strenuous exercise, an oxygen ________________ may develop, and ___________
_______ may be produced. Lactic acid may be responsible for the DOMS (_______________
__________ ____________ ______________) felt after strenuous weight lifting or sprinting
as the anaerobic system is activated.
1.
Lactic acid accumulation is also responsible for muscle ______________, and the
muscle loses its ability to contract.
D.
The amount of oxygen needed to convert accumulated lactic acid to glucose and to restore the
supplies of ATP and creatine phosphate is called ____________ __________.