The Muscular System
I. Muscle tissue
A. There are 3 types of muscle tissue in the body
1. ________ muscle
a. "red meat" attached to bones -- it is 40-50% of body weight
b. striated and multinucleate
c. voluntary - we control the contractions
2. ________ muscle
a. composes bulk of heart
b. striated and branched, one nucleus
c. involuntary
3. ________ or ________ muscle
a. found in walls of hollow visceral structures (organs) such as
digestive tract, blood
vessels, and ureters
b. nonstriated (appears smooth), one nucleus
c. involuntary
B. All muscle cells specialize in contraction
II. Characteristics of muscles
A. ___________ - the ability to shorten, unique to muscle tissue***
B. ___________- the ability to respond to certain stimuli
C. ___________- the ability to be stretched
D. ___________- the ability to return to its original length when relaxing
III. Functions of skeletal muscle
A. Movement
1. Muscles must be attached to bones (by ______) for leverage in
order to have something to pull against
2. Muscles only _____, never _____
3. The muscles of the body are arranged in __________ pairs.
a. one produces mvmt in a single direction called the
__________
b. the other in the opposite direction called the ___________
4. Another group help steady or stabilize and are called __________.
B. Posture or muscle tone
1. A specialized type of m contraction, called tonic contraction,
enables us to maintain body position
a. only a few of a muscle's fibers shorten at one time
b. produce no mvmt of body parts
c. maintain m tone called __________
2. Good vs bad posture
C. Heat production
1. Survival depends on the body's ability to maintain a constant body
temp
2. Contraction of m fibers produces most of the heat required to
maintain normal body temp
IV. Structure of Skeletal muscles
A. Macroscopic structure
1. Each skeletal muscle is an organ composed mainly of skeletal
muscle cells and connective tissue
2. Most skeletal muscles extend from one bone across a joint to
another bone
3. Parts of a skeletal muscle
a. ________-attachment to the bone that doesn't move (much)
b. _________-attachment to the bone that moves during
contraction
c. __________-main part of the muscle
4. Muscles attach to bone by _________-strong cords of fibrous
connective tissue
a. This fibrous tissue is called _______ (aka epimysium)
b. If the tissue forms sheets the tendons are called __________
c. Tendons attach to __________ of the bone
B. Microstructure
1. Muscle cells, called _________ ________, are long, cylindrical cells
a. sometimes run the entire length of the muscle
b. are about the diameter of a human hair
c. each fiber is surrounded by ____________
2. Muscle fibers are bundled together in groups of up to 150 fibers
a. the bundles are called ___________
b. fasciculi are surrounded by ____________
3. The parts inside a m. cell have different names
a. M. cell membrane is called the _____________
b. cytoplasm is called __________
c. endoplasmic reticulum is the ____________ ____________
4. Inside the sarcoplasm are hundreds to thousands of ___________
a. each myofibril is 1/100 the diameter of human hair
b. myofibrils contain the apparatus that contracts the m. cell
c. myofibrils hold two types of ____________: _____ and _____
d. myosin are thick filaments (1/10,000 diameter of hair) and
have ________-________
e. actin are thin but arranged in a double helix (like DNA)
f. myosin and actin are arranged longitudinally in the smallest
contractile unit of skeletal muscle called the ____________
C. Motor unit
1. Stimulation of a muscle by a nerve impulse is required before a
muscle can shorten and produce mvmt.
2. A motor _________ is this type of nerve
3. A ___________ _________ is the point of contact between a nerve
ending and the m fiber it innervates
4. A _______ _____ is the combination of a motor neuron with the
muscle cell or cells that it innervates
5. All or none law
V. Sliding Filament Theory (SFT) of muscle contraction
A. When the myofilaments _______ and ______ slide toward each other
the muscle shortens and when the filaments slide apart the muscle relaxes
B. This occurs in the _________
C. Contraction requires calcium and energy-rich _____ molecules
D. refer to handout "how muscles contract" and highlight
VI. Muscle fatigue
A. If muscle cells are stimulated repeatedly w/o adequate rest, the
strength of m contraction decreases, resulting in ________
B. If stimulation continues the muscle eventually loses its ability to
_________
C. During exercise, stored ____ becomes depleted but more can be made
with rapid consumption of _________ taken from the blood cells
D. When no more oxygen is available, the muscles switch to anaerobic
energy but this produces _____ ______ and creates muscle soreness
E. When exercise stops, metabolism and labored breathing remain high to
"pay the debt" for using all the oxygen -- this is _______ ________
VII. Types of skeletal muscle contractions
A. _________ contraction
1. quick, jerky response to a stimulus
2. seen in isolated muscles during research
3. normal mvmt requires smooth and sustained contraction, not jerky
B. _________ contraction
1. steady and sustained contraction
2. produced by a series of stimuli bombarding the muscle
3. contractions "melt" together to cause tetanus
C. _________ contraction
1. contraction of a muscle that produces mvmt at a joint
2. if the muscle lengthens it is called an ___________ contraction
3. if the muscle shortens it is called a _____________ contraction
4. most types of body mvmts are caused by isotonic contractions
D. _________ contraction
1. contraction of a muscle that does not produce mvmt
2. tension within the muscle does increase
3. important for rehabilitation if immobilized
VIII. Effects of exercise on skeletal muscles
A. Exercise should be done on a regular schedule and done correctly
1. improves _______ ________ and _________
2. results in more efficient ______ and _______ functioning
3. reduces fatigue
4. regular exercise increases muscle size, called ____________
5. prolonged inactivity causes ________ _________
B. Strength training is exercise involving contraction of muscle against
heavy resistance
1. increases the ______ of the muscle fiber by increasing actin and
myosin
2. cannot change the _________ of muscle fibers
3. sometimes called _________ training
C. Endurance training is exercise that increases a muscle's ability to sustain
moderate exercise over a long period
1. sometimes called ________ training
2. does not usually increase the _______ of the muscle fiber
3. makes a muscle more ________ in the delivery of oxygen and
nutrients