Muscular Flashcards
a system of the human body that provides motor
power for all movements of the body.
Muscular system
a system of the human body that provides motor
power for all movements of the body.
Muscular system
Muscular system is composed of specialized cells called
Myocytes or muscle fibers
body tissues that provide the force for all body movements.
Muscles
There are more than ____ muscles in the body, with ___ known muscles with names.
700
639
Functions of Muscular System
Movement of the body
Maintenance of posture
Respiration
Production of body heat
Communication
Constriction of organ and vessels
Contraction of the heart
Types of muscle tissues
Skeletal muscle
Cardiac muscle
Smooth muscle
Constitutes approximately 40% of the body weight
Skeletal muscle
• Attached to the skeletal muscle
• Voluntary and striated
Skeletal muscle
• Located only in the heart
• Involuntary, striated
Cardiac muscle
• Can be found on visceral hollow organs like the stomach, trachea, and urinary bladder
• Involuntary, not striated
Smooth muscle
Functional characteristics of muscle tissues
Contractility
Excitability
Extensibility
Elasticity
Ability of muscle to shorten forcefully or contract.
Contractility
Ability of muscle to respond to stimulus
Excitability
Muscles can be stretched beyond its normal resting length and still be able to contract
Extensibility
Ability of muscles to recoil to its original resting length after it has been stretched.
Elasticity
attachments between muscle and bone matrix
tendon
connective tissue around muscle cells
Endomysium
connective tissue around muscle fascicles
Perimysium
Connective tissue surrounding entire musle
Epimysium
under the cell membrane
Unique cells with several nuclei
Skeletal muscle fiber range from in what length
1mm - 4cm
Alternating ___ and ___ bands gives the striated or stripped appearance.
light and dark
2 main aspect to muscle contraction
electrical component
mechanical component
electrical components
sarcolemma
transverse tubules or t tubules
Sarcoplasmic reticulum
mechanical components
myofibrils
myofilaments
cell membrane of the muscle fibers
sarcolemma
tubelike fold of the sarcolemma.
T tubules
carry electrical impulses into the center of muscle fiber so that the muscle fiber contracts as a whole
T tubules
a highly specialized ER that stores high level of Ca2+.
Sarcoplasmic reticulum
threadlike structures that extend the
entire length of the muscle fiber.
Myofibrils
2 types are actin and myosin
Myofilaments
Types of myofilaments
Actin
Myosin
actin and myosin are arranged into highly ordered
units called
Sacromeres
joins end to end forming the myofibrils
sacromeres
Actin myofilament composed of 3 separate proteins:
Actin
Troponin
Tropomyosin
It is the relationship among the troponin and Tropomyosin that determines when the skeletal muscle will contract
Actin myofilament
3 subunits of actin myofilament
(1) Anchors the troponin to the actin
(2) Prevents the tropomyosin from uncovering the
attachment site during muscle relaxation.
(3) Binds Ca2+
long fibrous proteins that lies in the groove along
the fibrous actin strand
Tropomyosin
Covers attachment site during muscle relaxation
Tropomyosin
If Ca2+ is not present, the tropomyosin covers the attachment site, but with Ca2+ the ___ binds to troponin
attachment site
Composed of many elongated myosin molecules shaped like golf clubs
Myosin filament
Myosin molecules consist of
Rod portion and two myosin heads
Smallest portion of muscle that can contract.
Sacromeres
Each sarcomere extends from
Z disk to the next Z disk
hold myosin filaments in place
M line
Contains only myosin myofilament
H zone
Darker region ; contains both actin and myosin myofilament overlapping center except in the center
A band
Lighter region; contains only actin myofilament
I band
Forms a stationary anchor for actin myofilaments
Z disk
The primary stimulus for this action potential is the release of ___ from the motor neuron
acetylcholine
contribute to the electrical properties of both resting cell
and stimulated cell.
Ion channels
2 types ion channels
Gated
Leak
Specific for a particular ions.
Leak channels
In resting cells, it allows for the slow leak of ions down their concentration gradient.
Leak ion channels
Most important in stimulated cell, and it governs the
production of action potential.
Gated ion channels
The charge difference in unstimulated/relaxed cells. (NEGATIVE)
Resting membrane potential
Resting membrane potential is a result of 3 factors:
(1)higher concentration of K+ inside; (2)Higher concentration of Na+ outside; (3)the cell
membrane is more permeable to K+ than to Na+
The charge difference of stimulated/ excitable cell. (POSITIVE)
Action potential
This charge reversal occurs because ion channels open when a cell is stimulated.
Action potential
Action potential last from ___ to a ___
1 milliseconds to few milliseconds
2 phases of action potential
Depolarization
Repolarization
Types of muscle contraction
Isometric
Isotonic
Muscle do not shorten
Isometric contraction
increases tension in the muscle, but the length of the muscle stays the same.
Isometric contractions
Muscles shorten
Isotonic contractions
decreases the length of the muscle.
Isotonic contractions
Results in increase in tension as the muscles
shortens
Concentric
Tension is maintained in a muscle but opposing
resistance is great enough to cause muscle
to increase in length.
Eccentric
Fascicles arranged in a circle around an opening
Circular
Circular fasciles
Orbicular oris
Orbicular oculi
Broadly distributed fasciles converge at a single tendon
Convergent
Convergent fascicles
Pectoralis major
Pectoralis minor
