Muscular System Flashcards
It refers to the study of the muscular system
Myology
an organ system consisting of three different types of muscles: the skeletal, smooth and cardiac muscles.
Muscular system
It permits movement of the body, maintains postures and circulates blood throughout the body.
Muscular system
What are the five properties of the muscles
excitability or irritability, contractility, extensibility, elasticity, and tonicity.
The capacity of muscles to receive and respond to stimulus.
Excitability
The capacity of the muscles to shorten and tighten.
Contactility
The capacity of the muscles to stretch/extend upon the application of force.
Extensibility
The ability of the muscle to regain the original shape and size after being stretched.
Elasticity
Excitability is the ability to respond to certain stimuli by producing electrical signals called?
action potentials (impulses)
Action potentials in muscles are referred to as?
muscle action potentials
Action potentials in nerve cells are referred to as?
nerve action potentials
What are the functions of muscles?
- Movement or locomotion
- Heat production, heat is produced (85% body heat is derived from muscle contraction),
- Posture, Alters diameters of tubes and vessels in the body
- Protection of vital organs
What are two major types of muscles aaccording to the type of action
Voluntarily (can be made to contract) and involuntarily (can’t be controlled by the will)
One of the four primary tissue types of the body
Muscle
The body contains three types of muscle tissue
skeletal muscle, cardiac muscle, and smooth muscle.
The best-known feature of skeletal muscle is?
It’s ability to contract and cause movement
2 Characteristics of skeletal muscles
Striated and voluntarily
What are cardiac muscle fibers also known as?
Cardiocytes or heart muscle cells.
They are physically and electrically connected, allowing the entire heart to contract as one unit, called a?
syncytium
What is the built-in rhythm of the heart called?
Autorhythmicity.
What is the size of a cardiac muscle fiber?
Length: 50-100 μm
Diameter: 10-20 μm
2 Characteristics of Cardiac Muscle
Striated and Involuntary control
Small, spindle-shaped, mononucleated with lesser actin and myosin than the skeletal muscle.
Smooth muscle fibers
Ability of smooth muscle to be stretched without developing lasting high tension.
Plasticity
What is the size of a smooth muscle fiber?
Length: 30-200 μm
Width: 5-10 μm
Where is smooth muscle primarily located?
walls of small intestines, blood vessels, vagina, and stomach.
2 Characteristics of smooth muscle
Non-striated and involuntary
What is a skeletal muscle composed of?
striated muscle cells and connective tissue.
What are the connective tissue layers in skeletal muscle called?
mysia
A dense sheet or broad band of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body.
Fascia
connective tissue/ fascia surrounding the muscle.
Epimysium
connective tissue that extends inward from the epimysium and
surrounds/envelops muscle fasciculi/ bundles of muscle fibers (fascicles).
Perimysium
connective tissue that surrounds individual muscle fibers
Endomysium
Skeletal Muscle Attachments
Tendon, aponeuroses, and tendon sheath
a cord of dense fibrous connective tissue which becomes continuous. It
attaches a muscle to the periosteum of a bone.
Tendon
is a tendons that take the form of broad, flat layer of thin sheets that attach to the coverings of a bone, another muscle, or the skin. (When the connective tissue elements extend as a broad, flat sheet, it is called an?)
Aponeuroses
is a tubes of fibrous connective tissue that encloses certain tendons especially those at the wrist and ankle, permit tendons to slide back and forth more easily.
Tendon sheath
It is less movable and generally proximal, more fixed point of attachment, and the attachment of a muscle tendon to the stationary bone.
Original
It is more movable end and is generally distal to the movable bone.
Insertion
muscle in between the origin and insertion.
Belly or gaster
elongated cylindrical cells that lie parallel to one another
Myofibers
plasma membrane, thin membrane that surrounds the muscle fibers
Sacolemma
cytoplasm of a muscle fiber, which is multinucleated.
Sarcoplasm
What does the sarcoplasm contain?
enzymes, sarcoplasmic reticulum, and myofibrils
a netweork of membrane enclosed tubules comparable to smooth endoplasmic reticulum
Sarcoplasmic reticulum
dilated sacs of sarcoplasmic reticulum
Terminal cisterns
extensions of sarcolemma that opens to the outside of the muscle fiber
Transverse Tubules (T-tubules)
consists of transvers tubule and the segments of sarcoplasmic reticulum (terminal cisterns) on either side
Triad
Within myofibrils are smaller protein structures called
filaments or myofilaments
What are the two kinds of myofilaments in myofibrils?
Thin myofilaments and thick myofilaments.
What is the diameter of thin myofilaments?
6 nm in diameter.
What proteins make up thin myofilaments?
Thin myofilaments are composed of three proteins:
(1) Tropomyosin – loosely attached to actin in strands.
(2) Troponin – located at regular intervals on tropomyosin.
(3) Actin – arranged in a double helix and contains myosin-binding sites.
What are the three subunits of troponin, and what do they bind to?
Troponin has three subunits:
I – binds to actin.
C – binds to calcium.
T – binds to tropomyosin.
What is the diameter of thick myofilaments?
16 nm in diameter
What protein mainly composes thick myofilaments?
Myosin
contain the actin-binding site and an ATP binding site
Cross bridges
contain the actin-binding site and an ATP binding site
Cross bridges
- structural and functional unit of muscles
- fundamental unit of muscular contraction
- compartments where myofilaments of myofibrils are arranged
Sarcomeres
Proteins that generate force during muscle contractions.
Contractile proteins
Proteins that help switch muscle contraction process on and off.
Regulatory proteins
Proteins that keep thick and thin filaments of myofibrils in proper alignment, give myofibrils elasticity and extensibility, and link myofibrils to sarcolemma and extracellular matrix
Structural protein
What is the length and diameter of Cardiac Muscle?
50-100 um length, 10-20 um diameter
What is the length and width of smooth muscle?
Length of 30-200 um, width of 5-10 um
