Lesson 1: The Muscular System Flashcards
(157 cards)
1
Q
refers to the study of the muscular system.
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Myology
2
Q
an organ system consisting of three different types of muscles: the skeletal, smooth and cardiac muscles. It permits movement of the body, maintains postures and circulates blood throughout the body.
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Muscular System
3
Q
Enumerate the 5 Properties of Muscles:
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Excitability or Irritability
Contractility
Extensibility
Elasticity
Tonicity
4
Q
Property of Muscles:
- the capacity of muscles to receive and respond to stimulus.
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Excitability or Irritability
5
Q
Property of Muscles:
- the capacity of the muscles to shorten and tighten.
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Contractility
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Q
Property of Muscles:
- the capacity of the muscles to stretch/extend upon the application of force.
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Extensibility
7
Q
Property of Muscles:
- the ability of the muscle to regain the original shape and size after being stretched.
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Elasticity
8
Q
Property of Muscles:
- the ability of the muscle to steadily contract
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Tonicity
9
Q
Function of Muscles:
- muscles are attached to bones, and as muscle contracts, movement occurs.
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Movement or Locomotion
10
Q
Function of Muscles:
- as muscle contracts, heat is produced (85% body heat is derived from muscle contraction).
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Heat Production
11
Q
Function of Muscles:
- muscles maintain good posture or general attitude of the body.
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Posture
12
Q
Function of Muscles:
- accomplished through contraction and relaxation of smooth muscles.
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Alters diameters of tubes and vessels in the body
13
Q
Function of Muscles:
- muscles protect vital organs like heart and lungs.
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Protection of vital organs
14
Q
Enumerate the TWO major types of muscles according to the type of action:
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Voluntary
Involuntary
15
Q
Type of Action:
- can be made to contract
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Voluntary
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Q
Type of Action:
- can’t be controlled by the will
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Involuntary
17
Q
Enumerate the THREE types of muscles:
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Skeletal Muscles
Cardiac Muscles
Smooth Muscles
18
Q
are multinucleated structures that compose the skeletal muscle
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Skeletal Muscle Fibers
19
Q
They are attach into the skeleton of the body and make the skeleton move. The best-known feature of this is its ability to contract and cause movement
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Skeletal Muscles
20
Q
Characteristics of Skeletal Muscle:
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Striated & Voluntary
21
Q
have one to two nuclei and are physically and electrically connected to each other so that the entire heart contracts as one unit called a syncytium.
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Cardiac Muscle Fibers
22
Q
It is found in the walls of the heart. These muscle cells are also called cardiocytes/heart muscle. Moreover, it has a length of 50-100 μm and diameter of 10-20 μm.
A
Cardiac Muscles
23
Q
Characteristics of Cardiac Muscles:
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Striated & Involuntary
24
Q
are small, spindle-shaped, mononucleated with lesser actin and myosin than the skeletal muscle.
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Smooth Muscle Fibers
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It has a of length of 30-200 μm and a width of 5-10 μm. Primarily located in the walls of small intestines, blood vessels, vagina and stomach
Smooth Muscles
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Characteristics of Smooth Muscles:
Non - striated & Involuntary
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an organ composed mainly of striated muscle cells and connective tissue
Skeletal Muscle
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Each skeletal muscle has three layers of connective tissue called...
Mysia
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It is the sheath of dense fibrous connective tissue beneath the skin or around muscle fibers, holds muscle fibers together. There are three connective tissue components that cover a skeletal muscle tissue.
Connective Tissue Coverings or Fascia
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Types of Connective Tissue Coverings:
- connective tissue/ fascia surrounding the muscle.
Epimysium
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Types of Connective Tissue Coverings:
- connective tissue that extends inward from the epimysium and surrounds/envelops muscle fasciculi/ bundles of muscle fibers (fascicles).
Perimysium
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Types of Connective Tissue Coverings:
- connective tissue that surrounds individual muscle fibers.
Endomysium
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bundles of muscle fibers
Muscle Fascicles
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a cord of dense fibrous connective tissue which becomes continuous. It attaches a muscle to the periosteum of a bone.
Tendon
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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.
Aponeuroses
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are tubes of fibrous connective tissue that enclose certain tendons, especially those at the wrist and ankle, permitting tendons to slide back and forth more easily.
Tendon Sheaths
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It is less movable and generally proximal, more fixed point of attachment, and the attachment of a muscle tendon to the stationary bone.
Origin
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It is more movable end and is generally distal to the movable bone.
Insertion
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widest portion of a muscle in between the origin and insertion.
Belly or Gaster
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Enumerate the FIVE Skeletal Muscle Shapes:
Longitudinal/Parallel
Pennate
Convergent/Radiate
Circular
Fusiform
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Skeletal Muscle Shape:
The fasciculi are parallel with the long axis of the muscle and terminate at either end of flat tendons and typically quadrilateral in shape.
Longitudinal / Parallel
e.g. stylohyoid muscle, sartorius muscle
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Skeletal Muscle Shape:
The fasciculi are short in relation to the entire length of the muscle and the tendon extends nearly the entire length of the muscle. Moreover, they are directed obliquely toward the tendon like the plumes of a feather
Pennate
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Enumerate the THREE types of Pennate:
Unipennate
Bipennate
Multipennate
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Type of Pennate:
- The fasciculi are arranged on only one side of the tendon
Unipennate
e.g. extensor digitorium
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Type of Pennate:
- The fascicles arranged obliquely on both sides of a centrally positioned tendon.
Bipennate
e.g. rectus femoris muscle
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Type of Pennate:
- The fasciculi have complex arrangement that involves convergence of several tendons.
Multipennate
e.g. deltoid muscle
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Skeletal Muscle Shape:
- A broad origin of fasciculi converges to a narrow, restricted insertion and gives the muscle a triangular shape.
Convergent / Radiate
e.g. pectoralis major
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Skeletal Muscle Shape:
- The fasciculi are arranged in a circular pattern and enclose an orifice.
Circular
e.g. orbicularis oculi muscle
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Skeletal Muscle Shape:
- The fasciculi are nearly parallel with the longitudinal axis and terminate at either end in flat tendons, but the muscle tapers toward the tendons, where the diameter is less than that of the belly
Fusiform
e.g. biceps brachii
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- elongated cylindrical cells that lie parallel to one another
- diameter: 10 to 100 μm
- length: 30 μm or more
Muscle Fibers or Myofibers
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- plasma membrane, thin membrane that surrounds the muscle fibers
Sarcolemma
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- cytoplasm of muscle fiber, multinucleated
- contains enzymes, sarcoplasmic reticulum, and myofibrils
Sarcoplasm
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- a network of membrane enclosed tubules comparable to smooth endoplasmic reticulum
- it is where protein and lipids are manufactured, it also transports products within the muscle fiber
Sarcoplasmic Reticulum
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- dilated sacs of sarcoplasmic reticulum
- form ring like channels around myofibrils
Terminal Cisterns
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- extensions of sarcolemma that opens to the outside of the muscle fiber
- run transversely through the fiber and perpendicularly to the sarcoplasmic reticulum
Transverse Tubules or T-tubules
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- consists of transverse tubule and the segments of sarcoplasmic reticulum (terminal cisterns) on either side
Triad
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- cylindrical structures 1 to 2 μm in diameter
- consist of two kinds of myofilaments
Myofibrils
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Enumerate the TWO kinds of Myofilaments:
Thin myofilaments
Thick myofilaments
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- 6 nm in diameter
- composed of three kinds of protein
Thin myofilaments
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- 16 nm in diameter
- composed mainly of myosin (shaped like a golf club)
- has two bulbous head
Thick myofilament
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Enumerate the proteins of the THIN myofilament:
Tropomyosin
Troponin
Actin
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- arranged in strands that are loosely attached to actin
Tropomyosin
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- located at regular intervals on the surface of tropomyosin
- has 3 subunits:
I – binds with actin
C – binds with calcium
T – binds with tropomyosin
Troponin
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- the head of each myosin filament attach to the actin myofilament
- arranged in 2 single strands (double helix)
- contains myosin-binding site that interacts with a cross bridge of a myosin molecule
Actin
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the main component of thick myofilament
Myosin
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- contain the actin-binding site and an ATP binding site
Cross Bridges
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- structural and functional unit of muscles
- fundamental unit of muscular contraction
- compartments where myofilaments of myofibrils are arranged
Sarcomeres
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Band of Myofilament:
- light-colored, less dense area, composed of thin myofilaments only
I-Band or Isotropic
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the alternating dark A bands and the light I bands gives the muscle fiber its...
striated appearance
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Band of Myofilament:
- represents the length of thick myofilaments
- the sides are darkened by the overlapping of the thick and thin myofilaments
A-Band or Anisotropic
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Band of Myofilament:
- narrow zones of dense material that separates sarcomeres from one another
Z-line or Zuriachen
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Region of A-Band:
- narrow region in the center of A-Band, contains thick myofilaments only
H-Region
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Region of A-Band:
- located in the center of the H-zone
- series of fine threads that appear to connect the middle parts of adjacent thick myofilaments
M-Line
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Region of A-Band:
- where thick myofilaments at either end of the sarcomere overlap
Zone of Overlap
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- storehouse of the cell
Mitochondria
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- sliding of myofilaments and shortening of sarcomeres causes the shortening of the muscle fibers
Sliding Filament Theory
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- states that muscles either contract with all force possible under existing conditions or do not contract at all
All-or-None Principle
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- neuron that stiimulates muscle contraction
- deliver stimulus to muscle tissue
Motor Neuron
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- refers to the axon terminal of a motor neuron together with the motor end plate
Neuromuscular Junction or Myoneural Junction
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- the region of the sarcolemma adjacent to the axon terminal
Motor End Plate
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- membrane enclosed sacs contained in synaptic end bulbs
- store chemicals called neurotransmitters including acetylcholine
Synaptic Vesicles
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- expanded bulblike structures of the distal ends of the axon terminals
Synaptic End Bulbs
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- neurotransmitter released at neuromuscular junction in skeletal muscles
Acetylcholine
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- invaginate area of the sarcolemma under the axon terminal
Synaptic Gutter
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- space between the sarcolemma under the axon terminal
Synaptic Cleft
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- numerous folds of the sarcolemma along the synaptic gutter
Subneural Clefts
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- composed of motor neuron together with all the muscle fibers it stimulates
- single motor neuron may innervate about 150 muscle fibers, depending on the region of the body
Motor Unit
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Acetylcholine is rapidly destroyed by an enzyme called...
Acetylcholinesterase
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Specific Changes During Contraction:
- Sliding-Filament Theory
- for muscle contraction to occur, troponin undergoes structural change when bound with calcium ions troponin and tropomysin move into a groove between actin strands myosin binding sites of actin are exposed myofilaments attach each other release of energy
Structural Change
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Specific Changes During Contraction:
- in a resting state, muscle cell is negatively charged inside while the outer part is positively charged.
- potassium ions are higher inside the cell, sodium ions are higher outside the cell
- sodium ions move across the cell membrane due to increase in sodium permeability of the cell wall depolarization of muscle cells contraction of muscle
Electrical Change
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the period of lost excitability
Refractory Period
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- period when muscle cannot be stimulated
Absolute Refractory Period
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- period when a stronger stimulus cause excitation
Relative Refractory Period
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- a time when the cell is highly excitable that stimulus of minimal threshold can cause excitation
Supra normal
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Enumerate the THREE Phases of Contraction:
Lag Phase
Contraction Phase
Relaxation Phase
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Phase of Contraction:
- brief period between the application of stimulus to the beginning of contraction
- calcium ions are released from the sarcoplasmic reticulum and the onset of myosin cross bridge activity
Lag Phase
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Phase of Contraction:
- upward tracing
- caused by cross bridge activity
Contraction Phase
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Phase of Contraction:
- indicated by downward tracing
- caused by the active transport of calcium ions back into the sarcoplasmic reticulum
Relaxation Phase
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Enumerate the THREE types of Stimuli:
Liminal (threshold) stimulus
Subliminal (sub-threshold) stimulus
Maximal
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Type of Stimuli:
- weakest stimulus from a neuron but it has to be stronger enough to cause contraction
- the lowest limit of stimulus to perception or sensation
Liminal (threshold) stimulus
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Type of Stimuli:
- the stimulus is lesser in intensity that does not reach the patient’s consciousness; cannot initiate contraction
Subliminal (sub-threshold) stimulus
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Type of Stimuli:
- all motor units are excited with only single stimulus.
Maximal
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- heat release during actual contraction process and combination of 3 events of the contraction
Initial Heat
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- heat is produced from the breakdown of ATP to ADP and AMP
Heat of Activation
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- heat is deliberated when there is a change in the length of muscle
Heat of Shortening
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- heat is produced when contracted muscle relaxes
Heat of Relaxation
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ENUMERATE THE FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
Strength of Stimulus
Speed of Stimulus
Weight of Load
Duration
Summation or Summatotal
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FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
- the stronger the stimulus, the stronger also is the contraction
Strength of Stimulus
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FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
- the faster the speed of stimulus, the faster is the initiation of contraction of muscles
Speed of Stimulus
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FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
- the heavier the load, the stronger is the contraction
Weight of Load
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FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
- the longer the stimulus to stay, the longer the contraction
Duration
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FACTORS THAT AFFECT THE STRENGTH/HEIGHT OF CONTRACTION:
- if two maximal stimuli are delivered in quick succession there is an increase of muscular contraction
Summation or Summatotal
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composed of phosphocreatine and ATP
Phosphagen System
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- short-lived molecule which rapidly degenerates to a more stable ADP, used to provide energy for muscle contraction
ATP
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- a product of CHON metabolism
- maintains adequate amounts of ATP
Phosphocreatine
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- metabolic process by which glycogen or glucose from the blood is broken down to pyruvic acid – the process results in the synthesis of ATP.
Glycolysis
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- occurs in the absence of oxygen
- oocurs in the breakdown of glucose to yield ATP and lactic acid
Anaerobic Process
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- requires oxygen and breaks down glucose by glycolysis
- produces ATP, CO2 and H2O.
Aerobic System
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Kind of Muscle Contraction:
- does not produce movement but increases firmness of muscle that maintains posture
- characterized by a continuous muscular contraction
Tonic
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Kind of Muscle Contraction:
- responsible for movements of arms and legs
- the amount of tension produced by muscle is constant during contraction but the length of the muscle shortens
Isotonic
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Kind of Muscle Contraction:
- length of muscle does not change but the amount of tension increases during the contraction process.
Isometric
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Kind of Muscle Contraction:
- contraction of an entire muscle in response to a stimulus that causes an action potential in one or more muscle fibers.
Twitch
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Kind of Muscle Contraction:
- smooth, sustained contraction produced by a series of very rapid stimuli to a muscle
Tetanic
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Kind of Muscle Contraction:
- a staircase effect or phenomenon
- gradual increase in the amount of contraction by a muscle caused by rapid repeated stimuli of the same strength
Treppe
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Kind of Muscle Contraction:
-cardiac arrhythmia in which muscles of the heart function irregularly
- involuntary brief twitch of a muscle that is not visible under the skin and is not associated with the movement of the affected muscle
Fribrillation
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Kind of Muscle Contraction:
- a violent, involuntary contraction of the entire muscle group
Convulsion
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Kind of Tetatus:
- a rapid stimulation occurs in which tension produced will rise to a peak and a period of relaxation will be very short to brief.
Incomplete
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Kind of Tetatus:
- the frequency of stimulation is so high that the relaxation phase has been completely eliminated.
Complete
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- prime mover
- plays the major role in accomplishing a particular movement
Agonist
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- acts against the prime movers
Antagonist
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- muscles that work together to cause a movement
- enables the prime movers to perform smoothly and efficiently
Synergists
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- muscle which steadies the bone which gives the action of the prime movers so that insertion will move
- stabilizes the origin of the prime movers
Fixator
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- muscle that bends a limb at a join
Flexor
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- muscle that straightens/extends a limb at a joint
Extensor
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- muscle that moves a limb away from the midline of the body
Abductor
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- muscle that moves a limb toward the midline
Adductor
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- muscle that lowers or depresses a part
Depressor
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- muscle which lifts a body part
Levator
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- muscle that moves/turns the palm of the hand upward
Supinator
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- muscle that moves/turns the palm downward
Pronator
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- muscle surrounding an opening, acts as a valve
Sphincter
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- muscle that can straighten/stretch a limb, makes body part more rigid
Tensor
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- muscle which can turn about an axis
Rotator
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- an abnormal congenital condition characterized by progressive symmetric wasting of the leg and pelvic muscles
- it is an X-linked recessive disease that appears insidiously between 3 and 5 years of age and spreads from the leg and pelvic muscles to the involuntary muscles
Duchenne’s muscular dystrophy
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- decrease in muscle size as a result of disuse/immobility
Muscular atrophy
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- chronic, progressive degenerative disease resulting from the destruction of acetylcholine receptors in the neuromuscular junction
- usually begins in the face
- characterized by weakness but not accompanied by atrophy
Myasthenia gravis
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- painful spastic muscle contraction resulting from irritation within the muscle
Cramps
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- sudden involuntary contraction of skeletal muscle/ brief period of complete tetannus
- types: a. Tonic – if continuous/persistent
b. Clonic – if there is an alternate contraction and
relaxation
Spasm
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- strong involuntary contraction of the entire muscle group
Convulsion
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- shortening of muscle cells or muscle fibers
Contracture
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- loss of muscle tone wherein the muscle appears soft and flabby
Flaccidity
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- an increase in size of individual muscle cells due to chronic stimulation and use
Hypertrophy
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- increase in number of muscle cells
Hyperplasia
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- inflammation of muscle tissue
Myositis
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- muscle pain
Myalgia
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- inflammation of the surrounding connective tissues of the muscle
Fibrositis
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- tear or break in the ligaments in tendons
Sprain
