the study of muscles
myology
Muscular tissue accounts for ____-____% of total body mass
40-50%
This number varies from person to person
3 types of muscular tissue
1. Skeletal
2. Cardiac
3. Smooth
Skeletal
a. involuntary or voluntary?
b. striated or non-striated?
c. where is it found?
a. voluntary
b. striated
c. with bones
Cardiac
a. involuntary or voluntary?
b. striated or non-striated?
c. where is it found?
a. involuntary
b. striated
c. heart
unique feature of cardiac muscle; several hormones and neurotransmitters adjust the heart rate by speeding or slowing down the natural pacemaker
auto-rhythmicity
Smooth
a. involuntary or voluntary?
b. striated or non striated?
c. where is it found?
a. involuntary
b. non-striated
c. blood vessels and organs
Functions of muscular tissues
1. Produce body movement
2. Stabilize body positions
3. Store and move substances (blood, lymph, urine, air)
4. Produce heat
5. Support and protect
5 properties of muscular tissue
1. Electrical Excitability
2. Contratibility
3. Exetensibility
4. Elasticity
5. Conductivity
The ability of a muscle fiber to receive and respond to stimulus
Electrical excitability
The ability of muscles to shorten (contract) in response to a stimulus
Contratibility
The ability of a muscle tissue to stretch (without being damaged)
Exetensibility
The ability of a muscle to return to its original shape after contraction or extension
Elasticity
The ability to propagate a signal through a muscle
Conductivity
The largest and thickest part of a muscle that is connected to the skeleton by tendons.
Belly
Connects the body of the muscle to bone.
Tendon
Tendon is made up of parallel rows of what type of fibers?
Collagen
Sometimes a tendon forms a thin, flattened sheet called a ______________, this is a covering of a muscle that foes into a tendon after neuroses.
Aponeurosis
3 connective tissue layers that surround layers of skeletal muscle
1. Epimysium
2. Perimysium
3. Endomysium
layer surrounds the whole muscle; binds all of the fascicles together
Epimysium
layer surrounds each fascicle; binds all of the fibers together
Perimysium
layer surrounds each muscle fiber (cell)
Endomysium
The plasma membrane of the muscle fiber (muscle cell)
Sarcolemma
Thousands of tiny invaginations of the sarcolemma called ____________ ___________ tunnel in from the surface toward the center of the muscle fiber
transverse tubules (T Tubules)
Muscle action potentials propagate along the sarcolemma and through the ___________
T-Tubules
The cytoplasm within the muscle fiber
Sarcoplasm
__________ make up Myofibrils which make up Myofibers (Largest)
Myofilaments
unit of muscle fibers composed of thick myosin protein filaments and thin actin protein filaments
Myofibrils
A fluid filled system of membranous sacs called _____________ _______________ encircles each myofibril. It stores releases Calcium.
sarcoplasmic reticulum
Dialated end sacs of the sarcoplasmic reticulum called _________ _________ butt against the transverse tubules on both sides
terminal cisterns
One transverse tubules and two terminal cisterns on either side of it form a ________.
triad
part of triad responsible for transporting a muscle impulse from the sarcolemma throughout the muscle fiber
transverse tubule
part of triad responsible for releasing calcium ions to promote muscle contractions
two terminal cisterns
The pattern of overlap of thick (myosin) and thin (actin) bands consists of zones and bands, which make up the striated appearance of muscles. This causes...
the light and dark bands
The filaments (actin and myosin) of myofibrils are arranged in compartments called _____________.
sarcomeres
Separates one sarcomere from the next
Z-Disc
The darker, middle part of the sarcomere
A-Band
The end of each A band where thick and thin filaments lay side by side
Zone of Overlap
The lighter area that only contains thin filaments
I-Band
An area in each A band where there are thick filaments but no thin filaments
H-Zone
A region in the H zone; middle of the sarcomere
M-Line
increase in cell size
hypertrophy
increase in cell number
hyperplasia
the nerve and blood supply of a muscle
NAV (neurovascular bundle)
Myofibrils are built from three kinds of proteins:
1. Contractile proteins
2. Regulatory proteins
3. Structural proteins
Proteins that generate force during contraction; done by sliding over each other-sliding filament theory; A and I Bands don't change length
Contractile
2 types of contractile proteins
1. Actin
2. Myosin
A contractile protein that is the main component of the THIN filament
Actin
On each actin molecule is a myosin binding site where a... during muscle contraction.
myosin head of a thick filament binds
A contractile protein that is the main component of the THICK filament
Myosin
A myosin molecule consists of a tail and two myosin heads, which.... during muscle contraction.
bind to myosin binding sites on actin molecules
Myosin functions as motor protein that changes __________ energy to _________ energy.
chemical; mechanical
Proteins that regulate contractions by turning them on and off
Regulatory
2 types of regulatory proteins
1. Tropinin
2. Tropomyosin
4 proteins that keep thick and thin filaments in proper alignment: link myofibrils to the sarcolemma and extracellular matrix
Structural
(Titin, Myomesin, Nebulin, Dystrophin)
When a muscle contracts thick and thin filaments slide past each other and the sarcomere shortens.
The Sliding Filament Theory
What 5 changes occur in the sliding filament theory?
A-band?
H-zone?
Z-discs?
sarcomere?
I-bands?
1. A-Band remains constant
2. H-Zone disappears
3. Z-Discs move closer together
4. The sarcomeres narrow or shortens in length
5. I-Bands remain constant
Synapse between motor neurons and muscle fibers/cells
Neuromuscular Junction (NMJ)
Where the communication happens between two neurons or a neuron and a muscle fiber
Synapse
A small gap that separates nerve cells or the nerve cell and muscle fiber
Synaptic cleft
A chemical that allows cells to communicate and respond to nerve stimulus
Neurotransmitter
End of the motor neuron
Axon terminal
Branded off ends of the axon terminal
Synaptic end bulbs (vesicles)
Neurotransmitter found inside synaptic vesicles
Acetylcholine
Part of the sarcolemma opposite of synaptic bulb
Motor end plate
Where are the AChE receptors found?
On the muscle membrane
4 Steps of the NMJ
1. Release of acetylcholine (AChE) from the synaptic vesicle.
2. Activation of AChE receptors. Ach binds to Ach receptors.
3. Action potential is produced.
4. Termination of AChE. AchE is broken down and muscle action stops.
What happens to the Z discs during contraction?
Z-Discs slide towards each (Sliding filament mechanism)
5 steps of excitation contraction coupling:
1. A nerve impulse causes Ach release at the NMJ. Ach binds to receptor on the motor end plate, initiating muscle impulse in the fiber
2. The impulse spreads quickly along the sarcolemma and into the muscle fiber, traveling down tubules, causing calcium i
A ______ ______ is composed of a single motor neuron and all of the muscle fibers it controls.
motor unit
muscle principle states that a muscle fiber either contracts completely or does not contract at all.
all or none principle
The force and precision of muscle movement can be varied, depending on how many muscle fibers and motor units are activated.
Even at rest there is a small amount of tension on the muscles
muscle tone
Muscles do not change in length; no visible movement.
ex. a person trying to lift a heavy object and does not have enough force to lift it
Isometric
Tension in a muscle is generated and is constant, but muscle changes in length.
ex. when a person lifts a grocery bag out of car. tension is generated in the appropriate muscle and muscles shorten and lengthens to produce the force
Isotonic
Concentric contractions: actively (shorten/lengthen) a muscle
shorten
Eccentric contractions: actively (shorten/lengthen) a muscle
lengthen
Amount of myoglobin: (white/red) has more; (white/red) has less
red; white
Red is ______ twitch glycolytic
slow
White is ______ twitch glycolytic
fast
Would a long distance runner have slow oxidative (SO) or fast glycolytic type IIA or IIB?
Slow oxidative
Would a sprinter have slow oxidative (SO) or fast glycolytic type IIA or IIB?
Fast glycolytic
The relative ratio of fast glycolytic (FG) and slow oxidative (SO) fibers in each muscle is determined how? (3)
Genetics, individual difference in physical performance
Striated, involuntary, uniceleate, and branched muscle tissue
Cardiac
Property of cardiac muscle, irregular transverse thickening of the sarcolemma that connect neighboring cardiac muscle fibers
Intercalated Discs
The intercalated discs contain this. They hold the fiber together and gap junctions, which allow muscle action potentials to spread from one muscle fiber to its neighbor
Desmosomes
Communicators from cell to cell
Gap junctions
Cardiac muscle has an ____________ but lacks a _______ and ________.
Epimysium
Perimysium
Endomysium
endomysium; perimysium; epimysium
Involuntary, non-striated, uninecleate, and tapered cells in what muscle tissue?
Smooth
2 types of smooth muscle:
1. visceral single unit
2. multiunit
type of smooth muscle tissue found in the skin, in sheet that forms parts of walls of small arteries and veins, and in walls of hollow viscera, such as, the stomach, intestines, uterus, and bladder
Single unit smooth muscle
type of smooth muscle tissue found in the wall of large arteries and airway of lungs
Multi unit smooth muscle
A chronic non articular rheumatoid disorder that effects fiber tissues of muscles and tendons; forms tender points painful to tough
Symptoms: fatigue, depression, poor sleep
Treatments: stress reduction, therapy
Fibromyalgia
Inflammation of tendons that happens in the wrist, fingers, ankles, swelling due to bleeding and fluid
-Caused by excessive use of a body part
-Treated with anti-inflammatory
Tendosynovitis (tendonitis)
Caused from disuse; not used for six months, muscles will shrink muscle size 1/4 of original size, irreversibly replaced by fibrous connective tissue
Muscle atrophy
Loss in muscle tone, they become flaccid
Hypotonia
Increased muscle tone caused by spasticity and causes rigidity
Hypertonia
Way of testing that measures resting and contracting muscle electrical activity
EMG (electromyography)
An autoimmune disease; causes chronic and progressive damage of neuromuscular junction- presents like MS. Acetylcholine receptors become blocked. Muscles become weaker, fatigue easily, and will eventually cease to function.
Myasthenia Gravis
Between the ages of 30 and 50, and estimated ____% of muscle mass is lost. Another ____% is lost by age 80.
10%; 40%
Skeletal muscles that produce movements do so by exerting force on ____ , which in tern pull on _____ or other structures such as skin.
tendons; bones
Muscle attachment sites
Origin and insertion
Attachment of muscle to a stationary bone, usually proximal
Origin
attachment of muscle to the bone that it will move
Insertion
The nerve stimulus for the muscle contraction
innervation
a rigid structure that can move around a fixed point
lever
fixed point of lever system
Fulcrum
causes the movement of lever; the forces that is due to the muscle contraction
Effort
the weight of an object or some type of resistance
Load
The relative distance between the fulcrum and load and the point at which the effort is applied is what determines whether a lever operates at...
Mechanical Advantage or Mechanical Disadvantage
If the load is closer to the fulcrum and the effort is farther from the fulcrum then only a relatively small amount of effort is required to move a large load over a small distance
Mechanical Advantage or Mechanical Disadvantage?
Advantage
If the load is farther from the fulcrum and the effort applied is closer to the fulcrum then a relatively large effort is required to move a small load (but at a greater speed)
Mechanical Advantage or Mechanical Disadvantage?
Disadvantage
class levers: fulcrum in between effort and load
ex: head on the vertebral column
First
class levers: load in between fulcrum and effort
ex: standing on toes
Second
class levers: most common in our body. Effort is between fulcrum and load
ex: flexing biceps
Third
All muscle fibers are ___________ to one another within a single fascicle.
parallel
form patterns with respect to the tendons.
Fascicles
Types of fascicle arrangement
1. Parallel
2. Fusiform
3. Circular
4. Triangular
5. Pennate (unipennate, bipennate, multipennate)
2 muscle actions (contractions)
1. Concentric contraction
2. Eccentric contraction
Movements usually result from several skeletal muscles acting as a group: (4)
1. Prime mover or agonist
2. Antagonist
3. Synergist
4. Fixator
part of muscle group that causes most movement
Prime mover (agonist)
part of muscle group that opposes the prime mover
Antagonist
part of muscle group that stabilizes the intermediate joint
Synergist
part of muscle group that stabilizes the agonist, so that the agonist become more efficient
Fixator
When extending the forearm, the triceps act as the (antagonist/agonist) while the biceps act as the (antagonist/agonist)
triceps = agonist, extension
biceps = antagonist, flexion