Muscle Tissue Flashcards
T or F: In all its form, muscle tissue makes near ____ of the body’s mass
half
What are the 4 functions of muscle tissue
- movement
- posture
- joint stabilization
- body heat
What are the 4 special functional characteristics that make SKM unique?
- contractility
- excitability
- extensibility
- elasticity
What are the 3 types of muscle tissue
skeletal, cardiac, and smooth
A cell in skeletal and smooth muscle tissue are called ______
fibers
Muscle cells of ______ and _____ muscle tissues are called fibers
skeletal and smooth muscle
All 3 types of muscle tissue depend on _________ for contraction
myofilaments
the plasma membrane for all types of muscle cells is called the
sacrolemma
the cytoplasm for all muscle cells is called the
sacroplasm
striated, voluntary movement, attached to primarily to bones, multiple nuclei per cell
skeletal
striated, invol control, forms most of the heart, and single nucleus
cardiac
nonstriated, invol, walls fo hollow internal structures (visceral), single nucleus
smooth
T or F: SKM is vol striated muscle that is usually attached to one or more bones
True
Are most skeletal muscles controlled subconsciously to some extent
yes, ex diaphragm
Each Skeletal muscle is an ORGAN composed of
SKm tissue, CT, nervous tissue, BVs
Because of their length, SKm cells are usually called muscle fibers or
myofibers
T or F: each skeletal muscle is a separate organ composed of fibers
True
What type of CT is sk muscle made of
fibrous CT
__________ is a sheet/band of fibrous CT that is deep to the skin and surrounds muscles and other organs in the body
fascia
what are the 2 main types of fascia
superficial and deep
What does the superficial fascia do?
sep muscles from skin and provides a pathway from nerves and BVs, stores fat, insulates, and protects muscles from trauma
What does the deep fascia do?
Lines the body wall and limbs, holds muscles with similar functions together, allows free movement (fills space between muscles)
What are the 3 extensions of the deep fascia that cover individual muscle fibers
epimysium, perimysium, and endomysium
Outermost, covering the entire muscle
epimysium
covering bundles (fascicles)
perimysium
covering individual muscle fibers
endomysium
what are the 2 EXTENSIONS OF CT beyond muscle cells that attach muscle to bone or other muscle
tendon and aponeuroses
______ a cord of dense CT that attaches a muscle to the periosteum of a bone
Tendon
____________ a tendon that extends as a broad, flat layer
aponeurosis (cranial and abdominals)
Are collagen of muscles excitable/contractile or extensible/elastic
extensible/elastic
How does collagen protect the muscle from injury
resist excessive stretching when a muscle lengthens
How do skeletal muscles produce movments
exert force on tendons -> pull on bones or skin
T or F: most muscles cross at least 1 joint and are attached to the articulating bones that form the joint
True
When such a muscle contracts it _____ one articulating bone toward the other
draws
______: attachment of muscle tendon to STATIONARY bone
origin
______: attachment of other muscle tendon to MOVEABLE bone
insertion
________ is an inflammation of the tendons and synovial membranes surroundinging certain joints
tendonitis
What are in nerves that convey impulses for muscular contraction
motor neurons
What does the blood supply?
oxygen and nutrients
Intramuscular (IM) injections are used to administer rel large doses of drugs that can be dangerous or even fatal if injected directly into the _______
bloodstream
What should you palpate for to find the best location for an IM injection?
Greater trochanter
Why do IM injections cause less irritation and absorbed quicker
greater blood supply of muscles
what are the 3 main components of the skeletal muscle (think diagram)
whole muscle, fascicle, muscle fibers
What do skeletal muscle fibers look like?
long, cylindrical, multinucleate cells
how are skeletal muscle fibers formed
embryonic myoblasts
Is the number of SK muscle fibers set before you are born?
YES
Do most of these cells last a lifetime?
Yes
How does muscle grow then?
hypertrophy: enlargement of existing muscle fibers
The organized internal structure of a muscle fiber is closely tied to its _________ function
contractile
The light and dark striations in muscle fibers are from the internal structure of long, rod-shaped organelles called _________
myofibrils
Myofibrils make up more than ____% of the sacroplasm
80%
Fibers (cells) are covered by a ________ (cell membrane)
sacrolemma
what are tiny invaginations of the sarcolemma that quickly spread the muscle AP to all parts of the muscle fiber
T tubules
The sarcoplasm is the muscle cell cytoplasm and contains organelles like mitochondria and a large amount of ______ for E production and _______ for oxygen storage
glycogen, myoglobin
The sarcoplasm is occupied mainly by long protein bundles called _________
myofibrils
What is the shape of muscle fibers that are pressed against the inside of the sacrolemma
sausage-shaped
Most other organelles are packed into the ______ between the myofibrils
spaces
what encircles each myofibril
sacroplasmic reticulum (SR)
What is the equivalent in the smooth muscle as it stores calcium ions
endoplasmic reticulum
What are parallel, threadlike contractile organelles found in muscle tissue
myofibrils
what contractile proteins do myofibrils contain?
myofilaments
what 2 filaments are myofilaments made of?
Myosin and actin
Which are thick and which are thin
thick = myosin
thin = actin
Myosin and actin are arranged into units called, this is the FUNCTIONAL UNIT OF THE CELL
sarcomeres
What are the boundaries of a sacromere
1 Z line to the next
___ band = myosin w/ some actin overlapping
A band
___ band = consist of actin only
I band
Z (line) discs passes through the
center of the I band
___ zone inn the center of each A band contains myosin only
H
______ can result in torn sarcolemma, damaged myofibrils, and disrupted Z discs
exercise
What functions as a motor protein, pull/push cargo to convert ATP into mech E
myosin
What connects to the myosin for the sliding together of filaments
actin
Actin and myosin are the ________ proteins
contractile
The regulatory proteins are
tropomyosin and troponin
tropomyosin and troponin are part of the _______ filament
thin
In a relaxed muscle what does tropomyosin do?
blocks myosin-binding sites on actin preventing myosin from binding to actin
What is the most clinically important protein
dystrophin
what are the 2 structural proteins
titin and distrophonin
what is role of the structural proteins
give the myofibril elasticity and extensibility
______ is an elastic protein that helps a sarcomere return to its resting length after a muscle has contracted or been stretched
titin
______________ is an enormous protein located btwn the sarcolemma and outermost myofilaments
dystrophin
Dystrophin thru a series of links that leads ultimately to the fibrous __________ surrounding the muscle fiber
endomysium
When myofilaments move, they pull on dystrophin, and ultimately this pulls on the extracellular CT leading to the ______
tendon
what condition is associated with genetic defects in dystrophin
muscular dystrophy
general cell = cell, SKm cell =
muscle fiber
general cell membrane= cell, SKm cell =
sarcolemma, extensions of T-tubules
general cell = cytoplasm, SKm cell =
sacroplasm
general cell = endoplasmic recticulum, SKm cell =
sarcoplasmic reticulum (stores Ca2+)
general cell = organelles (many), SKm cell =
organelles (many), myofibrils are contractile
SKm muscle never contracts unless it is stimulated by a _______
nerve
what are nerve cells called?
somatic motor neurons
somatic motor neurons w/ cell bodies in the brainstem and spinal cord, stim mf via their axons, called somatic motor ______
fibers
A single motor fiber and all the muscle fibers it innervates are collectively called a
motor unit
the greater the contraction
the greater the number fibers
are axons of motor nuerons branched?
yes
T or F: A motor unit is a single neuron AND all of the muscle fibers it innervates
true
A single motor unit may innervate as few as 10 or as many 2,000 mf, with an average of what
150 fibers innervated by each motor neuron
smalll motor unit > fine control > eye movement (how many #)
3-20 muscle fibers by per neuron
large motor unit > gross > gastrocnemius
1,000 mf per neuron
What arises at the neuromuscular junction (NMJ), the synapse between a somatic motor neuron and a skeletal muscle fiber
Action potential (AP)
AP travels down a motor neuron to the axon terminal and causes the release of the neurotransmitter
acetylcholine (ACh)
ACh will bind to receptors on the _______ of the muscle fiber and causes muscle contraction; a decrease, stops it
sarcolemma
Which enzyme is attached to the sarcolemma immediately breaks ACh down into fragments to stop the stimulation of the mf
acetylcholinesterase (ACh-ase)
Muscle depolarization travels along sarcolemma, down T-tubules, causing release of Ca2+ from SR to
sacroplasm
Where does ATP attach?
myosin cross bridges (myosin)
This reaction transfers E from ATP to the myosin head, even before the contraction begins -> this leaves it an ________ state
energized
Explain the oar of a boat metaphor
myosin heads bind to actin and swivel toward the center of the sarcomere, drawing thin filaments past thick filaments toward the center of the sarcomere (H zone)
As myosin heads swivel, what do they release
ADP
the sarcomere shortens, do the thick and thin filaments change length?
no
The sliding of filaments and shortening of sacromeres causes the shortening of the whole muscle fiber and ultimately the entire muscle, this is called
sliding filament mechanism
when power stroke is ________, ATP again combines with the ATP-binding sites on the myosin heads
complete
As _____ binds, myosin head detaches from actin
ATP
ATP is split, giving energy and myosin returns to what
original upright position
What 3 things have to be available for the cycle to continue
ATP, Ca2+, ACh
when contraction is over, what returns calcium ions to the SR
calcium ion active transport pumps
Rigor mortis, a state of muscular rigidity following death, is caused by
lack of ATP to split myosin-actin cross bridges
what are the 2 main drugs/plants that block events at the NMJ
curare and botulinum toxin
_______ plant poison used on arrows and blowgun darts
curare
how does curare cause muscle paralysis
blocks ACh RECEPTORS, inhibits Na+ ion channels
what is a use of a derivative of curare
used during surgery to relax skeletal muscles
what does botulinum toxin (bacterial toxin) block?
blocks the release of ACh from synaptic vescicles
May be found in improperly canned foods, tiny amt can paralyze respiratory muscles =
death
what is the medical purpose?
botox
what things can botox treat?
- strabismus (crossed eyes)
- blepharospasm (uncontrollable blinking)
- spasm of vocal cords that interfere with speech
- cosmetic treatment: relax muscles that cause facial wrinkles
- alleviate chronic back pain
Are all Sk muscle fibers identical in structure and function?
NO
color varies according the content of __________, an oxygen storing reddish pigment
myoglobin
red muscle fibers have ____ myoglobin content while the myoglobin content of white muscle fibers is _____
high, low
what varies between cell types
fiber diameter (mitochondria), contraction velocity, and resistance to fatigue
What are the 3 skeletal muscle fiber classifications
slow oxidative, oxidative-glycolytic, and fast glycolytic fibers
red in color, resistant to fatigue, least powerful, smallest diameter, make ATP aerobically, lots of mitochondria
slow oxidative (slow twitch)
pink in color, hand and eye muscles, lots of mitochondria, myoglobin, and blood vessels
fast oxidative-glycolytic
Fast oxidative-glycolytic split ATP at a very fast rate, what activities show this
walking, marathon running
White in color, anaerobic activity for short duration, largest diameter, make ATP via glycolysis, fatigue quickly
Fast glycolytic (fast twitch)
what is an example of fast glycolytic exercise
bicep curls
Do most skeletal muscles contain a mixture of all 3 types
yes
Do all fibers of any one motor unit have the same fiber type
Yes
T or F: Although the # of diff sk muscle fibers does not change, the characteristics of those present can be altered by various types of exercise
True
_______ can improve physical performance by increasing joint flexibility allowing the joint to move thru a greater ROM
stretching
Muscular power and ROM are influenced by what
fascicle organization and leverage
how does stretching reduce the risk of injury
decrease resistance in various soft tissue -> less of a chance of exceeding max tissue extensibility
what are other benefits of stretching
less muscle soreness and improve posture (realign soft tissues)
Do skeletal muscles fibers undergo mitosis after they form
No
Do skeletal muscle fibers lengthen and thicken throughout childhood and adolescence
yes
Why is body strength of adult men usually greater than that of an adult women?
effects of androgen hormones in males
Aging results in increased amounts of CT in skeletal muscles and a decrease in number of muscle fibers known as
sarcopenia
Inflammation can be good, but what is a bad example that causes nerve compression?
compartment syndrome
order: fascicles, thick & thin filaments, myofibrils, muscle fibers (cells), muscle
muscle, fascicles, muscle fibers (cells), myofibrils, thick & thin filaments
Cardiac muscle has gap junctions that are called
intercalated disks
why is there more mitochondria in cardiac than SKm
Aerobic -> get ATP (need O) for cont., rhythmic activity
What tissue is smooth muscle made of?
Aerolar
what are the 2 main functions of smooth tissue
vasoconstriction (active) and vasodilation (relaxation)
Is there troponin and tropomyosin in smooth muscle
no, Ca2+ triggers activation and contraction
why are calcium channel blockers prescribed fro high BP?
cause vasodilation of the BVs, bc calcium is blocked so smooth muscle cant contract (aka vasoconstrict)
is smooth muscle organized into sarcomeres or does it just thick and thin filaments
no sarcomeres, sarcoplasm has thick and thin filaments
Is the duration of contraction longer for smooth muscle compared to SKm
Smooth is longer
can smooth muscle contract in multiple ways and stretch considerably w/o developing tension
yes
What does this construction of smooth muscle facilitate?
swift coordinated contraction, automatic
