muscle tissue Flashcards
Myo =
muscle
Sarco = flesh (muscle)
flesh (muscle)
syn =
together
ant =
against
agonist =
competitor
Iso =
same
Epi =
upon
Peri =
around
Endo =
within
what are the 4 functions of muscle tissue?
movement, maintain posture, heat production, and stabilize joints
What are the four characteristics that all muscles share?
excitability, contractibility, extensibility, and elasticity
what is the function of excitability?
can receive and respond to stimuli
what is the function of contractility?
can shorten when stimulated
what is the function of extensibility?
can stretch
what is the function of elasticity?
can return to original shape
T/F: muscle is an organ
true
what are the 3 features of the different tissues which make up skeletal muscle?
nerve and blood supply, connective tissue sheaths, and attachments
T/F: muscles are energetically expensive
true
every skeletal muscle fiber is innervated by a _________
nerve ending
muscle is highly vascularized for ___________________
nutrients, oxygen, energy, and waste removal
name the CT sheaths from external to internal
epimysium, perimysium, endomysium
what type of connective tissue makes up the epimysium?
dense irregular CT tissue
what does the epimysium surround?
the epimysium surrounds the whole muscle
what type of connective tissue makes up the perimysium?
dense regular connective tissue
what does dense regular CT allow the perimysium to do?
allows the muscle to move back and forth; pulls in the same direction
what does the perimysium surround?
the perimysium surrounds each fascicle
what type of connective tissue makes up the endomysium?
areolar loose CT
what does the endomysium surround?
surrounds each muscle fiber
what are the three things that make of a muscle fiber?
sarcolemma, sarcoplasm, and sarcoplasmic reticulum
characteristics of a muscle fiber
large cells; multi-nucleated
what are myofibrils?
organelles
what are myofilaments?
filaments
what are the two types of myofilaments?
myosin (thick) and actin (thin)
myosin =
thick
actin =
thin
what is the structure of a skeletal muscle in order
muscle, fascicle, muscle fiber, myofibrils, thick and thin filaments
the sarcolemma is under the ______
endomysium
what is included in the anatomy of a myofibril?
Z line (disc), M line, A band, I band, and sarcomere
function of Z line
anchor for thin filaments; actin moves where Z line moves
function of M line
anchor for thick filaments
A band:
dark area; extends length of the thick filaments
I band:
light area; thin myofilaments ONLY; Z disc is center of I band
Sarcomere:
functional unit of skeletal muscle; Z disc to z disc; aligned end to end within myofibril
in a sarcomere, what moves for a muscle contraction?
both Z lines pull in together
what is the functional unit of skeletal muscle?
sarcomere
which filament wants to bind to actin?
myosin
what makes up thick myofilaments?
myosin
myosin makes up thick myofilaments
characteristics of myosin
rodlike tail & 2 globular heads
what do the heads on myosin contain?
heads contain binding sites for actin & ATP
how would you describe the placement of actin on a myofilament?
extends across I band and part way in A band; anchored to Z discs
what makes up thin myofilaments?
actin
actin contains binding sites for _____
myosin heads
charactertisitcs of myosin
G-actin strung together; 2 twisting strands make up thin myofilaments
what is the name of the rod-shaped protein which runs along actin?
tropomyosin
when the muscle is relaxed, what blocks the myosin-binding sites on actin?
tropomyosin blocks myosin-binding sites on actin when muscle is relaxed
what is a key player in the sliding filament model of contraction?
tropinin
where is troponin located?
in thin myofilaments
T/F: troponin contains a 4 polypeptide subunit complex
FALSE
troponin contains a 3 polypeptide subunit complex
where does each of the 3 polypeptide subunit complexs in troponin bind to?
1 subunit bound to actin
1 subunit bound to tropomyosin
1 subunit binds to Ca2+
where is Ca2+ stored when the muscle is relaxed?
in the sarcoplasmic reticulum
definition of a thin filament:
a thin filament consists of two strands of actin subunits twisted into a helix plus two types of regulatory proteins (troponin and tropomyosin)
definition of a thick filament:
each thick filament consists of many myosin molecules whose heads protrude at opposite ends of the filament
in a relaxed state, thin and thick filaments…
overlap only slightly
upon stimulation, myosin heads bind to actin and ________
sliding begins
how many steps are in the sliding filament model?
4
what is the purpose of the sliding filament model?
it is an explanation for how muscles contract to produce force
what are some precursers for the events of contraction
Ca2+ binding to troponin to move tropomyosin and reveal binding sites
what are the four sequential events of contraction?
- cross bridge formation
- power stroke
- cross bridge detachment
- “cocking” of the myosin head
what happens in step one of the sliding filament model?
cross bridge formation
- myosin attaches to actin filament forming a cross bridge
what happens in step two of the sliding filament model?
powerstroke
- myosin head picots and pulls actin filament toward M line
what happens in step three of the sliding filament model?
cross bridge detachment
- myosin head releases from actin
what happens in step four of the sliding filament model?
“cocking” of the mysoin head
- energy from ATP “cocks” (or energizes) the myosin head for the next power stroke
