Studied by 26 peoplename the 3 types of msucles
-cardiac -smooth -skeletal
Describe the characteristics of skeletal muscle
Attached to the bone by tendons -striated -voluntary (somatic) -multi-nucleated
What causes the straitation on skeletal muscle?
it is based on the arrangement of filaments in the muscle cell cytoplasm (sarcoplasm)
Name some characteristics of smooth muscle
-not striated -involuntary (autonomic: blood vessels, organs)
Name some characteristics of cardiac muscles
-only found in heart -striated -involuntary -mono nucleated
What is a skeletal muscle cell called?
a muscle fiber
[bc they are long and thin]
Name some muscle fiber characteristics
usually short but can be as long as the entire muscle -multi-nucleated (due to fused muscle cells)
what is a muscle?
multiple skeletal muscle fibers bound together with connective tissue
Bundles of connective tissues are called....
tendons
how is muscle attached to bones?
through tendons
what does a muscle contraction result in?
increased muscle tension
Name the components of muscles from smallest largest
Myofilament --> myofibrils --> muscle fibers --> muscle fasicles --> skeletal muscle
[ --> = make up ]
a group of muscle fibers is called what?
muscle fascicle
a group of myofibrils is called what?
a muscle fiber (aka muscle cell)
what do myofibrils contain?
myofilaments
[think.. myoFILs up]
what are the dark lines called in skeletal muscle?
A bands = dark lines
what are the light bands in skeletal muscle called?
I bands
What is a neuromuscular junction?
The junction where muscle fibers and motor neurons meet
what type of neurons innervate skeletal muscle fibers?
motor neurons
If a motor neuron is stimulated, what happens?
the motor neurons causes action potential (AP) in muscle fibers
What happens when motor neurons release AP?
Acetylcholine releases into the neuromuscular junction
What happens when ACh is released in the neuromuscular junction?
Acetylcholine binds to nicotinic ACh receptors in the muscle fibers causing more action potential which then causes a contraction
describe 'motor unit'
when one motor neuron innervates many muscle fibers
what is special about smaller motor units?
they allow a finer muscle control
[fewer fibers per neuron]
Describe recruitment
bringing muscle fibers into a response, causing more motor units to activate, thus creating more tension
activation of more motor neurons/motor units lead to what?
increase in muscle tension
Describe summation
stimulation of more and more motor units at different times, causing stronger tension
[ex. holding up one book then slowly adding more]
[think.. summ = adding]
what is a bundle of myofilaments called?
myofibrils
what are sections of myofibrils called?
a sarcomere
a collection thick and thin myofilaments cause what?
striations on myofibrils
Name characteristics of THICK filaments
is also known as myosin -has two globular heads that form cross bridges with actin during muscle contraction -is the dark lines in striations
Name characteristics of THIN filaments
-is also known as actin -has regulatory proteins (troponin and tropomyosin) -are the light lines
Describe is troponin
a regulatory protein in actin that binds different chemicals based on the name
[ex. Troponin C binds calcium, Troponin T binds tropomyosin, I binds actin]
Describe Tropomyosin
a regulatory protein that blocks myosin from binding with actin (inhibits a contraction)
what divides myofibrils into sarcomeres?
Z lines are attached to each end dividing the myofibrils
how is thick mysoin anchored in place?
it anchored by titin.
why is the I band appear lighter?
I bands are thin filaments, because they are thinner, they are less compacted and lighter in color
Where are the thin filaments anchored to?
z lines
connection between myosin and actin during muscle contraction is called...
a cross bridge
describe contraction
an activation of the force-generating sites in muscle fibers (ex. cross bridges in myosin)
what is a sliding filament mechanism?
the overlapping of thick and thin filaments, in a sarcomere, move past each other to contract muscle fiber
How does the sliding filament mechanism start?
myosin MUST binds to actin for it to slides it, pulling the two Z lines closer together
when actin is blocked by tropomyosin, the muscle is in a ____ state.
relaxed
what holds tropomyosin in a blocking position?
troponin
After muscle fibers depolarizes, what happens?
Action potentials (AP) travels down the transverse tubules in the fiber and releases Ca2+
Where is Ca2+ stored?
in the sarcoplasmic reticulum
What happens when tropomyosin is moved out of it's blocking position?
Myosin can bind to actin, which causes a contraction
after the cross bridge forms, Pi is released to cause what?
a power stroke to move the actin filament
Where is Ca2+ released?
[hint: where is it stored?]
into the sarcoplasm
(like cytoplasm but for muscle cells)
What is a latent period?
a period between action potential (AP) and contraction
tbh idk just study this
...
what state is tropomyosin at during relaxation?
tropomyosin is in it's blocking state
what happens after contraction?
the muscle cell membrane repolarizes abd calcium moves back into the sarcoplasmic reticulum
define tension
force exerted on an object by contracting muscle
[opposite of load]
define load
force exerted on muscle by an object
[opposite of tension]
define twitch
a single contraction of a muscle fiber to a SINGLE action potential
define recruitment
basically, for more tension (strength), more motor units are activated
describe tetanus/tetany
sustained maximal contraction due to repetitive stimulation
[gripping on to something for a longtime and trying to maintain the same % of strength]
[think.. TeT = tt= same/constant ]
describe unfused/incomplete tetanus:
Partial dissipation of tension between stimuli
described fused/complete tetanus:
no time for latency period between rapid occurring stimuli
what is isotonic contraction
a contraction where tension remains the same but the muscle length changes (ex. bicep curls, bicep will change length)
[think... nic - changes (like ur lungs)]
what is isometric contraction
a contraction with the same tension, but the muscle doesn't change length.
[ex. planking]
Short sarcomeres produce ____ tension because they ____ room to slide
little // lack
optimal-length sarcomeres make ___ tension because they __
maximum // overlap
long sarcomeres make ___ tension because they __
little // do not overlap
t/f tension gets greater the closer it gets to resting percentage
False
Characteristics of slow twitches (Type I)
slow to reach maximum tension -small diameter -smlow to fatigue -respond well to repetitive stimulation without becoming fatigues
Characteristics of fast twitches (Type II)
reaches maximum tension quickly -large diameter -fatigues quickly
Characteristics of Type IIX twitches (fastest)
-used for quick burst of strong activation
(think of sprints)
Type IIA (intermediate) twitches
respond quickly to repetitive stimulation within intermediate time to fatigue
(think long distance walking)
Type I fibers are also called..
slow twitch fibers
Type II fibers are also called...
slow twitch
Type IIX are known as...
the fastest fibers
Type IIA fibers are known as...
intermediate fibers
describe muscle fatiuge
decease muscle tension over time due to repeated stimulation
what ___ and ___ depolarizes cardiac muscle contraction
Na+ and Ca2+
increase of calcium in cardiac muscle causes the sarcoplasmic recticulm to ____ release of calcium
Increase!
[this is a positive feedback]
how is smooth muscle arranged?
in layers!
where can we find smooth muscle?
in hollow organs that change in volume
[bladder, lungs, blood vessels etc]
what controls cross bridge activity in smooth muscle?
calcium
what controls cross bridge activity in cardiac muscle?
calcium
____ binds to troponin C
calcium
when troponin C binds with calcium, this causes what to react?
Troponin T
what does troponin T do?
Helps move tropomyosin out of blocking position
Note
Flashcard