Biology Chapter 11- musculoskeletal system
Sarcomeres are divided into lines, zones, and bands
What are the three Sarcomere Divisions?
The only way that we could stop the block of the myosin head from crossing over the actin is
by changing the conformation troponin, and moving tropomyosin out of the way
smooth muscle
hallow organs and blood vessels "Aorta" + involuntary + eye shaped * spindle shape with 1 nuclei
Autonomic Nervous system is divided into
involuntary SYMP= noradrenaline, norepinephrine " fight or flight" PARAS= Acetocholine, rest and digest
what could a tropomyosin do to the actin
it could block the myosin head from moving into the actin
Muscle
many myocytes in parallel
o During contraction, the H-zone, I-band, the distance between Z, distance between M-line all decrease; A-band stays the same
o During contraction, how do the bands/distances change?
Vagus nerve
This provides parasympathetic outflow to the heart and slows heart rate via the parasympathetic nervous system
What is the role of tropomyosin in muscle contraction?
To prevent myosin from continuing to slide up the actin filament
Red fibers/slow-twitch fibers:
o High myoglobin content - Mostly derive energy aerobically - Also contain mitochondria for oxidative phosphorylation - contract slowly, but can sustain activity for longer
Motor unit
this is a nerve terminal (called a motor end plate in a neuromuscular junction) and its group of myocytes
Thin Filament
this is a part of the sarcomere that is made of actin, troponin, tropomyosin
Thick Filament
this is a part of the sarcomere that is made of myosin
Myogenic activity
this is when smooth muscle contracts without nervous system input; the cells contract directly in response to stretch or other stimuli
tropomyosin could block the myosin head from crossing the actin
true
Somatic Nervous System
voluntary and acetocholine
sarcoplasmic reticulum
when the muscle contracting, the Ca++ from the SR gets out into the cytoplasm when the muscle relaxes, the Ca++ from the SR gets inside of the SR SR: is a storage place for Calcium!
A band
when the sarcomere contracts: I band change A band doesn't change and stays the same.
If injury happens to the UMN, what could potentially happen?
* weakness doesn't happen since there is no stop sign, the start keeps sending the signal. This causes spastic behavior in the muscle, this leads to constant contraction.
parts of the brain that control voluntary
*cerebral cortex *and spinal cord
PNS, myelin called:
*schwan cells
If injury happens to the LMN, what could potentially happen?
*weakness could result
neuron
+ dendrites receives signals * myelin sheath: insulates the signal (FAT) + axon: send the message though it + node of Ranvier: empty space that the signal jump though
sarcolemma receptors; depolarization
- Acetylcholine binds to _____ ______, causing ________
Smooth Muscle
- involved in the involuntary action controlled by the autonomic nervous system (ex. rhythmic contractions of the muscle in the digestive system --> peristalsis) - Capable of more sustained contraction - involved in the regulation of blood pressure by constricting and relaxing the vasculature
Myocyte
- muscle cell, or, muscle fiber - contains many myofibrils arranged in parallel o Nuclei usually found at the periphery of the cell
Muscle Contraction
- this requires steps that are repeated to induce further shortening - Process depends on ATP and Ca2+
How does the actin and myosin works?
1) ATP binds to myosin head 2) myosin still has the ATP but got released from actin 3) ATP now gets hydrolyze to ADP and PI but still attached to the myosin 3) PI gets released from the myosin but it is still attached to the ADP, now it pushed the actin and ADP also gets releases 4) it goes back to step 1 but 1 step further!
Type 1 muscle fibers
1) Red 2) contraction speed: slow 3) conduction: slow 4) aerobic activity 5) duration: long 6): Fatigue not easily 7) power: strong 8) In the form of triglyceride fatty acid. golden role: Type 1 contains lots of mitochondria
What is an aponeurosis?
A large, flat tendon that anchors muscle
- As signal decreases, calcium release ceases, and SR takes up calcium from the sarcoplasm - SR controls Ca so that muscles are contracted only when necessary - ATP binds to myosin heads to free them from actin - Sarcomere returns to the original width - w/out Ca2+, the myosin-binding sites are covered by tropomyosin and contraction is prevented
As the signal decreases, what happens?
How does your brain tell your brain to move your leg when dancing?
Brian tell (UMN) to send a signal to the (LMN) UMN has two jobs: start + stop LMN has one job: start only
Myogenic activity
Cardiac muscle cells can define and maintain their own rhythm through ____________
The hydrolysis of the ATP that is bound to myosin causes: Please choose from one of the following options.
Release of myosin head from the actin filament
Starting at the sinoatrial (SA) node, depolarization spreads using conduction pathways to atrioventricular (AV) node → depolarization spreads to bundle of His → Pukinje fibers
Order of depolarization of the heart pathway
Rapid and coordinated muscle cell depolarization and efficient contraction of cardiac muscle
Describe cardiac muscle depolarization/contraction...
Curare is a naturally-occurring compound that competitively binds to nicotinic acetylcholine receptors on muscle cells. Which of the following symptoms might be seen in a patient who has been exposed to curare? Excessive salivation Muscle spasticity Diaphragmatic paralysis Cardiac arrest
Diaphragmatic paralysis
Which of the following correctly identifies muscle components in order from largest to smallest? Please choose from one of the following options.
Fasciculus, muscle fiber, myofibril
The sarcolemma distributes action potential to all sarcomeres in muscle by using transverse tubules that are oriented perpendicularly to myofibrils
How does the sarcolemma distribute action potential to all sarcomeres in muscle?
Actin and myosin are arranged in repeating units (sarcomeres) and make muscle appear striated (looks striped)
In skeletal muscle, how are actin and myosin arranged?
- Uninucleated primarily, but sometimes contain two nuclei
Is cardiac muscle uni or multinucleated?
Skeletal muscle is multinucleated b/c individual muscle cells fuse together into long rods
Is skeletal muscle uninucleated or multinucleated?
No, Smooth muscle contains *unorganized actin and myosin*
Is smooth muscle organized in sarcomeres?
What is the role of acetylcholine in calcium release? Please choose from one of the following options.
Stimulates cellular contraction by opening voltage-gated ion channels
Sequence: o Myosin carrying hydrolyzed ATP is able to bind with myosin binding site. Release of inorganic phosphate and ADP provides energy for powerstroke and results in sliding of actin filament over myosin filament o ATP binds to the myosin head, releasing it from actin o This ATP is hydrolyzed to ADP and Pi, which recocks the myosin head so that it is in position to initiate another cross-bridge cycle o Repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament, causing sarcomere to shorten (sliding filament model) *it is the dissociation of ADP and Pi from myosin that drives the Powerstroke, not the hydrolysis of ATP. The binding of ATP is required for RELEASING the myosin head from the actin filament. *
What is the sequence of myosin binding?
Found in the respiratory tract, digestive tract, bladder, uterus, blood vessel walls, etc.
Where is smooth muscle found?
what two types of muscles have stripes
cardiac and skeletal
How do you employ myosin head? inotropy
either increase the calcium level or make the troponin C more sensitive to calcium.
Norepinephrine/epinephrine
o __________ from sympathetic neurons or _________________from the adrenal medulla binds to adrenergic receptors in the heart, causing increased heart rate and greater contractility • Both increase intracellular Ca2+ within cardiac myocytes
White fibers/fast-twitch fibers
o less myoglobin - less iron - lighter color - contract rapidly, but fatigue quickly
what is the space between the two Z lines
sarcomere
what two types of muscle have in voluntary control
smooth and cardiac
skeletal muscle
tendon + bone aponeurosis + muscle voluntary It is the fastest muscle Branched of nuclei, striated, found in the periphery.
Syncytium
the muscles are in synergy with each other when one contracts it causes the neighbor to contract as well. The entire neighborhood contracts together now.
acetylcholinesterase
the neurotransmitter responsible for muscle contraction is degraded in the synapse by THIS, which results in termination of the signal at the neuromuscular junction and allows the sarcolemma to repolarize
Myoglobin
the oxygen carrier that uses iron in a heme to bind oxygen
o A-band
these contain thick filaments in their entirety (ALL of the thick filament)
o Z-lines
these define the boundaries of each sarcomere (Z is end of alphabet and end of sarcomere)
o H-zone
these only have thick filaments (H is THICK)
o I-band
these only have thin filaments (I is THIN)
o M-lines
these run down center of sarcomere through middle of myosin (M = Middle/Myosin)
o Troponin and tropomyosin
These are proteins that regulate the interaction between actin and myosin
CNS, myelin is called:
* Brain and spinal cord. Oligodendrides
part of the brain that controls involuntary
* Brain steam * sympathetic ganglia (BEHIND ME)
Sarcomere
- Basic contractile unit of skeletal muscle - Contain thick (made of myosin) and thin filament (made of actin, troponin, tropomyosin)
troponin; tropomyosin; troponin o This causes myosin-binding sites on the actin thin filament to be exposed
- Ca binds to a subunit of _______________, triggering the change in the conformation of _______________ to which ________ is bound
intercalated discs; gap junctions
- Cardiac muscles are connected by ______________________ that contain _________________.
sarcolemma
- Cell membrane of a myocyte - Can propagate an action potential - Distributes action potential to all sarcomeres in muscle by using transverse tubules that are oriented perpendicularly to myofibrils
Gap Junctions
- Connections between the cytoplasm of adjacent cells that allow for the flow of ions directly between cells - these allow for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle
neuromuscular junctions; nervous; muscle; motor neurons
- Contraction starts at _____________________, where the _____ system communicates with a ______ via ________ ________
an action potential; the sarcolemma; T-Tubules
- Depolarization triggers __________, which spreads down ______ to _______
Cardiac Muscle
- Has characteristics of both smooth and skeletal muscle types - Involuntary + autonomic nervous system - this appears striated (thin parallel streaks)
end to end; myofibrils
- Sarcomeres are attached ____________ to form ___________
a neuron; the nerve terminal (synaptic bouton, motor endplate); acetylcholine
- Signal travels down ________ until it reaches _______________, where ___________ is released into the synapse
sarcoplasmic reticulum; reticulum; Ca2+
- T-tubules travel into ________, and when action potential reachies the _______, ______ is released
actin-myosin; myosin; actin; thin filaments; M-line; sarcomere
- The _________ cross bridges allow _____ to pull on _______, drawing _______ filaments toward the _______ and shortening the _________
Tonus
This is a constant state of low-level contraction for smooth muscle which is seen in the blood vessels
- Titin
This is a protein that anchors actin and myosin filaments together to prevent excessive stretching of the muscle
myosin; actin
- The free globular head of a _____ molecule binds to the exposed sites on _____
Simple Twitch
- This is a response of a single muscle fiber to a brief stimulus at or above the threshold - Consists of: the latent period (time between reaching threshold and onset of contraction; during this time, action potential spreads along the muscle and allows for Calcium release from SR) and the relaxation period
how does the troponin and tropomyosin works? both: protein.
1) if the calcium concentration goes low, the ca++ gets released from the troponin= this cause muscle relaxation 2) if the calcium concentration is high, the the Ca+ gets attached to the troponin and would help the myosin head bind to the actin so that it could cross over which would lead to muscle contraction.
Neuromuscular Junction
1) influx of Ca++ into the axon terminal 2) Ca++ binds to the NT 3) NT fuses with synaptic cleft 4) exocytosis happened 5) NT binds to the nitcotinic receptor causing Na+ open and ACTH enters (endocytosis) 6) As each NT enters, Na+ also enters this causing depolarization. 7) Most of the calcium gets hidden in SR ---When it enters called "calcium Induced Calcium release" 8) Now the muscle cells contract ( gap junction) all cations follow from one muscle to another
what are the 3 types of muscle?
1) smooth 2) cardiac 3) skeletal all known to have some type of movement
Type 2 muscle fibers
1) white 2) contraction speed: fast 3) conduction: fast 4) anaerobic activity 5) duration: slow 6): Fatigue easily 7) power: weak 8) ATP and creatine phosphate golden role: Type 1 contains lots of mitochondria
Smooth muscle has a single nucleus located in center of cell
Is smooth muscle uni/multinucleated?
White (fast-twitch) fiber; fatigue quicker b/c they have less oxygen
Muscles that contract quickly but fatigue quickly have what type of fiber?
Red (slow-twitch) fibers; can sustain activity b/c they have a lot of oxygen for aerobic metabolism
Muscles that contract slowly but that can sustain activity contain what type of fiber?
We would expect to find smooth muscle in all of the following EXCEPT: Please choose from one of the following options. Myocardial tissue Pulmonary circulatory tissue Esophagus Small intestine
Myocardial tissue
when is myosin head happy and when is unhappy?
Myosin head is happy when calcium is around because then it could bind to actin to form contraction, if calcium not around the the head is controlled by tropomyosin and there wont be contraction happening or it won't bind the actin molecule.
Which of the following is NOT innervated by the autonomic nervous system? Branching muscle cell Striated muscle cell Myocardial cell Intestinal muscle cell
Striated muscle cell, skeletal muscle (voluntary)
cardiac muscle
The only type of muscle in the heart. involuntary -branched, 1 or 2 nuclei -located in the middle of the cell -striated
There are how many types of troponin, and to what type the ca++ binds?
Type C, I, T calcium binds to type: C
Which of the following is accurate regarding Type I and Type II muscle fibers?
Type I fibers store much of their energy as triglycerides, whereas Type II fibers store energy as ATP or creatine phosphate
o Red fibers/slow-twitch fibers o White fibers/fast-twitch fibers
What are the 2 types of skeletal muscle fibers?
Sarcoplasm
modified cytoplasm located outside of sarcoplasmic reticulum
...the sarcoplasmic reticulum, a modified ER that contains Ca2+ ions
myofibrils are surrounded by...
