TEST 4 - MUSCLE Flashcards
Two types of muscle
Striated muscle
Smooth muscle
2 subdivisions of striated muscle
Skeletal
Cardiac
Skeletal muscle is further subdivided into what two types of muscle/fibers?
Fast twitch/ white muscle
Slow twitch/ red muscle
“Body builder” or centerfold boys involve what type of muscle
White muscle (fast twitch)
WHITE/RED MUSCLE
React rapidly for quick, powerful spurts of E.
White
White muscle has LARGER/SMALLER fibers for strength of contraction.
Larger
WHITE/RED MUSCLE?
Innervated by larger somatic motor neuron fibers
White
White muscle has large amounts of _________ enzymes to produce E through ________ glycolysis.
Glycolytic enzymes
Anaerobic glycolysis
How many ATP are produced in glycolysis?
4 total, 2 net ATP
_________ muscle has less extensive blood supply than ________ muscle.
White muscle has less blood supply than red muscle
WHITE/RED MUSCLE
Has fewer mitochondria– depend more on anaerobic metabolism for E source.
White muscle
Carries oxygen throughout the muscle fibers
Myoglobin
WHITE/RED MUSCLE
Less myoglobin.
White muscle
“Long distance runner” indicates what type of muscle
Red muscle (slow twitch)
WHITE/RED MUSCLE?
Respond slowly but prolonged contraction for prolonged activity
Red
WHITE OR RED MUSCLE?
Smaller fibers; innervated by smaller somatic motor neuron fibers.
Red
Red muscle has a more extensive blood supply–require more oxygen for ___________ ________ metabolism
Aerobic oxidative metabolism
WHITE/RED MUSCLE?
More mitochondria for aerobic oxidative metabolism
Red
Red muscle contains more ________ to transport oxygen throughout muscle fibers; also gives red muscle it’s color.
Myoglobin
Muscle is attached to bones via ________
Tendons
Muscles are composed of bundles of ________
Fibers
A bundle of muscle fibers is called what?
Fasciculus or fasciculi
Each fasciculus is composed of many _______
Muscle cells
Cell membrane of muscle fibers
Sarcolemma
Muscle cells have their own blood supply. TRUE/FALSE
TRUE
Skeletal muscle fibers tend to be mononuclear. TRUE/FALSE.
FALSE
Muscle fibers tend to be MULTINUCLEATED
Structure within the muscle fiber that contains Calcium (stored)
Sarcoplasmic reticulum
Invagination of the sarcolemma; extends form one side of the muscle fiber to the other side of the muscle fiber
Transverse tubule
ALL muscle fibers need mitochondria and need oxidative metabolism to some extent. TRUE/FALSE
TRUE
Subcellular structures that compose muscle cells
Myofibrils
What creates striations in striated muscle?
Light and dark bands of the myofibrils that compose muscle cells
Myofibrils are composed of many ________ along the myofibril
Sarcomeres
From ______ to _______ is a sarcomere
Z-disc to Z-disc
Myofibrils contain thousands of myofilaments; what are the two types of myofilament?
Actin myofilament
Myosin myofilament
________ myofilaments are attached to z-discs
Actin myofilaments
________ myofilaments are in the middle of the sarcomere.
Myosin myofilaments
Allows sarcomere to recoil back to original state after contraction
Titin filament
What type of nerves innervate skeletal muscle?
Lower somatic motor neuron
Upper motor neurons originate in the primary motor cortex, travel down the SC, and synapse with lower motor neuron where?
Anterior horn of the gray matter
Every single muscle fiber has to be innervated by a branch of a somatic motor neuron. TRUE/FALSE
TRUE
If a muscle fiber is not innervated by a somatic motor neuron, then _______ cannot occur in that fiber.
Contraction
Overlapping of ______ and _______ create striations.
Actin and myosin
Terminal portion of the sarcoplasmic reticulum; right next to the T tubule.
Terminal cisterna
Sarcoplasmic reticulum and T tubule make up what triad?
Terminal cisterna—T tubule— terminal cisterna
Most of the Ca found within the sarcoplasmic reticulum is stored where?
Terminal cisterna
Actin and myosin begin to interact with each other; ________ is pulled toward the center of the sarcomere until it reaches the fully contracted state.
Actin
_________ overlaps each other some in the fully contracted state
Actin
_____ actin molecules contain binding sites for myosin heads
G actin molecules
G actin molecules formed together make what?
F actin strands
Each actin myofilament is composed of ____ F actin strands.
2 strands
Lays directly over top myosin binding sites; contraction cannot occur
Tropomyosin
There are 3 subunits of troponin in skeletal muscle fiber. What are they?
Troponin I, T, and C
Troponin ___ is attached directly to the actin
Troponin I
Troponin ____ is attached to the tropomyosin strands
Troponin T
Troponin ____ is strongly attracted to calcium ions
Troponin C
________ myofilaments have a rod portion and two heads at the end
Myosin myofilaments
It’s takes ~ ______ myosin molecules to create and entire myosin myofilament
~200
The myosin head contains what enzyme ?
ATPase
What does ATPase at the myosin head do?
Breaks down ATP to
ADP and an inorganic phosphate
When ATPase converts ATP–ADP/Phos, it holds on to that E which cocks the myosin head back; it waits for an actin myofilament binding site for what to happen?
Cross bridge and power stroke (=muscle contraction)
In SKELETAL muscle, Each myofibril is composed of about ______ myosin myofilaments and about ________ actin myofilaments; so ration of Actin:Myson is ______.
1500 myosin myofilaments
3000 actin myofilaments
Ratio of actin:myosin = 2:1
What is the ratio of actin:myosin in SMOOTH muscle?
5-10 : 1
Where the somatic lower motor neuron approaches the sarcolemma of the muscle fiber
Neuromuscular synapse
At the terminal buton of the neuromuscular synapse, the synaptic vesicles in the presynaptic terminal contain _____ (NT)
Ach
AP’s travel through the axoplasm. TRUE/FALSE.
FALSE
AP travel along membrane of the somatic motor neuron
AP travel along the membrane, not the axoplasm, via ___________ conduction
Saltatory
When an impulse reaches the terminal portion of the axon, it opens voltage gated ______ channels.
Calcium channels
When v-g Ca channels are opened, Ca moves with its electrochemical gradient from outside to inside the axon, and floods the axoplasm; what happens next?
Calcium dependent exocytosis of Ach into the NM synapse
At the NM synapse, Ach moves across the synaptic cleft and binds with ________ receptors which are Ach-gated _________ channels
Binds with nicotinic type I receptors
N-1 are Ach-gated SODIUM channels
At the NM synapse when Ach gated Na channels open, Na moves with its gradient from the ________ to the ________ and brings RMP to TP
From the synaptic cleft to the muscle fiber
The AP in the muscle fiber at the synapse spreads ____________, in both directions along the _________ of the muscle fiber
Bidirectionally
Sarcolemma
How is Ach removed from N-1 receptors?
Acetylcholinesterase
Where is AchE found?
Inside the synaptic cleft
AchE breaks Ach down into what two things?
Acetic acid
Choline
Transported out of the synaptic cleft and into the blood to be metabolized by the liver
Acetic acid
__________ is taken back up into the presynaptic terminal, binds with more ___________ to form Ach, which is repackaged and used again.
Choline
Acetic acid
Area between the sarcoplasmic reticulum and the T tubule
Terminal cisterna
As AP travels along the membrane, it is also conducted through the transverse tubule, which is also transmitted through the sarcoplasmic reticulum (SR), this opens up voltage gated _________ channels in the SR.
V-g calcium channels
When V-g Ca channels are open in the SR, Ca moves from the SR to the ____________ and floods it with Ca ions
Sarcoplasm
When Ca floods the sarcoplasm, troponin ______ is attracted to the Ca ions
Troponin C
When troponin C is attracted to Ca ions, it pulls troponin _____ with it, which is on the tropomyosin, uncovering what?
Troponin T
Uncovers the binding sites for the myosin heads
As soon as troponin T is pulled away, the ________ heads are waiting and they cross bridge and Powerstroke, pulling the ________ myofilaments in towards the sarcomere, shortening it.
Myosin heads
Actin myofilaments
As the sarcomere shortens, the myofibrils shorten, muscle cells shorten, fasciculi shorten,a no the over all muscle group shorts, the is …
Skeletal muscle contraction
Most of the calcium for skeletal muscle contraction comes from where?
Inside the cell, in the SR
Most of the calcium for smooth muscle contraction comes from where?
Outside the cell
What happens as soon as the myosin head powerstrokes and brings actin in?
Cleaves another ATP, holds on to the E, releases and comes back out for another crossbridge and powerstroke
In order for skeletal muscle to relax, Ach must be removed from N-1 receptors by AchE. TRUE/FALSE
TRUE
IN order for relaxation following contraction, there has to be removal of _________ ions from the sarcoplasm
Calcium
Ca is actively pumped back out of the cell via _________
ATP-mediated Ca pumps
Where is calcium pumped out to from the sarcoplasm (2)?
SR
Extracellular fluid
When Ca molecules are removed, Troponin C starts to move back down, And Troponin T falls back down over what?
Binding sites on actin myofilaments
Muscle fiber relaxation lasts until the next ________ from a somatic motor neuron.
Impulse
Initial stimulus from somatic motor neuron must cause sarcolemma to move from RMP to TP for AP to occur; subthreshold stimulus will NOT lead to contraction; suprathreshold stimulus will not cause greater strength of contraction
All or nothing concept
What controls strength of contraction?
The brain
voluntary movement from somatic motor NS
________ stretch on the muscle fiber before contraction occurs leads to optimal strength/length of contraction
Optimal stretch
_________stretch of the muscle fiber before contraction, actin myofilaments overlap and leads to suboptimal strength/length of contraction
Understretch
________stretch on muscle fiber, actin is pulled away from myosin, and leads to suboptimal length/strength of contraction
Overstretch
Decreased muscle size r.t. Decrease size of individual sarcomeres, primarily related to decreased amount of proteins in actin and myosin myofilaments (not a decrease in #)
Atrophy
Increased muscle size r.t increased size of sarcomeres, primarily related to increased proteins in actin and myosin myofilaments (not an increase in #)
Hypertrophy
Increase in number of muscle fibers; rarely or minimally occurs even with extreme exercise and muscle conditioning
Hyperplasia
Skeletal muscle MUST have constant supply of ______ for contraction.
ATP
What 3 things do we need ATP for in skeletal muscle contraction?
Phosphorylation of myosin heads
Ca pumps to get Ca out of sarcoplasm
Na-K pumps to maintain Na and K conc, osm, volume, and MP
Free ATP in the sarcoplasm gives ________ sec of E
1-2 sec
Phosphocreatine gives _______ sec of E.
5-8 sec of E
What is phosphocreatine?
Extra ATP in the muscle fiber that attaches to creatine
When the E is needed, phosphocreatine can be enzymatically split into high E phosphate to convert ADP to ________ and __________.
ATP
Creatinine
Moves into the blood, transported to kidneys, and excreted in the urine; byproduct of phosphocreatine
Creatinine
Enzyme that generates phosphocreatine and breaks it down into E and creatinine
Creatinine phosphokinase
CPK
Glycogenolysis of glycogen stored in skeletal muscle fibers generates _____ min of E
1 min of E
Outcome of glycogenolysis of glycogen is ________ which undergoes glycolysis for ATP production.
G-6-P
Most of the E (95%) for skeletal muscle contraction comes from ____________ metabolism; extracellular sources.
Oxidative
Extracellular glucose crosses muscle cell membrane and undergoes oxidative metabolism; where does this glucose come from? (4)
Glucose already in blood
Hepatic glycogenolysis
Fats/lipids/triglycerides/fatty acids
Gluconeogenesis of proteins/AA
Succinylcholine binds with _________ receptors
N-1
Sux binds with N-1 receptors and activates them, opens _____ channels and _____ diffuses into the cell and causes depolarization, which causes _________.
Na channels
Na diffuses in
Fasciculations
Depolarization lasts ______ min because sux is not metabolized by AchE; this leaves the N-1 receptor in the _________ state
3-5 min
Depolarized state
How is sux metabolized?
Psuedocholinesterases
Or
Plasma cholinesterases
NDNMB bind with ________ receptors and competitively block them.
N-1
With NDNMB, sites are blocked, Ach cannot attach to N-1 receptors and _______ can not occur, so there is not muscle contraction and the pt is paralyzed
Depolarization does not occur
Contains multi unit and single-unit muscles
Smooth muscle
Contains many discrete smooth muscle fibers that contract independently of each other
Multiunit smooth muscle
Examples of multiunit smooth muscle (3)
Ciliary muscle of eye
Iris of eye
Piloerector muscles
Hundreds-thousands smooth muscle fibers that form a unit and contract together as a single unit
Single-unit smooth muscle
Examples of single unit smooth muscle; most smooth muscle fibers
GI tract Bile ducts Ureters Uterus Blood vessels Others
Smooth muscle has striations, just lighter in color. TRUE/FALSE.
FALSE
NOT striated
Smooth muscle fibers tend to be multinucleated. TRUE/FALSE
FALSE
MONOnucleated
In smooth muscle, actin filaments are attached to ________
Dense bodies
Smooth muscle contains NO: sarcomeres, tropomyosin or troponin. TRUE/FALSE
TRUE
Dense bodies attach to eachother and forms a _______ which allows for the free flow of ions from one muscle fiber to another.
Gap junction
AP can spread through dense bodies and gap Jxns, therefore smooth muscle fibers do NOT need individual muscle fibers to be innervated. TRUE/FALSE
TRUE
SMOOTH/SKELETAL
Innervation: every fiber; somatic motor NS
Skeletal
SKELETAL OR SMOOTH
Innervation: ANS and may be excited or inhibited by NT’s, hormones, chemicals, stretch, and other factors
Smooth
SMOOTH/SKELETAL
Striated, actin attached to Z-disks, tropomyosin and troponin
Skeletal
SKELETAL OR SMOOTH
Actin: myosin ratio 2:1
Skeletal
Smooth muscle activation from AP ~ _____ %; activation by other mechanisms ~_____%
~50%
~50%
SKELETAL OR SMOOTH
Actin attached to dense bodies, gap jxns, actin: myosin ratio of 5-10:1, NO tropomyosin/troponin
Smooth
SKELETAL OR SMOOTH
Require ATP and Ca for contraction
BOTH
SKELETAL OR SMOOTH
Most Ca from SR
Skeletal
SKELETAL OR SMOOTH
Some Ca from SR, but most from EC fluid
Smooth
_______ muscle is very sensitive to changes in EC Ca
Smooth
AP about _____ ms in skeletal muscle
0.2 ms
SKELETAL OR SMOOTH
Long AP
Smooth muscle
SKELETAL OR SMOOTH
Rapid contraction–relaxation
Skeletal
Slow, sustained contraction— mins, hours, or days; refers to ________ mechanism of __________ muscle
Latch mechanism
Smooth muscle
Because of the latch mechanism, less _____ is required for sustained contraction in smooth muscle
ATP
SKELETAL OR SMOOTH
Requires constant ATP for each contraction
Skeletal
When stress/stretch placed on smooth muscle it reflexively relaxes, this is what type of response?
Stress-relaxation response
SKELETAL OR SMOOTH
Greater maximal force of contraction
Smooth
SKELETAL OR SMOOTH
Greater percent of shortening of fibers: ~3/4 of stretched length
Smooth
SKELETAL OR SMOOTH
Shortening of fibers during contraction: ~1/3 of stretched length
Skeletal
Smooth muscle contraction is a G-protein activated mechanism. TRUE/FALSE
TRUE
In smooth muscle contraction, after G-protein is activated Alpha subunit breaks off and _____ is replaced with ______ to make a new complex.
GDP replaced with GTP
The alpha-GTP complex binds to ______ channels in the smooth muscle membrane
Calcium channels
After Ca channels are open, Ca moves from ______ compartment to the _______
Ca moves from EC compartment to the smooth muscle fiber
After Ca enters the smooth muscle fiber, the Ca ions bind to and activate the protein _________
Calmodulin
Calmodulin activates __________ which cleaves an ATP and breaks it down into ADP and an inorganic phosphate, adding E to the myosin head.
Myosin kinase
When the myosin head is energized in smooth muscle, it can immediately crossbridge and powerstroke. TRUE/FALSE
TRUE
This dephosphorilates the myosin head in smooth muscle, releasing it from actin and entering relaxed state
Myosin phophatase
Type of receptors that NE and epi bind to
Alpha-1
Beta-2
Receptors that lead to vascular smooth muscle contraction
Alpha-1
Selective vascular smooth muscle relaxation; bronchiolar smooth muscle relaxation; some GI smooth muscle relaxation (receptor)
Beta-2
What are the effects of Ach on muscarinic receptors?
Selective vascular smooth muscle relaxation (coronary arteries)
GI smooth muscle contraction
Effect of angiotensin II
(Profound) Vascular smooth muscle contraction
Effects of vasopressin at V-1 receptors
Vascular smooth muscle contraction; intense vasoconstriction
Allows for uterine smooth muscle contraction; mammary duct smooth muscle contraction = milk expression
Oxytocin
Effect of serotonin on vascular smooth muscle
Contraction
Why dont we use serotonin for vasoactive drug?
Neuro side effects
Effects of histamine at H-1 receptors
Vascular smooth muscle relaxation
Bronchiolar smooth muscle contraction
_____ oxygen = vasodilation
Decreased
________ CO2 = vasodilation
Increased
________ H+/_____ pH= vasodilation
Increased H+
Decreased pH
________ calcium = vasodilation
Decreased
________ K+ = vasodilation
Increased K
________ temperature = vasodilation
Increased
Presence of adenosine and lactate would cause vasodilation. TRUE/FALSE
TRUE
