Chapter 8- Skeletal Muscle Mechanism Flashcards
How do filaments on smooth muscle differ from filaments on skeletal?
a. They contain 2 M-lines
b. they cannot bind to actin sites
c. they do not have troponin
d. all the above
c.
Trypomyosin does not block actin from binding
True/False
true
The thick filaments of smooth muscle contain…
a. calmodulin
b. light chain kinase
c. PTSD
d. all above
b
**
Describe how contraction is regulated in smooth muscle
Ca+ activates calmoduin changing it to a bent conformation. This allows the bent calmoduin to bind and activate myosin light chain kinase. The kinase phosphoralates the light chain on myosin which activates myosin to bind to actin. If there is no Ca+ then no phosphorilation and therefore no myosin binding.
Smooth muscles don’t have T-tubules.
True/False
True
Where do V-gated Ca++ channels reside in smooth muscle?
a. T-tubules
b. Sacromeres
c. Plasma membrane
d. Sarcoplasmic reticulum
c.
When Ca++ binds to and opens Ca++ gated ryandine receptors
a. SERCA
b. CICR
c. Tonic SM
d. MLCK
b
Lable the steps of Ca++ regulation in order
Calcium enters the cell
Ca++ binds to ryandine receptors
Depolarization
Ca++ released from S.R.
V-gated Ca++ channels open
G-protien coupled receptors activate
IP3-gated channels on S.R. open
GPCR’s release IP3 messagers
3
5
1
4
2
6
8
7
What pumps Ca++ back into the S.R. in smooth and skeletal muscle?
SERCA Pump
What are the 2 types of smooth muscle?
multi-unit and single-unit
List the characteristics of single unit smooth muscle
- Contain gap junctions
- only some of the cells recieve direct neural signals
- found in the intestines
List the characteristics of multi-unit smooth muscle.
- found in the eye
- individual cells recieve drect neural signals
- contracts independantly
Which of the following means a cell is capable of initiating it’s own contration?
a. Myogenic
b. CIRC
c. Ryanocidic
d. Miogenic
a.
What are the 2 types of myogenic excitation potentials?
pacemaker and slow-wave
Slow wave potential is only seen in ….
a. Skeletal muscle
b. The digestive tract
c. Smooth muscle
d. A and B
b.
Draw slow-wave potential triggering an action potential
Week 6 slide 2
The smooth muscle alternates between depolarization and repolarizations
____ can nudge the starting Vm so that slow-wave may reach threshold
a. peptides
b. hormones
c. nucleotides
d. Ca++
b.
How is smooth muscle well suited for long-term contraction?
a. it consumes less ATP
b. it has slow removal of Ca++
c. troponin doesn’t cross bridge
d. A and B
d.
How is smooth musc. suited for moving contents through hollow organs
a. consumes less ATP
b. exerts tesion even when stretched
c. it’s striated with gap junctions
d. it contains a sliding filament system
b.
List the 5 features of Cardiac Muscle
- excitable cells
- striated with gap junctions
- sliding filament system
- involantary movement
- Ca++ release via CICR
The gap junctions found in skeletal and cardiac musc. are the same
true/false
False
cardiac muscles have T-tubules
true/false
true
Describe Cardiac Ca++ release
week 6 slide 5
T-tubules contain many voltage gated Ca++ channels which open when the AP is triggered. This is however, not enough to cause contraction so the Ca++ binds to a Ryandine receptor inside the muscle cell. This triggers a Ca++ release from the SR which is enough to trigger AP
Cardiac musc. fibers do not extend the length of the entire muscle
true/false
true
Describe the structure of cardiac muscle
They are branched and cnnected by intercalated disks. The boundy of the cell is at the disks.
(——) attach muscle to bones
a. ligaments.
b. Tendons.
c. Muscle fiber.
d. all above.
b
series elastic component involves…
a. tension generated by sacromeres and transmitted to bone by tendon.
b. contraction is generated by muscle fibers after signaling to the motor end plate.
c. an external load is pulled by tendons and stretched across a joint.
d. a and c
a
muscles push never pull
true/false
false
what are the 3 types of contraction?
- isotonic
- isokinetic
- isometric
Match the definations to thier type of contraction
Load is constant, muscle length changes
velocity is constant, muscle length changes
length is constant, tesion increase
- isotonic
- isokinetic
- isometric
varying amount of force generated in a whole muscle
a. tension
b. tetanus
c. graded contration
d. fatigue
c
what are the two primary factors that influence force generation?
- # of muscle fibers
- Tension developed by each fiber
List the factors that influence muscle tension
- frequency of stimulation
- Resistance to fatigue.
- Length of fiber at onset of contraction
- Thickness of the fiber.
Draw a single twitch
question 9 notebook
Draw what twitch summation looks like on a graph
week 5 slide 27
all fibers associated with a single motor neuron
a. Muscle unit.
b. Motor unit.
c. Neural unit.
d. None of the above.
b
which of the following best describes the relationship between muscle fibers and motor neurons
a. Each motor neuron only innervates one muscle fiber.
b. Each motor neuron branches to one motor neuron.
c. Each motor neuron innervates many muscle fibers, but can choose to contract a certain number.
d. Each motor neuron contracts, all associated fibers.
d
strength of contraction is determined by (——–)
a. Size of load.
b. Number of motor units recruited
c. Size of the muscle fiber.
d. Number of motor neurons.
b
which of the following vary from contraction to contraction?
a. frequency of stimulation.
b. Resistance to fatigue.
c. Thickness of fiber.
d. Size of load.
e. a and d
a
smooth sustained contraction at maximal strength due to rapid stimulation
a. tetanus
b. Twitch summation.
c. Tension.
d. Fatigue
a
Draw Tetanus
question 16 in notebook
why is it not ideal for muscle fibers to be longer?
a. Thin filaments, overlap, interfering with cross bridge.
b. Actin sites are pulled away from myosin.
c. Maximum Crossbridge generates maximum tension.
d. b and c
b
what two factors that influence muscle tension are constant?
resistance to fatigue and fiber thickness
which four steps in contraction use ATP?
- Power stroke.
- Cross bridge.
- SERCA
- Na/K pump
The ATP supply comes from
a. Hydrolysis.
b. Glycolysis.
c. My light chain.
d. All of the above.
b
which is not a pathway that supplies ATP to muscle muscles
a. Creatine phosphorylation.
b. Glycolysis.
c. Oxidative phosphorylation.
d. Oxygen hydrolysis.
d
you are a sprinter about to run a race. Once you start, where does your energy mostly come from?
a. Glycolysis.
b. Oxidative phosphorylation.
c. Creatine phosphorylation.
d. all of the above
c
Creatine acts as a (——-)?
storage molecules
In an aerobic enviorment which of the following occur?
a. glycolysis
b. ox-phos
c. creatine phos
d. all of the above
b
Which ATP source wold be utilized most on a long walk?
oxidative phosphorylation
Lable each characteristic as Glycolysis (G), Ox-phos (O), or Creatine phos (CP)
- 1st source of ATP
- anaerobic
- aerobic
- susbstitutes ox-phos
- used in long term exercise
- only works in presence of glucose
- used in short, high intensive activity
- fueled by glucose/fatty acids
- slowest
- storage for O2
- shortest duration
- CP
- G
- O
- G
- O
- G
- CP
- O
- O
- CP
- G
occurs when the muscle can no longer respond to stimuli with the same amount of contration
a. tetanus
b. fatigue
c. frequency
d. graded contraction
b
list the 3 main factors that contribute to muscle fatigue
- local increase in inorganic phosphate
- leakage of Ca+ out of the cell
- depletion of glycogen stores
a motor unit can be composed of 2 or more types of fibers
true/false
false
motor units have the ability to interconvert between fiber types
true/false
true
list the 3 major types of muscle fibers
- slow-oxidative
- fast oxidative
- fast glycolytic
which of the following use oxidation as it’s ATP source?
a. type I fibers
b. type IIa fibers
c. type IIx fibers
d. a and c
b
which of the skeletal muscle fiber types use glycolysis as their ATP source?
type IIx fibers
fast fibers have lower myosin ATPase activity than slow
true/false
false
which is not a factor that influences the speed of contraction?
a. size of load
b. atp source utilized
c. type of fiber
d. none of the above
d
how does myosin ATPase influence the speed of contraction?
the faster is can reset the faster cross bridging can re-trigger
label whether each characteristic belongs to oxidative fibers or glycolitic fibers?
- few mitochondria
- glycogen stores
- lots of myoglobulin
- lots of glycolytic enzymes
- lots of mitochondria
- lots of capillaries
- GF
- GF
- OF
- GF
- OF
- OF
Which types of muscles are involuntary?
unstriated and cardiac
smooth muscle is regulated by the sympathetic nervous system
true/fasle
f
smooth muscle is striated
true/false
f
smooth muscle uses myosin, actin, trypomyosin, and troponin
true/false
f
smooth muscle releases Ca+ using multiple mechanisms
true/false
t
list some places where smooth muscle is found
blood vessels, airways, eyes, uterus, stomach
why doesnt smooth cells appear striated?
they have no sacromeres
describe the structure of smooth muscle cells
question 45
