Muscle development Flashcards
Muscle development derived from?
paraxial mesoderm
Head muscles are formed by?
7 somitomeres
axial skeleton/abdomen body/limbs are composed of?
somites
Which molecule determines whether their is muscle differentiation or not?
BMP4
BMP4 molecule gives rise to which molecules?
MyoD and MyF5
What are the key structures of embryo development in charge of creating muscles?
dorsomedial muscle cells and ventrolateral muscle cells
What are some muscle development conditions?
poland sequence
muscle dystrophies(x-linked recessive) (dystrophin gene mutation)
What are the 3 types of muscle tissue?
- smooth
- cardiac
3.skeletal
What is the histological hallmark of cardiac muscle cells?
having intercalated discs
How many muscles are in the human body approx.?
640
Which is the smallest muscle in the human body?
stapedius
Which is the longest muscle in the human body?
sartorius
What is the sarcomere reffered to?
functional unit of the skeletal muscle
Myofibrils are the ones that…..?
produce the contraction
Which is the thin filament?
actin
Which is the thick filament?
myosin
What are the 2 proteins that maintains the skeletal arquitecture?
titin and nebulin
Which elastic protein holds myosin in place?
titin
Which elastic protein aligns actin?
nebulin
Thin filament(actin) is formed by the juncture of 3 molecules?
1.troponin
2.tropomyosin
3.G-actin
Troponin has 3 subunits?
T=has affinity to tropomyosin
I=has affinity to actin
C=has affinity to Ca+
Action potential travels along which type of neuron?
efferent neurons because are the ones that get to the effector site to produce a action
End Plate potential?
when ach released from NMJ enters muscle fiber and allows NA+,K+,Ca+ ions to enter causing fiber to produce ion modulated action potential
Dystrophin
-located on the plasma membrane of the muscle fibers
-glycoprotein
-provides mechanical reinforcement to sarcolemma
-if not present, will be digested by proteases
-loss of dystrophin can cause degeneration of muscle fibers thus causing muscle weakness
-Causes Muscle dystrophies(x-linked recessesive)
What are the dystrophinopathies called?
Becker and Duchenne
What is dystrophinopathies?
-mutation in dystrophinin gene
-leads to muscle dystrophies
-main symptom is WEAKNESS(due to degeneration of the muscle fibers)
Tubacurarine
blocks ACh release thus can not generate action potential
Toxin
reduces ACh release thus becomes too weak to generate an action potential
Which is the molecule that act as a Ca+ buffer in the sarcoplasmic reticulum? (molecule that holds excess Ca+)
calsequestrin
Ca+ will bind to _____________ and ___________ thus __________ binding sites
tropomyosin and troponin
unblocking
Each cross-bridge cycle(contraction) “walks” myosin head, how many nanometers?
10 nanometers along the actin filament
Muscles ALWAYS _____________________?
PULL
Heavier the weight= __________ muscle fiber shortens, _________ duration of contraction, ___________ speed of contraction
less shortens
less duration
slower speed
Lighter the weight= __________ muscle fiber shortens, _________ duration of contraction, ___________ speed of contraction
more shortens
more duration
faster speed
Isotonic
-movement
-muscle contracts and shortens(thus allowing movement)
Isometric
-NO movement
-muscle contracts BUT does nor shorten (thus not allowing movement)
Toxin of tetanus?
tetanospasmin
Fast reacting muscles, have …….
more neuronal tissue than muscle tissue
Slow reacting muscles, have…….
more muscle tissue than neuronal tissue
tetanization
continous contraction that cannot return to resting state
