Myology Flashcards
what are the functions of the muscular system
locomotion
vasoconstriction and vasodilation
peristalsis
cardiac motion
posture maintenance
heat generation
stabilize joints
vasoconstriction and vasodilation
constriction and dilation of blood vessel walls are the results of smooth muscle contraction
peristalsis
wavelike motion along digestive tract produced by the smooth muscle
posture maintenance
contraction of skeletal muscles maintains the body posture and muscle tone
heat generation
75% ATP energy used in muscle contraction is released as heat
stabilise joints
even as they pull on bones to cause movement they strengthen and stabilise the joints of the skeleton
properties of skeletal, cardiac and smooth muscles
striation
nucleus
transverse tubule
intercalated disk
control
striation
only present in skeletal and cardiac uscles
absent in smooth
nucleus
smooth and cardia are uni-nucleated
skeletal are multi-nucleated
transverse tubule
well developed in skeletal and cardiac muscles to transport calcium
absent in smooth muscle
intercalated disk
specialised intercellular junction that only occurs in cardiac muscle
control
skeletal muscle is always under voluntary control
some exceptions such as tongue and pili arrector
smooth and cardiac are under involuntary control
describe skeletal muscle
describe cardiac muscle
describe smooth muscle
components of muscles
epimysium
muscle fascicle
muscle fibre
myofibrils
sarcolemma
sarcoplasm
sarcoplasmic reticuluum
epimysium
outer layer of connective tissue covering an entire muscle
muscle fascicle
bundle fo skeletal muscle fibres surrounded by perimysium
muscle fibre
surrounded by a thin layer of connective tissue the endomysium
contains several hundred to thousand myofibrils
myofibrils
composed of myofilaments (actin and myosin)
sarcolemma
thin membrane enclosing skeletal muscle fibre
sarcoplasm
intracellular fluid between myofibrils
sarcoplasmic reticulum
specialised endoplasmic reticulum of skeletal muscle
what is the triad and what is it composed of
each t tubule runs between pair of sacs formed by sarcoplasmic reticulum fusion
terminal cistern
can act as conduit for action potentials but no direct connection
myofibril structure
composed of actin and myosin
light bands are only actin, I bands, isotropic to polarised light
dark bands are myosin filaments and ends of actin filaments, A bands, anisotropic to polarised light
2 different bands
I and A
which are light and dark respectively
light bands
I bands
only actin filaments
isotropic to polarised light
dark bands
A bands
myosin filaments and ends of actin filaments
anisotropic to polarised light
what is a Z disk
filamentous protein
segment of myofibril between 2 successive Z disks is called what
sarcomere
what is Titin
filamentous molecule to keep myosin and actin filaments in place
what is a myofibril comprised of
actin and myosin
what is an actin filament composed of
actin
troponin
tropomyosin
structure of an actin filament
backbone of actin is double stranded F-actin protein
2 strands wound in helix
each strand of F is composed of G actin molecules
one ADP attached per one G-actin
ADP believed to be active sites
bases of actin filaments inserted into the Z disks
label the image
tropomyosin
another protein component of actin filament
wrapped spirally around sides of F-actin
lies on active sites of actin strands
what does troponin have
3 subunits
T,I and C
troponin T
strong affinity for tropomyosin
troponin I
strong affinity for actin (inhibition)
troponin C
strong affinity for calcium ion
myosin structure
2 heavy chains and 4 light chains
2 heay wrap around to form double helix, called tail
end of each is folded bilaterally into globular polypeptide called myosin head
light chains help function during muscle contraction
label the image
2 main types of synapses
chemical
electrical
chemical synapses
synaptic cleft
neurotransmitters
skeletal muscles
electrical synapses
gap junction
cardiac ventricular muscle in the uterus and in the bladder
which type of synapse is this
chemical
which type of synapse is this
electrical
which type of synapse is this
electrical
nerve excitation process
Action potentials are propagated down the motoneuron
Calcium entry into the presynaptic terminus
Release of Ach from synaptic vesicles, diffusion across synaptic cleft and binding with post-synaptic receptors
ACh diffuses across the synaptic cleft to the postsynaptic membrane. This specialized region of the muscle fibre is called the motor end plate, which contains nicotinic receptors for ACh
Opening of Na+ /K+ channels on post-synaptic membrane
Postsynaptic membrane depolarization (End Plate Potential)
Ach breakdown via acetyl cholinesterase
label the image of the synthesis and degradation of acetylcholine
