Micro anatomy of muscle Flashcards
What serves as attachment for actin myofilaments
Z disk
What is a z disk
Filamentous network of protein
Describe the beginning and end point of the I band
From the end of one myosin to the beginning of the next
A bands are the length of the
Myosin myofilament from end to end
Describe the H zone
A portion of the a band where actin and myosin don’t overlap
What denotes the middle of the h zone and is the delicate filaments that hold what in place
M line holds myosin myofilaments in place
Which section of the sarcomere contains only actin?
I band
The A band contains
The actin and myosin overlap
Where would you find only myosin?
H zone
Titin filaments
Elastic chains of amino acids
What is responsible for making muscles extensible and elastic
Titin filaments
A ______ is an axon terminal resting in an invagination of the ________
Synapse – sarcolemma
Name the three components of a neuromuscular junction
Presynaptic terminal
Synaptic cleft
Post synaptic membrane
An axon terminal with presynaptic vesicles is called
Presynaptic terminal
The space between the presynaptic terminal and the post synaptic membrane is called
Synaptic cleft
The post synaptic membrane is aka
Motor end plate
______ in the presynaptic terminal form and release the neurotransmitter _______
Synaptic vesicles
Acetylcholine (Ach)
A degrading enzyme in the synaptic cleft is
Acetylchoninesterase
How does the sliding filament model work?
Actin and myosin don’t shorten, the sarcomeres do=skeletal muscle cntx
Actin myofilaments slide over the myosin to shorten sarcomeres
Sarcomeres
Z disk to z disk
During relaxation, what causes the sarcomeres to lengthen
Some external force like cntx of antagonistic muscles
How does the nervous system control the muscle cntx
Action potentials and release of neurotransmitter chemical
Describe resting membrane potential
Because more + charged particles exist immediately outside the cell membrane and more - charged particles exist immediately inside the cell membrane, there is a voltage difference btwn the inside and outside of the membrane
What is the resting membrane potential of skeletal muscle cells
~-85 mV
What are the types of ion channels
Ligand gated and voltage gated
The neurotransmitter chemical binds to what type of receptor
Ach (acetylcholine) binds to ligand-gated ion channels
What causes voltage-gated Na+ channels to open
Small voltage changes across the plasma membrane
name the 7 functions of the muscle system
maintenance of posture heart beat movement respiration production of body heat communication constriction of organs and vessels
what are the four properties of muscle
contractability
excitabiltity
extensibility
elasticity
describe muscle elasticity
the ability to stretch and recoil to its original resting length
describe muscle excitability
capacity to respond to stimulus
describe contractility
ability of muscle to shorten
describe extensibility
muscle can be stretched to its normal resting length and beyond to a limited degree
what is a muscle fiber?
a muscle cell
what is the connective tissue that surrounds individual muscles and groups of muscles
muscular fascia
deep to the fascia is a layer of connective tissue called the
epimyseum
a muscle is composed of numerous visible bundles of _____ called _____ which are surrounded by a layer of connective tissue called _____
fibers
fasciculi
perimyseum
an _______ and 1 or 2 _______ extend together with a ______ through the connective tissue layers of skeletal muscles
artery
veins
neuron
what supplies blood to and surrounds the muscle fibers?
capillary beds
what types of multinucleated cells produe muscle fibers
myoblasts
hypertrophy
enlargement of muscles after birth in children and adults
the plasma membrane of the muscle fiber
sarcolemma
what is the superior layer of the sarcolemma called?
endomysium
transverse tubules
t tubules, invaginations of the sarcolemma
myofibril
bundles of myofilaments that extend from one end of the muscle fiber to the other
