Histology and Physiology of Muscles and Nerves - Skeletal Flashcards
What is the role of muscle cells?
Specialized contractile cells, generate motile forces through contraction
Move body parts or temporarily alter the shape of internal organs
What generates motile forces in muscles?
Motile forces are generated by the interaction of the proteins Actin and Myosin (Contractile proteins)
Name structures A-D
cross section shown
Name the structures in the histogram
A = A band
I = I band
C = capillary
N = nucleus
P = perimysium
Z = Z disc
E = endomysium
S = sarcomere
F = muscle fibre
SC = satellite cell
H = H zone
CT = connective tissue
What is the sarcomere?
A sarcomere is the most basic repeating structural unit of skeletal muscles and occurs between two Z lines of the actin and myosin filaments.
Name components A and B
A = Z disc
B - M line
Name structures A and B
A = I band
B = A band
Name structures A and B
A = thin filament
B = thick filament
Name structures A-C
A = A band
B = Z disk
C = I band
What type of muscle is this and name A and B
Where are the nuclei arranged in skeletal muscle?
Nuclei arranged at the cell periphery
What is contraction controlled by?
motor unit
What does the size of the fasciculi reflect?
function of the muscle
example
Ocular muscles – Small fasciculi & large
supporting tissue
Gluteal muscles– Large fasciculi & little
supporting tissue
What is a neuromuscular junction?
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber
How is each skeletal muscle fibre contracted?
Each skeletal muscle fibre is contacted by a single nerve terminal from a motor neurone
How many muscle fibres does 1 motor neuron contact?
each motor neurone contacts many muscle fibres at motor end plates (= motor unit)
What is Myasthenia Gravis?
autoimmune disorder
NMJ disintigrate
Antibodies produced against acetylcholine receptors
Increased weakening of skeletal muscles
What disease cause weakening of the skeletal muscles?
Myasthenia Gravis
What areas are effcted first by Myasthenia Gravis?
Muscles of the face, eyes and tongue are affected first
Muscles of respiration affects later lead to respiratory insufficiency
What is a motor unit?
The combination of an individual motor neuron and all of the muscle fibers that it innervates
What is shown in this diagram?
motor end plates
What are muscle spindles?
are stretch receptors that signal the length and changes in length of muscles
Tell the brain how much the muscle is stretching or expanding.
regulate muscle tone
What regulated muscle tone?
muscle spindle
Are muscle spindle present in all skeletal muscles?
YES
Where are muscle spindles numerous?
in fine precision movements (intrinsic muscles of the hand)
Name components A and B
What are the 2 types of skeletal muscle?
slow fibres
fast fibres
What are slow fibres?
fatigue resistant
contract for along time
What are fast fibres?
fatigue easily
Decipher what fibre is fast and slow
A = slow
B = fast
What is R and W? (muscle fibres)
What are myofilaments?
Myofilaments are contractile proteins - actin & myosin
What myofilament is thick?
myosin
What myofilament is thin?
actin
What is the repeating pattern myofibrils ?
cross-striations
What creates the striations in skeletal muscle?
Striations are due to the highly ordered arrangement of contractile proteins (electron microscopy)
Name structures A-G
Describe the sliding filament theory
Energy released from ATP
Thick and thin filaments slide over one another
Causing shortening of contractile units – sarcomere – I band almost disappears
Large number of accessory proteins also play a part in filament alignment and regulation of contraction
When ATP is bound to myosin, do the fibres contract?
YES
