7: Histology - bone structure, core MSK Flashcards
Skeletal muscle cells are (striated / unstriated).
striated
Skeletal muscle cells are (branched / unbranched).
unbranched
very long and tubular, myocytes span the entire length of the muscle
How many nuclei do skeletal muscle cells have?
Hundreds - tens of thousands
In skeletal muscle cells, nuclei are found at the (centre / periphery) of the cell.
periphery
(In cardiac muscle, single nuclei at the centre.)
What is the plasma membrane of skeletal muscle cells called?
Sarcolemma
What is the level of organisation one above single muscle fibres?
Fascicles
(bundles of muscle fibres)
A muscle is typically split up into several ___.
fascicles
Connective tissue surrounding the whole muscle is called the ___.
epimysium
Connective tissue surrounding a single fascicle is called the ___.
perimysium
Connective tissue surrounding single muscle fibres is called the ___.
endomysium
Complete:
Skeletal muscle > Fascicles > ____ > ____ > Sarcomeres > Actin and myosin filaments
… Fascicles > Muscle fibres > Myofibrils …
What is the specialised endoplasmic reticulum found in muscle cells?
Sarcoplasmic reticulum
Apart from muscle cells, what do skeletal muscles (as organs) contain?
Blood vessels
Connective tissue
Lymphatic vessels
What are the functional units of muscle?
Sarcomere
Sarcomeres extend from one __ ___ to the next.
Z line
(see Physiology I for the other terms)
To produce contraction, ___ filaments slide along ___ filaments and the Z lines move (closer together / further apart).
myosin , actin
closer together
Why are skeletal muscle cells striated?
Alternating light and dark bands of actin and myosin are in alignment across each myofibril
(There’s nothing continuously running through the cell - optical illusion.)
Myofibrils are held in ___ with one another.
registry
i.e aligned
What is a motor unit?
Alpha motor neuron PLUS all the muscle fibres it supplies
Motor neuron branches synapse with muscle fibres at ___ ___.
neuromuscular junctions
Whether a muscle produces powerful or fine, precision movement depends on the number of ___ ___ in its motor units.
muscle fibres
Which group of muscles has the least number of muscle fibres in its motor units (and therefore the most precise movements)?
Extraocular muscles
Which type of muscle fibres are also known as red fibres?
Type I (slow oxidative / slow-twitch) fibres
Type I muscle fibres depend on ___ metabolism and have lots of ___ and ___.
aerobic
mitochondria , myoglobin
Type I fibres are resistant to ___.
fatigue
Type IIa fibres are both ___ and resistant to ___.
fast , resistant to fatigue
What colour are Type IIb/x fibres?
Why?
White
Less myoglobin as they don’t require oxygen
Type IIb/x fibres use ___ metabolism, so they don’t have a lot of ___.
anaerobic
mitochondria
