Muscles & Nerves Flashcards
What are the three types of muscle?
Skeletal, cardiac, smooth
What do skeletal muscle cells look like histologically?
Nuclei are located peripherally, can see striations in longitudinal section
What do cardiac muscle cells look like histologically?
In cross section look similar to skeletal muscle except nuclei are central, peripherally make a messy network
What do smooth muscle cells look like histologically?
In cross section they are smaller than skeletal or cardiac muscles, longitudinally the nucleus is long thin and drawn out
What are myofibrils?
Myofibrils are the contractile part of the muscle cell, they consist of repeating sarcomeres
What is a sarcomere?
A sarcomere is a section of overlapping actin and myosin from z disc to z disc
What is the mechanism of contraction?
The sliding filament mechanism
What is the sarcoplasmic reticulum?
The sarcoplasmic reticulum is a specialised type of endoplasmic reticulum with lots of calcium ATPases to pump calcium into the cytoplasm
What are T-tubules?
T-tubules take the AP into the muscle cell to the SR - there is two for each sarcomere
Where are the mitochondria in a muscle cell?
Between the myofibrils
What are intercalated discs?
Intercalated discs are like the z-discs for cardiac muscle - they connect muscle cells together via fascia adherentes
How else are cardiac muscles connected?
Via desmosomes between t-tubules and mitochondria and via gap junctions longitudinally between cells
What is the function of gap junctions?
They electrically couple cardiac cells to coordinate action potentials
What structure allows smooth muscle cells to contract?
Smooth muscle cells have ‘dense bodies’ which anchors actin filaments, there is a network of actin and myosin which radiates out and when contracts it pulls the cell in
What are the three types of skeletal muscle?
red (I), intermediate (IIa) and white (IIb)
Which fibres are darkest in a PAS stain (glycogen)?
Type II fibres
Which fibres are darkest in an ATPase stain?
Type II fibres
Which fibres are darkest in a succinate dehydrogenase stain (mitochondria)?
Type I fibres
How does skeletal muscle regenerate?
Satellite cells can convert into skeletal muscle cells
Do cardiac and smooth muscle cells regenerate?
Cardiac no but smooth muscle yes
What are myoepithelial cells?
Myoepithelial cells are contractile cells that are not muscle cells. They surround glands and act to squeeze out contents
What are myofibroblasts?
Myofibroblasts are contractile cells that are not muscle cells. They act to pull wounds closed.
What are pericytes?
Pericytes are contractile cells that are not muscle cells. They are around capillaries and act to regulate blood flow.
Can you see myelin in an H&E stain?
No - need a different stain e.g. toluidine blue
