Lecture 2.13 Muscles & Nerves

Question 1

What are the features of skeletal muscle?

Answer 1

Voluntary, striated, strong discontinuous contractions, attaches to bone, muscle fibers and giant elongated multinucleate cells with nuclei at the periphery, each muscle fibre same CSA and each bundle wrapped by connective tissue

Question 2

What are the features of cardiac muscle?

Answer 2

Quick continuous involuntary contractions, striations, central nuclei (1-2 per cell), contracts spontaneously, fibres are thick and uniform in CSA, fibres branch and connect up with other fibres

Question 3

What are the features of smooth muscle?

Answer 3

Not striated, spindle shaped cells, central nucleus (cigar shaped), continuous contractions with low force, inherent rhythmic contractility, doesn’t really fatigue, cells differ in CSA, no myofibrils, sarcomeres or t-tubules, corkscrew shaped nucleus when contracted, dense bodies on membrane and in cytoplasm to anchor actin lattice, can contract by 80%

Question 4

What are the features of intercalated discs?

Answer 4

Found in cardiac muscle, desmosomes to reinforce myofibril joints, adherens to anchor actin and gap junctions to spread depolarization

Question 5

What do myoepithelial cells do?

Answer 5

Surround exocrine gland and squeeze out contents

Question 6

What do pericytes do?

Answer 6

Extend around capillaries and regulate blood flow

Question 7

What are the layers surrounding nerves?

Answer 7

Epineurium around nerve, perineurium around fascicles and endoneurium around axons

Question 8

What are schwann cells and nodes of ranvier and are these visible with H&E?

Answer 8

Schwann cells cover axons to form myelin (internodes) and the spaces where the axon is not myelinated are the nodes of ranvier. Myelin isn’t visible with H&E but can be seen with toluidine