MSKS Histology Lecture 2_Nuromuscular Histology

Question 1

Describe the histological charicteristics of smooth muscle including: fiber orientation, number of nuclei, etc.

Answer 1

Question 2

How do smooth muscle cells communicate and what does this allow?

Answer 2

Smooth muscle cells comunicate through gap junctions (remember gap junctions basically make the cytosol of connected cells continuose). This facilites graded contractions because of varying Ca consentrations.

Question 3

Describe the structure of smooth muscle cells.

Answer 3

Thick filliments conect to thin filliments that connect to dense bodies. Dense bodies of one cell couples to the dense bodies of an adjacent cell.

Question 4

Describe the histologic characteristics of the three muscle sub types

Answer 4

Question 5

Of Hypertrophy and Hyperplasia, which method do each tissue subtype use to grow to meet increased demand?

Answer 5

Smooth Muscle: Both

Skeletal muscle: Hypertrophy ( there are some satalite cells that can diferentiate while this is not true hyperplasia it serves the same function of replacing damaged cells)

Cardiac Muscle: Hypertrophy (no satalite cells)

Question 6

What are Leiomyomas

Answer 6

benign tumors that develop from sooth muscle myofibers; typically do not cause problems. When they occur in the uterine wall, they are often called fibroids

Question 7

What embryonic germ-layer gives rise to myoblasts

Answer 7

paraxial mesoderm

Question 8

How is a myofiber formed

Answer 8

Multiple myoblasts fuse and
differentiate to form a single muscle
fiber (myofiber). This is why skeletal muscle is multi nucleated

Question 9

What are the different parts of a Muscle Tendon Unit (MTU)

Answer 9

Question 10

Describe the histology of epimysium, perimysium, and endomysium

Answer 10

Question 11

What kind of connective tissue are tendons?

Answer 11

dense regular CT

Question 12

What do blood vesscles and nerves look like under a light microscope?

Answer 12

Question 13

Describe the formation of a nerve bundle

Answer 13

Note the increased smooth muscle around the artery

Question 14

Describe the 4 contractile filliments of a myofibril

Answer 14

Question 15

Describe the parts of a sarcomere including A band, H zone, M line, Z disk, and I band

Answer 15

Question 16

Describe the function of associated myofibril associated proteins including Titin, α-actinin, Desmin, Dystrophin

Answer 16

Question 17

Describe Sliding Filament Theory

Answer 17

Due to increased overlapping of thin and thick
filaments, the sarcomeres shorten:
• A band remains the same width
• I band decreases in width
• H zone decreases in width