Skeletal and Smooth Muscle Histology

Question 1

Large, multinucleate cells with nuclei on the periphery of cell
Somatic nervous system
20-100 micron diameter

Answer 1

striated skeletal muscle fiber

Question 2

small, single nucleated cells
nucleus in the middle of the cell
autonomic nervous system
3-20 microns in diameter

Answer 2

smooth muscle cell

Question 3

Shared principles of all muscle types

Answer 3

sliding filament mechanism - myosin filmantes bind to and move actin (shortening)
myosin and actin interactions regulated by calcium
changes in mem potential lead to contraction (EC coupling)

Question 4

changes in membrane potential regulated lead to contraction

Answer 4

Excitation-contraction coupling (EC coupling)

Question 5

Epimysium
Perimysium
Endomysium

All examples of:

Answer 5

DICT (dense irregular connective tissue)

Question 6

Muscle fibers (=cell) are made of

Answer 6

myofibrils

Question 7

Muscle fibers are arranged in bundles can a

Answer 7

fascicle

Question 8

_______ cells are a sort of stem cell that helps repair muscle

Answer 8

Satellite

Question 9

In smooth muscle, thin filaments are diagonally anchored to the plasma membrane by ___________ (analogous to z lines)

Answer 9

dense bodies

Question 10

Smooth muscle filaments are anchored to plasma membrane and ___________ network to actually shorten cell (alpha actinin - in both skeletal and smooth)

Answer 10

intermediate filament

Question 11

In smooth muscle, cycling is controlled by calcium which regulates _________, not actin

Answer 11

myosin

Question 12

Myosin ATPase in smooth muscle is 10-100x _________ than in skeletal muscle

Answer 12

slower

Question 13

In smooth muscle contraction, Ca2+ activates calmodulin, to activate calcium-calmodulin myosin light-chain kinase, which phosphorylates ______________ which forces cross-bridge towards the actin filament, cross bridge cycling then occurs (same process but slower than skeletal) until intracellular calcium decreases and myosin-light chain phosphatase removes phosphate

Answer 13

myosin light chain

Question 14

Smooth muscles cells are responsive to multiple inputs (can cause contraction or relaxation) and therefore has a __________ response

All affect intracellular calcium concentration: 
Spontaneous (pacemaker) -GI
Stretch -arterioles 
Hormones -uterus (oxytocin) 
Autonomic NT
Local changes in ECF

Answer 14

graded

Question 15

Unstable resting membrane potenitals open _____________ resulting in rhythmic patterns of action potentials and contraction in smooth muscle cells with pace-maker activity (GI tract)

Answer 15

Voltage-gates Ca2+ channels

Question 16

Smooth muscle is controlled by ____________ nervous system, and skeletal muscle is controlled by the somatic nervous system

Answer 16

autonomic

Question 17

In single-unit smooth muscle, NTs reach only a few cels. __________ spread the membrane potentials between neighboring cells resulting in synchronous changes in activity

Answer 17

gap junctions

Question 18

Properties of \_\_\_\_\_\_\_\_\_ smooth muscle cells: 
gap junctions 
pacemaker cells 
can be stretch-activated 
In stomach, uterus, small blood vessels

Answer 18

Single-unit

Question 19

In _________ smooth muscle, each cell is innervated. There are few to no gap junctions. These cells are not activated by stretch receptors. Allows for graded responses and fine control.
In large arteries, large airways, muscle for “goose bumps”
Usually has a spectrum of characteristics

Answer 19

Multi-unit

Question 20

If smooth muscle is contracted, the nucleus may have a _________ shape in longitudinal section

Answer 20

corkscrew

Question 21

The effect of nerve stimulation on smooth muscle can be either: excitatory or __________. Skeletal muscle is always excitatory .

Answer 21

inhibitory