Smooth muscles

Question 1

aka smooth muscles

Answer 1

• Nonstriated involuntary muscle

Question 2

“Smooth” because cells do not have what under the microscope?

Answer 2

Striped appearance

Question 3

 Large sheets of cells in the walls of some hollow organs

Answer 3

o Visceral smooth muscles

Question 4

 Small, discrete groups of cells

Answer 4

o Multi unit smooth muscles

Question 5

o Small and spindle shaped (tapered at the ends)
o Single nucleus in the center

Answer 5

microscopic anatomy of smooth muscles

Question 6

Small, contractile units of actin and myosin _________ the cell at various angles and attach to ________ of dense bodies that correspond to the _________ of skeletal muscle

Answer 6

crisscross
both ends
Z lines

Question 7

When contractile units shorten, they cause the cells to _________ as it contracts.

Answer 7

ball up

Question 8

Smooth muscles can _________ to a greater extent that skeletal or cardiac muscle cells

Answer 8

shorten

Question 9

o Found in the walls of many intestinal soft organs
o Experience large, rhythmic waves of contraction
o Contracts without the need for external stimulation
o Reacts to stretching by contracting more strongly
o Has a nerve supply that serves to modify contractions (not initiate contractions)
o Consists of sympathetic and parasympathetic divisions of the nervous system

Answer 9

Visceral smooth muscles

Question 10

Where are visceral smooth muscles found?

Answer 10

Stomach, intestine, uterus and bladder

Question 11

Which nervous system effects visceral smooth muscles by:
* Decreases muscle activity
* Prepares an animal for intense physical activity
o Blood is diverted away from the viscera and redirected to the heart, skeletal muscles and brain
 Helps to deal with the “threat”

Answer 11

Sympathetic

Question 12

Which nervous system effects visceral smooth muscles by:
* Increases muscle activity when animal is relaxed
* Predominates and enhances functions such as GI activity to help supply nutrients to the body cells during “down time

Answer 12

 Parasympathetic

Question 13

o Small and delicate
o Made up of individual smooth muscle cells or small groups of cells
o Found where small, delicate contractions are needed
 Iris and ciliary body of the eye, walls of small blood vessels, around small air passageways in the lungs
o Contractions are not automatic – require specific impulses from autonomic nerves to contract
o Specific and carefully controlled

Answer 13

Multi unit smooth muscles