smooth muscle

Question 1

what are the characteristics of smooth muscle?

Answer 1

• fusiform cells
• one nucleus per cell
• nonstraited
  -involontary
  slow - wave-like contractions

Question 2

whats the characteristics of a smooth muscle?

Answer 2

• (NOT STRIATED) spindle-shaped cells with a single central nucleus
• no sarcomere
• found in walls of hollow organs, blood vessels, eye, gland, uterus, skin
• involuntary
• AUTOMATIC
• GAP JUNCTIONS
• no striations (not arrange in the sarcosome patterns=
• dense bodies instead of a Z-disks
• NO TUBULES

Question 3

what is the function of sarcosome reticulum in a smooth muscle?

Answer 3

-poorly developed (ca++ comes from ECF (extracellular fluid)
-fewer mitochondria compared to skeleton muscle
The cell has 3 types of filament:
-Thick MYOSIN filament - longer than those in a skeleton muscle
-Thin ACTIN filaments (contain tropomyosin but NO troponin)
- Intermediate filament
* do not directly participate in contractions
*form part of the cytoskeletal framework supports the cell

contraction regulatory protein = calmodulin (CaM)

Question 4

what are the 2 classifications of smooth muscle?

Answer 4

Multi-unit smooth muscle
- neurogenic

single-unit smooth muscle
- myogenic

Question 5

which nervous system controls the smooth muscle

Answer 5

autonomic

Question 6

where are multiunit smooth muscle found?

Answer 6

neurogenic worksytrough nervosu stimuli (autonomic N.S)

• in the wallsof large vessels
  -large airways to lungs
  -ciliary muscle of the eyethat adjust lens for near or far vision
  irirs of the eye
• pilo-erectormuscle

Question 7

where is singleunit smooth muscle found?

Answer 7

myogenic, autoexitable CAN CONTRACT SPONTANEOUSLY ( not requier nervous stimulation to contract) also called visceral muscle (assosiaded with internal organs)
- syncytium ( togheter)
- slow contraction - energy efficent
-found in wall if gastrointestinal(GIT)
large blood wessles
ureter, bile duct and uterus

Question 8

what is the membrane potential in multiunit smooth muscle)

Answer 8

action potential is not produced.

only localized depolaryization in respone to excitation

Question 9

what are´the membrane potential in singleunit smooth muscle (myogenic)

Answer 9

spike potential
action potential with plateau
spikes (nervinpuls) superimposed ( placed over one of another) on slow wave