Lecture 14: Muscle 8 Flashcards
Where are smooth muscle cells found
in the walls of hollow organs and tubes.
What roles do smooth muscles play in the cardiovascular systems
-Cardiovascular: Provides control over peripheral distribution of blood and assists in regulating blood pressure
What roles do smooth muscles play in the respiratory systems
-Respiratory: Contraction or relaxation alters the diameters of respiratory passages and changes the resistance of flow
What roles do smooth muscle play in digestive system
Assists in mechanical processing and movement along GI tract
Contraction of smooth muscle in the wall of the gallbladder -> ejection of bile into the digestive tract
What roles do smooth muscles play in the urinary system
- In the walls of the ureters, transports urine to the urinary bladder
- In the walls of the urinary bladder forces urine out of the body
What roles do smooth muscles play in the reproductive system
- In male, moving sperm along the reproductive tract
- In females, for moving ova along reproductive tract and for expelling the fetus from uterus at delivery (parturition)
Two functions of smooth muscle
- To produce motility
2. To maintain tension
Two examples of motility produced by smooth muscle
- Propel chime along GI tract
- Propel urine along ureter
Example of tension maintained by smooth muscle
-In walls of blood vessels
Structural organization of skeletal vs smooth muscle
- Skeletal: Long, elongated, multinucleated. Extends the full length of muscle
- Smooth: Small, spindle shaped with single nucleus. Groups of muscle cells are arranged in sheets rather than extending full length of muscle
What muscle types are actin and myosin present in?
Both smooth and skeletal
Do smooth muscle fibers form myofibrils? Are they organized into sarcomeres?
No and no
Do smooth muscles have Z lines?
No
Location of dense bodies
Distributed throughout the sarcoplasm in a network of intermediate filaments, some firmly attached to the sarcolema
Purpose of dense bodies and intermediate filaments
Anchor the thin filaments so when sliding occurs between thick and then, the cell shortens and bulges out between the points where the dense bodies are attached to the sarcolemma
