Smooth Muscle Flashcards
What are the length/width of SMCs
20-200μm long, 5-10μm wide
What is the shape of cells/nucleus no & location?
Fusiform and single central nucleus
Do SMCs have sarcomeres and T tubules?
No
How are SMCs arranged?
Forming sheets and bundles or layers containing 1000s of cells
Name 4 areas you would find SMCs
Vascular, Gut, Respiratory, GU
Name 3 pathologies related to SMCs dysfunction
3 of:
Hypertension Dysmenorrhea Asthma Detrusor Muscle Instability Abnormal Gut Motility (IBS) Atherosclerosis
Name 2 types of modified SMCs and what they do
Myoepithelial cells - stellate cells form basketwork around secretory units of some exocrine glands (sweat, salivary, mammary). Also in iris to DILATE pupils
Myofibroblasts - at sites of wound healing, help produce collagen but also contract (have actin and myosin) - wound contraction & tooth eruption
Does SMC need Ca2+? Does it shorten or twist on contraction
Yes and twists
Name 5 things about the contraction of SMCs
1) Innervated by ANS - neurotransmitter into wide synaptic cleft from an ANS varicosity
2) Relies on actin and myosin interactions that are different
3) Slower - less ATP
4) More sustained - Hours/Days
5) Can be stretched (unlike cardiac)
6) Responds to nerves, hormones, drugs, local concentrations of blood gases
Can SMCs regenerate? Give an example
Yes they retain mitotic activity e.g. in pregnant woman uterus hyperplasia and hypertrophy.
Do SMCs respond to hormones?
Yes
How is the release of NT different with SMC compared to cardiac and skeletal?
NA released from varicosities
How is contraction different?
Basketwork of intermediate filaments and dense bodies help to contract by twisting
Which is the one type of muscle cell that retains mitotic activity? Give an example
SMCs e.g. in uterus hyperplasia
