cervix
The cervix, or cervix uteri, is the ring of muscle found at the base of the uterus.
Nothing. The anus is the opening of the digestive tract. The opening is closed by the sphincter which is a strong ring of muscle.
It's from a Latin word meaning "ring" because it's a ring of muscle.
The opening between the stomach and the small intestine is called the Pyloric Sphincter- it is a ring of muscle that contracts when the stomach is full, to seal off the opening to the small intestine whilst foodstuffs are liquified in the stomach. When this has been done, the sphincter muscle relaxes, re-opening the channel to allow the liquified nutrients into the intestines.
The Iris.
An abdominal ring is either of the two openings in the abdominal muscle wall allowing the inguinal canal to pass through.
The color ring of muscle that controls the size of the pupil is called the iris. It can expand or contract to regulate the amount of light entering the eye.
A captive bead ring is a ring where then opening is blocked by a bead held captive in the opening of the ring by the tension of the ring.
No, a tampon cannot get stuck in the uterus. Tampons sit within the vaginal canal, at the top of the vaginal canal is the cervix which is the opening to the uterus - the opening within the cervix is too small for a tampon to pass through, also the tampon sits slightly lower down than the cervix.
The anal canal has a ring of muscle, called the anal sphincter
The muscular ring through which feces passes out of the body is called the anal sphincter. It consists of two muscle groups: the internal anal sphincter, which is involuntary, and the external anal sphincter, which is under voluntary control.
Ring-opening polymerization involves the opening of cyclic monomers with formation of linear polymer chains, while ring-opening metathesis polymerization involves the redistribution of double bonds in cyclic monomers to form a polymer chain. Ring-opening polymerization can use a variety of monomers, whereas ring-opening metathesis polymerization is typically limited to cyclic olefins. Additionally, ring-opening polymerization relies on nucleophilic or electrophilic initiators, while ring-opening metathesis polymerization relies on metal catalysts.