Licensing factor is necessary for initiation of replication at each origin. Licensing factor is present in the nucleus prior to replication, but is removed, inactivated, or destroyed by replication. Initiation of another replication cycle becomes possible only after licensing factor reenters the nucleus after mitosis.

TLS Online TPP Program

#Id: 1216

#Unit 7. System Physiology – Animal

The chief cells of the parathyroid glands synthesize and secrete PTH.

TLS Online TPP Program

#Id: 1217

#Unit 7. System Physiology – Animal

The parathyroid cell membrane contains Ca2+ sensing receptors that are linked, via a G protein (Gq).

TLS Online TPP Program

#Id: 1218

#Unit 7. System Physiology – Animal

When extracellular Ca2+ concentration is increased  Ca2+ binds to the receptor  activates phospholipase C inhibits PTH secretion.

TLS Online TPP Program

#Id: 1219

#Unit 7. System Physiology – Animal

When extracellular Ca2+ is decreased decreased Ca2+ binding to the receptor stimulates PTH secretion

TLS Online TPP Program

#Id: 1220

#Unit 7. System Physiology – Animal

When extracellular Ca2+ is decreased decreased Ca2+ binding to the receptor stimulates PTH secretion

TLS Online TPP Program

#Id: 1221

#Unit 7. System Physiology – Animal

The receptor for PTH is coupled, via a Gs protein, to adenylyl cyclase.