Regulatory Mechanisms and Stem Cell Biology

Vocabulary flashcards covering cellular regulatory mechanisms (intrinsic vs. extrinsic), blood glucose control, and the three degrees of stem cell potency.

Intrinsic Mechanism

A regulatory process where cells within an organ sense changes occurring inside or around it and signal neighboring cells to respond accordingly.

Extrinsic Mechanism

A regulatory process where changes in an organ are brought about by signals from external sources, namely the nervous system or the endocrine system.

Islets of Langerhans

Structures in the pancreas containing beta cells that secrete insulin when blood glucose rises, and adjust insulin and glucagon levels during fasting.

Insulin

A hormone secreted by the beta cells in the pancreas when blood glucose levels rise, signaling cells to uptake glucose and causing blood glucose levels to fall.

Glucagon

A hormone secreted by the islets of Langerhans during fasting that instructs cells to increase glucose secretion by the liver, causing blood glucose levels to rise.

Stem Cells

Completely undifferentiated cells that have the ability to transform into other cell types to replace or restore lost cells.

Totipotency

The highest degree of stem cell power, characteristic of the zygote, which allows a cell to give rise to all body cells plus the cells of the placenta.

Zygote

A fertilized egg, which represents the only truly totipotent cell in the human body.

Pluripotency

The degree of stem cell power possessed by embryonic stem cells, allowing them to give rise to all body cells, but not the cells of the placenta.

Embryonic Stem Cells

Pluripotent stem cells formed after the zygote divides and implants, capable of developing into all body cells except the placenta.

Multipotency

The degree of stem cell power found in adult stem cells, restricting their development to a narrow range of specific cell types.

Adult Stem Cells

Multipotent stem cells found in babies, children, and adults that have a limited development potential restricted to a narrow range of cells.

Hematopoietic Stem Cells

Multipotent bone marrow stem cells that have the ability to give rise specifically to red blood cells, white blood cells, and platelets.