Cytology · MU Pleven

Topic 24. Cytophysiology – cellular growth, aging and cell death

Covers cell proliferation, then cell differentiation through gene expression and signalling, with the three categories of specialised cells and the unipotent and pluripotent stem cell types. It then explains growth factors and the PI 3-kinase pathway, apoptosis as deprivation-driven death, and necrosis with the nuclear changes pyknosis, karyorrhexis and karyolysis.

Inside: 3 sections · 16 flashcards · 4 min

Topic 24 of 59 in the MU Pleven syllabus for Cytology (Medicine, Year 1). The free AceMed note covers it in 3 sections, about 637 words (4 min of reading), with 16 flashcards.

In this note

  1. TOPIC 24 Cytophysiology– cellular growth, aging and cell death
  2. Cell differentiation
  3. Cellular growth, aging and death

TOPIC 24 Cytophysiology– cellular growth, aging and cell death

Cell proliferation- It is the rapid increase in the number of cells It can be of 2 types:

  • Normal proliferating cell
  • Proliferating cancer cell

Cell differentiation

All cells of the body contain the same genetic material or DNA and this is what makes organisms unique Cell differentiation is how embryonic cells become specialised cells. This occurs through a process called gene expression. Gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates the function of a cell. Gene expression occurs because of certain signals in your body, both inside and outside

Cell differentiation occurs during multiple stages of development. During cell differentiation, the cell size and shape changes dramatically as well as its ability to respond to signalling molecules.

Signalling molecules are molecules that bring messages to cells that inform the cell on which activities and processes to perform. Signalling molecules carry a message to a cell receptor, which interprets the message through a signal transduction pathway. This pathway translates the message into something the cell can recognise and understand and this is what tells a cell how to function

Three categories of specialized cells:

  • Fully differentiated, non-dividing cells
  • Potentially dividing cells
  • Not terminally differentiated, renewal by stem cells:
  1. A. Unipotent cells: In cell biology, a unipotent cell is the concept that one stem cell has the capacity to differentiate into only one cell type. Example: Hepatoblasts, which differentiate into hepatocytes
  2. B. Pluripotent (multipotent) cells: pluripotency refers to a stem cell that has the potential to differentiate into any of the three germ layers –
  • endoderm (interior stomach lining, gastrointestinal tract, the lungs),
  • mesoderm (muscle, bone, blood, urogenital), or
  • ectoderm (epidermal tissues and nervous system)

* Potency – the capacity to differentiate into specialised cell types

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