Growth Activity and Functional Differentiation of Cells

Flashcards covering normal and abnormal cell growth, the cell cycle, hyperplasia, dysplasia, carcinoma in situ, cellular differentiation, and characteristics of malignant cells.

What is cytology, and what is the role of a cytologist?

Cytology is the study of the microscopic appearance of cells. Cytologists are trained to identify cell types normally present in body regions and detect morphological changes or inappropriate cells associated with specific conditions.

How is anaplasia defined?

Anaplasia is the loss of mature or specialized features of a cell or tissue, commonly seen in malignant tumours.

How is dysplasia defined in anatomical pathology?

Dysplasia (also used as an alternative term for CIN) describes the presence of abnormal cells within a tissue or organ.

What is metaplasia?

Metaplasia is the transformation of one type of mature epithelium into another, usually in response to a stimulus.

What is hyperplasia?

Hyperplasia is an increase in the number of cells in an organ or tissue resulting from cell proliferation. Under a microscope, these cells appear normal.

What defines cell growth at the cellular level?

Cell growth is the increase in total cell mass (including cytoplasmic, nuclear, and organelle volume), occurring when cellular biosynthesis (anabolism) exceeds cellular degradation (catabolism).

How does cell proliferation differ from cell growth alone?

Cell proliferation combines cell growth and cell division, where a mother cell grows and divides to produce two daughter cells.

What cellular processes are illustrated in this diagram comparing cell division, cell growth, and cell proliferation?

The diagram illustrates cell division (splitting without size increase), cell growth (increase in mass/size without splitting), and cell proliferation (combined growth and division).

How is cell turnover maintained in the basal layer of the skin epidermis?

When a basal cell divides, one daughter cell stays in the basal layer to divide again, while the other cell migrates outward, stops dividing, and eventually sheds off as a dead cell.

Which two balanced processes regulate normal tissue cell growth, and what happens if they fail?

Proliferation (cell growth/division) and apoptosis (programmed cell death). If disrupted, cells may proliferate uncontrollably, fail to die, or both, potentially leading to cancer.

What are the two primary periods of the cell cycle?

Interphase (cell growth and preparation) and the Mitotic phase (cell division).

What occurs during the $G_1$, S, and $G_2$ phases of interphase?

In $G_1$, the cell synthesizes proteins needed for DNA replication; in S phase, DNA synthesis/replication occurs; in $G_2$, the cell produces proteins needed for final division preparations.

Which main phases and sub-phases of the cell cycle are shown in this diagram?

The cell cycle consists of Interphase (comprising $G_1$, S, and $G_2$ phases) and the Mitotic phase (M phase).

How do feedback loops control cell proliferation in normal tissues?

When cells reach proper numbers and crowd each other, growth inhibitory factors trigger negative feedback to slow growth. Abnormal positive feedback occurs when cells produce excess growth factors.

Why is skin callus formation considered a form of noncancerous hyperplasia?

It consists of a larger-than-normal number of structurally normal skin cells rapidly dividing in response to repetitive mechanical irritation.

How does dysplasia differ from hyperplasia?

Dysplasia involves abnormal cell structure (especially nuclear changes) and loss of normal tissue arrangement, whereas hyperplastic cells maintain normal architecture and microscopic appearance.

What is carcinoma in situ, and why is it surgically removed?

Carcinoma in situ is severe dysplasia representing uncontrolled cell growth confined to its original location ('in place') without invasion; it is removed because it carries a high risk of becoming invasive cancer.

What sequence of abnormal cell growth steps is depicted in this diagram?

The diagram displays the stages: Normal tissue $\rightarrow$ Hyperplasia $\rightarrow$ Mild dysplasia $\rightarrow$ Carcinoma in situ (severe dysplasia) $\rightarrow$ Cancer.

How does a cell's level of differentiation relate to its rate of proliferation and cancer aggressiveness?

Poorly differentiated cells (such as stem cells) proliferate rapidly and are common in aggressive cancers; well-differentiated cells are mature, functionally specialized, and proliferate slowly or not at all.

What are the two major mechanisms the body uses to regulate cell proliferation?

Growth factors (which stimulate mitosis and cellular differentiation) and contact inhibition (which halts cell division when physical contact between crowding cells triggers inhibitory factors).

What functional characteristics define a malignant cell?

Acceleration of the cell cycle, genomic alterations, invasive growth, increased cell mobility, chemotaxis, cell surface changes, and secretion of lytic factors.

What morphological characteristics describe the nucleus and cytoplasm of a cancerous cell?

The nucleus is enlarged, irregularly shaped and sized, with prominent nucleoli; the cytoplasm is scarce, often basophilic due to RNA accumulation, and frequently contains vacuoles.