Epithelial tissue and defects in regulation of cell divisions Flashcards
what are the two types of stem cells?
Adult stem cells
Embryonic stem cells
what are the features of adult stem cells?
- undifferentiated cell found amongst differentiated cells in tissue/organ
- can renew itself and can differentiate to major cell types of tissue/organ (multipotent)
- primary roles of adult stem cells in living tissue is maintenance and repair
what are the features of embryonic stem cells?
- defined by origin, inner cell mass of blastocyst
- can become all types of cells in the body (pluripotents)
what are the different types of stem cell plasticity?
-multipotent
-plurpotent
what is multipotent?
able to generate many types of cells within a restricted tissue family
what is plurypotent?
able to generable all tissue types
what is the cell turn over of the epidermis?
~2 months
how are skin cells regenerated?
skin stem cells are found in a bulge under the sebaceous gland. They translocate to the basal layer of the epidermis
how are skin cells regenerated?
skin stem cells are found in a bulge under the sebaceous gland. They translocate to the basal layer of the epidermiswh
what cells can the intestinal stem cells give rise too?
absorptive cells, goblet cells, Paneth cells, enteroendocrine cells
what is the turnover of intestinal cells?
~few days
how to cells adapt to environmental changes?
homeostatic mechanisms
- physiological conditions- to adapt to normal changes
-Pathological conditions- to limit damage in response to disease processes
what is hyperplasia?
increase in size of tissue/organ by increased cell reproduction rate
what is hypertrophy?
increase in size of tissue/organ by increase of cell size
what is cell/tissue atrophy?
decrease in size
what is metaplasia?
reversible transition of one cell type to another
what is dysplasia?
presence of abnormal type of cells
what is neoplasia?
New, uncontrolled growth of cells
how do cells alter their pattern of growth in response to tolerable environmental changes?
Cell size
Cell division
Cell differentiation
what is an example of physiological adaptation?
breast epithelial cells increase in size and number during pregnancy under endocrine stimulation
what is an example of pathological adaptation?
Endometrial cells increase in number under abnormal endocrine stimulation from oestrogen-secreting ovarian tumours.
what is tissue atrophy?
decrease in cell number/size
what is cell atrophy?
decrease in cell size
what is metaplasia?
one mature, fully differentiated cell type adopts totally different fully differentiated cell type
morphology changes in response to cellular environment
adaptive response - cells are better equipped to withstand new environment
common in epithelial tissue
what is Barrett’s oesophagus?
-metaplastic transformation of the esophageal lining
- squamous epithelium typical of normal oesophagus
-columnar cells with goblet cells, typical of intestinal type of epithelium
what is dysplasia?
-the presence of abnormal cells
-increased rate of cell division coupled with incomplete maturation of immature cells
what are some examples of dysplasia?
-epidermis of sun exposed skin
-squamous epithelium at columnar junction of cevix
how does dysplasia effect skin?
loss of cell maturation due to increase rate of cell division
nuceli present in keratin layer
how does dysplasia effect the cervical epithelium?
increased number of the more basal, nucleated cells reaching the vagina.
how can dysplasia of the cervical epithelium lead to neoplasm?
there is a spectrum of progression, with the stratified layer losing its differentiation and becoming neoplastic
what is a neoplastic state?
poorly regulated cell division in which mass of cells form (neoplasm)
Cellular proliferation and growth occur in absence of any continuing external stimulus
Neoplastic cells exhibit various states of differentiation and commonly fail to achieve highly differentiated state
what are the events in neoplastic formation?
-stimulus causes genetic alteration to the cell
- altered genes for, growth factors, growth factor receptors, signal transduction, transcription regulation, DNA repair, cell survival
- transformed cell proliferates with poor regulation of growth as a result of genetic changes and develops additional mutations
what is benign in surface epithelium?
papilloma
what is malignant in surface epithelium?
carcinoma
what is benign in solid glandular epithelium?
adenoma
what is malignant in solid glandular epithelium?
adenocarcinoma
what is benign?
well defined- similar structure to the tissue of origin
Progress and slow
what is malignant?
can lack differentiation
Erratic growth
Locally invasive
Matastatic
what are the cellular events needed for metastasis?
detachment from the main neoplasm
breaking through the basememt membranse and connective tissue
molility
enter the passage for movement (lymph, blood stream)
enter another tissue
how do tumours spread?
4 main routes
- local
-trans-coelomic (peritoneal, pleural)
-Lymphatic
-Blood borne
what are three ways to classify epithelium?
Morphologically
Surface specializations
Surface or glandular
