Lecture 7 - Cellular Adaptations Flashcards
where is the most critical checkpoint of the cell cycle?
end of g1 restriction point
passage past is governed by retinoblastoma protein
what is regeneration?
replacement of cell losses by identical cells to maintain tissue or organ size
what is hyperplasia?
increase in tissue or organ size due to increased cell numbers
what is hypertrophy?
increase in tissue or organ size due to increased cell size
what is atrophy?
shrinkage of tissue or organ due to acquired decrease in size and/or number of cells
what is metaplasia?
reversible change of one differentiated cell type to another
what is aplasia?
complete failure of a specific tissue or organ to develop
what is hypoplasia?
incomplete development of tissue or organ
what is dysplasia?
abnormal maturation of cells within a tissue
when does hyperplasia occur?
only in labile or stable cell populations
physiological causes - proliferative endometrium, bone marrow at altitude
pathological causes - thyroid goitre
when does hypertrophy occur?
in permanent cells where hyperplasia cant occur
may occur with hyperplasia elsewhere
physiological causes - skeletal muscle, pregnant uterus (with hyperplasia)
pathological causes - ventricular cardiac muscle, bladder smooth muscle
when does atrophy occur?
combination of atrophy and apoptosis
physiological causes - ovarian atrophy post menopause
pathological causes - muscle atrophy (denervation), cerebral atrophy (alzheimers)
when does metaplasia occur?
most clearly adaptive in epithelial tissues
change tends to be suited to new environment eg smoker goes from pseudostratified to squamous (more robust)
sometimes prelude to dysplasia and cancer
