Cellular adaptations Flashcards
(25 cards)
Which genes regulate normal cell proliferation?
- Proto-oncogenes
- Tumour suppressor genes
Which checkpoint in the cell cycle is the most critical?
Restriction (R) checkpoint
What happens when checkpoints are activated?
- Delays cell cycle
- p53 genome
- Trigger DNA repair mechanism or apoptosis
What are cyclins and cyclin-dependent kinase (CDKs)?
-Proteins that drive the cell cycle through phosphorylation of other proteins such as RB proteins
(some growth factors work by stimulating cyclin production)
How are CDKs activated?
Formation of cyclin-CDK complexes (bind to each other)
How are CDKs regulated?
CDK inhibitors
What is retinoblastoma susceptibility protein (RB)?
- From tumour suppressor genes
- Prevent DNA replication
- Inhibited by cyclin D/CDK4 complex
What is hyperplasia? (definition, types of tissues, cause)
- An increase in tissue or organ size from increased cell number
- Labile or stable
- from increased functional demand or hormonal stimulus
What are physiological examples of hyperplasia?
- Proliferation of endometrium (menstruation) under oestrogen
- BM in response to hypoxia
What are pathological examples of hyperplasia?
- Eczema
- Psoriasis
- Thyroid goitre (from iodine deficiency)
What is hypertrophy? (definition, types of tissues, cause)
- Increase in tissue or organ size from increased cell size
- Labile, stable but especially permanent (only way/no replicative potential)
- From increase functional demand or hormonal stimulation
- Cells contain more structural components (workload is shared by a greater mass if cellular components)
What are physiological examples of hypertrophy?
- Skeletal muscle
- Pregnant uterus
- Athlete’s heavy heart
What are pathological examples of hypertrophy?
- Ventricular cardiac muscle from hypertension
- Intestinal stenosis (smooth muscle)
- Prostatic hypertrophy
What is compensatory hypertrophy?
Removal of one of an organ that comes in pairs leading to hypertrophy in the remaining organ e.g. kidneys
What is atrophy?
Shrinkage of a tissue/organ due to an acquired decrease in size and/or no. of cells
- Shrink to a point where survival is still possible
- Reduced structural components
(organ atrophy usually a combination of cell atrophy and apoptosis)
What are physiological examples of atrophy?
- Post menopausal women (ovaries)
- Parturition (after giving birth)
What are pathological CAUSES of atrophy?
- Disuse
- Denervation
- Inadequate blood supply
- Inadequate nutrition
- Loss of endocrine stimuli
- Persistent injury
- Ageing
- Pressure
- Toxic agents
What is metaplasia?
- Reversible change of one differentiated cell type to another
- Labile or stable (altered stem cell differentiation)
- No metaplasia across germ layer (e.g. bone to epithelium)
What are metaplasia examples?
- Bronchial psudostratified ciliated to stratified squamous in smoking
- Stratified squamous to gastric glandular in Barrett’s oesophagus (persistent acid reflux)
What is aplasia? (and give examples)
- Complete failure of a specific tissue or organ to develop (embryonic development disorder)
- Thymic aplasia, aplasia of kidneys
What is hypoplasia? (and give examples)
- Underdevelopment or incomplete development of tissue or organ at embryonic stage
- E.g. renal, breast and chambers of the heart
What is involution? (and give examples)
- Normal programmed shrinkage of an organ
- E.g. uterus after birth, thymus, pro- and mesonephrons
What is reconstitution?
Replacement of a lost body part
What is atresia? (and give examples)
- Congenital imperforation of an opening (no orfice)
- E.g. anus, vagina, small bowel
