Cellular Adaptations Flashcards
What are growth factors, their role in cellular growth and some examples?
Proteins that function to regulate the cell cycle and cell division
e.g. VEGF, EPO, EGF (epidermal growth factor, GH)
What are the diff stages of the cell cycle?
Interphase: G1, S, G2. Mitosis
What is the restriction (R) point?
Most critical checkpoint near the end of G1,
majority of cell that pass will complete cell cycle,
point of no return,
altered in cancer,
checkpoint activation delays cells cycle and triggers repair/apoptosis via p53
What is the role of cyclins and CDK?
Cell cycle control mechanism
to move forward in cell cycle, cyclin must bind CDK (cyclin dependent kinase) + target protein = activated = phosphorylation of target protein to move on
How many times can a cell divide?
61.3
What is the role of RB protein?
Retinoblastoma susceptibility protein
substrate target enzyme needing to be phosphorylated for cell cycle to continue past checkpoint
Define regeneration
Restitution with no, or minimal evidence that there was a previous injury
Which tissues can undergo regeneration and which cannot?
Can = labile/stable tissue e.g. liver, skin.
Cannot = permanent tissue e.g. nerve, skeletal, cardiac
Define hyperplasia
Increase in tissue or organ size, by increased cell number
due to increased functional demand or hormonal stim
Under physiological control and is reversible
Which tissues can undergo hyperplasia?
Labile or stable tissue
Give physiological and pathological examples of hyperplasia
Phy = prolif endometrium by oestrogen, bone marrow prod RBC by hypoxia.
Path = eczema, goitre by iodine def
Define hypertrophy
Increased in tissue/organ size due to increased cell size
due to increased functional demand or hormonal control
Which tissues can undergo hypertrophy?
Labile, stable but especially permeant tissues
Give an example of physiological hypertrophy
Skeletal muscle, pregnant uterus
Outline some pathological examples of hypertrophy
ventricles of the heart (heart always slightly hypoxic – cant form enough vessels to maintain O2 demand),
urinary bladder when constricted
What is compensatory hypertrophy?
Combination of hypertrophy and hyperplasia – when one organ makes up for the deficit in another
Define atrophy
Shrinkage of a tissue/organ due to an acquired decrease in size and/or number of cells
Give an example of physiological atrophy
Ovarian atrophy in post-menopausal women
Give an example of pathological atrophy
Atrophy of disuse = reduced function demand/workload.
Loss of innervation = denervation atrophy.
Inadequate blood supply/nutrition = gradual process.
Loss of endocrine stim.
Persistent injury.
Ageing = senile atrophy.
Pressure = swelling, ischemia
Define metaplasia
Reversible change of one differentiated cell type to another due to altered stem cell differentiation
Why does metaplasia occur?
Altered stem cell differentiation – may represent adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the adverse environment
Give an example of metaplasia
Smoking = bronchila pseudostratified ciliated epithelium –> stratified squamous epithelium
Barretts oesophagus (reflux) = stratified squamous epithelium –> simple columnar epithelium with goblet cells
Define aplasia
Complete failure of tissue/organ to devel
aplasia of bone marrow = aplastic anaemia
Define hypoplasia
Undevel/incomplete devel of tissue/organ at embryonic stage, inadequate number of cells
Define involution
Form of atrophy
Normal programmed shrinkage of an organ
uterus after childbirth
Define reconstitution
Replacement of a lost part of the body
Define atresia
No orifice = congenital imperforation of an opening
Define dysplasia
Abnormal maturation of cells within a tissue – often pre-cancerous condition
What are the causes and complications of left ventricular hypertrophy?
causes = exercise, hypertension, aortic stenosis
complications = heart failure, arrhythmia
What are the causes and complications of Barretts oesophagus?
replacement of the normal stratified squamous epithelium lining of the esophagus by simple columnar epithelium with goblet cells
cause = reflux
complications = esophageal adenocarcinoma
What is traumatic myositis ossificans?
heterotopic ossification (calcification) of muscle
inappropriate differentiation of fibroblasts into bone-forming cells (osteoblasts).
odema of CT proceeds to tissue with foci of calcification and then to maturation of calcification and ossifications
What is the macroscopic appearance and complications of benign prostate hyperplasia?
macroscopic = noncancerous increase in size
complications = urethra obstruction, urinary tract infections, bladder stones, and chronic kidney disease
What is the presentation, appearance and pathophysiology of psoriasis?
presentation = itchy red patches with white scales on top, pus
microscopic = immune cells
macroscopic = red, scaly
pathophysiology = autoimmune triggered by environmental factors
