Pathology Flashcards
What are the 3 types of growth receptor?
tyrosine kinase receptors; GPCRs and receptors without tyrosine kinase activity
What are the main stages of the cell cycle?
G1, S, G2 and M
What controls the steps of the cell cycle?
cyclin dependent kinases that activate each other and other enzymes
What is the main cyclin expressed during metaphase?
cyclin B
What happens in G1?
cell gets bigger with increased protein synthesis
What CDK is actiavted during G1?
CDK4
What is the effect of CDK4?
phosphorylates the retinoblastoma protein
What cyclin activates CDK4?
cyclin D
What is the retinoblastoma protein usually bound to?
E2F
What is the function of E2F?
stimulates cell division
What is the function of the phosphorylation of Rb?
Rb can’t bind to E2F so E2F is able to stimulate cell disivion
What cyclin does E2F increase the levels of?
cyclin A
What CDK does cyclin A actiavte?
CDK2
What is the function of CDK2?
promotes DNA replication
What should be present at the end of S phase in the cell?
2 copies of genome
What is the main chekcpoint protein at the end of G2?
p53
What is the function of p53?
checks for DNA mistakes
Give an example of a cell which is terminally differentiated (can’t divide) or exhibit replicative sensence?
neurons
What is the function of telomeres?
provides protection and stops chromosome ends from degradation and fusion
Where does hypertrophy occur in isolation without hyperplasia?
in non-dividing cells eg cardiac myocytes and SK muscle
Which hormones promote degradation and atrophy?
glucocorticoids and thyroid hormone
What pathway are proteins often degraded by?
ubiquitin proteasome pathway
What is vasodilation in inflammation mediated by?
histamine and nitric oxide
What allows white cell margination?
vascular dilatation which slows rate of flow
What do selectins bind to?
proteoglycans on white cellls
Where are integrins found?
surface of white cells
what do integrins bind to?
ICAM
What factors increase selectin expression?
histamine and thrombin
What factors increase cell expression of VCAM and ICAM?
TNF and IL1
What is the function of chemokines on the endothelial cell surface?
bind to proteoglycans to increase the affinity of VCAMs and ICAMs for integrins
What substances cause endothelial contraction?
histamine; bradykinin; substance P; leukotrienes
What mediates transcytosis?
VEGF
What is chemotaxis?
cells follow a chemical gradient
What is pain in inflammation mediated by?
prostaglandins and bradykinin
What is resolution?
complete restoration of the itssue to nomral after removal of inflammatory components
What is required for resolution?
tissue capacity for repair; good vascular supply; scaffold
What healing is favoured if damage goes beyond the basemenet membrane?
organisation and repair
What happens after granulation tissue?
defect is slowly infiltrated by capillaries and then myofibroblasts which deposit collagen and SM
When is chronic inflammation favoured?
suppuration; persistence of injury and types of injury e.g autoimmune
Waht is chronic inflammation characterisedby?
lymphocytes and macrophages
What are the outcomes of acute inflammation?
resolution; suppuration; repair organisation and fibrosis; chornci inflammation
What does increased calcium in the cell stimulate?
ATPase; phospholipase; proteases; endonucleases; mitochondrial permeability
What is pyknosis?
irreversible condensation of chromatin in a cell undergoing necrosis or apoptosis
What are the first signs of necrosis?
cells shrink; become red; darkened nucleus and marginal contraction bands appear