Pathology Flashcards
3 types of growth receptors
Receptors with intrinsic tyrosine kinase activity
7 transmembrane GPCR
Receptors without intrinsice tyrosine kinase activity
What controls progression through the cell cycle
Cyclin dependant kinases (CDK) activate each other and other enzymes. CDKs are activated by cyclins D, E, A, B
What happens in G1 phase of cell cycle
Growth, cell gets bigger with increased protein synthesis, CDK4 is activated by cyclin D. CDK 4 activates retinoblastoma protein
How does retinoblastoma protein (Rb) regulate cell growth
E2F is responsible for cell division but is stopped from doing so by Rb. When CDK4 phosphorylates Rb, E2F starts cell division
What happens in S phase of cell cycle
Synthesis phase, E2F initiates DNA replication, increases levels of cyclin A. Cyclin A activates CDK2; this promotes DNA replication. Two copies of genome
What happens at G2
Second growth phase, cells get bigger and more protein synthesis. p53 is main checkpoint at end G2
What are TAG repeats
Chromosomes are capped with TTAGGG repeats called Telomeres. This gets smaller with every division
Physiological hyperplasia
Breast tissue formation during puberty
Hyperplasia of endometrial lining of uterus - Pregnancy
Pathological hyperplasia
Excess oestrogen leads to endometrial hyperplasia and abnormal menstrual bleeding, often post menopausal
Lymph nodal swelling is due to hyperplasia or trophy?
Hyperplasia
Physiological atrophy
Uterus after parturition, certain embryological structures
Pathological atrophy
Brain during ischaemia, muscles with reduced workload
Main cell of acute inflammation
Neutrophils
What mediates vasodilation after injury
Histamine and Nitric Oxide
Major cellular changes after injury
Vasodilation - Stasis White cell margination Rolling Adhesion Migration
What is white cell margination
Blood flow slows with vasodilation, hence white cells are able to move along the periphery
What do vessel walls express that bind to white cells
Vascular Cell Adhesion Molecules - VCAM
Intercellular Cell Adhesion Molecule - ICAM
What’s expressed on white cells that bind to vessel walls
Selectins which bind CAMs on endothelial surface
What increase carbohydrate expression on WBCs for selections in endothelial cells
Histamine and Thrombin from inflammatory cells
What increases endothelial expression of ICAM and VCAM
Tumour necrosis factor - TNF and Interleukin 1 - IL1
What increases affinity of VCAM and ICAM for Integrins
Chemokines from site on injury bind to proteoglycans
How do WBCs recognise bacterial/pathogen
Bacteria have terminal mannose residues, WBCs have mannose receptors
What are opsonins
An antibody or other substance which binds to foreign microorganisms or cells making them more susceptible to phagocytosis
How does killing and degradation occur in the phagolysosome
Reactive oxygen species-NADPH oxidase; oxygen gains an electron from NADPH and becomes superoxide
Reactive Nitrogen Species-Nitric Oxide Synthase combines NO with superoxide and produces ONOO