MOD Flashcards
Define neoplasia
Abnormal growth of cells that persists after the initial stimulus has been removed.
How may growth control be altered?
With increased cell proliferation- more cells enter cell cycle, reduced cell death/ longer life span- cell may be resistant to apoptosis e.g. abnomal expression of bcl-2 gene which inhibits cytochrome C release from mit., altered GFs/hormones and receptors- VEGF induces angiogenesis, angiostatin/endostatin- opposes VEGF action and altered cell-cell interactions- lack of E-cadherin- adhesion molecule.
Name 2 products of endothelium which impede platelet adhesion and activation, and so haemostasis.
Prostacyclin and NO
What cofactor is important for anti-thrombin activity?
Heparin
How is vitamin K obtained by the body?
From intestinal bacteria and food, so disorders of fat absorption or liver disease can cause vit.K deficiency and defective clotting.
Which clotting factors require vit K for their correct synthesis?
II(prothrombin), VII, IX and X
Define a thrombus
A solid mass of blood that forms within the circulatory system, during life.
Describe the look of a venous thrombus
Soft, gelatinous, deep red, higher cell content
Where do most venous thrombi begin?
At valves- natural degree of turbulence as protrude into vessels lumen and may be damaged by trauma, stasis or occlusion.
Histological appearance of coagulative necrosis, and name 3 other types of necrosis
‘Ghost outline’ of cells, with cellular architecture preserved.
Liquefactive, caseous and fat necrosis
What colour infarct would you expect an MI to be and why?
White infarct as coronary arteries occluded are functional end arteries, providing the sole source of blood supply to areas of the heart.
Nuclear changes in necrotic cells with light microscope
Pyknosis- nuclear shrinkage, Karyolysis-nuclear dissolution and Karyohexis- nuclear fragmentation
Why does the cell cytoplasm swell in ischaemia and list other reversible cell changes in ischaemia.
Ischaemia- blood supply hence oxygen supply cut off to cells, so insufficient O2 for oxidative phosphorylation which produces ATP, so deficit of ATP required for Na+/K+/ATPase to function normally, Na+ not pumped out of cell so remains inside cell, so H20 influx as Na+ is an osmotically active ion.
Chromatin clumping, reduced eosinophilic staining of cytoplasm
Irreversible cell changes in ischaemia
Pyknosis, Karyolysis, Karyohexis, lysosomal rupture, ER lysis, membrane defects.
Define necrosis
The morphologic changes that follow cell death in a living tissue, largely due to progressive degradative action of enzymes on cell.
Define apoptosis
Active process of programmed cell death of single cells.
Pathological and Physiological example of apoptosis
Pathological: graft versus host disease
Physiological: limb development- digit sculpting
List 4 histological features where necrosis different from apoptosis
Necrosis Apoptosis
Death of contiguous Single cell
groups of cells death
Adjacent inflammation None
Cell size increases but shrinkage in apoptosis.
Pyknosis, Karyohexis and Karyolysis but fragmentation of nucleus into nucleosome size fragments in apoptosis.
4 clinical features of acute inflammation
Rubor, Calor, Dolor, Tumor
Define disease
Consequence of failed homeostasis with consequent morphological and/or functional disturbances.
When does cell injury become irreversible?
Massive cytosolic accumulation of Ca2+, espec. from stores in organelles e.g. ER and mit. Array of potent enzymes activated: ATPases, Phospholipases, Endonucleases, Proteases and protein Kinases.
Name 2 local mediators important for increased vascular permeability in inflamed tissues
Histamine and leukotrienes
Name 2 endogenous pyrogens responsible for fever in acute inflammation
TNF-alpha and IL-1
What is the molecular abnormality in inherited angio-oedema?
Absence of the inhibitor of the first component of complement- C1 esterase inhibitor. This causes tissue swelling, especially of the face.
Name the bacterium implicated in gastric ulceration and explain why the gastric ulcer will heal with a scar.
Helicobacter pylori. Imbalance between acid production and mucosal defence, and collagen framework destroyed.
Name the 3 main cells involved with chronic inflammation.
Lymphocytes, Macrophages and Plasma cells.
Name 2 complications of chronic inflammation
Fibrosis, atrophy, stimulation of an immune response
Name an AI disease that causes hyperthyroidism. What other mechanism, apart from autoimmunity, involves the immune system causing cell injury?
Grave’s disease
Hypersensitivity reactions.
Name 2 complications of granulomatous inflammation that might occur in the bowel
Strictures, fistulae
Name 3 types of multinucleated giant cells
Langhans’ giant cell, Touton giant cell and foreign body giant cell.
Name the principal cellular constituents of granulation tissue
Fibroblasts, myofibroblasts, endothelial cells- capillaries and lymphatics
What is DIC?
Disseminated intravascular coagulation: widespread activation of the clotting cascade with subsequent consumption of clotting factors, with resultant increased risk of bleeding as increase in time it takes for blood to clot. A combination of haemorrhage and thrombosis complicates another disorder. Increased PTT and APTP. Must treat identifiable cause e.g. fracture/infection. Can give fresh frozen plasma which contains clotting factors.
What clinical features seen on a patient may suggest hyperlipidaemia?
Xanthelasma, Corneal arcus, Xanthoma
Why is an inflammatory response absent in apoptosis?
Plasma membrane remains intact.
How can a paracetemol overdose cause liver damage?
Paracetemol normally undergoes phase II drug met. but at an excess dosage, these pathways become saturated and it instead undergoes phase I metabolism, producing the toxic metabolite NAPQI- toxic to hepatocytes as binds to sulphydryl groups on their membranes, causing nercrosis and liver failure. NAPQI undergoes phase I met. with glutathione, depleting cells of this important anti-oxidant for protection against ROS.
What could be used to treat a paracetemol OD and explain how this works?
N-acetyl cysteine, this increases the availability of hepatic glutathione, an important defence against anti-oxidants and necessary as glutathione depleted in drug OD.
Which three cancers are there national screening programmes in place for in the UK?
Breast, bowel and cervical
Define a protooncogene
signal transducers that act to regulate normal cell division and growth. If mutated, form oncogenes-causes cellular transformation.
What do the G1 and G2 phases in the cell cycle allow?
Time for cell growth and cell cycle checkpoints so that incorporation of DNA damage is prevented before a cell undergoes division.
Which phase of the cell cycle do permanent cells reside in?
The terminal differentiation phase, from G0.
How do GFs regulate cell proliferation?
They bind to specific cell surface receptors, which are generally transmembrane proteins with cytoplasmic tyrosine kinase domains. Activation of tyrosine kinase causes phosphorylation of receptor on specific cytoplasmic domains creating sites for protein-protein interactions, so recruitment and activation of signalling enzymes or adaptor molecules, which are signal transducers, can occur. These transducers serve as enzyme modulators for signalling enzymes.
GF stimulation induces proteins such as CDKs and cyclins.
Name 2 tumour suppressor proteins
p53 and retinoblastoma. These are most frequently disrupted in cancer cells.