Tissue Injury Flashcards
what cellular adaptation may occur in response to increased demand?
hyperplasia
hypertrophy
what cellular adaptation may occur in response to decreased stimulus?
atrophy
what cellular adaptation may occur in response to altered stimulus?
metaplasia
what is hypertophy?
cells get bigger
what is hyperplasia?
cells increase in number
what two ways can we adapt by growth?
hyperplasia
hypertrophy
what are the three categories of growth receptors?
receptors with intrinsic tyrosine kinase activity
7 transmembrane G protein coupled receptors
receptors without intrinsic tyrosine kinase activity
what are the four main stages of the cell cycle?
G1
S
G2
M
what controls the steps of the cell cycle?
cyclin dependant kinases (CDKs)
they activate each other and other enzymes in a step wise fashion
what activates each CDK?
a specific cyclin molecule
name four cyclins in the order in which they are predominant in the cell cycle
D E A B
what is G1?
the first growth step
what happens during G1?
the cell gets bigger with increased protein synthesis
what CDK is activated in G1 and what activates it?
CDK4
activated by cyclin D
what does CDK4 do during G1?
phosphorylates the retinoblastoma protein
what is the S phase?
synthesis phase
what initiates DNA replication in the S phase and what else does this do?
E2F
increases levels of cyclin A
what CDK is activated in the S phase and what activates it?
CDK2
activated by cyclin A
what should the cell have by the end of the S phase?
two copies of its genome
what is G2?
the second growth phase
what occurs in G2?
the cell gets bigger
more protein synthesis
where is the main checkpoint of the cell cycle found?
at the end of G2
what is the main checkpoint protein of the cell cycle?
p53
what is retinoblastoma (Rb) normally bound to?
E2F
what does E2F do?
starts cell division, only when Rb is bound
what happens when Rb is phosphorylated by CDK4?
it can’t bind to E2F
E2F starts cell division
what does p53 do at the checkpoint?
checks the cell for any mistakes
what happens if p53 finds a mistake in the cell?
cell cycle is paused
repair is attempted
what happens if cell repair is unsuccessul?
the cell undergoes apoptosis
name a cell that cannot divide
neurons
