Lecture 3 Flashcards
What happens to cells when they become stressed?
Adapt to the stressful conditions (try to alleviate the stress), or die.
What are two factors that determine the way a cell adapts?
1) Cell Cycle
a) Labile - continuously dividing cells
b) Stable - can enter cell cycle upon request
c) Permanent - once damaged can’t be replaced - scar formation.
2) Stimulus: GF, mechanical, environment
For the different types of cell cycles - what is an adaptation response?
1) Labile - hyperplasia
2) Stable - hypertrophy
3) Permanent - hypertrophy
In cardiac and skeletal muscle cells - what happens when the stretch receptors/growth factor receptors are activated?
Binding-> Increase transcription factors -> Increase Contractile Pns (increase intracellular structures to feed/support contractile proteins)-> increase size -> Hypertrophy - increase size + increase structures + increase nucleus
What is hyperplasia?
- Increase in the number of cells in response to physiological or pathological conditions.
- Labile/Stable cell populations
- Hypertrophy usually occurs at the same time.
- GF can cause both hypertrophy and hyperplasia.
When does hyperplasia occur physiologically?
Endometrial lining/ hormonal dependent.
When does hyperplasia occur pathologically?
renal failure: increase phosphate = binds calcium -> decreases calcium -> increase the number of cells in the PT to increase PTH production
Microscopically: Fat is replaced by cells
In what condition can you see mixed hyperplasia/hypertrophy?
Graves Disease - autoimmune disease - Ab stimulates the thyroid hormone -> increase cell size and number by increasing the occupation of the colloid space.
What is metaplasia?
A reversible change in shape due to altered environment of the cell. Usually occurs at junctions between epithelial cells.
-Physiologically - @ puberty - endocervix swells - thus allowing it to interact with the low pH ->change in shape from column to stratified squamous epithelia
Pathologically - Barrett’s Esophagus; GERD - the esophagus interacts with the acidic environment usually due to regurgitation -> change in shape from stratified squamous to columnar epithelia.
Is metaplasia reversible? Is it beneficial?
Yes, it is reversible. It does not have to be beneficial, it can do nothing.
What is the difference between hyperplasia/hypertrophy and neoplasia?
Hyperplasia/Hypertrophy: controlled divisions, regulated, reversible upon removal of stimulus, change in gene transcription rather than the genome itself
Neoplasia: uncontrolled cell division, doesn’t need a stimulus, usually due to a mutation in the genome
What is atrophy?
a decrease in cell size; reversible if the cell doesn’t die or fibrose. Usually occurs due to a loss in blood supply, or nerve supply - if you don’t use it - you lose it.
What is physiological myocardial hypertrophy?
- Occurs during development and exercise (reversible)
- no loss in systolic or diastolic function
- increase in size & increase in capillary density
What is pathological myocardial hypertrophy?
Ie. Pathological valvular hypertension
- turns on embryonic/fetal stem cells
- deposition of matrix
Concentric Hypertrophy
Increase work of the heart without increasing the cell size/stretch
- increase diameter of the cell (plumpiness)
- increase thickness of the wall
- occurs due to pressure increase
Eccentric Hypertrophy
Increase work of the heart with the increase in cell size/stretch
- increase in cell length
- no increase in thickness of the wall
- occurs due to volume increase
Can the two types of hypertrophy interchange?
Yes, Concentric can turn into eccentric hypertrophy at end stage cardiac failure
-concentric, eccentric, remodelling, mixed concentric/eccentric
What is the macro structure of the wall?
LV thickness <5mm
What is the weight of the heart in each gender (average)
Males - >500g
Females - >400g
The mass is dependent on Mass/Height = BMI
What is the microscopic difference between normal and hypertrophic heart cells?
Normal Cells - one SMALL ROUND nucleus, sometimes can see two.
Hypertrophic cells - LARGE RECTANGULAR nucleus, mostly 2 nuclei per cell.
What are some complications of hypertrophy?
Ischemia, Fibrosis, Cardiac Failure, Arrhythmia, Death
Decrease in cardiac/cell perfusion ->ischemia -> cell death and fibrosis -> a)arrhythmia OR b) cardiac failure -> decreased renal perfusion ->fluid retention->increased volume ->increase dilation ->leads back to decreased perfusion -> cycle
A sign of Left Cardiac Failure?
Pulmonary Edema
A sign of Right CF?
Peripheral Edema + Liver Failure; NUTMEG
What is a degenerative aortic valve?
Calcification/balls of calcium amongst the leaflets -> stenosis
Congenital bicuspid Aortic Valve - increase Pr(calcification)
What is Myxomatous Mitral Valve?
Squishy/jelly like leaflets of the valve -> mitral prolapse/regurgitation
What is Rheumatic Heart Disease?
Ab against strep.pyogenes. This Ab also acts against our endocardium/myosin due to the structural similarity of strep.
Latent until adulthood - can attack all or some of the valves ->Stenosis or Regurgitation
What is infective endocarditis?
The combination of bacteria and blood are stuck on the valve.
