Lecture 3

Question 1

What happens to cells when they become stressed?

Answer 1

Adapt to the stressful conditions (try to alleviate the stress), or die.

Question 2

What are two factors that determine the way a cell adapts?

Answer 2

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

Question 3

For the different types of cell cycles - what is an adaptation response?

Answer 3

1) Labile - hyperplasia
2) Stable - hypertrophy
3) Permanent - hypertrophy

Question 4

In cardiac and skeletal muscle cells - what happens when the stretch receptors/growth factor receptors are activated?

Answer 4

Binding-> Increase transcription factors -> Increase Contractile Pns (increase intracellular structures to feed/support contractile proteins)-> increase size -> Hypertrophy - increase size + increase structures + increase nucleus

Question 5

What is hyperplasia?

Answer 5

• 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.

Question 6

When does hyperplasia occur physiologically?

Answer 6

Endometrial lining/ hormonal dependent.

Question 7

When does hyperplasia occur pathologically?

Answer 7

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

Question 8

In what condition can you see mixed hyperplasia/hypertrophy?

Answer 8

Graves Disease - autoimmune disease - Ab stimulates the thyroid hormone -> increase cell size and number by increasing the occupation of the colloid space.

Question 9

What is metaplasia?

Answer 9

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.

Question 10

Is metaplasia reversible? Is it beneficial?

Answer 10

Yes, it is reversible. It does not have to be beneficial, it can do nothing.

Question 11

What is the difference between hyperplasia/hypertrophy and neoplasia?

Answer 11

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

Question 12

What is atrophy?

Answer 12

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.

Question 13

What is physiological myocardial hypertrophy?

Answer 13

• Occurs during development and exercise (reversible)
• no loss in systolic or diastolic function
• increase in size & increase in capillary density

Question 14

What is pathological myocardial hypertrophy?

Answer 14

Ie. Pathological valvular hypertension

• turns on embryonic/fetal stem cells
• deposition of matrix

Question 15

Concentric Hypertrophy

Answer 15

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

Question 16

Eccentric Hypertrophy

Answer 16

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

Question 17

Can the two types of hypertrophy interchange?

Answer 17

Yes, Concentric can turn into eccentric hypertrophy at end stage cardiac failure
-concentric, eccentric, remodelling, mixed concentric/eccentric

Question 18

What is the macro structure of the wall?

Answer 18

LV thickness <5mm

Question 19

What is the weight of the heart in each gender (average)

Answer 19

Males - >500g
Females - >400g

The mass is dependent on Mass/Height = BMI

Question 20

What is the microscopic difference between normal and hypertrophic heart cells?

Answer 20

Normal Cells - one SMALL ROUND nucleus, sometimes can see two.
Hypertrophic cells - LARGE RECTANGULAR nucleus, mostly 2 nuclei per cell.

Question 21

What are some complications of hypertrophy?

Answer 21

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

Question 22

A sign of Left Cardiac Failure?

Answer 22

Pulmonary Edema

Question 23

A sign of Right CF?

Answer 23

Peripheral Edema + Liver Failure; NUTMEG

Question 24

What is a degenerative aortic valve?

Answer 24

Calcification/balls of calcium amongst the leaflets -> stenosis
Congenital bicuspid Aortic Valve - increase Pr(calcification)

Question 25

What is Myxomatous Mitral Valve?

Answer 25

Squishy/jelly like leaflets of the valve -> mitral prolapse/regurgitation

Question 26

What is Rheumatic Heart Disease?

Answer 26

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

Question 27

What is infective endocarditis?

Answer 27

The combination of bacteria and blood are stuck on the valve.