L12

Question 1

what 3 increases in functional demand cause hypertrophy and hyperplasia?

Answer 1

increases in work and metabolic demand, excess endocrine stimulation and persistent tissue injury

Question 2

what is hypertrophy?

Answer 2

increased cell size

Question 3

what is hyperplasia?

Answer 3

increased cell number

Question 4

what are the precursors of muscle cells

Answer 4

myoblasts

Question 5

what happens to myoblasts during development?

Answer 5

proliferation

Question 6

what fuses to form muscle cells?

Answer 6

proliferated myoblasts

Question 7

what can influence degree of proliferation?

Answer 7

genes

Question 8

what slows myoblast proliferation?

Answer 8

myostatin

Question 9

a mutated myostatin gene leads to?

Answer 9

more skeletal muscle fibres being produced during development

Question 10

why would a ventricle have a hypertrophic wall because of a narrowing of it’s aortic valve?

Answer 10

increased workload

Question 11

what kind of nuclei would you find in hypertrophic myocardium?

Answer 11

large, often polyploid nuclei

Question 12

what effect does the thickened ventricular wall of hypertrophic myocardium have?

Answer 12

reduces outflow and impairs relaxation phase

Question 13

what leads to hypertrophy of smooth muscle?

Answer 13

obstructions of bladder

Question 14

what is an example of an obstructed bladder causing hypertrophy of smooth muscle?

Answer 14

prostate cancer

Question 15

hyperplasia and hypertrophy can occur together in response to? example?

Answer 15

increased functional requirements e.g. pregnant myometrium

Question 16

what is cell atrophy?

Answer 16

reduced cell size

Question 17

what is involution of tissue?

Answer 17

reduced cell number

Question 18

what is the severe type of muscle atrophy called?

Answer 18

neurogenic atrophy

Question 19

when does neurogenic atrophy occur?

Answer 19

when there is injury or disease to a nerve

Question 20

does neurogenic or disuse atrophy occur more suddenly?

Answer 20

neurogenic

Question 21

what causes muscle fibres to decrease in size?

Answer 21

the cease of nervous stimulation of the muscle

Question 22

what can reduced endocrine stimuli cause?

Answer 22

muscle atrophy

Question 23

what 3 anabolic hormones cause the muscle atrophy?

Answer 23

testosterone, growth hormone, IGF-1

Question 24

what naturally occurring process can also cause muscle atrophy?

Answer 24

ageing

Question 25

what 2 mechanisms underlie atrophy and involution?

Answer 25

autophagy in cell atrophy and apoptosis

Question 26

what is autophagy in cell atrophy?

Answer 26

the degradation and recycling of cellular components

Question 27

what are the types of autophagy?

Answer 27

macroautophagy, microautophagy and chaperone-mediated autophagy

Question 28

during macroautophagy, when are the phosphoryl groups detached?

Answer 28

when at optimal pH of less than 7

Question 29

during macroautophagy, what protects the cell incase the lysosomal enzymes escape?

Answer 29

a lower lysosomal pH

Question 30

what is apoptosis?

Answer 30

programmed cell death

Question 31

what is apoptosis an important mechanism for?

Answer 31

in developing and adult tissues for eliminating cells that are no longer needed

Question 32

what is activation of apoptosis initiated by?

Answer 32

extracellular or intercellular death signals

Question 33

what is apoptosis mediated by?

Answer 33

caspases

Question 34

what do caspases exist in all cells as?

Answer 34

inactive procaspases

Question 35

what activates inactive procaspases?

Answer 35

cleavage by other caspases

Question 36

what are the 4 phases of apoptosis?

Answer 36

induction/signalling, effector/executioner, degradation, phagocytic phases

Question 37

what happens in the induction/signalling phase and how does the cell appear?

Answer 37

cell receives an internal or external signal initiating apoptosis and cell looks normal

Question 38

what happens in the effector/executioner phase?

Answer 38

protease enzymes cause severe structural changes

Question 39

what are the 3 main structural changes that protease causes in effector/executioner phase of apoptosis?

Answer 39

cell shrinkage, loss of surface specialisations, condensed chromatin

Question 40

what happens in the degradation phase of apoptosis?

Answer 40

cell splits into apoptotic bodies, nucleus also fragments

Question 41

in degradation phase of apoptosis, what does each fragment of the cell contain?

Answer 41

viable mitochondria and intact organelles

Question 42

what is an apoptotic body?

Answer 42

when a cell has received a death signal and splits into smaller fragments

Question 43

what happens during the phagocytic phase of apoptosis?

Answer 43

apoptotic bodies are recognised and phagocytosed by adjacent cells where they are destroyed

Question 44

what else can happen to some fragments during phagocytic phase of apoptosis?

Answer 44

some fragments degenerate extracellularly, some fragments are ingested by phagocytic cells