cellular adaptation

Question 1

what is cellular adaptation

Answer 1

this is how cells respond to stress in order to stay alive

Question 2

what are the five main adaptations

Answer 2

atrophy
hypertrophy
metaplasia
hyperplasia
dysplasia

Question 3

what are labile cells

Answer 3

those that are constantly replicating and are very mitotically active

Question 4

what are stable cells

Answer 4

asleep cells that are not copying themselves but can if they need to

Question 5

what are permanent cells

Answer 5

these never undergo mitosis and cannot copy themselves to repair

Question 6

what are some permanent cell types

Answer 6

muscle and neural cells

Question 7

describe atrophy

Answer 7

reduction in cell size
caused by reduction in work demand or due to hormones
decreased size makes the cells more efficient so if they are not being used they will shrink to become more energy efficient

Question 8

what are the physiological causes for atrophy

Answer 8

muscles in the uterus become large during pregnancy but once hormone levels drop after birth the muscles return to normal size

Question 9

what are the pathological causes for atrophy

Answer 9

ischaemia - if there is reduced blood flow due to peripheral vascular disease, a reduced blood flow to leg will mean the muscle in the leg will atrophy due to inadequate blood supply

Question 10

does the number of cells change in atrophy

Answer 10

no, just the size of the cell

Question 11

which cells are likley to be affected by atrophy

Answer 11

stable or permanent cells - often happens with muscle

Question 12

describe hypertrophy

Answer 12

this is an increase in cell size
often occurs in skeletal and cardiac muscle cells
stimulus is usually in response to mechanical force or stretch like contraction, hormonal stimulation or growth factor stimulation

Question 13

describe a physiological cause for hypertrophy

Answer 13

going to the gym and lifting weights will increase mechanical stress on the muscle, so the muscle will respond by increasing the gene expression to make more proteins making the cells larger

Question 14

describe a pathological cause for hypertrophy

Answer 14

cardiac myopathy where increased muscle in the heart occurs. as muscle increases, the heart can become inefficient and have issues with contraction

Question 15

which cell types usually experiene hypertrophy

Answer 15

muscle cells - permanent cells

Question 16

describe hyperplasia

Answer 16

this is when tissue size increases due to an increase in cell numbers rather than cell size
usually occurs in labile or stable cells
cells respond to stress by increasing their number

Question 17

what are some physiological causes for hyperplasia

Answer 17

inducing agent of hormone levels can lead to hyperplasia of the breast during puberty and pregnancy to increase ability to produce milk

Question 18

what is a change in stable cells that can be caused by hypertrophy at a physiological level

Answer 18

hepatocytes in the liver, if the liver was ever cut in half the hepatocytes would be activated and increase mitosis so there is more replication and the cell number increases

Question 19

describe why hyperplasia may occur in an athlete

Answer 19

constant exposure to hypoxia, more red blood cell production in the bone marrow, increased oxygen carrying capability

Question 20

describe a pathological cause for hyperplasia

Answer 20

prostate gland exposed to androgen hormone can increase the prostate size
papilloma virus causes warts

Question 21

describe metaplasia

Answer 21

change in cell type or morphology due to chronic irritation or inflammation
when the environment of the cells are exposed long term to inflammation, the cells must change to be more appropriate to the environment so they can survive

Question 22

give examples of when metaplasia would occur

Answer 22

• if cells are exposed to lower pH, like in barrets oesophagus due to reflux, they would want to be more like cells in the stomach that can withstand the lower pH.
• if exposed to cigarette smoke, the respiratory epithelium would change from cilia to stratified squamous for protection against soot

Question 23

is metaplasia irreversible

Answer 23

no, cells will return to normal once the stimulus is removed

Question 24

describe how metaplasia occurs

Answer 24

genes in the cells are activated to cause differentiation, so the cells being affected have to be stem cells like epithelium - bone and muscle cells cannot change their cell type, but epithelial cells can

Question 25

describe dysplasia

Answer 25

disordered growth, stimulus is chronic irritation or inflammation, the response is deranged growth

increase in cell number and cell shape
precursor for neoplasia

can be reversible but this is unlikely

pathological causes rather than physiological